Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Dec. 31, 2017	Feb. 16, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	RPX Corporation
Document Type	10-K
Current Fiscal Year End Date	--12-31
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Entity Common Stock, Shares Outstanding		49,899,559
Amendment Flag	false
Entity Central Index Key	0001509432
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Fiscal Period Focus	FY
Entity Public Float			$ 645.1

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 138,710	$ 100,111
Short-term investments	18,455	90,877
Restricted cash	249	500
Accounts receivable, net	51,544	64,395
Prepaid expenses and other current assets	25,687	4,524
Total current assets	234,645	260,407
Patent assets, net	163,048	212,999
Property and equipment, net	5,090	6,948
Intangible assets, net	49,087	56,050
Goodwill	70,756	151,322
Restricted cash, less current portion	968	965
Other assets	3,664	8,337
Deferred tax assets	23,572	38,261
Total assets	550,830	735,289
Current liabilities:
Accounts payable	2,225	3,197
Accrued liabilities	15,736	16,798
Deferred revenue	105,150	118,856
Current portion of long-term debt	0	6,474
Other current liabilities	1,485	1,484
Total current liabilities	124,596	146,809
Deferred revenue, less current portion	1,718	11,552
Deferred tax liabilities	3,657	4,023
Long-term debt, less current portion	0	88,110
Other liabilities	11,104	10,514
Total liabilities	141,075	261,008
Commitments and contingencies (Note 12)
Stockholders’ equity:
Common stock, $0.0001 par value — 200,000 shares authorized; 49,627 and 48,776 issued and outstanding as of December 31, 2017 and 2016, respectively	5	5
Additional paid-in capital	376,793	360,462
Retained earnings	39,411	130,249
Accumulated other comprehensive loss	(6,454)	(16,435)
Total stockholders’ equity	409,755	474,281
Total liabilities and stockholders’ equity	$ 550,830	$ 735,289

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common stock, par value per share (in dollars per share)	$ 0.0001	$ 0.0001
Common stock authorized (in shares)	200,000	200,000
Common stock issued (in shares)	49,627	48,776
Common stock outstanding (in shares)	49,627	48,776
Preferred stock par value per share (in dollars per share)	$ 0.0001	$ 0.0001
Preferred shares authorized (in shares)	10,000	10,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue	$ 330,457	$ 333,107	$ 291,881
Cost of revenue	203,709	197,262	148,858
Selling, general and administrative expenses	90,507	100,457	77,428
Impairment losses	94,051	0	0
Gain on sale of patent assets, net	0	0	(592)
Operating income (loss)	(57,810)	35,388	66,187
Interest and other income (expense), net:
Interest income	1,063	506	740
Interest expense	(4,540)	(3,015)	0
Other income (expense), net	2,222	(570)	(1,428)
Total interest and other income (expense), net	(1,255)	(3,079)	(688)
Income (loss) before provision for income taxes	(59,065)	32,309	65,499
Provision for income taxes	20,078	14,074	26,077
Net income (loss)	$ (79,143)	$ 18,235	$ 39,422
Net income (loss) per share:
Basic (USD per share)	$ (1.61)	$ 0.36	$ 0.72
Diluted (USD per share)	$ (1.61)	$ 0.36	$ 0.71
Weighted-average shares used in computing net income (loss) per share:
Basic (shares)	49,240	50,462	54,432
Diluted (shares)	49,240	51,001	55,410
Dividends (USD per share)	$ 0.05	$ 0.00	$ 0.00

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ (79,143)	$ 18,235	$ 39,422
Unrealized gains (losses) on available-for-sale investments:
Unrealized holding gains (losses) arising during the period	145	97	(572)
Less: reclassification adjustment for losses included in net income	0	0	429
Net unrealized gains (losses) on available-for-sale investments, net of tax	145	97	(143)
Foreign currency translation adjustments	9,836	(16,281)	0
Comprehensive income (loss)	$ (69,162)	$ 2,051	$ 39,279

Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2014		54,062
Balance at Dec. 31, 2014	$ 485,045	$ 5	$ 326,280	$ 158,868	$ (108)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	39,422			39,422
Unrealized loss on available-for-sale investments, net of tax	(143)				(143)
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other common stock issuances (shares)		1,420
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other common stock issuances	5,013		5,013
Repurchase of common stock (shares)		(1,993)
Repurchase of common stock	(26,175)			(26,175)
Stock-based compensation	17,728		17,728
Tax benefit of equity award deductions	686		686
Tax withholdings related to net share settlements of restricted stock units	(5,097)		(5,097)
Balance (in shares) at Dec. 31, 2015		53,489
Balance at Dec. 31, 2015	516,479	$ 5	344,610	172,115	(251)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,235			18,235
Unrealized loss on available-for-sale investments, net of tax	97				97
Foreign currency translation adjustments	(16,281)				(16,281)
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other common stock issuances (shares)		1,211
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other common stock issuances	3,778		3,778
Repurchase of common stock (shares)		(5,924)
Repurchase of common stock	(60,101)			(60,101)
Stock-based compensation	18,378		18,378
Tax benefit of equity award deductions	(2,119)		(2,119)
Tax withholdings related to net share settlements of restricted stock units	(4,185)		(4,185)
Balance (in shares) at Dec. 31, 2016		48,776
Balance at Dec. 31, 2016	474,281	$ 5	360,462	130,249	(16,435)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(79,143)			(79,143)
Unrealized loss on available-for-sale investments, net of tax	145
Foreign currency translation adjustments	9,836
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other common stock issuances (shares)		1,551
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other common stock issuances	5,964		5,964
Repurchase of common stock (shares)		(700)
Repurchase of common stock	(8,290)			(8,290)
Dividends	(2,482)			(2,482)
Stock-based compensation	14,642		14,642
Tax withholdings related to net share settlements of restricted stock units	(5,683)		(5,683)
Balance (in shares) at Dec. 31, 2017		49,627
Balance at Dec. 31, 2017	409,755	$ 5	376,793	39,411	$ (6,454)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment from adoption of ASU 2016-09	$ 485		$ 1,408	$ (923)

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income	$ (79,143,000)	$ 18,235,000	$ 39,422,000
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	168,143,000	171,623,000	145,835,000
Stock-based compensation	14,599,000	18,275,000	17,594,000
Excess tax benefit from stock-based compensation	0	(103,000)	(1,593,000)
Gain on sale of patent assets, net	0	0	(592,000)
Amortization of premium and discount on investments	1,273,000	2,247,000	6,666,000
Deferred taxes	14,451,000	(13,951,000)	(13,010,000)
Unrealized foreign currency (gain) loss	(1,957,000)	2,689,000	0
Fair value adjustments on deferred payment obligations	0	(1,920,000)	(3,887,000)
Gain on extinguishment of deferred payment obligation	0	(463,000)	(3,000,000)
Impairment losses	94,051,000	0	0
Impairment losses	0	0	5,096,000
Realized loss on exchange of short-term investments	0	290,000	3,444,000
Other	1,792,000	2,457,000	(60,000)
Changes in assets and liabilities, net of business acquired:
Accounts receivable	14,136,000	(39,737,000)	10,888,000
Prepaid expenses and other assets	(21,168,000)	10,344,000	(17,651,000)
Accounts payable	(1,080,000)	923,000	724,000
Accrued and other liabilities	(80,000)	1,693,000	4,631,000
Deferred revenue	(23,539,000)	14,654,000	(21,284,000)
Net cash provided by operating activities	181,478,000	187,256,000	173,223,000
Investing activities
Purchases of investments	(39,491,000)	(70,980,000)	(273,853,000)
Maturities of investments	107,115,000	60,143,000	254,360,000
Sales of investments	3,300,000	145,925,000	21,650,000
Business acquisition, net of cash acquired	0	(228,452,000)	(425,000)
Decrease in restricted cash	248,000	298,000	247,000
Purchases of property and equipment	(1,316,000)	(3,667,000)	(2,163,000)
Acquisitions of patent assets	(106,343,000)	(116,742,000)	(132,834,000)
Proceeds from sale of patent assets	0	0	650,000
Acquisition of other assets	0	0	(2,500,000)
Net cash used in investing activities	(36,487,000)	(213,475,000)	(134,868,000)
Financing activities
Repayments of principal on deferred payment obligations	0	0	(2,935,000)
Proceeds from deferred payment obligations	0	0	6,270,000
Proceeds from issuance of term debt	0	100,000,000	0
Payment of debt issuance costs	0	(2,003,000)	0
Repayment of principal on term debt	(96,250,000)	(3,750,000)	0
Deferred acquisition payment	0	(1,320,000)	0
Proceeds from exercise of stock options	5,964,000	3,766,000	4,953,000
Taxes paid related to net-share settlements of restricted stock units	(5,683,000)	(4,185,000)	(5,097,000)
Excess tax benefit from stock-based compensation	0	103,000	1,593,000
Payments of capital leases	(345,000)	(461,000)	0
Payments of Dividends	(2,482,000)	0	0
Repurchase of common stock	(8,290,000)	(60,101,000)	(26,175,000)
Net cash provided by (used in) financing activities	(107,086,000)	32,049,000	(21,391,000)
Foreign-currency effect on cash and cash equivalents	694,000	(702,000)	0
Net increase in cash and cash equivalents	38,599,000	5,128,000	16,964,000
Cash and cash equivalents at beginning of period	100,111,000	94,983,000	78,019,000
Cash and cash equivalents at end of period	138,710,000	100,111,000	94,983,000
Supplemental disclosures of cash flow information
Cash paid for interest	2,874,000	2,571,000	0
Cash paid for income taxes	7,905,000	15,078,000	23,969,000
Non-cash investing and financing activities
Change in patent assets purchased and accrued but not paid	333,000	333,000	0
Change in fixed assets purchased and accrued but not paid	0	565,000	0
Patent assets and intangible assets received in barter transactions	0	381,000	2,203,000
Nonmonetary exchange for investments	$ 0	$ 0	$ 5,935,000

Nature of Business	12 Months Ended
Nature of Business	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature Of Business	Nature of Business RPX Corporation (also referred to herein as “RPX” or the “Company”) helps companies reduce patent litigation risk and corporate legal expense through two primary service offerings: its patent risk management services and its discovery services. The Company's patent risk management services help companies reduce patent-related risk and expense through subscription-based services that facilitate more efficient exchanges of value between owners and users of patents compared to transactions driven by actual or threatened litigation. The Company’s patent risk management membership clients pay an annual subscription fee and in return, receive access to substantially all of the Company's patent portfolio as well as an array of services provided throughout their membership. Access to these services is available primarily through discussions with the Company's professionals—particularly client services and its team of patent experts, as well as through a proprietary database, and attendance of regularly scheduled conferences. In addition to its subscription-based patent risk management services, the Company underwrites patent infringement liability insurance policies to insure against certain costs of litigation. The Company uses a reinsurance subsidiary company to assume a portion of the underwriting risk on the insurance policies that the Company issues on behalf of third party underwriters. To date, the effect of the insurance policies that the Company has assumed through its reinsurance business has not been material to the Company’s results of operations, financial condition, or cash flows. In January 2016, the Company acquired Inventus Solutions, Inc. ("Inventus"), now a wholly owned subsidiary of the Company, and began offering its discovery services, which consist of technology-enabled services to assist law firms and corporate legal departments manage costs and risks related to the legal discovery process. The Company's discovery services include data hosting and backup, data processing and collection, project management, document review, and traditional document production. All of these services are designed to streamline the administration of litigation, investigations, and regulatory compliance.

Basis of Presentation and Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis Of Presentation And Significant Accounting Policies

Basis of Presentation and Significant Accounting Policies

Basis of Presentation

These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) and include the accounts of RPX and its wholly owned subsidiaries. All intercompany transactions have been eliminated.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, contingent assets and liabilities, and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and reported amounts of revenues and expenses during the reporting period covered by the consolidated financial statements and accompanying notes. The Company bases its estimates on various factors and information which may include, but are not limited to, history and prior experience, expected future results, new related events and current economic conditions, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates.

Significant estimates and assumptions made by management include the determination of:


•	the assumptions and methods used in deriving the fair value of goodwill and long-lived assets;


•	the estimated economic useful lives of patent assets;


•	the fair value of assets acquired and liabilities assumed for business combinations;


•	recognition and measurement of current and deferred income taxes, any related valuation allowances, and uncertain tax positions;


•	the fair value of stock awards issued;


•	the assumptions and methods used in deriving the fair value of deferred payment obligations;


•	the determination of a best estimated selling price of a subscription and patent infringement liability insurance;


•	the estimated reserves for known and incurred but not reported claims; and


•	trade receivable allowance for doubtful accounts.

Revenue Recognition

Through December 31, 2017, the Company recognized revenue in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 605, Revenue Recognition (“ASC 605”) and related authoritative guidance, our policy on which is included below. Effective January 1, 2018, the Company began recognizing revenue in accordance with ASC 606 which is explained further below under the heading "Revenue from Contracts with Customers" in this "Basis of Presentation and Significant Accounting Policies" footnote.

Patent Risk Management

The primary source of the Company's revenue from its patent risk management services offering is fees paid by its clients under subscription agreements. The Company believes that the subscription component of its patent risk management service offering comprises a single deliverable and thus it recognizes each subscription fee ratably over the period for which the fee applies. Revenue is recognized net of any discounts or other contractual incentives. The Company starts recognizing revenue when all of the following criteria have been met:


•	Persuasive evidence of an arrangement exists. All subscription fees are supported by an executed subscription agreement.

•

Delivery has occurred or services have been rendered. The subscription agreement calls for the Company to provide its patent risk management services over a specific term commencing on the agreement effective date. Because services are not on an individualized basis (i.e., the Company generally performs its services on behalf of all of its clients as opposed to each client individually), delivery occurs automatically with the passage of time. Consequently, the Company recognizes subscription revenue ratably.

•

Seller’s price to the buyer is fixed or determinable. Each client’s annual subscription fee is based either on a rate card in effect at the time of the client’s initial agreement or through a fixed fee which is risk-adjusted based on the client's specific patent risk profile. A client’s subscription fee on rate card is generally determined using its rate card and its normalized operating income, which is defined as the greater of (i) the average of its operating income for the three most recently reported fiscal years and (ii) 5% of its revenue for the most recently reported fiscal year. The fee for the first year of the agreement is typically determined and invoiced at the time of contract execution. The fee for each subsequent year of the agreement is generally calculated and invoiced in advance prior to each anniversary date of the agreement.


•	Collectability is reasonably assured. Subscription fees are generally collected on or near the effective date of the agreement and again at or near each anniversary date thereof. The Company does not recognize revenue in instances where collectability is not reasonably assured. Generally, the Company's subscription agreements state that all fees paid are non-refundable.

In some limited instances, the subscription agreement includes a contingency clause, giving one or both parties an option to terminate the agreement and receive a full refund if contingencies are not resolved within a defined time period. In those instances, revenue will not be recognized until the contingency has been satisfied. The revenue earned during the period between the effective date of the agreement and the contingency removal date is recognized on the contingency removal date. Thereafter, revenue is recognized ratably over the remaining subscription term.

The Company's patent risk management clients generally receive a term license to, and a release from all prior damages associated with, patent assets in the Company's portfolio. The term license to each patent asset typically converts to a perpetual license at the end of a contractually specified vesting period, provided that the client is a member at such time. The Company does not view the conversion from term license to perpetual license to be a separate deliverable in its arrangements with its clients because the utility of, access to and freedom to practice the inventions covered by the patent asset is no different between a term and perpetual license.

In some instances, the Company accepts a payment from a client to finance part or all of a patent asset acquisition. We refer to such transactions as syndicated acquisitions. The accounting for syndicated acquisitions can be complex and often requires judgments on the part of management as to the appropriate accounting treatment. In accordance with ASC 605-45, Revenue Recognition: Principal Agent Considerations, in instances where the Company substantively acts as an agent to acquire patent rights from a seller on behalf of clients who are paying for such rights separately from their subscription agreements, the Company may treat the client payments on a net basis. When treated on a net basis, there may be little or no revenue recognized for such contributions, and the basis of the acquired patent rights may exclude the amounts paid by the contributing client based on our determination that the Company is not the principal in these transactions. In these situations, where the Company substantively acts as an agent, the contributing clients are typically defendants in an active or threatened patent infringement litigation filed by the owner of a patent. The Company's involvement is to assist our clients to secure a dismissal from litigation and a license to the underlying patents.

Key indicators evaluated to determine the Company's role as either principal or agent in the transaction include, among others:


•	the entity to grant the license of the patent(s) is generally viewed as the primary obligor in the arrangement, given that it owns and controls the underlying patent(s) and thus has the absolute authority to grant and deliver any release from past damages and dismissal from litigation, and typically determines the general terms of the license(s) granted;


•	the Company's inventory risk in the transaction, which is typically mitigated, as its clients often enter into contractual obligations with the Company prior to or contemporaneous with the Company entering into a contractual obligation with the seller;


•	the Company has pricing latitude as it negotiates client contributions, however, this latitude is often limited as the economics of the transaction ultimately depend on the sales price set by the seller;


•	the Company is not involved in the determination of the product or service specification and has no ability to change the product or perform any part of the service in connection with these transactions, as the seller owns the underlying patent(s); and


•	the Company's credit risk taken on the transaction, which is generally limited as each respective client has a contractually binding obligation, such clients are generally of high credit quality and in some instances, the Company collects the client contribution prior to making a payment to the seller.

In certain syndicated transactions, the Company may recognize revenue upon the sale of licenses to specific patent assets and/or upon completion of the rendering of advisory services.

Revenue recognition for arrangements with multiple deliverables. A multiple-element arrangement may include the sale of a subscription to the Company's patent risk management services and an insurance policy to cover certain costs associated with patent infringement litigation, each of which are individually considered separate units of accounting. Each element within a multiple-element arrangement is accounted for as a separate unit of accounting given that the delivered products have value to the customer on a standalone basis. The Company considers a deliverable to have standalone value if the product or service is sold separately by us or another vendor. The delivery of insurance coverage is not dependent on a client’s subscription to the Company's patent risk management services. While the Company believes its insurance product offering is unique, its clients are able to purchase insurance coverage as a standalone product from other providers. The Company sells the components of its patent risk management services on a standalone basis. To date, the effect of the insurance policies that the Company has assumed through its reinsurance business has not been material to the Company’s results of operations, financial condition, or cash flows.

