InterDigital (IDCC) 10-Q 1 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	INTERDIGITAL, INC.
Entity Central Index Key	1,405,495
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		33,842,244
Entity Small Business	false
Entity Emerging Growth Company	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 508,829	$ 433,014
Short-term investments	549,521	724,981
Accounts receivable, less allowances of $456	29,769	216,293
Prepaid and other current assets	102,793	21,506
Total current assets	1,190,912	1,395,794
NON-CURRENT ASSETS:
PROPERTY AND EQUIPMENT, NET	10,278	10,673
PATENTS, NET	462,965	325,408
DEFERRED TAX ASSETS	60,056	84,582
OTHER NON-CURRENT ASSETS	63,877	37,963
Total non-current assets	597,176	458,626
TOTAL ASSETS	1,788,088	1,854,420
CURRENT LIABILITIES:
Accounts payable	17,528	10,260
Accrued compensation and related expenses	19,384	24,571
Deferred revenue	134,197	307,142
Taxes payable	98,022	14,881
Dividends payable	11,996	12,156
Other accrued expenses	12,425	7,431
Total current liabilities	293,552	376,441
NON-CURRENT LIABILITIES
LONG-TERM DEBT	313,527	285,126
LONG-TERM DEFERRED REVENUE	135,465	309,671
OTHER LONG-TERM LIABILITIES	30,495	10,034
TOTAL LIABILITIES	773,039	981,272
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY:
Preferred Stock, $0.10 par value, 14,399 shares authorized, 0 shares issued and outstanding	0	0
Common Stock, $0.01 par value, 100,000 shares authorized, 71,117 and 70,749 shares issued and 34,442 and 34,622 shares outstanding	711	707
Additional paid-in capital	683,140	680,040
Retained earnings	1,436,171	1,249,091
Accumulated other comprehensive loss	(3,436)	(2,083)
TOTAL SHAREHOLDERS’ EQUITY	2,116,586	1,927,755
Treasury stock, 36,675 and 36,127 shares of common held at cost	1,115,995	1,072,488
Total InterDigital, Inc. shareholders’ equity	1,000,591	855,267
Noncontrolling interest	14,458	17,881
Total equity	1,015,049	873,148
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 1,788,088	$ 1,854,420

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 456	$ 456
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	71,117,000	70,749,000
Common stock, shares outstanding	34,442,000	34,622,000
Preferred stock, par value (in usd per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized	14,399,000	14,399,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Treasury stock, shares	36,675,000	36,127,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
REVENUES	$ 75,079	$ 97,325	$ 232,078	$ 327,634
OPERATING EXPENSES:
Patent administration and licensing	32,077	26,517	85,480	76,629
Development	17,276	17,293	49,279	56,172
Selling, general and administrative	12,806	12,640	38,569	39,042
Total Operating Expenses	62,159	56,450	173,328	171,843
Income from operations	12,920	40,875	58,750	155,791
OTHER EXPENSE (NET)	(13,953)	(2,187)	(25,136)	(7,331)
Income (loss) before income taxes	(1,033)	38,688	33,614	148,460
INCOME TAX BENEFIT (PROVISION)	21,143	(3,963)	25,001	(29,413)
NET INCOME	20,110	34,725	58,615	119,047
Net loss attributable to noncontrolling interest	(1,297)	(811)	(3,423)	(2,744)
NET INCOME ATTRIBUTABLE TO INTERDIGITAL, INC.	$ 21,407	$ 35,536	$ 62,038	$ 121,791
NET INCOME PER COMMON SHARE — BASIC (in usd per share)	$ 0.62	$ 1.02	$ 1.79	$ 3.52
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING — BASIC (in shares)	34,651	34,709	34,687	34,589
NET INCOME PER COMMON SHARE — DILUTED (in usd per share)	$ 0.60	$ 1	$ 1.74	$ 3.40
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING — DILUTED (in shares)	35,607	35,388	35,614	35,865
CASH DIVIDENDS DECLARED PER COMMON SHARE (in usd per share)	$ 0.35	$ 0.35	$ 1.05	$ 0.95
Patent licensing royalties
REVENUES	$ 74,045	$ 92,566	$ 230,018	$ 314,113
Technology solutions
REVENUES	$ 1,034	$ 4,759	$ 2,060	$ 13,521

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 20,110	$ 34,725	$ 58,615	$ 119,047
Unrealized (loss) gain on investments, net of tax	467	(94)	(904)	(181)
Comprehensive income	20,577	34,631	57,711	118,866
Comprehensive loss attributable to noncontrolling interest	(1,297)	(811)	(3,423)	(2,744)
Total comprehensive income attributable to InterDigital, Inc.	$ 21,874	$ 35,442	$ 61,134	$ 121,610

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 58,615	$ 119,047
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	47,024	42,809
Non-cash interest expense	10,684	9,753
Change in deferred revenue	9,822	90,056
Deferred income taxes	(27,673)	(7,853)
Share-based compensation	4,875	13,901
Loss on disposal of assets	8,176	0
Other	198	(4)
(Increase) decrease in assets:
Receivables	36,861	(171,662)
Deferred charges and other assets	(63,783)	(13,316)
Increase (decrease) in liabilities:
Accounts payable	5,640	(3,198)
Accrued compensation and other expenses	(5,618)	(1,798)
Accrued taxes payable and other tax contingencies	91,796	20,606
Net cash provided by operating activities	176,617	98,341
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of short-term investments	(142,562)	(813,267)
Sales of short-term investments	317,447	678,119
Purchases of property and equipment	(1,882)	(942)
Capitalized patent costs	(23,845)	(26,306)
Acquisition of patents	(2,250)	0
Acquisition of business, net of cash acquired	(142,985)	0
Long-term investments	(6,686)	(3,201)
Net cash used in investing activities	(2,763)	(165,597)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from exercise of stock options	6,362	82
Dividends paid	(36,472)	(31,107)
Taxes withheld upon restricted stock unit vestings	(8,479)	(22,236)
Repurchase of common stock	(43,508)	0
Net cash used in financing activities	(82,097)	(53,261)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	91,757	(120,517)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD	433,014	404,074
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF PERIOD	524,771	283,557
Interest paid	4,740	4,740
Income taxes paid, including foreign withholding taxes	24,459	29,173
Dividends payable	11,996	12,149
Non-cash acquisition of patents	0	12,800
Accrued capitalized patent costs, property and equipment, and acquisition of patents	$ (1,513)	$ (548)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	BASIS OF PRESENTATION In the opinion of management, the accompanying unaudited, condensed consolidated financial statements contain all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the financial position of InterDigital, Inc. (individually and/or collectively with its subsidiaries referred to as “InterDigital,” the “Company,” “we,” “us” or “our,” unless otherwise indicated) as of September 30, 2018 , and the results of our operations for the three and nine months ended September 30, 2018 and 2017 and our cash flows for the nine months ended September 30, 2018 and 2017 . The accompanying unaudited, condensed consolidated financial statements have been prepared in accordance with the instructions for Form 10-Q and, accordingly, do not include all of the detailed schedules, information and notes necessary to state fairly the financial condition, results of operations and cash flows in conformity with United States generally accepted accounting principles (“GAAP”). The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP for year-end financial statements. Therefore, these financial statements should be read in conjunction with the financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 (our “ 2017 Form 10-K ”) as filed with the Securities and Exchange Commission (“SEC”) on February 22, 2018. The results of operations for interim periods are not necessarily indicative of the results to be expected for the entire year. We have one reportable segment. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities as of the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. Change in Accounting Policies There have been no material changes or updates to our existing accounting policies from the disclosures included in our 2017 Form 10-K , except as indicated in the following footnotes: • Note 1 - Basis of Presentation; and • Note 9 - Business Combinations. Reclassifications Certain reclassifications have been made to prior year amounts to conform to the current year presentation. New Accounting Guidance Accounting Standards Update: Revenue Recognition In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, "Revenue from Contracts with Customers (Topic 606)" ("ASC 606") which superseded most prior revenue recognition guidance, including industry-specific guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from an entity’s contracts with customers. We adopted the requirements of the new standard as of January 1, 2018 using the modified retrospective transition method applied to those contracts that were not completed as of January 1, 2018. Accordingly, all periods prior to