Multiple deliverables included in an arrangement are separated into different units of accounting and the arrangement consideration is allocated to the identified separate units based on a relative selling price hierarchy. For our patent risk management service offering, we determine the relative selling price for a deliverable based on its best estimate of selling price ("BESP"). We have determined that vendor-specific objective evidence ("VSOE") and third-party evidence ("TPE") are not available for our patent risk management deliverables.

The Company has determined its BESP for a subscription to our patent risk management services based on the following:

•

List price, which represents the rates listed on our annual rate card. The Company publishes a standard rate card annually. Each client’s subscription fee is typically calculated using the applicable rate card and its normalized operating income, which is defined as the greater of (i) 5% of the client’s most recently reported fiscal year’s revenue, and (ii) the average of the three most recently reported fiscal years’ operating income of the client. Each client’s annual subscription fee is reset annually based on its normalized operating income for its most recently completed fiscal years.

The Company has determined its BESP for its insurance product based on the following:

•

Actuarially determined factors. Although the Company sells its insurance product both on a standalone basis and as a component of a multiple-element arrangement, the pricing is not affected by the subscription to our patent risk management services. The Company uses an actuarial model that calculates an individual client’s insurance premium based on its projected annual frequency (i.e., number of claims during the policy term) and severity (i.e., the amount which it expects to settle a claim).

Discovery Services

Revenue from the Company's discovery services is primarily generated from the following:


•	data hosting fees based on data stored and number of users;


•	fees for month-to-month delivery of services, such as data processing (conversion of data into organized, searchable electronic database), project management and data collection services;


•	document review services which assist clients in the manual review of data responsive to a legal matter; and


•	printing and binding services (paper-based services).

The Company enters into agreements pursuant to which the Company offers various discovery services. Clients are generally billed monthly based on contractual unit prices and volumes for services delivered. The agreements are typically for an indefinite period of time, however, they are cancelable at will by either party. The Company is entitled to all fees incurred for services performed. The majority of the Company's discovery services revenue comes from two types of billing arrangements: usage based and fixed fee.

Usage-based arrangements require the client to pay based upon predetermined unit prices and volumes for data hosing, data processing and paper-based services. Project management and review hours are billed based upon the number of hours worked by certain client service professionals at agreed upon rates.

In fixed-fee billing arrangements, the Company agrees to a pre-established monthly fee over a specified term in exchange for various services. The fees are not tied to the attainment of any contractually defined objectives and the monthly fee is nonrefundable.

Based on an evaluation of the discovery services delivered to each client, the Company has determined that each deliverable has stand-alone value to the client as each of the Company’s discovery services can be sold on a stand-alone basis by the Company and the discovery services are available from other vendors. Additionally, discovery services do not carry a significant degree of risk or unique acceptance criteria that would require a dependency on the performance of future services. The Company recognizes revenue from these arrangements based on contractually stated prices. The Company allocates revenue to the various units of accounting in its arrangements based on the best estimate of selling price for each unit of accounting, which are consistent with the stated prices in those arrangements.

Based on an evaluation of the discovery services delivered to each client, the Company determined each deliverable has stand-alone value to the client as each of its discovery services can be sold on a stand-alone basis by the Company and the discovery services are available from other vendors. Additionally, discovery services do not carry a significant degree of risk or unique acceptance criteria that would require a dependency on the performance of future services.

The Company determines the relative selling price for a discovery services deliverable based on its VSOE, if available, or its BESP, if VSOE is not available. The Company has determined that TPE is not a practical alternative due to differences in its service offerings compared to other parties and the availability of relevant third-party pricing information. The Company allocates revenue to the various units of accounting in its arrangements based on the BESP for each unit of accounting, which are consistent with the stated prices in those arrangements.

The Company’s discovery services arrangements do not include any substantive general rights of return or other contingencies.

Sales and value added taxes collected from clients are not considered revenue and are included in accrued liabilities in the Company's consolidated balance sheets until remitted to the taxing authorities.

Accounting for Payments to Clients

The Company occasionally agrees to provide payments, discounts or other contractual incentives to clients in exchange for specified consideration. The Company accounts for such contract provisions in accordance with ASC 605-50, Revenue Recognition: Customer Payments and Incentives, which requires the Company to offset the amount of the payment, discount or other contractual incentive against revenue if the Company is unable to demonstrate both receipt of an identifiable benefit and determine the fair value of the benefit received.

Deferred Revenue

The Company generally invoices its patent risk management clients upon execution of a new agreement and prior to their anniversary date for existing agreements. The Company records the amount of fees billed as deferred revenue and recognizes such amounts as revenue ratably over the period for which they apply. The Company typically records deferred revenue when it has the legal right to bill amounts owed and the applicable service period has commenced. In an instance where a term has commenced but the fees have not yet been invoiced, the Company records an unbilled receivable. Deferred revenue that will be recognized during the succeeding 12-month period from the respective balance sheet date is recorded as deferred revenue, current, and the remaining portion is recorded as non-current.

Accounts Receivable

Accounts receivable are recorded at the invoiced amount and are non-interest bearing. The Company maintains an allowance for doubtful accounts to reserve for potentially uncollectible receivables. The allowance for doubtful accounts is based on the expected ability to collect accounts receivable. The Company reviews accounts receivable to identify amounts due from clients which are past due to identify specific clients with known disputes or collectability issues. In determining the allowance for doubtful accounts, the Company makes judgments about the creditworthiness of significant customers based on ongoing credit evaluations. The Company's allowance for doubtful accounts was $0.6 million and $0.9 million as of December 31, 2017 and 2016, respectively.

Concentration of Risk

The Company is subject to concentrations of credit risk principally attributable to cash, cash equivalents, investments, accounts receivable and other receivables. The Company’s non-restricted cash balances deposited in U.S. banks are non-interest bearing and are insured up to the Federal Deposit Insurance Corporation (“FDIC”) limits. Cash equivalents primarily consist of institutional money market funds and municipal bonds denominated primarily in U.S. dollars. Investment policies have been implemented that limit purchases of debt securities to investment-grade securities.

As of December 31, 2017, two clients individually accounted for 15% and 11% of accounts receivable. As of December 31, 2016, one client individually accounted for 39% of accounts receivable. No client accounted for 10% or more of revenue in any of the years ended December 31, 2017, 2016 or 2015.

Fair Value Measurements

The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. The Company defines fair value as the price that would be received from selling an asset or that would be paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities, which are required to be recorded at fair value, the Company considers the principal or most advantageous market in which the Company would transact and the market-based risk measurements or assumptions that market participants would use in pricing the asset or liability, such as risks inherent in valuation techniques, transfer restrictions and credit risk. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

Level 1 – Valuations based on quoted prices in active markets for identical assets or liabilities and readily accessible by the Company at the reporting date.

Level 2 – Valuations based on inputs other than quoted prices included within Level 1 that are observable for assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument.

Level 3 – Valuations based on inputs that are unobservable.

The carrying amounts of the Company’s financial instruments, which include cash equivalents, short-term investments, accounts receivable, other receivables and accounts payable, approximate their fair values due to their short maturities.

Cash and Cash Equivalents

The Company’s cash and cash equivalents principally consist of commercial paper, institutional money market funds, municipal and corporate bonds, and U.S. government and agency securities denominated primarily in U.S. dollars. Cash equivalents are highly liquid, short-term investments having an original maturity of 90 days or less that are readily convertible to known amounts of cash.

Short-Term Investments

The Company holds short-term investments in municipal and corporate bonds primarily maturing between 90 days and 12 months, commercial paper, and U.S. government and agency securities. The Company considers its investments as available to support current operations. As a result, the Company classifies its investments, including those with stated maturities beyond twelve months, as current assets in the accompanying consolidated balance sheets. The Company primarily classifies these securities as “available-for-sale” and carries them at fair value in the consolidated balance sheets. Unrealized gains or losses are recorded, net of estimated taxes, in accumulated other comprehensive income (loss), a component of stockholders’ equity. Realized gains and losses are recognized upon sale or exchange. The specific identification method is used to determine the cost basis of fixed income securities sold.

The Company periodically evaluates its investments for impairment due to declines in market value considered to be “other-than-temporary.” This evaluation consists of several qualitative and quantitative factors, including the Company’s ability and intent to hold the investment until a forecasted recovery occurs, as well as any decline in the investment quality of the security and the severity and duration of the unrealized loss. In the event of a determination that a decline in market value is other-than-temporary, the Company will recognize an impairment loss, and a new cost basis in the investment will be established. The Company did not record an other-than-temporary impairment on its short-term investments in either year ended December 31, 2017 or 2016 and recorded an other-than-temporary impairment on its short-term investments of $5.1 million in the year ended December 31, 2015.

Property and Equipment, Net

Property and equipment are stated at cost less accumulated depreciation. Depreciation is computed using a straight-line method over the estimated useful lives of the related assets, which are generally three to five years. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the consolidated balance sheet and any resulting gain or loss is reflected in the consolidated statement of operations in the period realized. Leasehold improvements are amortized on a straight-line basis over the term of the lease, or the useful life of the assets, whichever is shorter.

Internal-Use Software and Website Development Costs

The Company capitalizes development costs related to internal-use software and its website and records such amounts as property and equipment, net, in its consolidated balance sheets. These costs include personnel-related expenses and consultant fees incurred during the application development stages of the project. Costs related to preliminary project activities, minor enhancement and maintenance, and post implementation activities are expensed as incurred. Internal-use software is amortized on a straight-line basis over its useful life, which is generally three years, beginning on the date the software is placed into service. Management evaluates the useful lives of these assets on an annual basis and tests for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets.

During the years ended December 31, 2017, 2016 and 2015, the Company capitalized $0.8 million, $1.3 million, and $2.3 million, respectively, of internal-use software and website development costs. Amortization of internal-use software was $1.4 million, $1.5 million, $1.1 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Patent Assets, Net

The Company generally acquires patent assets from third parties using cash. Patent assets are recorded at fair value at acquisition. The fair value of the assets acquired is generally based on the fair value of the consideration exchanged. The asset value includes the cost of external legal and other fees associated with the acquisition of the assets. Costs incurred to maintain and prosecute patents and patent applications are expensed as incurred.

Because each client generally receives a license to the majority of the Company’s patent assets, the Company is unable to reliably determine the pattern over which its patent assets are consumed. As a result, the Company amortizes each patent asset on a straight-line basis. The amortization period is equal to the asset’s estimated economic useful life. Estimating the economic useful life of patent assets requires significant management judgment. The Company considers various factors in estimating the economic useful lives of its patent assets, including the remaining statutory life of the underlying patents, the applicability of the assets to future clients, the vesting period for current clients to obtain perpetual licenses to such patent assets, any contractual commitments by clients that are related to such patent assets, its estimate of the period of time during which the Company may sign subscription agreements with prospective clients that may find relevance in the patent assets, and the remaining contractual term of the Company’s existing clients at the time of acquisition. In certain instances, where the Company acquires patent assets and secures related client committed cash flows that extend beyond the statutory life of the underlying patent assets, the useful life may extend beyond the statutory life of the patent assets. As of December 31, 2017, the estimated economic useful life of the Company’s patent assets generally ranged from 24 to 60 months. The weighted-average estimated economic useful life of patent assets acquired since inception was 38 months. The weighted-average estimated economic useful life of patent assets acquired during the year ended December 31, 2017 was 25 months. The Company periodically evaluates whether events and circumstances have occurred that may warrant a revision to the remaining estimated useful life of its patent assets.

In some instances, the Company accepts a payment from a client to finance part or all of an acquisition involving patent assets that may cost more than the Company is prepared to spend with its own capital resources or that are relevant only to a small number of clients. In these instances, the Company facilitates syndicated transactions that include cash contributions from participating clients in addition to their annual subscription fees.

In instances where the Company sells patent assets, the amount of consideration received is compared to the asset’s carrying value to determine and recognize a gain or loss, which is recorded within gain on sale of patent assets, net in the Company's consolidated statements of operations.

Intangible Assets, Net

Intangible assets, net primarily consists of intangible assets acquired through business combinations. Such assets are capitalized and amortized on a straight-line basis over their estimated useful lives. Intangible assets, net excludes patent related intangible assets, which are recorded within patent assets, net in the consolidated balance sheets.

Impairment of Long-Lived Assets

The Company assesses the recoverability of its long-lived assets, which include patent assets, other intangible assets, and property and equipment, when events or changes in circumstances indicate their carrying value may not be recoverable. Such events or changes in circumstances may include: a significant adverse change in the extent or manner in which a long-lived asset is being used, a significant adverse change in legal factors or in the business climate that could affect the value of a long-lived asset, an accumulation of costs significantly in excess of the amount originally expected for the acquisition or development of a long-lived asset, current or future operating or cash flow losses that demonstrate continuing losses associated with the use of a long-lived asset or a current expectation that, more-likely-than-not, a long-lived asset will be sold or otherwise disposed of significantly before the end of its previously estimated useful life. The Company licenses a majority of the portfolio of patent assets to all of its membership clients and thus views these assets as a single asset group. The Company assesses recoverability of a long-lived asset by determining whether the carrying value of these assets can be recovered through projected undiscounted cash flows. If the carrying value of the assets exceeds the forecasted undiscounted cash flows, an impairment loss is recognized, and is recorded as the amount by which the carrying value exceeds the estimated fair value. An impairment loss is charged to operations in the period in which management determines such impairment. To date, there have been no impairments of long-lived assets identified.

Goodwill

The Company reviews goodwill for impairment annually or more frequently if events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. A company may first assess the qualitative factors to determine whether it is more likely than not that the fair value of its reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the quantitative goodwill impairment. If the quantitative goodwill impairment test is performed, the fair value of the reporting unit is compared to its carrying amount. Such valuations require making significant estimates and assumptions, especially with respect to intangible assets. Significant estimates in valuing certain intangible assets include, but are not limited to, future expected cash flows from acquired and current clients, acquired technology, and trade names from a market participant perspective, useful lives, and discount rates. If the carrying amount of a reporting unit exceeds its fair value, any excess of the goodwill carrying amount over the implied fair value is recognized as an impairment charge, and the carrying value of goodwill is written down to fair value.

The Company performed its 2017 annual goodwill impairment test using a quantitative approach for its discovery services reporting units and a qualitative approach for its patent risk management business. The quantitative approach used for its discovery services segment includes comparing the carrying value to the fair values of each reporting unit using a discounted cash flow methodology with a comparable business approach which utilizes Level 3 inputs. Cash flow projections are based on management’s estimates of growth rates and operating margins, taking into consideration industry and market conditions. The discount rate used is based on the weighted-average cost of capital adjusted for the relevant risk associated with business-specific characteristics and the uncertainty related to the reporting units' ability to execute on the projected cash flows. These tests resulted in the carrying values of the discovery services reporting units exceeding the fair values primarily due to (1) decreased expected future cash flows from pricing pressures and competition in the discovery services marketplace as well as significant fluctuations due to the project-based nature of these cash flows, and (2) a decrease in estimated peer company values. As a result, the Company recognized a goodwill impairment loss of $89.0 million in its consolidated statement of operations during the year ended December 31, 2017. No other goodwill impairment losses were recorded as a part of the Company's annual impairment analyses.

Other Assets

The Company's other assets consist primarily of cost method investments that are long term in nature. The Company reviews these investments for recoverability and if a decline in fair value is considered to be other-than-temporary, an impairment loss is recorded in the consolidated statements of operations. During the year ended December 31, 2017, the Company recorded an impairment loss of $5.0 million related to these cost method investments reducing the recorded value to its new amortized cost basis which represents its estimated fair value of $0.6 million.

Advertising Costs

The Company expenses advertising costs as they are incurred. Advertising expenses were not material for any period presented.

Foreign Currency Accounting

The functional currencies of the Company’s international subsidiaries are the U.S. dollar and British pound sterling. The Company's primary foreign subsidiary uses the local currency of its respective country as its functional currency. Assets and liabilities are translated into U.S. dollars using exchange rates prevailing at the balance sheet date, while revenues and expenses are translated at average exchange rates during the year. Gains and losses resulting from the translation of our consolidated balance sheet are recorded as a component of accumulated other comprehensive income (loss).

Gains and losses from foreign currency transactions are recognized in other income (expense), net in the consolidated statements of operations.

Income Taxes

The Company accounts for income taxes using an asset and liability approach, which requires the recognition of deferred tax assets or liabilities for the tax-effected temporary differences between the financial reporting and tax bases of its assets and liabilities and for net operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The measurement of deferred tax assets is reduced, if necessary, by the amount of any tax benefits that, based on available evidence, are not expected to be realized.

The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income, and to the extent the Company believes that recovery is not likely, the Company establishes a valuation allowance. Judgment is required in determining the Company’s provision for income taxes, deferred tax assets and liabilities, and any valuation allowance recorded against the net deferred tax assets.

The calculation of the Company’s tax liabilities involves uncertainties in the application of complex tax laws and regulations in a multitude of jurisdictions across its global operations. ASC 740, Income Taxes (“ASC 740”) provides that a tax benefit from an uncertain tax position may be recognized when it is more-likely-than-not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, on the basis of the technical merits. ASC 740 also provides guidance on measurement, derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition.

The Company recognizes tax liabilities in accordance with ASC 740 and adjusts these liabilities when its judgment changes as a result of the evaluation of new information not previously available. Because of the complexity of some of these uncertainties, the ultimate resolution may result in a payment that is materially different from its current estimate of the tax liabilities. These differences will be reflected as increases or decreases to income tax expense in the period in which new information is available.

The tax expense or benefit for unusual or infrequently occurring items and items that do not represent a tax effect of current-year ordinary income are treated as discrete items and recorded in the interim period in which the events occur.

Stock-Based Compensation

The Company accounts for stock-based compensation for equity-settled awards issued to employees and directors under ASC 718, Compensation-Stock Compensation (“ASC 718”). ASC 718 requires that stock-based compensation expense for equity-settled awards made to employees and directors be measured based on the estimated grant date fair value and recognized over the requisite service period. These equity-settled awards include stock options, restricted stock units (“RSUs”) and performance-based RSUs which include a service condition, some of which also include a market condition or performance condition (“PBRSUs”).

The fair value of stock options is estimated as of the date of grant using the Black-Scholes option-pricing model. The fair value of RSUs is estimated based on the fair market value of the Company’s common stock on the date of grant. For stock options and RSUs, the fair value of an award is recognized as compensation expense on a straight-line basis over the requisite service period. Through 2016, forfeitures were estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from initial estimates. Starting in 2017, forfeitures are recognized as they occur as a reduction to compensation expense.