January 1, 2018 are presented in accordance with ASC Topic 605, "Revenue Recognition" (“ASC 605”). The adoption of the new guidance affected our recognition of revenue from both our fixed-fee and per-unit license agreements. For accounting purposes under this new guidance, we separate our fixed-fee license agreements into two categories: (i) those agreements that provide rights, over the term of the license, to future technologies that are highly interdependent or highly interrelated to the technologies provided at the inception of the agreement (“Dynamic Fixed-Fee Agreements”) and (ii) those agreements that do not provide for rights to such future technologies (“Static Fixed-Fee Agreements”). Under our previous accounting practices, after the fair value allocation between the past and future components of the agreement, we recognized the future components of revenue from all fixed-fee license agreements on a straight-line basis over the term of the related license agreement. As a result of our adoption of the new guidance, we will continue to recognize revenue from Dynamic Fixed-Fee Agreements on a straight-line basis over the term of the related license agreement, while we expect to recognize most or all of the revenue from Static Fixed-Fee Agreements in the quarter the license agreement is signed. We will not recognize any ongoing revenue from Static Fixed-Fee Agreements already in existence at the time the guidance was adopted. Additionally, in the event a significant financing component is determined to exist in any of our agreements, we will recognize more or less revenue and corresponding interest expense or income, as appropriate. In addition, under our previous accounting practices, we recognized revenue from our per-unit license agreements in the period in which we received the related royalty report, generally one quarter in arrears from the period in which the underlying sales occurred (i.e. on a "quarter-lag"). We are now required to record per-unit royalty revenue in the same period in which the licensee’s underlying sales occur. Because we generally do not receive the per-unit licensee royalty reports for sales during a given quarter within the time frame necessary to adequately review the reports and include the actual amounts in our quarterly results for such quarter, we accrue the related revenue based on estimates of our licensees’ underlying sales, subject to certain constraints on our ability to estimate such amounts. As a result of accruing revenue for the quarter based on such estimates, adjustments will be required in the following quarter to true-up revenue to the actual amounts reported by our licensees. In addition, to the extent we receive non-refundable prepayments related to per-unit license agreements that do not provide rights over the term of the license to future technologies that are highly interdependent or highly interrelated to the technologies provided at the inception of the agreement, we will recognize such prepayments as revenue in the period in which all remaining revenue recognition criteria have been met. Finally, under our previous accounting practices, we established a receivable, and any related deferred tax asset for foreign withholding taxes, for payments expected to be received within twelve months from the balance sheet date, based on the terms of the license agreement. Our reporting of such payments resulted in increases to: accounts receivable and deferred revenue; and deferred tax assets and taxes payable. Under ASC 606, we will only recognize those amounts as they become due. Timing of revenue recognition may differ significantly from the timing of invoicing to customers. Contract assets are included in accounts receivable and represent unbilled amounts expected to be received from customers in future periods, where the revenue recognized to date (or cumulative adjustments to retained earnings in the initial period of adopting ASC 606) exceeds the amount billed, and right to payment is subject to the underlying contractual terms. Contract assets are classified as long-term assets if the payments are expected to be received more than one year from the reporting date. See below for a summary of adjustments related to our adoption of ASC 606. Amounts are in thousands. December 31, 2017 Static Fixed-Fee Agreements Static Prepayments Elimination of Quarter-Lag Reporting Significant Financing Component Related Tax Effects and Other Balance Sheet Impacts Total Adjustments January 1, 2018 Accounts Receivable $ 216,293 $ 6,000 $ — $ 10,948 $ — $ (171,727 ) $ (154,779 ) $ 61,514 Deferred Tax Assets 84,582 — — — — (52,199 ) (52,199 ) 32,383 Taxes Payable (14,881 ) — — — — 8,655 8,655 (6,226 ) Deferred Revenue (616,813 ) 99,466 85,146 — 3,235 171,727 359,574 (257,239 ) Retained Earnings (1,249,091 ) (105,466 ) (85,146 ) (10,948 ) (3,235 ) 43,544 (161,251 ) (1,410,342 ) Disaggregated Revenue The following tables present the disaggregation of our revenue for the three and nine months ended September 30, 2018 under ASC 606. Revenues for the three and nine months ended September 30, 2017 are presented in accordance with ASC 605. Amounts are in thousands. For the Three Months Ended September 30, 2018 2017 Increase/(Decrease) Variable patent royalty revenue $ 13,645 $ 10,081 $ 3,564 35 % Fixed-fee royalty revenue 60,272 73,653 (13,381 ) (18 )% Current patent royalties a 73,917 83,734 (9,817 ) (12 )% Non-current patent royalties b 128 8,832 (8,704 ) (99 )% Total patent royalties 74,045 92,566 (18,521 ) (20 )% Current technology solutions revenue a 1,034 4,759 (3,725 ) (78 )% Total revenue $ 75,079 $ 97,325 $ (22,246 ) (23 )% For the Nine Months Ended September 30, 2018 2017 Increase/(Decrease) Variable patent royalty revenue $ 26,322 $ 37,338 $ (11,016 ) (30 )% Fixed-fee royalty revenue 178,207 220,083 (41,876 ) (19 )% Current patent royalties a 204,529 257,421 (52,892 ) (21 )% Non-current patent royalties b 25,489 56,692 (31,203 ) (55 )% Total patent royalties 230,018 314,113 (84,095 ) (27 )% Current technology solutions revenue a 2,060 13,521 (11,461 ) (85 )% Total revenue $ 232,078 $ 327,634 $ (95,556 ) (29 )% a. Recurring revenues consist of current patent royalties, inclusive of Dynamic Fixed-Fee Agreement royalties, and current technology solutions revenue. b. Non-current patent royalties for the three and nine months ended September 30, 2018 consist of past patent royalties and royalties from static agreements. For the three and nine months ended September 30, 2017, non-current patent royalties consist of past patent royalties. During first nine months 2018 , we recognized $54.1 million of revenue that had been included in deferred revenue as of the beginning of the period. Additionally, upon adoption of ASC 606 on January 1, 2018, we had $24.7 million of contract assets. As of September 30, 2018 , we had contract assets of $22.0 million and $5.5 million included within accounts receivable and other non-current assets, respectively. Impact of Adoption of ASC 606 In accordance with the new revenue standard requirements, the disclosure of the impact of adoption on our condensed current period consolidated income statement and balance sheet is presented below. We believe this additional information is vital during the transition year to allow readers of our financial statements to compare financial results from the preceding financial year given the absence of restatement of the prior period. The adoption of ASC 606 did not affect our reported total amounts of cash flows from operating, investing and financing activities. Amounts contained in the tables below are in thousands, except per share data. For the Three Months Ended September 30, 2018 2017 As Reported ASC 606 Adjustment ASC 605 As Reported (ASC 605) REVENUES: Variable patent royalty revenue $ 13,645 $ (5,242 ) $ 8,403 $ 10,081 Fixed-fee royalty revenue 60,272 20,309 80,581 73,653 Current patent royalties 73,917 15,067 88,984 83,734 Non-current patent royalties 128 — 128 8,832 Total patent royalties 74,045 15,067 89,112 92,566 Current technology solutions revenue 1,034 1,197 2,231 4,759 $ 75,079 $ 16,264 $ 91,343 $ 97,325 OPERATING EXPENSES: 62,159 — 62,159 56,450 Income from operations 12,920 16,264 29,184 40,875 OTHER EXPENSE (NET) (13,953 ) 3,993 (9,960 ) (2,187 ) Income before income taxes (1,033 ) 20,257 19,224 38,688 INCOME TAX BENEFIT (EXPENSE) 21,143 (6,676 ) 14,467 (3,963 ) NET INCOME $ 20,110 $ 13,581 $ 33,691 $ 34,725 Net loss attributable to noncontrolling interest (1,297 ) — (1,297 ) (811 ) NET INCOME ATTRIBUTABLE TO INTERDIGITAL, INC. $ 21,407 $ 13,581 $ 34,988 $ 35,536 NET INCOME PER COMMON SHARE — BASIC $ 0.62 $ 0.39 $ 1.01 $ 1.02 NET INCOME PER COMMON