The fair value of PBRSUs that include performance conditions is estimated by reference to the fair value of the underlying shares on the date of grant. The fair value of PBRSUs that include market conditions is estimated as of the date of grant using the Monte-Carlo simulation model. Stock-based compensation expense for PBRSUs is recognized over the derived service period for each tranche (or market or performance condition). Because the Company’s PBRSUs have multiple derived service periods, it uses the graded-vesting attribution method. The graded vesting attribution method requires a company to recognize compensation expense over the requisite service period for each vesting tranche of the award as though the award were, in substance, multiple awards. The compensation expense for PBRSUs with market conditions will only be reversible if the employee terminates prior to completing the requisite service periods for these awards (i.e., compensation expense will not be reversed if the market condition is not met). For PBRSUs that include performance conditions, the Company only recognizes compensation expense for those awards for which vesting is determined to be probable upon satisfaction of certain performance criteria.

Estimates of the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option-pricing model and a Monte-Carlo simulation model, are affected by assumptions regarding a number of complex variables. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. The Company calculates the expected term for stock options based on historical exercise patterns and post-vesting termination behavior. Volatility is calculated based on the implied volatility of the Company's publicly traded stock. The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award.

Business Combinations

The Company applies the provisions of ASC 805, Business Combinations (“ASC 805”), in the accounting for its business acquisitions. ASC 805 requires companies to recognize goodwill separately from the assets acquired and liabilities assumed, which are valued at their acquisition date fair values. Goodwill as of the acquisition date represents the excess of the purchase price over the fair values of the assets acquired and the liabilities assumed.

The Company uses significant estimates and assumptions, including fair value estimates, to determine fair value of assets acquired, liabilities assumed and, when applicable, the related useful lives of the acquired assets, as of the business combination date. When those estimates are provisional, the Company refines them as necessary during the measurement period. The measurement period is the period after the acquisition date, not to exceed one year, in which the Company may gather new information about facts and circumstances that existed as of the acquisition date to adjust the provisional amounts recognized. Measurement period adjustments are applied retrospectively. All other adjustments are recorded in the consolidated statements of operations.

Reserves for Known and Incurred but not Reported Claims

Reserves for known and incurred but not reported claims represent estimated claims costs and related expenses for patent infringement liability insurance policies in effect. Reserves for known claims are established based on individual case estimates. The Company uses actuarial models and techniques to estimate the reserve for incurred but not reported claims.

Loss expense for known and incurred but not reported claims are charged to earnings after deducting recoverable amounts under our reinsurance contract. Loss expense for known and incurred but not reported claims associated with policies that the Company issued on behalf of third party underwriters are charged to earnings for the portion of the underwriting risk that the Company assumes.

Recent Accounting Pronouncements

In May 2017, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting ("ASU 2017-09") which clarifies the changes to terms or conditions of a share-based payment award that require an entity to apply modification accounting. ASU 2017-09 is effective for annual reporting periods, and interim periods therein, beginning after December 15, 2017. Early application is permitted and prospective application is required. The Company does not expect the adoption of this guidance to have a material impact on its consolidated financial statements.

In March 2017, the FASB issued ASU No. 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities (“ASU 2017-08”), which shortens the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. For public entities, ASU 2017-08 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The Company does not expect the adoption of this guidance to have a material impact on its consolidated financial statements.

In February 2017, the FASB issued ASU No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets: Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets. This ASU was issued to clarify the scope of the previous standard and to add guidance for partial sales of nonfinancial assets and is effective for fiscal years and interim periods within those years beginning after December 15, 2017. The Company does not expect the adoption of this guidance to have a material impact on its consolidated financial statements.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment, which simplifies the subsequent measurement of goodwill and eliminates the two-step goodwill impairment test. Under the new guidance, an annual or interim goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount, and an impairment charge is recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value. The amendment also eliminates the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and two-step goodwill impairment test. The ASU is effective prospectively for fiscal years and interim periods within those years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company early adopted this ASU for goodwill impairment tests beginning in 2017.

In January 2017, the FASB issued ASU No. 2017-01, Business Combinations: Clarifying the Definition of a Business, which provides a more robust framework to use in determining when a set of assets and activities is a business. This ASU is effective prospectively for fiscal years and interim periods within those years beginning after December 15, 2017. The Company will apply this guidance to applicable transactions after the adoption date.

In February 2016 the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”), which requires lessees to put most leases on their balance sheets but recognize the expenses on their income statements in a manner similar to current practice. ASU 2016-02 states that a lessee would recognize a lease liability for the obligation to make lease payments and a right-to-use asset for the right to use the underlying asset for the lease term. The new standard is effective for interim and annual periods beginning after December 15, 2018 and early adoption is permitted. The Company is currently evaluating the impact of this guidance on its consolidated financial statements.

Revenue from Contracts with Customers

Through December 31, 2017, the Company recognized revenue in accordance with FASB ASC 605, Revenue Recognition (“ASC 605”) and related authoritative guidance. Effective January 1, 2018, the Company began recognizing revenue in accordance with FASB ASC 606, Revenue from Contracts with Customers ("ASC 606" or the "standard") under which revenue is recognized when a customer obtains control of promised goods or services in an amount that reflects the consideration the entity expects to receive in exchange for those goods or services. In addition, ASC 606 requires disclosure of the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers.

Two methods of adoption are permitted: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). The Company adopted the standard on January 1, 2018 using the full retrospective method to restate each prior reporting period presented. In preparation for adoption of the standard, the Company implemented internal controls to enable the preparation of financial information and has reached conclusions on key accounting assessments related to the standard.

The new standard’s most significant impact to the Company’s financial information relates to the identification of multiple performance obligations from its patent risk management membership subscription and the timing and amount of recognition for these separable performance obligations. Specifically, the Company recognizes separate performance obligations under ASC 606 for certain discrete patent assets transferred to its membership clients (“catalyst license”) as well as for access to the patent portfolio that clients obtain when becoming a member or renewing membership (“portfolio access license”). The revenue generated from these additional performance obligations is recognized at a point in time under ASC 606. Formerly, under ASC 605, the Company generally recognized membership fees ratably on a gross basis over the term of the customer contract. Therefore, the adoption of ASC 606 increases the variability of revenue recognized from the Company's patent risk management services from period to period as well as reduces revenue and patent assets, and related amortization of these patent assets, previously treated on a gross basis under ASC 605 that are treated on a net basis against patent assets under ASC 606 due to the additional separable performance obligations.

ASC 606 also requires the Company to make significant judgments in determining stand-alone selling price (“SSP”) for each distinct performance obligation. The Company’s patent licenses are not sold or priced separately from its patent risk management service and are sold at a broad range of amounts which is in the form of a bundled membership fee. The Company typically has more than one SSP for the same licenses and services based on a member’s individual perceived patent risk. As such, the Company is required to determine SSP using inputs that are not directly observable. The Company considers all information that is available and maximizes the use of observable inputs in its determination of SSP.

Revenue recognition related to the Company’s discovery services segment and its patent risk management insurance offering is not materially changed under ASC 606.

The adoption of ASC 606 is expected to result in an estimated reduction of revenue of approximately $36 million and $23 million for fiscal years 2017 and 2016, respectively, with a corresponding expected decrease in cost of revenue of approximately $27 million and $32 million for fiscal years 2017 and 2016, respectively. This decrease in revenue and cost of revenue is primarily attributable to a portion of the Company’s catalyst license revenue and patent assets being treated on a net basis under ASC 606 as well as variability in the timing of revenue recognition of the patent licenses being recognized at a point in time. The Company's selling, general and administrative expenses is expected to increase in 2017 by approximately $1 million and decrease in 2016 by approximately $1 million due to the assessment of collectability as a result of adopting ASC 606. The Company is still assessing the impact of ASC 606 to its provision for income taxes and consolidated balance sheets and expects these impacts to be material.

Net Income Available to Common Stockholders

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Net Income Available to Common Stockholders

Net Income (Loss) Per Share

Basic and diluted net income (loss) per share are computed by dividing net income (loss) by the weighted-average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is computed by using the weighted-average number of shares of common stock outstanding during the period, including potentially dilutive shares. Potentially dilutive shares include outstanding stock options, RSUs, and PBRSUs. The dilutive effect of potentially dilutive shares is reflected in diluted earnings per share by application of the treasury stock method. Under the treasury stock method, an increase in the fair value of the Company's common stock can result in a greater dilutive effect from potentially dilutive shares.

The following table presents the calculation of basic and diluted net income (loss) per share (in thousands, except for per share data):



	Year Ended December 31,
	2017			2016		2015
Net income (loss) per share:
Numerator:
Net income (loss)	$	(79,143	)	$	18,235	$	39,422
Denominator:
Basic shares:
Weighted-average shares used in computing basic net income (loss) per share	49,240			50,462		54,432
Diluted shares:
Weighted-average shares used in computing basic net income (loss) per share	49,240			50,462		54,432
Dilutive effect of stock options and restricted stock units using treasury-stock method	—			539		978
Weighted-average shares used in computing diluted net income (loss) per share	49,240			51,001		55,410
Net income (loss) per share:
Basic	$	(1.61	)	$	0.36	$	0.72
Diluted	$	(1.61	)	$	0.36	$	0.71

For the years ended December 31, 2017, 2016 and 2015 the following securities were not included in the calculation of diluted shares outstanding, as the effect would have been anti-dilutive (in thousands):



	Year Ended December 31,
	2017	2016	2015
Weighted-average:
Stock options outstanding	901	—	663
Restricted stock units outstanding	740	2	263

Financial Instruments

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Financial Instruments

The following tables present the Company's financial assets and liabilities measured at fair value on a recurring basis (in thousands):



	December 31, 2017
	Amortized Cost		Unrealized					Estimated Fair Value		Level 1		Level 2
	Amortized Cost		Gains		Losses			Estimated Fair Value		Level 1		Level 2
Cash equivalents:
Commercial paper	$	13,035	$	—	$	—		$	13,035	$	—	$	13,035
Corporate bonds	1,205		—		—			1,205		—		1,205
Money market funds	52,267		—		—			52,267		52,267		—
Municipal bonds	13,060		—		—			13,060		—		13,060
U.S. government and agency securities	13,101		—		—			13,101		—		13,101
	$	92,668	$	—	$	—		$	92,668	$	52,267	$	40,401
Short-term investments:
Commercial paper	$	1,994	$	—	$	—		$	1,994	$	—	$	1,994
Corporate bonds	3,074		—		(3		)	3,071		—		3,071
Municipal bonds	11,888		—		(3		)	11,885		—		11,885
U.S. government and agency securities	1,508		—		(3		)	1,505		—		1,505
	$	18,464	$	—	$	(9	)	$	18,455	$	—	$	18,455



	December 31, 2016
	Amortized Cost		Unrealized					Estimated Fair Value		Level 1		Level 2
	Amortized Cost		Gains		Losses			Estimated Fair Value		Level 1		Level 2
Cash equivalents:
Money market funds	$	30,286	$	—	$	—		$	30,286	$	30,286	$	—
Municipal bonds	3,070		—		—			3,070		—		3,070
	$	33,356	$	—	$	—		$	33,356	$	30,286	$	3,070
Short-term investments:
Commercial paper	$	4,296	$	—	$	(3	)	$	4,293	$	—	$	4,293
Corporate bonds	10,856		—		(13		)	10,843		—		10,843
Equity securities	123		—		(78		)	45		45		—
Municipal bonds	55,723		—		(65		)	55,658		—		55,658
U.S. government and agency securities	20,033		9		(4		)	20,038		20,038		—
	$	91,031	$	9	$	(163	)	$	90,877	$	20,083	$	70,794

The Company's financial investments are generally classified as available-for-sale. Available-for-sale securities are reported at fair value, with unrealized gains and losses, net of tax, included as a separate component of stockholders’ equity within accumulated other comprehensive income (loss). During the years ended December 31, 2017, 2016, 2015, the Company realized losses on the sales and exchanges of short-term investments of nil , $0.3 million, and $3.4 million, respectively, and other-than-temporary impairments on its short-term investments of nil ,nil, and $5.1 million respectively, which are included in the consolidated statements of operations within other income (expense), net.

As of December 31, 2017 and 2016, approximately 100% and 96%, respectively, of the Company's marketable security investments mature within one year and 0% and 4%, respectively, mature within one to five years. As of December 31, 2017, no individual security incurred continuous unrealized losses for greater than 12 months.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Patent Assets, Net

12 Months Ended

Dec. 31, 2017

Patent Assets [Abstract]

Patent Assets, Net

Patent assets, net consisted of the following (in thousands):



	December 31, 2016			Additions			Disposals			December 31, 2017
Patent assets	$	932,283		$	106,010		$	(7,857	)	$	1,030,436
Accumulated amortization	(719,284		)	(155,592		)	7,488			(867,388		)
Patent assets, net	$	212,999								$	163,048



	December 31, 2015			Additions			Disposals			December 31, 2016
Patent assets	$	824,258		$	117,457		$	(9,432	)	$	932,283
Accumulated amortization	(569,698		)	(158,814		)	9,228			(719,284		)
Patent assets, net	$	254,560								$	212,999

The Company’s acquired patent assets relate to technologies used or supplied by companies in a variety of market sectors, including automotive, consumer electronics, e-commerce, financial services, media distribution, mobile communications, networking, semiconductors, and software. The Company amortizes each acquired portfolio of patent assets on a straight-line basis over its estimated economic useful life. As of December 31, 2017, the estimated economic useful lives of the Company’s patent assets acquired since inception generally ranged from 24 to 60 months with a weighted-average estimated economic useful life at the time of acquisition of 38 months. Patent assets acquired during the year ended December 31, 2017 had a weighted-average estimated economic useful life at the time of acquisition of 25 months.

As of December 31, 2017, the Company expects amortization expense in future periods to be as follows (in thousands):



2018	$	103,088
2019	48,232
2020	11,728
Total estimated future amortization expense	$	163,048

Amortization expense was $156.0 million, $159.0 million and $142.4 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Syndicated Acquisitions

Syndicated acquisitions are transactions involving patent assets that may cost more than the Company is prepared to spend with its own capital resources and/or that are relevant only to a limited number of clients. In such transactions, the Company may work to acquire these assets with financial assistance from the particular clients against whom they are being or may be asserted. Such clients either pay amounts separate from their subscription fee or, less frequently, lend the Company funds to be used in the transaction. As discussed in the revenue recognition policy in Note 2, "Basis of Presentation and Significant Accounting Policies," the Company may treat the contributions from such clients as revenue on a gross or net basis depending on the specific facts and circumstances of the transaction. In the event that such contributions are recognized on a net basis, the Company will only capitalize the acquired asset that relates to its non-contributing clients. As a result, in such situations the cost basis of the acquired patent rights excludes the amounts paid by the contributing clients.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2017

Property and Equipment, Net

Property and Equipment, Net

Property and equipment, net, consisted of the following (in thousands):



	December 31,
	2017			2016
Internal-use software	$	8,530		$	7,827
Leasehold improvements	2,098			2,169
Computer, equipment and software	5,960			5,204
Furniture and fixtures	755			935
Construction-in-progress	21			183
Total property and equipment, gross	17,364			16,318
Less: Accumulated depreciation and amortization	(12,274		)	(9,370		)
Total property and equipment, net	$	5,090		$	6,948

Depreciation and amortization expense related to our property and equipment was $3.3 million, $3.0 million and $1.7 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Business Combinations

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Business Combinations

On January 22, 2016, the Company completed its acquisition of all of the issued and outstanding shares of Inventus, to expand into the legal discovery services market. The final purchase price for Inventus was approximately $232 million, net of working capital adjustments, which the Company paid in January 2016. The following table summarizes the cash paid and the estimated fair values of the assets and the liabilities assumed (in thousands) and the estimated useful lives of the acquired identifiable intangible assets:



	Estimated Fair Value			Estimated useful life
Current assets	$	19,357
Intangible assets:
Customer relationships	58,000			9 - 10 years
Trademarks	3,200			1 - 6 years
Developed technology	6,400			3 years
Goodwill	145,984
Property, plant, equipment and other long term assets	3,347
Deferred tax asset	10,595
Current liabilities	(7,280		)
Deferred tax liability	(5,477		)
Other long term liabilities	(826		)
Cash purchase consideration paid	$	233,300

Intangible assets acquired through the Company's acquisition of Inventus are amortized on a straight-line basis which reflects the pattern in which the economic benefits of the intangible assets are expected to be utilized. The goodwill recorded is primarily attributable to the Company's opportunity to expand into the legal discovery services market and is not deductible for tax purposes. For the year ended December 31, 2016, the Company recorded acquisition-related costs of $1.2 million which were expensed as incurred and included in selling, general and administrative expenses in the Company's consolidated statements of operations. The Company has included the following financial results of Inventus in its consolidated financial statements (in thousands):



	Year Ended December 31,
		2016
Discovery Services
Revenue		$	66,112
Cost of revenue		33,397
Selling, general and administrative expenses		23,990
Impairment losses		—
Operating income		$	8,725

The unaudited pro forma financial information in the table below summarizes the combined results of operations for the Company and Inventus as though the companies had been consolidated as of January 1, 2015, and includes the accounting effects resulting from the acquisition including amortization charges from the acquired intangible assets, $13.5 million of transaction costs incurred which were directly attributable to the acquisition of Inventus, and elimination of interest expenses and debt issuance and extinguishment costs associated with Inventus's historical debt which was extinguished upon the Company's acquisition of Inventus. This unaudited pro forma information also adjusts for Inventus's acquisition of London-based Unified OS Limited and certain of its affiliates as well as certain assets of Kooby LLP as though it had been consolidated as of January 1, 2015. These accounting effects do not have any impact on the Company's 2017 financial information.