SHARE — DILUTED $ 0.60 $ 0.38 $ 0.98 $ 1.00 For the Nine Months Ended September 30, 2018 2017 As Reported ASC 606 Adjustment ASC 605 As Reported (ASC 605) REVENUES: Variable patent royalty revenue $ 26,322 $ (466 ) $ 25,856 $ 37,338 Fixed-fee royalty revenue 178,207 60,081 238,288 220,083 Current patent royalties 204,529 59,615 264,144 257,421 Non-current patent royalties 25,489 (10,000 ) 15,489 56,692 Total patent royalties 230,018 49,615 279,633 314,113 Current technology solutions revenue 2,060 5,232 7,292 13,521 $ 232,078 $ 54,847 $ 286,925 $ 327,634 OPERATING EXPENSES: 173,328 — 173,328 171,843 Income from operations 58,750 54,847 113,597 155,791 OTHER EXPENSE (NET) (25,136 ) 13,004 (12,132 ) (7,331 ) Income before income taxes 33,614 67,851 101,465 148,460 INCOME TAX BENEFIT (EXPENSE) 25,001 (15,607 ) 9,394 (29,413 ) NET INCOME $ 58,615 $ 52,244 $ 110,859 $ 119,047 Net loss attributable to noncontrolling interest (3,423 ) — (3,423 ) (2,744 ) NET INCOME ATTRIBUTABLE TO INTERDIGITAL, INC. $ 62,038 $ 52,244 $ 114,282 $ 121,791 NET INCOME PER COMMON SHARE — BASIC $ 1.79 $ 1.50 $ 3.29 $ 3.52 NET INCOME PER COMMON SHARE — DILUTED $ 1.74 $ 1.47 $ 3.21 $ 3.40 September 30, 2018 December 31, 2017 As Reported ASC 606 Adjustment ASC 605 As Reported (ASC 605) Accounts Receivable, net $ 29,769 $ 206,079 $ 235,848 $ 216,293 Deferred Tax Assets 60,056 46,098 106,154 84,582 Other Non-current Assets 63,877 (5,500 ) 58,377 37,963 Taxes Payable (98,022 ) (16,438 ) (114,460 ) (14,881 ) Deferred Revenue (269,662 ) (341,816 ) (611,478 ) (616,813 ) Retained Earnings (1,436,171 ) 111,577 (1,324,594 ) (1,249,091 ) Contracted Revenue Based on contracts signed and committed Dynamic Fixed-Fee Agreement payments as of September 30, 2018, we expect to recognize the following amounts of revenue over the term of such contracts (in thousands): Revenue Remainder 2018 $ 60,272 2019 237,339 2020 236,089 2021 169,039 2022 85,228 See below for our revised Revenue Recognition accounting policy upon adoption of the new guidance. Revenue Recognition We derive the vast majority of our revenue from patent licensing. The timing and amount of revenue recognized from each licensee depends upon a variety of factors, including the specific terms of each agreement and the nature of the deliverables and obligations. Such agreements are often complex and include multiple performance obligations. These agreements can include, without limitation, performance obligations related to the settlement of past patent infringement liabilities, patent and/or know-how licensing royalties on covered products sold by licensees, access to a portfolio of technology as it exists at a point in time, and access to a portfolio of technology at a point in time along with a promises to provide any technology updates to the portfolio during the term. All agreements have been accounted for under ASC 606. This guidance requires the use of a five-step model to achieve the core underlying principle that an entity should recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. These steps include (1) identifying the contract with the customer, (2) identifying the performance obligations, (3) determining the transaction price, (4) allocating the transaction price to the performance obligations, and (5) recognizing revenue as the entity satisfies the performance obligation(s). Additionally, we have elected to utilize certain practical expedients in the application of ASC 606. In evaluating the presence of a significant financing component in our agreements, we utilize the practical expedient to exclude any contracts wherein the gap between payment by our customers and the delivery of our performance obligation is less than one year. We have also elected to utilize the practical expedient related to costs of obtaining a contract where an entity may recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that the entity otherwise would have recognized is one year or less. Timing of revenue recognition may differ significantly from the timing of invoicing to customers. Contract assets are included in accounts receivable and represent unbilled amounts expected to be received from customers in future periods, where the revenue recognized to date (or cumulative adjustments to retained earnings in the initial period of adopting ASC 606) exceeds the amount billed, and