The following unaudited pro forma financial information is for information purposes only and is not necessarily indicative of the results of operations that would have been achieved if the acquisition had taken place as of January 1, 2015 (in thousands, except per share data):



	Year Ended December 31,
	2017			2016
Revenue	$	330,457		$	336,047
Net income (loss)	(79,143		)	18,824
Basic net income (loss) per share	(1.61		)	0.37
Diluted net income (loss) per share	(1.61		)	0.37

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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-Section 50
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 4
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Publisher FASB
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Goodwill

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill

The changes in the carrying amounts of goodwill by operating segment were as follows (in thousands):



	Patent Risk Management		Discovery Services			Total
Balance as of December 31, 2016	$	19,978	$	131,344		$	151,322
Impairment losses	—		(89,035		)	(89,035		)
Foreign currency translation adjustments	—		8,469			8,469
Balance as of December 31, 2017	$	19,978	$	50,778		$	70,756

The Company reviews goodwill for impairment annually or more frequently if events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. The Company performed its annual goodwill impairment test using a quantitative approach for its discovery services reporting units and a qualitative approach for its patent risk management business. The quantitative approach used for its discovery services segment includes comparing the carrying value to the fair values of each reporting unit using a discounted cash flow methodology with a comparable business approach which utilizes Level 3 inputs. Cash flow projections are based on management’s estimates of growth rates and operating margins, taking into consideration industry and market conditions. The discount rate used is based on the weighted-average cost of capital adjusted for the relevant risk associated with business-specific characteristics and the uncertainty related to the reporting units' ability to execute on the projected cash flows. These tests resulted in the carrying values of the discovery services reporting units exceeding the fair values primarily due to (1) decreased expected future cash flows from pricing pressures and competition in the discovery services marketplace as well as significant fluctuations due to the project-based nature of these cash flows, and (2) a decrease in estimated peer company values. As a result, the Company recognized a goodwill impairment loss of $89.0 million in its consolidated statement of operations during the year ended December 31, 2017. No other goodwill impairment charges were recorded as a part of the Company's annual impairment analyses.

Intangible Assets, Net

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets, Net

Intangible assets, net, as of December 31, 2017 and 2016 consisted of the following (in thousands, except years):



	December 31, 2017								December 31, 2016
	Weighted-Average Life (years)	Carrying Amount		Accumulated Amortization			Net Carrying Amount		Carrying Amount		Accumulated Amortization			Net Carrying Amount
Customer relationships	9.4	$	56,688	$	(11,764	)	$	44,924	$	55,719	$	(6,323	)	$	49,396
Trademarks	6.0	2,900		(938		)	1,962		4,879		(2,439		)	2,440
Developed technology	3.0	6,237		(4,036		)	2,201		5,802		(1,978		)	3,824
Covenant not to compete		—		—			—		1,900		(1,604		)	296
Proprietary data and models		—		—			—		2,100		(2,006		)	94
		$	65,825	$	(16,738	)	$	49,087	$	70,400	$	(14,350	)	$	56,050

As of December 31, 2017, the Company expects amortization expense in future periods to be as follows (in thousands):



2018	$	8,562
2019	6,644
2020	6,523
2021	6,523
2022	6,069
Thereafter	14,766
Total estimated future amortization expense	$	49,087

Amortization expense related to intangible assets was $8.9 million, $9.6 million, and $1.7 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Debt	12 Months Ended
Debt	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	Debt On February 26, 2016, the Company entered into a Credit Agreement (the "Credit Agreement") which provided for a $100 million five-year term facility (the "Term Facility") and a $50 million five-year revolving credit facility (the "Revolving Credit Facility"). The Term Facility bore interest which is payable quarterly in arrears at the Company's option equal to either a base rate plus a margin ranging from 1.25% to 1.75% per annum or, at the Company's election, the one-, two-, three-, or six-month London interbank offered rate ("LIBOR") plus a margin ranging from 2.25% to 2.75% per annum, based upon the ratio of the Company's debt to consolidated EBITDA ratio. During the year ended December 31, 2016, the Term Facility bore interest at an average interest rate of 3.0%, which approximated fair value. The Revolving Credit Facility bore a commitment fee on undrawn balances of 0.35% to 0.45% per annum, also based upon the Company's debt to consolidated adjusted EBITDA ratio, that was expensed as incurred. The Company paid down the outstanding balance of the Term Facility in full in November 2017 and terminated the Credit Agreement in December 2017 and therefore as of December 31, 2017, there were no outstanding obligations.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments And Contingencies

Commitments and Contingencies

Operating Lease Commitments

The Company leases its facilities under non-cancelable lease agreements. Certain of these arrangements have free rent, escalating rent payment provisions and tenant allowances. Under such arrangements the Company recognizes rent expense on a straight line basis over the non-cancelable lease term and records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability within other current liabilities and other liabilities for the current and non-current portion, respectively, in the Company's consolidated balance sheets.

In March 2012, the Company entered into an amended lease agreement related to its San Francisco, California office space. The amendment, which took effect on May 1, 2013, increased the rentable space to approximately 67,000 total square feet and extended the term through October 2019. In June 2017, the Company executed an additional amendment to this lease and in accordance with the additional amendment, effective August 2017, the Company reduced its leased space by approximately 18,000 square feet, which reduced the Company's future operating lease commitments at that time by approximately $2.4 million over the remaining lease term.

In October 2013, the Company entered into an agreement to sublease a portion of its San Francisco, California office space. This sublease took effect on February 1, 2014 for a 36-month term through January 2017 and was subsequently renewed through October 2019.

The following table summarizes rent expense related to non-cancelable operating leases (in millions):



	Year Ended December 31,
	2017		2016		2015
Rent expense	$	6.0	$	5.9	$	4.1
Sublease income	1.1		0.7		0.6
Rent expense, net of sublease income	$	4.9	$	5.2	$	3.5

As of December 31, 2017, the future minimum lease payments required under non-cancelable operating leases and the future minimum payments to be received from non-cancelable subleases were as follows (in thousands):



2018	$	4,528
2019	3,619
2020	654
2021	227
2022	232
Thereafter	379
Future non-cancelable minimum operating lease payments	9,639
Less: minimum payments to be received from non-cancelable subleases	(2,202		)
Total future non-cancelable minimum operating lease payments, net	$	7,437

Litigation

From time to time, the Company may be a party to various litigation claims in the normal course of business. Legal fees and other costs associated with such actions are expensed as incurred. The Company assesses, in conjunction with its legal counsel, the need to record a liability for litigation or contingencies. A liability is recorded when and if it is determined that such a liability for litigation or contingencies is both probable and reasonably estimable. No liability for legal contingencies was recorded as of December 31, 2017 or 2016.

In June 2013, Kevin O’Halloran, as Trustee of the Liquidating Trust of Tectonics, Inc. (the “Debtor”), filed a complaint in the U.S. Bankruptcy Court for the Middle District of Florida against the Company and Harris Corporation (the “Defendants”). The complaint alleges that the Defendants are liable under federal and state bankruptcy law regarding fraudulent transfers for the value of a patent portfolio purchased by the Company from Harris Corporation pursuant to an agreement entered into in January 2009, and within four years of the date the Debtor filed its petition in bankruptcy. In February 2015, the Court held a trial and in November 2015 entered judgment in favor of the Defendants. In December 2015, the Debtor filed an appeal of the judgment to the U.S. District Court for the Middle District of Florida. In August 2016, the District Court affirmed the judgment in favor of the Defendants. In September 2016, the Debtor filed an appeal of the judgment to the U.S. Court of Appeals for the Eleventh Circuit. The appellate briefing was completed in January 2017, and oral argument occurred on December 14, 2017. The Company is not currently able to determine whether there is a reasonable possibility that a loss has been incurred, nor can it estimate the potential loss or range of the potential loss that may result from this litigation.

In March 2012, Cascades Computer Innovations LLC filed a complaint in U.S. District Court for the Northern District of California (the “District Court”) against the Company and five of its clients (collectively the “Defendants”). The complaint alleges that the Defendants violated federal antitrust law, California antitrust law and California unfair competition law. The complaint further alleged that after the Company terminated its negotiations with the plaintiff to license certain patents held by the plaintiff, the Defendants violated the law by jointly refusing to negotiate or accept licenses under the plaintiff’s patents. The plaintiff sought unspecified monetary damages and injunctive relief. In January 2013, the District Court dismissed the complaint against the Defendants and granted the plaintiff leave to amend its complaint. In February 2013, the plaintiff filed an amended lawsuit alleging that the Defendants violated federal antitrust law, California antitrust law and California unfair competition law. In April 2016, the District Court entered a final judgment in favor of the Defendants on all the plaintiff's claims. In April 2016, the plaintiff filed an appeal of the judgment. On December 11, 2017, the U.S. Court of Appeals for the Ninth Circuit affirmed the District Court in full, and the order took effect on January 2, 2018.

Guarantees and Indemnifications

The Company has, in connection with the sale of patent assets, agreed to indemnify and hold harmless the buyer of such patent assets for losses resulting from breaches of representations and warranties made by the Company. The terms of these indemnification agreements are generally perpetual. The maximum amount of potential future indemnification is unlimited. To date, the Company has not paid any significant amount to settle claims or defend lawsuits. The Company is unable to reasonably estimate the maximum amount that could be payable under these arrangements since these obligations are not capped but are conditional to the unique facts and circumstances involved. Accordingly, the Company had no liabilities recorded for these agreements as of December 31, 2017 or 2016. The Company has no reason to believe that there is any material liability related to such indemnification provisions. The Company does not indemnify its clients for patent infringement.

As part of the Company's discovery services offering, the Company generally warrants that it will perform the services in good faith and in a timely and professional manner, and that it will exercise the same level of professional care commonly found in the industry. Additionally, the Company has agreed to provisions for indemnifying customers against liabilities if its discovery services infringe a third party’s intellectual property rights or if it breaches agreed privacy, security and/or confidentiality obligations. To date, the Company has not incurred any material costs, and it has not accrued any liabilities in the accompanying consolidated financial statements, as a result of these obligations. The Company also enters into service-level agreements with its discovery services clients that specify required levels of application uptime and may permit customers to receive credits or to terminate their agreements in the event that the Company fails to meet required performance levels. To date, the Company has not experienced any significant failures to meet defined levels of performance and, as a result, has not accrued any liabilities related to these agreements in its consolidated financial statements.

In accordance with its amended and restated bylaws, the Company also indemnifies certain officers and employees for losses incurred in connection with actions, suits or proceedings threatened or brought against such officer or employee arising from his or her service to the Company as an officer or employee, subject to certain limitations. The term of the indemnification period is indefinite. The maximum amount of potential future indemnification is unspecified. The Company has no reason to believe that there is any material liability for actions, events or occurrences that have occurred to date.

Reserves for Known and Incurred but not Reported Claims

In August 2012, the Company began offering insurance to cover certain costs of patent litigation brought against its insured clients. As of December 31, 2017 and 2016, the Company recorded a reserve of $1.1 million and $0.9 million, respectively, for known and incurred but not reported claims that represent estimated claim costs and related expenses.

The Company regularly reviews loss reserves using a variety of actuarial techniques and updates them as its loss experience develops.

Stockholders' Equity

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Stockholder's Equity

Common Stock

As of December 31, 2017, under the Company’s amended and restated certificate of incorporation, the Company is authorized to issue 200 million shares of common stock with a par value of $0.0001 per share.

Preferred Stock

As of December 31, 2017, under the Company’s amended and restated certificate of incorporation, the Company is authorized to issue 10 million shares of preferred stock with a par value of $0.0001 per share. The Board of Directors is authorized to provide for the issuance of one or more series of preferred stock and to establish the powers, preferences and rights of the preferred shares.

Equity Plans

In February 2011, the Company’s Board of Directors adopted the 2011 Equity Incentive Plan (the “2011 Plan”), which became effective on the date of the Company’s initial public offering. The 2011 Plan provides for the issuance of incentive stock options, non-qualified stock options, stock appreciation rights, restricted shares of the Company’s common stock and stock units to employees, directors and non-employees. The Board of Directors initially reserved 1,500,000 shares of common stock for future issuance under the 2011 Plan pursuant to automatic increases permitted under the 2011 Plan. During 2017 and 2016, the Company reserved an additional 1,000,000 and 2,000,000 shares, respectively, of common stock for future issuance under the 2011 Plan. As of December 31, 2017, there were 4.7 million shares available for grant under the 2011 Plan.

In August 2008, the Company’s Board of Directors adopted the 2008 Plan (the “2008 Plan”) which provided for the issuance of incentive stock options, non-qualified stock options, as well as the direct award or sale of shares of common stock to employees, directors and non-employees for up to 9,019,474 shares of common stock, as amended. No further awards have been made under the 2008 Plan since the 2011 plan became effective; however, all awards outstanding under the 2008 Plan will continue to be governed by the existing terms.

Under both the 2011 Plan and 2008 Plan, incentive stock options and non-qualified stock options are to be granted at a price that is not less than 100% of the fair value of the stock at the date of grant. Stock options granted to newly hired employees vest 25% on the first anniversary of the date of hire and ratably each month over the ensuing 36-month period. Stock options granted to existing employees generally vest ratably over the 48-months following the date of grant. Stock options are exercisable for a maximum period of 10 years after date of grant. Incentive stock options granted to stockholders who own more than 10% of the outstanding stock of the Company at the time of grant must be issued at an exercise price not to be less than 110% of the fair value of the stock on the date of grant. RSUs granted to newly hired employees vest 25% on the first Company-established vest date after the first anniversary of the employee’s date of hire and ratably each quarter over the ensuing 12-quarter period. RSUs granted to existing employees generally vest ratably each quarter over the 16 quarters following the date of grant. PBRSUs with market conditions granted to employees may vest 25% on each anniversary of the grant date, provided that the market conditions are satisfied. PBRSUs with performance conditions granted to employees generally vest 25% annually if the performance criteria is satisfied.

A summary of the Company’s activity under its equity-settled award plans and related information is as follows (in thousands, except per share data and years):



			Options Outstanding
	Shares Available for Grant		Number of Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life in Years	Aggregate Intrinsic Value
Balance - December 31, 2016	3,586		1,768		$	11.63
Shares authorized	1,000		—		—
Options exercised	—		(690	)	8.64
Options forfeited	99		(99	)	16.16
Restricted stock units granted	(2,006	)	—		—
Restricted stock units forfeited	1,597		—		—
Restricted stock units withheld related to net share settlement of restricted stock units	452		—		—
Balance - December 31, 2017	4,728		979		13.29		2.6	$	2,396
Vested and exercisable - December 31, 2017			979		13.29		2.6	2,396
Vested and expected to vest - December 31, 2017			979		13.29		2.6	2,396

The aggregate intrinsic value of stock options exercised during the years ended December 31, 2017, 2016 and 2015 was $2.8 million, $0.9 million and $6.8 million, respectively. The total fair value of stock options vested during the years ended December 31, 2017, 2016 and 2015 was nil, $1.3 million and $3.3 million, respectively.

Restricted Stock Units

The summary of restricted stock unit activity, which includes PBRSUs, is as follows (in thousands, except per share data):



	Number of Shares		Weighted-Average Grant Date Fair Value		Aggregate Intrinsic Value
Non-vested units - December 31, 2016	3,424		$	11.53
Granted	2,006		11.86
Vested	(1,313	)	12.23
Forfeited	(1,597	)	10.73
Non-vested units - December 31, 2017	2,520		11.95		$	33,874

The total fair value of RSUs vested during the years ended December 31, 2017, 2016 and 2015 was $16.6 million, $11.9 million and $14.4 million, respectively.

In October 2013, the Board of Directors approved net-share settlement for tax withholdings on RSU vesting. In 2017 and 2016, the Company withheld issuing 451,770 and 418,201 shares of its common stock, respectively, based on the value of the RSUs on their vesting dates as determined by the Company’s closing common stock price. Total payments for the employees’ minimum tax obligations to taxing authorities were $5.7 million and $4.2 million for the years ended December 31, 2017 and 2016, respectively, and were recorded as a reduction to additional paid-in capital and reflected as a financing activity within the consolidated statements of cash flows. The net-share settlements reduced the number of shares that would have otherwise been issued on the vesting date and increased the number of shares reserved for future issuance under the 2011 Plan.

Stock-Based Compensation Related to Employees and Directors

The fair value of RSUs granted to employees and non-employee directors is measured by reference to the fair value of the underlying shares on the date of grant.

PBRSUs granted during the years ended December 31, 2017 and 2016 contain service, performance, and/or market conditions that affect the quantity of awards that will vest. PBRSUs granted during the year ended December 31, 2015 contain both service and performance conditions that affect the quantity of awards that will vest. During the years ended December 31, 2017, 2016, and 2015, the Company granted 102,790, 115,657, and 54,375 PBRSUs, respectively. The Company estimates the grant date fair value of PBRSUs which include performance conditions by reference to the fair value of the underlying shares on the date of grant. The Company estimates the grant date fair value of PBRSUs which include market conditions using the Monte Carlo simulation model.

The weighted-average assumptions used to estimate the fair value of PBRSUs with market conditions and the resulting fair values are as follows:



	Year Ended December 31,
	2017			2016			2015
Dividend yield	—			—			n/a
Risk free rate	1.03		%	1.08		%	n/a
Expected volatility	32		%	38		%	n/a
Grant date fair value	$	11.95		$	6.28		n/a

Stock-based compensation expense related to stock options granted to employees and non-employee directors was nil, $0.9 million and $2.9 million for the years ended December 31, 2017, 2016 and 2015, respectively. Stock-based compensation expense related to RSUs and PBRSUs granted to employees and non-employee directors was $14.7 million, $17.5 million and $14.9 million for the years ended December 31, 2017, 2016 and 2015, respectively.

As of December 31, 2017, there was $25.4 million of unrecognized compensation cost related to RSUs, including PBRSUs, which is expected to be recognized over a weighted-average period of 2.5 years. Future grants of equity awards will increase the amount of stock-based compensation expense to be recorded.

Stock Repurchase Program

On February 10, 2015, the Company announced that its Board of Directors had authorized a share repurchase program under which the Company is authorized to repurchase up to $75.0 million of its outstanding common stock with no expiration date from the date of authorization. In March 2016 and May 2016, the Company increased its share repurchase program by $25 million and $50 million, respectively, for a total amount authorized of $150 million. As of December 31, 2017, the Company repurchased $94.6 million of the outstanding common stock. Under the program, shares may be purchased in open market transactions, including through block purchases, through privately negotiated transactions, or pursuant to any trading plan that may be adopted in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). The share repurchase program does not have an expiration date and may be suspended, terminated or modified at any time for any reason. The Company’s share repurchase program does not obligate it to acquire any specific number of shares. The Company repurchased shares of its common stock in the open market, which were retired upon repurchase. The purchase price for the repurchased shares are reflected as a reduction to common stock and retained earnings in the Company's consolidated balance sheet during the period presented as follows (in thousands, except per share data):



	Shares Repurchased	Average Price per Share		Value of Shares Repurchased
Cumulative shares repurchased as of January 1, 2017	7,917	$	10.90	$	86,276
Repurchase of shares of common stock	700	11.84		8,290
Cumulative shares repurchased as of December 31, 2017	8,617	$	10.97	$	94,566

Dividends

During 2017, the Company's Board of Directors declared a quarterly cash dividend of $0.05 per share of common stock, the first which was paid on December 5, 2017, to shareholders of record on November 20, 2017.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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Reference 14: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

Income or loss before provision for income tax consists of the following (in thousands):



	Year Ended December 31,
	2017			2016		2015
Domestic	$	(8,078	)	$	28,536	$	65,445
International	(50,987		)	3,773		54
Total income (loss) before provision for income taxes	$	(59,065	)	$	32,309	$	65,499

The components of the provision for income taxes are as follows (in thousands):



	Year Ended December 31,
	2017			2016			2015
Current:
Federal	$	3,886		$	(12,400	)	$	(23,456	)
State	207			(4,038		)	(2,790		)
Foreign	(9,743		)	(11,097		)	(12,406		)
Total current provision for income taxes	(5,650		)	(27,535		)	(38,652		)
Deferred:
Federal	(15,354		)	11,596			12,022
State	238			1,097			553
Foreign	688			768			—
Total deferred benefit (expense) for income taxes	(14,428		)	13,461			12,575
Total provision for income taxes	$	(20,078	)	$	(14,074	)	$	(26,077	)

Net deferred tax assets consist of the following (in thousands):



	December 31,
	2017			2016
Deferred tax assets:
Deferred revenue	$	2,687		$	1,843
Reserves and other	4,016			6,292
Stock-based compensation	2,643			5,682
Depreciation and amortization	10,516			14,050
Net operating loss carryforwards	1,768			7,246
Foreign tax credits	1,095			—
Total deferred tax assets	22,725			35,113
Valuation allowance	(2,810		)	(875		)
Net deferred tax assets	$	19,915		$	34,238

The following is a reconciliation of the statutory federal income tax to the Company’s effective tax (in thousands):



	Year Ended December 31,
	2017			2016			2015
Tax at statutory federal rate	$	(20,673	)	$	11,307		$	22,939
State tax – net of federal benefit	(1,649		)	1,674			1,459
Permanent differences	6,138			1,000			663
Foreign tax	27,164			8,969			12,370
Foreign tax credits	(7,571		)	(9,191		)	(12,370		)
Foreign income not taxed at federal rate	—			—			3
Change in valuation allowance	2,944			(222		)	1,097
Rate differential impact from Tax Cuts and Jobs Act	14,557			—			—
Other	(832		)	537			(84		)
Total provision for income taxes	$	20,078		$	14,074		$	26,077

As of December 31, 2017, the Company had federal and state capital loss carryforwards of $6.5 million available to reduce future taxable income which expire in 2020 if not utilized. As of December 31, 2017, the Company had federal and state net operating loss carryforwards of $18.9 million which will begin to expire in 2023 if not utilized. The utilization of these carryforwards may be limited if there are certain changes in the Company's ownership.

On December 22, 2017, the Tax Cuts and Jobs Act was signed into law. Among other changes is a permanent reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018. As a result of the reduction in the corporate income tax rate, the Company was required to remeasure its net deferred tax asset as of December 31, 2017, which resulted in a reduction in the deferred tax asset value of approximately $14.4 million, offset by a change in valuation allowance of $1.0 million, which resulted in a deferred tax expense of $13.4 million.

In transitioning to the new territorial tax system, the Tax Cuts and Jobs Act requires the Company to include certain untaxed foreign earnings of non-U.S. subsidiaries in its taxable income for the year ended December 31, 2017. Such foreign earnings are subject to a one-time transition tax, which was estimated to be $1.1 million as of December 31, 2017, and was recorded within the Company’s provision for income taxes for the year ended December 31, 2017. The Company intends to elect to pay the transition tax over a period of eight years as permitted by the Tax Cuts and Jobs Act.

In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (“SAB 118”), which allows the Company to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. Due to the Company’s ongoing analysis and expected guidance and accounting interpretations over the next 12 months, the accounting of the transition tax and net deferred tax asset remeasurements are considered provisional. The Company expects to complete its analysis within the measurement period in accordance with SAB 118.

In assessing the realization of deferred tax assets, the Company considers whether it is more-likely-than-not that some portion or all of deferred assets will not be realized. The ultimate realization of the deferred tax asset is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Based on the available objective evidence as of December 31, 2017, the Company believes it is not more-likely-than-not that the net deferred tax asset related to certain capital losses and foreign tax credits will be fully realized. The Company's valuation allowance (excluding the impact of the Tax Cuts and Jobs Act as discussed above) increased by $1.9 million during the year ended December 31, 2017 due to additional capital losses and foreign tax credits in 2017 which the Company does not expect to be realized.

Internal Revenue Code Section 382 places a limitation (the Section 382 Limitation) on the amount of taxable income that can be offset by net operating loss carryforwards after a change in control (generally greater than 50% change in ownership) of a loss corporation. California has similar rules. Generally, after a change in control, a loss corporation cannot deduct operating loss carryforwards in excess of the Section 382 Limitation. The Company has considered the impact of such limitation in determining the utilization of its operating loss carryforwards against taxable income in future periods.

Deferred tax liabilities have not been recognized for undistributed earnings for foreign subsidiaries because it is the Company's intention to indefinitely reinvest such undistributed earnings outside the U.S. Generally, such earnings are subject to potential foreign withholding tax and the U.S. tax upon remittance of dividends and under certain other circumstances. The Company believes that the potential liability would not be material.

Uncertain Tax Positions

As of December 31, 2017, the Company’s total amount of unrecognized tax benefits was $7.7 million, all of which would impact the Company’s effective tax rate, if recognized.

The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands):



	2017			2016			2015
Balance as of January 1,	$	8,300		$	5,315		$	3,707
Gross increase related to current period tax positions	597			1,567			1,606
Gross increase related to prior period tax positions	—			1,841			2
Gross decrease related to prior period tax positions	(1,236		)	(423		)	—
Balance as of December 31,	$	7,661		$	8,300		$	5,315

The Company does not believe it is reasonably possible that its unrecognized tax benefits will materially change within the next twelve months.

The Company’s policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. During the years ended December 31, 2017, 2016 and 2015, the Company recognized $0.1 million, $0.6 million, and $0.4 million, respectively, of interest and penalties associated with unrecognized tax benefits.

The 2013 through 2017 tax periods are open to examination by the Internal Revenue Service and the 2013 through 2017 tax periods remain open to examination by most state tax authorities. The Internal Revenue Service's examination of Inventus's federal income tax return for fiscal year 2013 was closed during the three months ended March 31, 2017 with no material adjustments. The Company's 2015 through 2016 tax periods remain open to examination in the United Kingdom.

Related-Party Transactions

12 Months Ended

Dec. 31, 2017

Related Party Transactions

Related-Party Transactions

During the year ended December 31, 2017, 2016, and 2015, three, four, and four members, respectively, of the Company’s Board of Directors served on the boards of directors of RPX clients.

The Company recognized the following from these clients (in millions):



	Year Ended December 31,
	2017		2016		2015
Revenue	$	7.4	$	9.8	$	9.3
Selling, general and administrative expenses	0.5		0.8		0.3

As of December 31, 2017 and 2016, there were $1.5 million and $1.3 million of receivables due from these clients, respectively.

Segment Reporting

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Segment Reporting

Operating segments are components of an enterprise about which separate financial information is available. Operating segments are reported in a manner consistent with the internal reporting provided to the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is its Chief Executive Officer. Prior to the acquisition of Inventus in January 2016, the Company’s Chief Executive Officer reviewed financial information presented on a consolidated basis and, as a result, the Company concluded that there was only one operating and reportable segment. Subsequent to the acquisition of Inventus (see Note 7, "Business Combinations"), the Company's Chief Executive Officer reviews separate financial information for the patent risk management and discovery services businesses. Therefore as of January 2016, the Company has two reportable segments: 1) patent risk management which generates its revenues primarily from membership subscriptions, premiums earned from insurance policies, and management fees for marketing, underwriting, and claim management and 2) discovery services which generates its revenues primarily from fees generated for data collection, hosting and processing, project management, and document review services. There are no material internal revenue transactions between these two reportable segments.

Although adjusted EBITDA and adjusted operating income are not measures of financial performance determined in accordance with GAAP, the Company's chief operating decision maker evaluates segment financial performance by utilizing the segment's adjusted EBITDA and adjusted operating income because the Company believes it is a useful supplemental measure that reflects core operating performance and provides an indicator of the segment's ability to generate cash.

The Company defines adjusted EBITDA as net income (loss) exclusive of provision for income taxes, interest and other income (expense), net, impairment losses, stock-based compensation and related employer payroll taxes, depreciation, and amortization. The Company defines adjusted operating income as GAAP operating income exclusive of non-cash impairment losses. There are limitations in using the Company's measures of financial performance that are not determined in accordance with GAAP and these may be different from other financial measures not determined in accordance with GAAP used by other companies. These financial measures are limited in value because they exclude certain items that may have a material impact on the Company's reported financial results. In addition, they are subject to inherent limitations as they reflect the exercise of judgment by the Company about which items are adjusted to calculate its financial measures not determined in accordance with GAAP. The presentation of financial measures not determined in accordance with GAAP should not be considered in isolation or as a substitute for, or superior to, financial results determined in accordance with GAAP.

Summarized financial information by segment for the years ended December 31, 2017 and 2016 utilized by the Company's chief operating decision maker is as follows (in thousands):



	Year Ended December 31,
	2017		2016
Patent Risk Management
Revenue	$	252,253	$	266,995
Cost of revenue	161,409		163,865
Selling, general and administrative expenses	63,795		76,467
Adjusted operating income	27,049		26,663
Stock-based compensation, including related taxes	13,197		17,633
Depreciation and amortization	158,297		162,262
Adjusted EBITDA	$	198,543	$	206,558

Discovery Services
Revenue	$	78,204	$	66,112
Cost of revenue	42,300		33,397
Selling, general and administrative expenses	26,712		23,990
Adjusted operating income	9,192		8,725
Stock-based compensation, including related taxes	1,791		935
Depreciation and amortization	9,846		9,361
Adjusted EBITDA	$	20,829	$	19,021

The following table reconciles the Company's subtotal segment adjusted EBITDA to consolidated net income (loss) (in thousands):



	Year Ended December 31,
	2017			2016

Subtotal segment adjusted EBITDA	$	219,372		$	225,579
Depreciation and amortization	(168,143		)	(171,623		)
Stock-based compensation, including related taxes	(14,988		)	(18,568		)
Impairment losses	(94,051		)	—
Interest and other expense, net	(1,255		)	(3,079		)
Provision for income taxes	(20,078		)	(14,074		)
Net income (loss)	$	(79,143	)	$	18,235

The following table reconciles the Company's subtotal segment adjusted operating income to consolidated operating income (loss) (in thousands):



	Year Ended December 31,
	2017			2016

Subtotal segment adjusted operating income	$	36,241		$	35,388
Impairment losses	(94,051		)	—
Operating income (loss)	$	(57,810	)	$	35,388

The following table summarizes total assets by segment (in thousands):



	December 31,
	2017		2016
Patent risk management	$	388,559	$	501,540
Discovery services ⁽¹⁾	162,271		233,749
Total assets	$	550,830	$	735,289

⁽¹⁾Includes goodwill and intangible assets acquired through the Company's acquisition of Inventus in January 2016.

The Company markets its services to companies around the world. Revenue is generally attributed to geographic areas based on the country in which the client is domiciled. The following table presents revenue by location and revenue generated by country as a percentage of total revenue for the applicable period, for countries representing 10% or more of revenues for one or more of the periods presented (dollars in thousands):



	Year Ended December 31,
	2017				2016				2015
United States	$	196,454	59	%	$	194,196	58	%	$	186,439	64	%
Japan	34,844		11		37,200		11		36,195		12
Korea	18,414		6		25,288		8		28,319		10
Rest of world	80,745		24		76,423		23		40,928		14
Total revenue	$	330,457	100	%	$	333,107	100	%	$	291,881	100	%

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Selected Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Information (Unaudited)

Summarized quarterly financial information for the years ended December 31, 2017 and 2016 is as follows (in thousands, except per share data):



	Three Months Ended
	March 31, 2017				June 30, 2017		September 30, 2017		December 31, 2017
Revenue	$	82,512			$	80,434	$	85,702	$	81,809
Cost of revenue	51,298				51,142		52,282		48,987
Selling, general and administrative expenses	21,121				23,124		22,517		23,745
Impairment losses⁽¹⁾	—			—	—		—		94,051
Operating income (loss)	10,093				6,168		10,903		(84,974		)
Interest and other income (expense), net ⁽²⁾	(533		)		427		88		(1,237		)
Income (loss) before provision for income taxes	9,560				6,595		10,991		(86,211		)
Provision for income taxes	3,567				2,403		4,625		9,483
Net income (loss)	$	5,993			$	4,192	$	6,366	$	(95,694	)

Net income (loss) per share⁽³⁾:
Basic	$	0.12			$	0.09	$	0.13	$	(1.93	)
Diluted	$	0.12			$	0.08	$	0.13	$	(1.93	)

Other Data:
Deferred revenue, including current portion	$	136,227			$	114,561	$	102,939	$	106,868
Stock-based compensation expense	$	2,734			$	4,343	$	3,798	$	3,724



	Three Months Ended
	March 31, 2016		June 30, 2016			September 30, 2016			December 31, 2016
Revenue	$	79,735	$	83,109		$	88,461		$	81,802
Cost of revenue	47,666		49,070			50,830			49,696
Selling, general and administrative expenses	26,895		25,904			23,615			24,043
Operating income	5,174		8,135			14,016			8,063
Interest and other income (expense), net ⁽²⁾	1,805		(1,549		)	(1,250		)	(2,085		)
Income before provision for income taxes	6,979		6,586			12,766			5,978
Provision for income taxes	2,742		2,436			4,651			4,245
Net income	$	4,237	$	4,150		$	8,115		$	1,733

Net income per share⁽³⁾:
Basic	$	0.08	$	0.08		$	0.16		$	0.04
Diluted	$	0.08	$	0.08		$	0.16		$	0.03

Other Data:
Deferred revenue, including current portion	$	139,992	$	123,133		$	102,691		$	130,408
Stock-based compensation expense	$	4,929	$	4,899		$	4,269		$	4,178

⁽¹⁾The Company recorded impairment losses related to its discovery services goodwill and patent risk management cost method investments during the three months ended December 31, 2017. See further information in Note 2, "Basis of Presentation and Significant Accounting Policies" and Note 8, "Goodwill."

⁽²⁾See Note 12, "Commitments and Contingencies" and Note 11, "Debt" for further information regarding interest and other income (expense), net.

⁽³⁾Basic and diluted earnings per share are computed independently for each of the quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted earnings per share.

Basis of Presentation and Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

Use of Estimates

Significant estimates and assumptions made by management include the determination of:


•	the assumptions and methods used in deriving the fair value of goodwill and long-lived assets;


•	the estimated economic useful lives of patent assets;


•	the fair value of assets acquired and liabilities assumed for business combinations;


•	recognition and measurement of current and deferred income taxes, any related valuation allowances, and uncertain tax positions;


•	the fair value of stock awards issued;


•	the assumptions and methods used in deriving the fair value of deferred payment obligations;


•	the determination of a best estimated selling price of a subscription and patent infringement liability insurance;


•	the estimated reserves for known and incurred but not reported claims

Revenue Recognition

Patent Risk Management


•	Persuasive evidence of an arrangement exists. All subscription fees are supported by an executed subscription agreement.

•


•	Collectability is reasonably assured. Subscription fees are generally collected on or near the effective date of the agreement and again at or near each anniversary date thereof. The Company does not recognize revenue in instances where collectability is not reasonably assured. Generally, the Company's subscription agreements state that all fees paid are non-refundable.

Key indicators evaluated to determine the Company's role as either principal or agent in the transaction include, among others:


•	the entity to grant the license of the patent(s) is generally viewed as the primary obligor in the arrangement, given that it owns and controls the underlying patent(s) and thus has the absolute authority to grant and deliver any release from past damages and dismissal from litigation, and typically determines the general terms of the license(s) granted;


•	the Company's inventory risk in the transaction, which is typically mitigated, as its clients often enter into contractual obligations with the Company prior to or contemporaneous with the Company entering into a contractual obligation with the seller;


•	the Company has pricing latitude as it negotiates client contributions, however, this latitude is often limited as the economics of the transaction ultimately depend on the sales price set by the seller;


•	the Company is not involved in the determination of the product or service specification and has no ability to change the product or perform any part of the service in connection with these transactions, as the seller owns the underlying patent(s); and


•	the Company's credit risk taken on the transaction, which is generally limited as each respective client has a contractually binding obligation, such clients are generally of high credit quality and in some instances, the Company collects the client contribution prior to making a payment to the seller.

In certain syndicated transactions, the Company may recognize revenue upon the sale of licenses to specific patent assets and/or upon completion of the rendering of advisory services.

The Company has determined its BESP for a subscription to our patent risk management services based on the following:

•

The Company has determined its BESP for its insurance product based on the following:

•

Discovery Services

Revenue from the Company's discovery services is primarily generated from the following:


•	data hosting fees based on data stored and number of users;


•	fees for month-to-month delivery of services, such as data processing (conversion of data into organized, searchable electronic database), project management and data collection services;


•	document review services which assist clients in the manual review of data responsive to a legal matter; and


•	printing and binding services (paper-based services).

The Company’s discovery services arrangements do not include any substantive general rights of return or other contingencies.

Accounting fo Payments to Clients

Accounting for Payments to Clients

Deferred Revenue

Accounts Receivable

Concentration of Risk

Fair Value Measurements

Level 1 – Valuations based on quoted prices in active markets for identical assets or liabilities and readily accessible by the Company at the reporting date.

Level 3 – Valuations based on inputs that are unobservable.

Cash and Cash Equivalents

Short-Term Investments

Property and Equipment

Property and Equipment, Net

Internal-Use Software and Website Development Costs

Patent Assets, Net

In instances where the Company sells patent assets, the amount of consideration received is compared to the asset’s carrying value to determine and recognize a gain or loss

Impairment of Long-Lived Assets

Intangible Assets, Net

Impairment of Long-Lived Assets

Goodwill

Advertising Costs

The Company expenses advertising costs as they are incurred. Advertising expenses were not material for any period presented

Foreign Currency Accounting

Gains and losses from foreign currency transactions are recognized in other income (expense), net in the consolidated statements of operations.

Income Taxes

Stock-Based Compensation

Business Combinations

Reserves for Known and Incurred but not Reported Claims

Recently Adopted Accounting Standards

Recent Accounting Pronouncements

Revenue from Contracts with Customers

Revenue recognition related to the Company’s discovery services segment and its patent risk management insurance offering is not materially changed under ASC 606.

Net Income Available to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Basic and Diluted Net Income Per Share Available To Common Stockholders

The following table presents the calculation of basic and diluted net income (loss) per share (in thousands, except for per share data):



	Year Ended December 31,
	2017			2016		2015
Net income (loss) per share:
Numerator:
Net income (loss)	$	(79,143	)	$	18,235	$	39,422
Denominator:
Basic shares:
Weighted-average shares used in computing basic net income (loss) per share	49,240			50,462		54,432
Diluted shares:
Weighted-average shares used in computing basic net income (loss) per share	49,240			50,462		54,432
Dilutive effect of stock options and restricted stock units using treasury-stock method	—			539		978
Weighted-average shares used in computing diluted net income (loss) per share	49,240			51,001		55,410
Net income (loss) per share:
Basic	$	(1.61	)	$	0.36	$	0.72
Diluted	$	(1.61	)	$	0.36	$	0.71

Anti-Dilutive Securities Not Included In Diluted Shares Outstanding Calculation



	Year Ended December 31,
	2017	2016	2015
Weighted-average:
Stock options outstanding	901	—	663
Restricted stock units outstanding	740	2	263

Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of financial assets and liabilities measured at fair value on a recurring basis



	December 31, 2017
	Amortized Cost		Unrealized					Estimated Fair Value		Level 1		Level 2
	Amortized Cost		Gains		Losses			Estimated Fair Value		Level 1		Level 2
Cash equivalents:
Commercial paper	$	13,035	$	—	$	—		$	13,035	$	—	$	13,035
Corporate bonds	1,205		—		—			1,205		—		1,205
Money market funds	52,267		—		—			52,267		52,267		—
Municipal bonds	13,060		—		—			13,060		—		13,060
U.S. government and agency securities	13,101		—		—			13,101		—		13,101
	$	92,668	$	—	$	—		$	92,668	$	52,267	$	40,401
Short-term investments:
Commercial paper	$	1,994	$	—	$	—		$	1,994	$	—	$	1,994
Corporate bonds	3,074		—		(3		)	3,071		—		3,071
Municipal bonds	11,888		—		(3		)	11,885		—		11,885
U.S. government and agency securities	1,508		—		(3		)	1,505		—		1,505
	$	18,464	$	—	$	(9	)	$	18,455	$	—	$	18,455



	December 31, 2016
	Amortized Cost		Unrealized					Estimated Fair Value		Level 1		Level 2
	Amortized Cost		Gains		Losses			Estimated Fair Value		Level 1		Level 2
Cash equivalents:
Money market funds	$	30,286	$	—	$	—		$	30,286	$	30,286	$	—
Municipal bonds	3,070		—		—			3,070		—		3,070
	$	33,356	$	—	$	—		$	33,356	$	30,286	$	3,070
Short-term investments:
Commercial paper	$	4,296	$	—	$	(3	)	$	4,293	$	—	$	4,293
Corporate bonds	10,856		—		(13		)	10,843		—		10,843
Equity securities	123		—		(78		)	45		45		—
Municipal bonds	55,723		—		(65		)	55,658		—		55,658
U.S. government and agency securities	20,033		9		(4		)	20,038		20,038		—
	$	91,031	$	9	$	(163	)	$	90,877	$	20,083	$	70,794

Patent Assets, Net (Tables)

12 Months Ended

Dec. 31, 2017

Patent Assets [Abstract]

Patent Assets, Net

Patent assets, net consisted of the following (in thousands):



	December 31, 2016			Additions			Disposals			December 31, 2017
Patent assets	$	932,283		$	106,010		$	(7,857	)	$	1,030,436
Accumulated amortization	(719,284		)	(155,592		)	7,488			(867,388		)
Patent assets, net	$	212,999								$	163,048



	December 31, 2015			Additions			Disposals			December 31, 2016
Patent assets	$	824,258		$	117,457		$	(9,432	)	$	932,283
Accumulated amortization	(569,698		)	(158,814		)	9,228			(719,284		)
Patent assets, net	$	254,560								$	212,999

Expected Future Annual Amortization Of Patent Assets

s of December 31, 2017, the Company expects amortization expense in future periods to be as follows (in thousands):



2018	$	103,088
2019	48,232
2020	11,728
Total estimated future amortization expense	$	163,048

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2017

Property and Equipment, Net

Property And Equipment, Net

Property and equipment, net, consisted of the following (in thousands):



	December 31,
	2017			2016
Internal-use software	$	8,530		$	7,827
Leasehold improvements	2,098			2,169
Computer, equipment and software	5,960			5,204
Furniture and fixtures	755			935
Construction-in-progress	21			183
Total property and equipment, gross	17,364			16,318
Less: Accumulated depreciation and amortization	(12,274		)	(9,370		)
Total property and equipment, net	$	5,090		$	6,948

Business Combinations (Tables)

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Schedule of Business Acquisitions

The following table summarizes the cash paid and the estimated fair values of the assets and the liabilities assumed (in thousands) and the estimated useful lives of the acquired identifiable intangible assets:



	Estimated Fair Value			Estimated useful life
Current assets	$	19,357
Intangible assets:
Customer relationships	58,000			9 - 10 years
Trademarks	3,200			1 - 6 years
Developed technology	6,400			3 years
Goodwill	145,984
Property, plant, equipment and other long term assets	3,347
Deferred tax asset	10,595
Current liabilities	(7,280		)
Deferred tax liability	(5,477		)
Other long term liabilities	(826		)
Cash purchase consideration paid	$	233,300

Schedule of proforma information



	Year Ended December 31,
	2017			2016
Revenue	$	330,457		$	336,047
Net income (loss)	(79,143		)	18,824
Basic net income (loss) per share	(1.61		)	0.37
Diluted net income (loss) per share	(1.61		)	0.37

Goodwill (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill



	Patent Risk Management		Discovery Services			Total
Balance as of December 31, 2016	$	19,978	$	131,344		$	151,322
Impairment losses	—		(89,035		)	(89,035		)
Foreign currency translation adjustments	—		8,469			8,469
Balance as of December 31, 2017	$	19,978	$	50,778		$	70,756

The Company reviews goodwill for impairment annually or more frequently if events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. The Company performed its annual goodwill impairment test using a quantitative approach for its discovery services reporting units and a qualitative approach for its patent risk management business. The quantitative approach used for its discovery services segment includes comparing the carrying value to the fair values of each reporting unit using a discounted cash flow methodology with a comparable business approach which utilizes Level 3 inputs. Cash flow projections are based on management’s estimates of growth rates and operating margins, taking into consideration industry and market conditions. The discount rate used is based on the weighted-average cost of capital adjusted for the relevant risk associated with business-specific characteristics and the uncertainty related to the reporting units' ability to execute on the projected cash flows. These tests resulted in the carrying values of the discovery services reporting units exceeding the fair values primarily due to (1) decreased expected future cash flows from pricing pressures and competition in the discovery services marketplace as well as significant fluctuations due to the project-based nature of these cash flows, and (2) a decrease in estimated peer company values. As a result, the Company recognized a goodwill impairment loss of $89.0 million in its consolidated statement of operations during the year ended December 31, 2017. No other goodwill impairment charges were recorded as a part of the Company's annual impairment analyses.

Intangible Assets, Net (Tables)

12 Months Ended

Dec. 31, 2017

Acquired Finite-Lived Intangible Assets [Line Items]

Intangible Assets, Net

Intangible assets, net, as of December 31, 2017 and 2016 consisted of the following (in thousands, except years):



	December 31, 2017								December 31, 2016
	Weighted-Average Life (years)	Carrying Amount		Accumulated Amortization			Net Carrying Amount		Carrying Amount		Accumulated Amortization			Net Carrying Amount
Customer relationships	9.4	$	56,688	$	(11,764	)	$	44,924	$	55,719	$	(6,323	)	$	49,396
Trademarks	6.0	2,900		(938		)	1,962		4,879		(2,439		)	2,440
Developed technology	3.0	6,237		(4,036		)	2,201		5,802		(1,978		)	3,824
Covenant not to compete		—		—			—		1,900		(1,604		)	296
Proprietary data and models		—		—			—		2,100		(2,006		)	94
		$	65,825	$	(16,738	)	$	49,087	$	70,400	$	(14,350	)	$	56,050

Expected Future Annual Amortization Of Intangible Assets

s of December 31, 2017, the Company expects amortization expense in future periods to be as follows (in thousands):



2018	$	103,088
2019	48,232
2020	11,728
Total estimated future amortization expense	$	163,048

Intangible Assets Net

Acquired Finite-Lived Intangible Assets [Line Items]

Expected Future Annual Amortization Of Intangible Assets

(in thousands):



2018	$	8,562
2019	6,644
2020	6,523
2021	6,523
2022	6,069
Thereafter	14,766
Total estimated future amortization expense	$	49,087

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Aggregate Future Non-Cancelable Minimum Lease Payments For Operating Leases



2018	$	4,528
2019	3,619
2020	654
2021	227
2022	232
Thereafter	379
Future non-cancelable minimum operating lease payments	9,639
Less: minimum payments to be received from non-cancelable subleases	(2,202		)
Total future non-cancelable minimum operating lease payments, net	$	7,437

Stockholder's Equity (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Activity Under Equity Settled Award Plans And Related Information

A summary of the Company’s activity under its equity-settled award plans and related information is as follows (in thousands, except per share data and years):



			Options Outstanding
	Shares Available for Grant		Number of Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life in Years	Aggregate Intrinsic Value
Balance - December 31, 2016	3,586		1,768		$	11.63
Shares authorized	1,000		—		—
Options exercised	—		(690	)	8.64
Options forfeited	99		(99	)	16.16
Restricted stock units granted	(2,006	)	—		—
Restricted stock units forfeited	1,597		—		—
Restricted stock units withheld related to net share settlement of restricted stock units	452		—		—
Balance - December 31, 2017	4,728		979		13.29		2.6	$	2,396
Vested and exercisable - December 31, 2017			979		13.29		2.6	2,396
Vested and expected to vest - December 31, 2017			979		13.29		2.6	2,396

Restricted Stock Unit Activity

The summary of restricted stock unit activity, which includes PBRSUs, is as follows (in thousands, except per share data):



	Number of Shares		Weighted-Average Grant Date Fair Value		Aggregate Intrinsic Value
Non-vested units - December 31, 2016	3,424		$	11.53
Granted	2,006		11.86
Vested	(1,313	)	12.23
Forfeited	(1,597	)	10.73
Non-vested units - December 31, 2017	2,520		11.95		$	33,874

Weighted-Average Assumptions Used To Estimate The Fair Value Of PBRSUs



	Year Ended December 31,
	2017			2016			2015
Dividend yield	—			—			n/a
Risk free rate	1.03		%	1.08		%	n/a
Expected volatility	32		%	38		%	n/a
Grant date fair value	$	11.95		$	6.28		n/a

Stock repurchase activity

The purchase price for the repurchased shares are reflected as a reduction to common stock and retained earnings in the Company's consolidated balance sheet during the period presented as follows (in thousands, except per share data):



	Shares Repurchased	Average Price per Share		Value of Shares Repurchased
Cumulative shares repurchased as of January 1, 2017	7,917	$	10.90	$	86,276
Repurchase of shares of common stock	700	11.84		8,290
Cumulative shares repurchased as of December 31, 2017	8,617	$	10.97	$	94,566

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Before Income Tax Provision

Income or loss before provision for income tax consists of the following (in thousands):



	Year Ended December 31,
	2017			2016		2015
Domestic	$	(8,078	)	$	28,536	$	65,445
International	(50,987		)	3,773		54
Total income (loss) before provision for income taxes	$	(59,065	)	$	32,309	$	65,499

Components Of The Provision For Income Taxes

The components of the provision for income taxes are as follows (in thousands):



	Year Ended December 31,
	2017			2016			2015
Current:
Federal	$	3,886		$	(12,400	)	$	(23,456	)
State	207			(4,038		)	(2,790		)
Foreign	(9,743		)	(11,097		)	(12,406		)
Total current provision for income taxes	(5,650		)	(27,535		)	(38,652		)
Deferred:
Federal	(15,354		)	11,596			12,022
State	238			1,097			553
Foreign	688			768			—
Total deferred benefit (expense) for income taxes	(14,428		)	13,461			12,575
Total provision for income taxes	$	(20,078	)	$	(14,074	)	$	(26,077	)

Net Deferred Tax Liabilities

Net deferred tax assets consist of the following (in thousands):



	December 31,
	2017			2016
Deferred tax assets:
Deferred revenue	$	2,687		$	1,843
Reserves and other	4,016			6,292
Stock-based compensation	2,643			5,682
Depreciation and amortization	10,516			14,050
Net operating loss carryforwards	1,768			7,246
Foreign tax credits	1,095			—
Total deferred tax assets	22,725			35,113
Valuation allowance	(2,810		)	(875		)
Net deferred tax assets	$	19,915		$	34,238

Reconciliation Of The Statutory Federal Income Tax To Effective Tax

The following is a reconciliation of the statutory federal income tax to the Company’s effective tax (in thousands):



	Year Ended December 31,
	2017			2016			2015
Tax at statutory federal rate	$	(20,673	)	$	11,307		$	22,939
State tax – net of federal benefit	(1,649		)	1,674			1,459
Permanent differences	6,138			1,000			663
Foreign tax	27,164			8,969			12,370
Foreign tax credits	(7,571		)	(9,191		)	(12,370		)
Foreign income not taxed at federal rate	—			—			3
Change in valuation allowance	2,944			(222		)	1,097
Rate differential impact from Tax Cuts and Jobs Act	14,557			—			—
Other	(832		)	537			(84		)
Total provision for income taxes	$	20,078		$	14,074		$	26,077

Unrecognized Tax Benefits

The following table summarizes the activity related to the Company’s unrecognized tax benefits (in thousands):



	2017			2016			2015
Balance as of January 1,	$	8,300		$	5,315		$	3,707
Gross increase related to current period tax positions	597			1,567			1,606
Gross increase related to prior period tax positions	—			1,841			2
Gross decrease related to prior period tax positions	(1,236		)	(423		)	—
Balance as of December 31,	$	7,661		$	8,300		$	5,315

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

Summarized financial information by segment for the years ended December 31, 2017 and 2016 utilized by the Company's chief operating decision maker is as follows (in thousands):



	Year Ended December 31,
	2017		2016
Patent Risk Management
Revenue	$	252,253	$	266,995
Cost of revenue	161,409		163,865
Selling, general and administrative expenses	63,795		76,467
Adjusted operating income	27,049		26,663
Stock-based compensation, including related taxes	13,197		17,633
Depreciation and amortization	158,297		162,262
Adjusted EBITDA	$	198,543	$	206,558

Discovery Services
Revenue	$	78,204	$	66,112
Cost of revenue	42,300		33,397
Selling, general and administrative expenses	26,712		23,990
Adjusted operating income	9,192		8,725
Stock-based compensation, including related taxes	1,791		935
Depreciation and amortization	9,846		9,361
Adjusted EBITDA	$	20,829	$	19,021

Schedule of Revenue by Location

The following table presents revenue by location and revenue generated by country as a percentage of total revenue for the applicable period, for countries representing 10% or more of revenues for one or more of the periods presented (dollars in thousands):



	Year Ended December 31,
	2017				2016				2015
United States	$	196,454	59	%	$	194,196	58	%	$	186,439	64	%
Japan	34,844		11		37,200		11		36,195		12
Korea	18,414		6		25,288		8		28,319		10
Rest of world	80,745		24		76,423		23		40,928		14
Total revenue	$	330,457	100	%	$	333,107	100	%	$	291,881	100	%

Selected Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Information (Unaudited)

Summarized quarterly financial information for the years ended December 31, 2017 and 2016 is as follows (in thousands, except per share data):



	Three Months Ended
	March 31, 2017				June 30, 2017		September 30, 2017		December 31, 2017
Revenue	$	82,512			$	80,434	$	85,702	$	81,809
Cost of revenue	51,298				51,142		52,282		48,987
Selling, general and administrative expenses	21,121				23,124		22,517		23,745
Impairment losses⁽¹⁾	—			—	—		—		94,051
Operating income (loss)	10,093				6,168		10,903		(84,974		)
Interest and other income (expense), net ⁽²⁾	(533		)		427		88		(1,237		)
Income (loss) before provision for income taxes	9,560				6,595		10,991		(86,211		)
Provision for income taxes	3,567				2,403		4,625		9,483
Net income (loss)	$	5,993			$	4,192	$	6,366	$	(95,694	)

Net income (loss) per share⁽³⁾:
Basic	$	0.12			$	0.09	$	0.13	$	(1.93	)
Diluted	$	0.12			$	0.08	$	0.13	$	(1.93	)

Other Data:
Deferred revenue, including current portion	$	136,227			$	114,561	$	102,939	$	106,868
Stock-based compensation expense	$	2,734			$	4,343	$	3,798	$	3,724



	Three Months Ended
	March 31, 2016		June 30, 2016			September 30, 2016			December 31, 2016
Revenue	$	79,735	$	83,109		$	88,461		$	81,802
Cost of revenue	47,666		49,070			50,830			49,696
Selling, general and administrative expenses	26,895		25,904			23,615			24,043
Operating income	5,174		8,135			14,016			8,063
Interest and other income (expense), net ⁽²⁾	1,805		(1,549		)	(1,250		)	(2,085		)
Income before provision for income taxes	6,979		6,586			12,766			5,978
Provision for income taxes	2,742		2,436			4,651			4,245
Net income	$	4,237	$	4,150		$	8,115		$	1,733

Net income per share⁽³⁾:
Basic	$	0.08	$	0.08		$	0.16		$	0.04
Diluted	$	0.08	$	0.08		$	0.16		$	0.03

Other Data:
Deferred revenue, including current portion	$	139,992	$	123,133		$	102,691		$	130,408
Stock-based compensation expense	$	4,929	$	4,899		$	4,269		$	4,178

⁽²⁾See Note 12, "Commitments and Contingencies" and Note 11, "Debt" for further information regarding interest and other income (expense), net.

Basis of Presentation and Significant Accounting Policies - Narrative (Details)	3 Months Ended								12 Months Ended			114 Months Ended
	Dec. 31, 2017 USD ($) significant_client	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) significant_client	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) significant_client	Dec. 31, 2016 USD ($) significant_client	Dec. 31, 2015 USD ($) significant_client	Dec. 31, 2017 USD ($) significant_client
Basis of Presentation and Significant Accounting Polcies [Line Items]
Gain (Loss) on Sale of Investments									$ 0	$ (290,000)	$ (3,444,000)
Impairment losses									0	0	5,096,000
Revenue	$ 81,809,000	$ 85,702,000	$ 80,434,000	$ 82,512,000	$ 81,802,000	$ 88,461,000	$ 83,109,000	$ 79,735,000	$ 330,457,000	333,107,000	291,881,000
BESP 5pct of Revenue	0.00%								0.00%			0.00%
Allowance for doubtful accounts receivable	$ 600,000				900,000				$ 600,000	900,000		$ 600,000
Other-than-temporary impairment loss on investments											5,100,000
Capitalization of internal-use sofware and website development costs									800,000	1,300,000	2,300,000
Amortization of internal-use sofware and website development costs									1,400,000	1,500,000	1,100,000
Goodwill impairment loss									89,035,000
Pre-tax non-cash impairment loss	5,000,000
Fair value of cost method investments	600,000								600,000			600,000
Valuation allowance	2,810,000				875,000				2,810,000	875,000		$ 2,810,000
Cost of revenue	48,987,000	52,282,000	51,142,000	51,298,000	49,696,000	50,830,000	49,070,000	47,666,000	203,709,000	197,262,000	148,858,000
Selling, general and administrative expenses	$ 23,745,000	$ 22,517,000	$ 23,124,000	$ 21,121,000	$ 24,043,000	$ 23,615,000	$ 25,904,000	$ 26,895,000	$ 90,507,000	$ 100,457,000	$ 77,428,000
Accounts receivable
Basis of Presentation and Significant Accounting Polcies [Line Items]
Number of significant clients \| significant_client	2				1				2	1		2
Sales Revenue, Subscription Fee
Basis of Presentation and Significant Accounting Polcies [Line Items]
Number of significant clients \| significant_client	0				0				0	0	0	0
Client One \| Accounts receivable
Basis of Presentation and Significant Accounting Polcies [Line Items]
Concentration of credit risk, percentage									15.00%	39.00%
Client Two \| Accounts receivable
Basis of Presentation and Significant Accounting Polcies [Line Items]
Concentration of credit risk, percentage									11.00%
Internal-use software
Basis of Presentation and Significant Accounting Polcies [Line Items]
Patent assets, useful life									3 years
Weighted Average \| Patents
Basis of Presentation and Significant Accounting Polcies [Line Items]
Patent assets, useful life									25 months			38 months
Maximum
Basis of Presentation and Significant Accounting Polcies [Line Items]
Useful life of property, plant and equipment								5 years
Maximum \| Patents
Basis of Presentation and Significant Accounting Polcies [Line Items]
Patent assets, useful life									60 months
Minimum
Basis of Presentation and Significant Accounting Polcies [Line Items]
Useful life of property, plant and equipment								3 years
Minimum \| Patents
Basis of Presentation and Significant Accounting Polcies [Line Items]
Patent assets, useful life									24 months
Difference between Revenue Guidance in Effect before and after Topic 606 \| Accounting Standards Update 2014-09
Basis of Presentation and Significant Accounting Polcies [Line Items]
Revenue									$ 36,000,000	$ 23,000,000
Cost of revenue									27,000,000	32,000,000
Selling, general and administrative expenses									$ 1,000,000	$ 1,000,000

Net Income Available to Common Stockholders (Detail) - Basic and Diluted Net Income Per Share Available To Common Stockholders - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic:
Net income	$ (95,694)	$ 6,366	$ 4,192	$ 5,993	$ 1,733	$ 8,115	$ 4,150	$ 4,237	$ (79,143)	$ 18,235	$ 39,422
Basic shares:
Weighted-average shares used in computing basic net income available to common stockholders (shares)									49,240	50,462	54,432
Diluted shares:
Dilutive effect of stock options and restricted stock units using treasury-stock method									0	539	978
Weighted-average shares used in computing diluted net income available to common stockholders (shares)									49,240	51,001	55,410
Net income per common share available to common stockholders:
Basic (USD per share)	$ (1.93)	$ 0.13	$ 0.09	$ 0.12	$ 0.04	$ 0.16	$ 0.08	$ 0.08	$ (1.61)	$ 0.36	$ 0.72
Diluted (USD per share)	$ (1.93)	$ 0.13	$ 0.08	$ 0.12	$ 0.03	$ 0.16	$ 0.08	$ 0.08	$ (1.61)	$ 0.36	$ 0.71

Financial Instruments - Schedule of Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets:
Cash equivalents:	$ 92,668	$ 33,356
Short-term investments:
Short-term investments amortized cost	18,464	91,031
Short-term investments unrealized gains	0	9
Short-term investments unrealized losses	(9)	(163)
Estimated fair value	18,455	90,877
Level 1
Assets:
Cash equivalents:	52,267	30,286
Short-term investments:
Short-term investments fair value levels	0	20,083
Level 2
Assets:
Cash equivalents:	40,401	3,070
Short-term investments:
Short-term investments fair value levels	18,455	70,794
Commercial paper
Short-term investments:
Short-term investments amortized cost	1,994	4,296
Short-term investments unrealized gains	0	0
Short-term investments unrealized losses	0	(3)
Estimated fair value	1,994	4,293
Commercial paper \| Level 1
Short-term investments:
Short-term investments fair value levels	0	0
Commercial paper \| Level 2
Short-term investments:
Short-term investments fair value levels	1,994	4,293
Corporate bonds
Short-term investments:
Short-term investments amortized cost	3,074	10,856
Short-term investments unrealized gains	0	0
Short-term investments unrealized losses	(3)	(13)
Estimated fair value	3,071	10,843
Corporate bonds \| Level 1
Short-term investments:
Short-term investments fair value levels	0	0
Corporate bonds \| Level 2
Short-term investments:
Short-term investments fair value levels	3,071	10,843
Equity Securities
Short-term investments:
Short-term investments amortized cost		123
Short-term investments unrealized gains		0
Short-term investments unrealized losses		(78)
Estimated fair value		45
Equity Securities \| Level 1
Short-term investments:
Short-term investments fair value levels		45
Equity Securities \| Level 2
Short-term investments:
Short-term investments fair value levels		0
Municipal bonds
Short-term investments:
Short-term investments amortized cost	11,888	55,723
Short-term investments unrealized gains	0	0
Short-term investments unrealized losses	(3)	(65)
Estimated fair value	11,885	55,658
Municipal bonds \| Level 1
Short-term investments:
Short-term investments fair value levels	0	0
Municipal bonds \| Level 2
Short-term investments:
Short-term investments fair value levels	11,885	55,658
U.S. government and agency securities
Short-term investments:
Short-term investments amortized cost	1,508	20,033
Short-term investments unrealized gains	0	9
Short-term investments unrealized losses	(3)	(4)
Estimated fair value	1,505	20,038
U.S. government and agency securities \| Level 1
Short-term investments:
Short-term investments fair value levels	0	20,038
U.S. government and agency securities \| Level 2
Short-term investments:
Short-term investments fair value levels	1,505	0
Corporate bonds
Assets:
Cash equivalents:	1,205
Corporate bonds \| Level 1
Assets:
Cash equivalents:	0
Corporate bonds \| Level 2
Assets:
Cash equivalents:	1,205
US Government Agencies Debt Securities [Member]
Assets:
Cash equivalents:	13,101
US Government Agencies Debt Securities [Member] \| Level 1
Assets:
Cash equivalents:	0
US Government Agencies Debt Securities [Member] \| Level 2
Assets:
Cash equivalents:	13,101
Commercial paper
Assets:
Cash equivalents:	13,035
Commercial paper \| Level 1
Assets:
Cash equivalents:	0
Commercial paper \| Level 2
Assets:
Cash equivalents:	13,035
Municipal bonds
Assets:
Cash equivalents:	13,060	3,070
Municipal bonds \| Level 1
Assets:
Cash equivalents:	0	0
Municipal bonds \| Level 2
Assets:
Cash equivalents:	13,060	3,070
Money market funds
Assets:
Cash equivalents:	52,267	30,286
Money market funds \| Level 1
Assets:
Cash equivalents:	52,267	30,286
Money market funds \| Level 2
Assets:
Cash equivalents:	$ 0	$ 0

Financial Instruments - Narrative (Details) - USD ($)	12 Months Ended
Financial Instruments - Narrative (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized loss on exchange of short-term investments	$ 0	$ 290,000	$ 3,444,000
Impairment losses	$ 0	$ 0	$ 5,096,000
Percentage of marketable security investments that mature in one year	100.00%	96.00%
Percentage of marketable security investments that mature within one to five years	0.00%	4.00%
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period	1 year
Maturity period, year two through five	1 year
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period, year two through five	5 years

Patent Assets, Net (Detail) - USD ($) $ in Millions	12 Months Ended			114 Months Ended
Patent Assets, Net (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of patent assets	$ 8.9	$ 9.6	$ 1.7
Patents
Finite-Lived Intangible Assets [Line Items]
Amortization of patent assets	$ 156.0	$ 159.0	$ 142.4
Minimum \| Patents
Finite-Lived Intangible Assets [Line Items]
Patent assets, useful life	24 months
Maximum \| Patents
Finite-Lived Intangible Assets [Line Items]
Patent assets, useful life	60 months
Weighted Average \| Patents
Finite-Lived Intangible Assets [Line Items]
Patent assets, useful life	25 months			38 months

Patent Assets, Net (Detail) - Patent Assets, Net - USD ($) $ in Thousands	12 Months Ended	114 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Patent assets	$ (65,825)	$ (65,825)	$ (70,400)
Accumulated amortization	(16,738)	(16,738)	(14,350)
Patent assets, net	163,048	163,048	212,999
Patents
Finite-Lived Intangible Assets [Line Items]
Patent assets	(1,030,436)	(1,030,436)	(932,283)	$ (824,258)
Accumulated amortization	(867,388)	(867,388)	(719,284)	(569,698)
Patent assets, net	163,048	163,048	212,999	$ 254,560
Additions \| Patents
Finite-Lived Intangible Assets [Line Items]
Patent assets	(106,010)	(106,010)	(117,457)
Accumulated amortization	(155,592)	(155,592)	(158,814)
Dispositions \| Patents
Finite-Lived Intangible Assets [Line Items]
Patent assets	(7,857)	(7,857)	(9,432)
Accumulated amortization	$ (7,488)	$ (7,488)	$ (9,228)
Weighted Average \| Patents
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	25 months	38 months

Patent Assets, Net (Detail) - Expected Future Annual Amortization Expense Of Patent Assets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
2017	$ 8,562
2018	6,644
2019	6,523
2020	6,523
Total estimated future amortization expense	163,048	$ 212,999
Patents
Finite-Lived Intangible Assets [Line Items]
2017	103,088
2018	48,232
2019	11,728
Total estimated future amortization expense	$ 163,048	$ 212,999	$ 254,560

Property and Equipment, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 168,143	$ 171,623	$ 145,835
Property and equipment, types
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 3,300	$ 3,000	$ 1,700

Property and Equipment, Net (Detail) - Property And Equipment, Net - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 17,364	$ 16,318
Less: Accumulated depreciation and amortization	(12,274)	(9,370)
Total property and equipment, net	5,090	6,948
Internal-use software
Property, Plant and Equipment [Line Items]
Internal-use software	8,530	7,827
Leasehold improvements
Property, Plant and Equipment [Line Items]
Leasehold improvements	2,098	2,169
Computer, equipment and software
Property, Plant and Equipment [Line Items]
Computer, equipment and software	5,960	5,204
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Furniture and fixtures	755	935
Construction-in-progress
Property, Plant and Equipment [Line Items]
Construction-in-progress	$ 21	$ 183

Business Combinations - Narrative and Schedule of Business Acquisitions (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Jan. 22, 2016	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 70,756				$ 151,322				$ 70,756	$ 151,322
Cash purchase consideration paid	$ 232,000									0	228,452	$ 425
Revenue		81,809	$ 85,702	$ 80,434	$ 82,512	81,802	$ 88,461	$ 83,109	$ 79,735	330,457	333,107	291,881
Operating income (loss)		(84,974)	$ 10,903	$ 6,168	$ 10,093	8,063	$ 14,016	$ 8,135	$ 5,174	(57,810)	35,388	$ 66,187
Inventus Solutions Inc., Discovery Services
Business Acquisition [Line Items]
Current assets		19,357								19,357
Property, plant, equipment and other long term assets		3,347								3,347
Deferred tax asset		10,595								10,595
Current liabilities		(7,280)								(7,280)
Deferred tax liability		(5,477)								(5,477)
Other long term liabilities		(826)								(826)
Cash purchase consideration paid	$ 233,300
Inventus Solutions Inc., Discovery Services
Business Acquisition [Line Items]
Acquisition related costs										1,200
Revenue										78,204	66,112
Transaction costs		13,500								13,500
Inventus Solutions Inc., Discovery Services \| Operating Segments
Business Acquisition [Line Items]
Goodwill		50,778				$ 131,344				50,778	131,344
Operating income (loss)											$ 8,725
Goodwill from business acquisition										$ 145,984
Customer relationships
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life										9 years 5 months
Customer relationships \| Inventus Solutions Inc., Discovery Services
Business Acquisition [Line Items]
Intangible assets		58,000								$ 58,000
Trademarks
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life										6 years
Trademarks \| Inventus Solutions Inc., Discovery Services
Business Acquisition [Line Items]
Intangible assets		3,200								$ 3,200
Developed technology
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life										3 years
Developed technology \| Inventus Solutions Inc., Discovery Services
Business Acquisition [Line Items]
Intangible assets		$ 6,400								$ 6,400
Minimum \| Customer relationships
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life										9 years
Minimum \| Trademarks
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life										1 year
Maximum \| Customer relationships
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life										10 years
Maximum \| Trademarks
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life										6 years

Business Combinations - Schedule of Proforma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Document Fiscal Year Focus									2017
Operating income (loss)	$ (84,974)	$ 10,903	$ 6,168	$ 10,093	$ 8,063	$ 14,016	$ 8,135	$ 5,174	$ (57,810)	$ 35,388	$ 66,187
Revenue									330,457	336,047
Net income									$ (79,143)	$ 18,824
Pro forma earnings per share - basic (in usd per share)									$ (1.61)	$ 0.37
Pro forma earnings per share - diluted (in usd per share)									$ (1.61)	$ 0.37
Inventus Solutions Inc., Discovery Services
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Transaction costs	$ 13,500								$ 13,500

Business Combinations Business Combinations - Discovery Services (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition, Pro Forma Information
Revenue	$ 81,809	$ 85,702	$ 80,434	$ 82,512	$ 81,802	$ 88,461	$ 83,109	$ 79,735	$ 330,457	$ 333,107	$ 291,881
Cost of revenue	48,987	52,282	51,142	51,298	49,696	50,830	49,070	47,666	203,709	197,262	148,858
Selling, general and administrative expenses	23,745	22,517	23,124	21,121	24,043	23,615	25,904	26,895	90,507	100,457	77,428
Goodwill, Impairment Loss									89,035
Operating income (loss)	$ (84,974)	$ 10,903	$ 6,168	$ 10,093	$ 8,063	$ 14,016	$ 8,135	$ 5,174	(57,810)	35,388	$ 66,187
Inventus Solutions Inc., Discovery Services
Business Acquisition, Pro Forma Information
Revenue									$ 78,204	$ 66,112

Goodwill - Summary of Changes in Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Goodwill [Roll Forward]
Goodwill	$ 151,322
Impairment losses	(89,035)
Foreign currency translation adjustments	8,469
Goodwill	70,756
Operating Segments \| Inventus Solutions Inc., Discovery Services
Goodwill [Roll Forward]
Goodwill	131,344
Impairment losses	89,035
Foreign currency translation adjustments	8,469
Goodwill	50,778
Operating Segments \| Patent Risk Management
Goodwill [Roll Forward]
Goodwill	19,978
Impairment losses	0
Foreign currency translation adjustments	0
Goodwill	$ 19,978

Intangible Assets, Net - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 8.9	$ 9.6	$ 1.7

Intangible Assets, Net (Detail) - Intangible Assets, Net - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Carrying amount	$ 65,825	$ 70,400
Accumulated amortization	(16,738)	(14,350)
Net carrying amount	$ 49,087	56,050
Proprietary data and models
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life
Carrying amount	$ 0	2,100
Accumulated amortization	0	(2,006)
Net carrying amount	$ 0	94
Trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	6 years
Carrying amount	$ 2,900	4,879
Accumulated amortization	(938)	(2,439)
Net carrying amount	$ 1,962	2,440
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Carrying amount	$ 6,237	5,802
Accumulated amortization	(4,036)	(1,978)
Net carrying amount	$ 2,201	3,824
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	9 years 5 months
Carrying amount	$ 56,688	55,719
Accumulated amortization	(11,764)	(6,323)
Net carrying amount	$ 44,924	49,396
Covenant not to compete
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life
Carrying amount	$ 0	1,900
Accumulated amortization	0	(1,604)
Net carrying amount	$ 0	$ 296

Intangible Assets, Net (Detail) - Estimated Future Amortization Expenses For Intangible Assets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2017	$ 8,562
2018	6,644
2019	6,523
2020	6,523
2021	6,069
Thereafter	14,766
Total estimated future amortization expense	$ 49,087	$ 56,050

Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Accrued liabilities	$ 15,736	$ 16,798
Other current liabilities	1,485	1,484
Accrued payroll-related expenses
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Accrued liabilities	10,669	11,516
Accrued expenses
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Accrued liabilities	$ 5,067	$ 5,282

Debt (Details)	Feb. 26, 2016 USD ($)
Term Facility
Debt Instrument [Line Items]
Amount of credit facility	$ 100,000,000
Term of credit facility	5 years
Term Facility \| Base Rate \| Minimum
Debt Instrument [Line Items]
Percentage margin	1.25%
Term Facility \| Base Rate \| Maximum
Debt Instrument [Line Items]
Percentage margin	1.75%
Term Facility \| London Interbank Offered Rate (LIBOR) \| Minimum
Debt Instrument [Line Items]
Percentage margin	2.25%
Term Facility \| London Interbank Offered Rate (LIBOR) \| Maximum
Debt Instrument [Line Items]
Percentage margin	2.75%
Revolving Credit Facility
Debt Instrument [Line Items]
Amount of credit facility	$ 50,000,000
Term of credit facility	5 years
Revolving Credit Facility \| Minimum
Debt Instrument [Line Items]
Commitment fee on undrawn balances (as a percent)	0.35%
Revolving Credit Facility \| Maximum
Debt Instrument [Line Items]
Commitment fee on undrawn balances (as a percent)	0.45%

Commitments and Contingencies (Detail)	1 Months Ended	12 Months Ended
Commitments and Contingencies (Detail)	Jun. 30, 2017 ft²	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2013 ft²
Commitments and Contingencies Disclosure [Abstract]
Area of real estate property (in square feet) \| ft²					67,000
Reduction in area of real estate property (in square feet) \| ft²	18,000
Reduction of future operating lease commitments		$ 2,400,000
Estimated litigation liability		0
Reserves for known and incurred but not reported claims		1,100,000	$ 900,000
Operating Leases, Rent Expense, Net [Abstract]
Rent expense		6,000,000	5,900,000	$ 4,100,000
Sublease income		1,100,000	700,000	600,000
Rent expense, net of sublease income		$ 4,900,000	$ 5,200,000	$ 3,500,000

Commitments and Contingencies - Aggregate Future Non-Cancelable Minimum Lease Payments For Operating Leases (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2018	$ 4,528
2019	3,619
2020	654
2021	227
2022	232
Thereafter	379
Future non-cancelable minimum operating lease payments	9,639
Less: minimum payments to be received from non-cancelable subleases	(2,202)
Total future non-cancelable minimum operating lease payments, net	$ 7,437

Stockholder's Equity - Narrative (Detail) - USD ($)	3 Months Ended								12 Months Ended
Stockholder's Equity - Narrative (Detail) - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	Feb. 10, 2015	Aug. 31, 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized (in shares)	200,000,000				200,000,000				200,000,000	200,000,000
Common stock, par value per share (in dollars per share)	$ 0.0001				$ 0.0001				$ 0.0001	$ 0.0001
Preferred shares authorized (in shares)	10,000,000				10,000,000				10,000,000	10,000,000
Preferred stock par value per share (in dollars per share)	$ 0.0001				$ 0.0001				$ 0.0001	$ 0.0001
Additional shares of common stock reserved for issuance under the 2011 Plan (in shares)									1,000,000
Shares available for grant (shares)	4,728,000				3,586,000				4,728,000	3,586,000
Aggregate intrinsic value of stock options exercised									$ 2,800,000	$ 900,000	$ 6,800,000
Total fair value of stock options vested									0	1,300,000	3,300,000
Total fair value of RSUs vested									$ 16,600,000	$ 11,900,000	14,400,000
Shares withheld for tax withholdings (in shares)									451,770	418,201
Total payments for the employees’ minimum tax obligations to taxing authorities									$ 5,683,000	$ 4,185,000	$ 5,097,000
Stock-based compensation expense	$ 3,724,000	$ 3,798,000	$ 4,343,000	$ 2,734,000	$ 4,178,000	$ 4,269,000	$ 4,899,000	$ 4,929,000
Restricted stock units granted under equity award plans (in shares)									2,006,000
Stock Repurchase Program, Authorized Amount	150,000,000								$ 150,000,000				$ 75,000,000
Stock Repurchase Program, Increase in Authorized Amount								$ 25,000,000				$ 50,000,000
Stock Repurchased, Accumulated Value	94,566,000				$ 86,276,000				$ 94,566,000	$ 86,276,000
Dividends (USD per share)									$ 0.05	$ 0.00	$ 0.00
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense									$ 0	$ 900,000	$ 2,900,000
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested equity awards	$ 25,400,000								$ 25,400,000
Weighted-average service period of unrecognized compensation cost related to unvested equity awards									2 years 6 months
Performance-based restricted stock units with a market condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate									0.00%	0.00%
PBRSUs granted (in shares)									102,790	115,657	54,375
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate									1.03%	1.08%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate									32.00%	38.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value									$ 11.95	$ 6.28
PBRSUs and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense									$ 14,700,000	$ 17,500,000	$ 14,900,000
2011 and 2008 Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Grant Exercise Price, Percent of Fair Value									100.00%
2011 and 2008 Plan \| Incentive stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Grant Exercise Price, Percent of Fair Value									110.00%
Share-based Compensation Arrangement by Share-based Payment Award, Amount of Options Owned, Percent									10.00%
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)											1,500,000
Additional shares of common stock reserved for issuance under the 2011 Plan (in shares)									1,000,000	2,000,000
2008 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)														9,019,474
Newly hired employees \| 2011 and 2008 Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage									25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period									36 months
Newly hired employees \| 2011 and 2008 Plan \| Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage									25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period									3 years
Existing employees \| 2011 and 2008 Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period									48 months
Existing employees \| 2011 and 2008 Plan \| Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period									4 years
Existing employees \| 2011 and 2008 Plan \| Performance-based restricted stock units with a market condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage									25.00%
Maximum \| 2011 and 2008 Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Stock Options Exercise Period									10 years

Stockholder's Equity (Detail) - Activity Under Equity Award Plans And Related Information $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding (in shares)	3,586
Outstanding (in shares)	4,728
Outstanding (in shares)	1,768
Outstanding (in shares)	979
Outstanding (in dollars per share) \| $ / shares	$ 11.63
Outstanding (in dollars per share) \| $ / shares	$ 13.29
Shares authorized (in shares)	1,000
Options exercised (in shares)	(690)
Options exercised (in dollars per share) \| $ / shares	$ 8.64
Options forfeited (in shares)	(99)
Options forfeited (in shares)	(99)
Options forfeited (in dollars per share) \| $ / shares	$ 16.16
Restricted stock units granted (in shares)	(2,006)
Restricted stock units forfeited (in shares)	1,597
Outstanding (weighted-average contractual life)	2 years 7 months
Outstanding (intrinsic value) \| $	$ 2,396
Vested and exercisable
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested and exercisable (shares)	979
Vested and exercisable (in dollars per share) \| $ / shares	$ 13.29
Vested and exercisable (weighted-average contractual life)	2 years 7 months
Vested and exercisable (intrinsic value) \| $	$ 2,396
Vested and expected to vest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested and expected to vest (shares)	979
Vested and expected to vest (in dollars per share) \| $ / shares	$ 13.29
Vested and expected to vest (weighted-average contractual life)	2 years 7 months
Vested and expected to vest (intrinsic value) \| $	$ 2,396

Stockholder's Equity (Detail) - Restricted Stock Unit Activity - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested units (in shares)	3,424,000
Non-vested units (in dollars per share)	$ 11.53
Granted (in shares)	2,006,000
Forfeited (in shares)	(1,597,000)
Non-vested units (in shares)	2,520,000	3,424,000
Non-vested units (in dollars per share)	$ 11.95	$ 11.53
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, intrinsic value	$ 33,874
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	102,790	115,657	54,375
Restricted stock units granted
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	2,006,000
Granted (in dollars per share)	$ 11.86
Restricted stock units vested
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested (in shares)	(1,313,000)
Vested (in dollars per share)	$ 12.23
Restricted stock units forfeited
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Forfeited (in shares)	(1,597,000)
Forfeited (in dollars per share)	$ 10.73

Stockholder's Equity (Detail) - Weighted Average Assumptions To Estimate The Fair Value Of Equity Awards - Performance-based restricted stock units with a market condition - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%
Risk-free rate	1.03%	1.08%
Expected volatility	32.00%	38.00%
Grant date fair value	$ 11.95	$ 6.28

Stockholder's Equity Stockholder's Equity (Detail) - Share Repurchase - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Share Repurchase Utilized	8,617	7,917
Stock Repurchased, Accumulated, Weighted Average Price	$ 10.97	$ 10.90
Stock Repurchased, Accumulated Value	$ 94,566	$ 86,276
Stock Repurchased and Retired During Period, Shares	700
Stock Repurchased During Period Weighted Average Price	$ 11.84
Stock Repurchased During Period, Value	$ 8,290	$ 60,101	$ 26,175

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Net capital loss carryforwards	$ 6,500
Net operating loss carryforwards	18,900
Increase in deferred tax asset resulting from TCJA	14,400
Decrease in deferred tax asset valuation allowance resulting from TCJA	1,000
Increase in deferred tax asset resulting from TCJA, net of valuation allowance	13,400
Transition tax on accumulated foreign earnings related to the TCJA	1,100
Increase (decrease) in valuation allowance of deferred tax asset excluding effects of TCJA	1,935
Unrecognized tax benefits	7,661	$ 8,300	$ 5,315	$ 3,707
Interest and penalties associated with unrecognized tax benefits	$ 100	$ 600	$ 400

Income Taxes (Details) - Income Before Income Tax Provision - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic									$ (8,078)	$ 28,536	$ 65,445
International									(50,987)	3,773	54
Total income before income tax provision	$ (86,211)	$ 10,991	$ 6,595	$ 9,560	$ 5,978	$ 12,766	$ 6,586	$ 6,979	$ (59,065)	$ 32,309	$ 65,499

Income Taxes (Details) - Components Of The Provision For Income Taxes - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Federal									$ 3,886	$ (12,400)	$ (23,456)
State									207	(4,038)	(2,790)
Foreign									(9,743)	(11,097)	(12,406)
Total current provision for income taxes									(5,650)	(27,535)	(38,652)
Deferred
Federal									(15,354)	11,596	12,022
State									238	1,097	553
Deferred Foreign Income Tax Expense (Benefit)									688	768	0
Total deferred provision for income taxes									(14,428)	13,461	12,575
Income Tax Expense (Benefit)	$ (9,483)	$ (4,625)	$ (2,403)	$ (3,567)	$ (4,245)	$ (4,651)	$ (2,436)	$ (2,742)	$ (20,078)	$ (14,074)	$ (26,077)

Income Taxes Income Taxes (Details) - Net Deferred Tax Liabilities - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Deferred revenue	$ 2,687	$ 1,843
Reserves and other	4,016	6,292
Stock-based compensation	2,643	5,682
Deferred Tax Assets, Goodwill and Intangible Assets	10,516	14,050
Operating Loss Carryforwards	1,768	7,246
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	1,095	0
Total deferred tax assets	22,725	35,113
Valuation allowance	(2,810)	(875)
Net deferred tax assets	$ 19,915	$ 34,238

Income Taxes Income Taxes (Details) - Reconciliation Of The Statutory Federal Income Tax To The Effective Tax - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax at statutory federal rate									$ 20,673	$ 11,307	$ 22,939
State tax - net of federal benefit									1,649	1,674	1,459
Permanent differences									6,138	1,000	663
Foreign tax									27,164	8,969	12,370
Foreign tax credits									(7,571)	(9,191)	(12,370)
Foreign income not taxed at federal rate									0	0	3
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount									(2,944)	(222)	(1,097)
Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Income Tax Expense (Benefit)									14,557	0	0
Other									832	537	84
Income Tax Expense (Benefit)	$ (9,483)	$ (4,625)	$ (2,403)	$ (3,567)	$ (4,245)	$ (4,651)	$ (2,436)	$ (2,742)	$ (20,078)	$ (14,074)	$ (26,077)

Income Taxes Income Taxes (Details) - Unrecognized Tax Benefits - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Balance as of January 1,		$ 8,300	$ 5,315	$ 3,707
Gross increase related to current period tax positions		597	1,567	1,606
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	$ 0		1,841	2
Gross decrease related to prior period tax positions	$ (1,236)		(423)	0
Balance as of December 31,		$ 7,661	$ 8,300	$ 5,315

Related-Party Transactions (Detail) $ in Millions	12 Months Ended
Related-Party Transactions (Detail) $ in Millions	Dec. 31, 2017 USD ($) board_member	Dec. 31, 2016 USD ($) board_member	Dec. 31, 2015 USD ($) board_member
Related Party Transactions [Abstract]
Number of Directors that also served on client boards \| board_member	3	4	4
Revenue	$ 7.4	$ 9.8	$ 9.3
Selling, general and administrative expenses	0.5	0.8	$ 0.3
Receivables due from related parties	$ 1.5	$ 1.3

Segment Reporting (Detail) $ in Thousands	3 Months Ended								12 Months Ended
Segment Reporting (Detail) $ in Thousands	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments									2
Revenue	$ 81,809	$ 85,702	$ 80,434	$ 82,512	$ 81,802	$ 88,461	$ 83,109	$ 79,735	$ 330,457	$ 333,107	$ 291,881
Cost of revenue	48,987	52,282	51,142	51,298	49,696	50,830	49,070	47,666	203,709	197,262	148,858
Selling, general and administrative expenses	$ 23,745	$ 22,517	$ 23,124	$ 21,121	$ 24,043	$ 23,615	$ 25,904	$ 26,895	90,507	100,457	77,428
Adjusted operating income									36,241	35,388
Depreciation and amortization expense									168,143	171,623	$ 145,835
Inventus Solutions Inc., Discovery Services
Segment Reporting Information [Line Items]
Revenue									78,204	66,112
Adjusted operating income									9,192	8,725
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA									219,372	225,579
Operating Segments \| Inventus Solutions Inc., Discovery Services
Segment Reporting Information [Line Items]
Cost of revenue									42,300	33,397
Selling, general and administrative expenses									26,712	23,990
Allocated Share-based Compensation Expense, Net of Tax									1,791	935
Depreciation and amortization expense									9,846	9,361
Adjusted EBITDA									20,829	19,021
Operating Segments \| Patent Risk Management
Segment Reporting Information [Line Items]
Revenue									252,253	266,995
Cost of revenue									161,409	163,865
Selling, general and administrative expenses									63,795	76,467
Adjusted operating income									27,049	26,663
Allocated Share-based Compensation Expense, Net of Tax									13,197	17,633
Depreciation and amortization expense									158,297	162,262
Adjusted EBITDA									$ 198,543	$ 206,558

Segment Reporting - Subtotal Segment Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Depreciation and amortization expense									$ (168,143)	$ (171,623)	$ (145,835)
Stock-based Compensation, including payroll taxes									(14,988)	(18,568)
Asset Impairment Charges	$ (94,051)								(94,051)	0	0
Nonoperating Income (Expense)									(1,255)	(3,079)	(688)
Income Tax Expense (Benefit)	(9,483)	$ (4,625)	$ (2,403)	$ (3,567)	$ (4,245)	$ (4,651)	$ (2,436)	$ (2,742)	(20,078)	(14,074)	(26,077)
Net income (loss)	(95,694)	6,366	4,192	5,993	1,733	8,115	4,150	4,237	(79,143)	18,235	39,422
Subtotal segment adjusted operating income									36,241	35,388
Operating income (loss)	$ (84,974)	$ 10,903	$ 6,168	$ 10,093	$ 8,063	$ 14,016	$ 8,135	$ 5,174	(57,810)	35,388	66,187
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA									219,372	225,579
Retained Earnings
Segment Reporting Information [Line Items]
Net income (loss)									$ (79,143)	$ 18,235	$ 39,422

Segment Reporting - Revenue By Location (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue	$ 81,809	$ 85,702	$ 80,434	$ 82,512	$ 81,802	$ 88,461	$ 83,109	$ 79,735	$ 330,457	$ 333,107	$ 291,881
Total revenue (in dollars)	$ 81,809	$ 85,702	$ 80,434	$ 82,512	$ 81,802	$ 88,461	$ 83,109	$ 79,735	$ 330,457	$ 333,107	$ 291,881
Total revenue									100.00%	100.00%	100.00%
United States
Revenue									$ 196,454	$ 194,196	$ 186,439
United States									59.00%	58.00%	64.00%
Total revenue (in dollars)									$ 196,454	$ 194,196	$ 186,439
Japan
Revenue									$ 18,414	$ 25,288	$ 28,319
United States										11.00%	12.00%
Other foreign country									11.00%
Total revenue (in dollars)									$ 18,414	$ 25,288	$ 28,319
Korea
Revenue									$ 34,844	$ 37,200	$ 36,195
Other foreign country									6.00%	8.00%	10.00%
Total revenue (in dollars)									$ 34,844	$ 37,200	$ 36,195
Rest of world
Revenue									$ 80,745	$ 76,423	$ 40,928
Other foreign country									24.00%	23.00%	14.00%
Total revenue (in dollars)									$ 80,745	$ 76,423	$ 40,928

Segment Reporting Total Assets by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Assets	$ 550,830	$ 735,289
Operating Segments \| Inventus Solutions Inc., Discovery Services
Segment Reporting Information [Line Items]
Assets	162,271	233,749
Operating Segments \| Patent Risk Management
Segment Reporting Information [Line Items]
Assets	$ 388,559	$ 501,540

Selected Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 81,809	$ 85,702	$ 80,434	$ 82,512	$ 81,802	$ 88,461	$ 83,109	$ 79,735	$ 330,457	$ 333,107	$ 291,881
Cost of revenue	48,987	52,282	51,142	51,298	49,696	50,830	49,070	47,666	203,709	197,262	148,858
Selling, general and administrative expenses	23,745	22,517	23,124	21,121	24,043	23,615	25,904	26,895	90,507	100,457	77,428
Impairment losses	94,051								94,051	0	0
Operating income (loss)	(84,974)	10,903	6,168	10,093	8,063	14,016	8,135	5,174	(57,810)	35,388	66,187
Interest and other income (expense), net	(1,237)	88	427	(533)	(2,085)	(1,250)	(1,549)	1,805	2,222	(570)	(1,428)
Income (loss) before provision for income taxes	(86,211)	10,991	6,595	9,560	5,978	12,766	6,586	6,979	(59,065)	32,309	65,499
Provision for income taxes	9,483	4,625	2,403	3,567	4,245	4,651	2,436	2,742	20,078	14,074	26,077
Net income (loss)	$ (95,694)	$ 6,366	$ 4,192	$ 5,993	$ 1,733	$ 8,115	$ 4,150	$ 4,237	$ (79,143)	$ 18,235	$ 39,422
Net income available to common stockholders per common share(1):
Basic (USD per share)	$ (1.93)	$ 0.13	$ 0.09	$ 0.12	$ 0.04	$ 0.16	$ 0.08	$ 0.08	$ (1.61)	$ 0.36	$ 0.72
Diluted (USD per share)	$ (1.93)	$ 0.13	$ 0.08	$ 0.12	$ 0.03	$ 0.16	$ 0.08	$ 0.08	$ (1.61)	$ 0.36	$ 0.71
Other Data:
Deferred revenue, including current portion	$ 106,868				$ 130,408				$ 106,868	$ 130,408		$ 102,939	$ 114,561	$ 136,227	$ 102,691	$ 123,133	$ 139,992
Stock-based compensation expense	$ 3,724	$ 3,798	$ 4,343	$ 2,734	$ 4,178	$ 4,269	$ 4,899	$ 4,929

Debt (Tables)	12 Months Ended
Debt (Tables)	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of repayments of principal	.