right to payment is subject to the underlying contractual terms. Contract assets are classified as long-term assets if the payments are expected to be received more than one year from the reporting date. Contract assets due within less than twelve months of the balance sheet date are included within accounts receivable in our Condensed Consolidated Balance Sheets. Contract assets due more than twelve months after the balance sheet date are included in Other non-current assets. Patent License Agreements Upon signing a patent license agreement, we provide the licensee permission to use our patented inventions in specific applications. We account for patent license agreements in accordance with the guidance indicated above. Under our patent license agreements, we typically receive one or a combination of the following forms of payment as consideration for permitting our licensees to use our patented inventions in their applications and products: Consideration for Past Patent Royalties Consideration related to a licensee’s product sales from prior periods may result from a negotiated agreement with a licensee that utilized our patented inventions prior to signing a patent license agreement with us or from the resolution of a disagreement or arbitration with a licensee over the specific terms of an existing license agreement. We may also receive consideration for past patent royalties in connection with the settlement of patent litigation where there was no prior patent license agreement. In each of these cases, we record the consideration as revenue as prescribed by the five-step model. Fixed-Fee Agreements Fixed-fee agreements include fixed, non-refundable royalty payments that fulfill the licensee’s obligations to us under a patent license agreement for a specified time period or for the term of the agreement for specified products, under certain patents or patent claims, for sales in certain countries, or a combination thereof - in each case for a specified time period (including for the life of the patents licensed under the agreement). Dynamic fixed-fee license agreements contain a single performance obligation that represents ongoing access to a portfolio of technology over the license term, since our promise to transfer to the licensee access to the portfolio as it exists at inception of the license, along with promises to provide any technology updates to the portfolio during the term, are not separately identifiable. Upon entering a new agreement, we allocate the transaction price to the performance obligations delivered at signing (e.g. our existing patent portfolio) and future performance obligations (e.g. the technology updates). We use a time-based input method of progress to determine the timing of revenue recognition, and as such we recognize the future deliverables on a straight-line basis over the term of the agreement. We utilize the straight-line method as we believe that it best depicts efforts expended to develop and transfer updates to the customer evenly throughout the term of the agreement. Static fixed-fee license agreements are fixed-price contracts that generally do not include updates to technology we create after the inception of the license agreement or in which the customer does not stand to substantively benefit from those updates during the term. Generally, our performance obligations are satisfied at contract signing, and as such revenue is recognized at that time. Variable Agreements Upon entering a new variable patent license agreement, the licensee typically agrees to pay royalties or license fees on licensed products sold during the term of the agreement. We utilize the sales- or usage- based royalty exception for these agreements and recognize revenues during the contract term when the underlying sale or usage occurs. Our licensees under variable agreements provide us with quarterly royalty reports that summarize their sales of covered products and their related royalty obligations to us. We typically receive these royalty reports subsequent to the period in which our licensees’ underlying sales occurred. As a result, we are required to estimate revenues, subject to the constraint on our ability to estimate such amounts. Technology Solutions Technology solutions revenue consists primarily of revenue from royalty payments. We recognize revenue from royalty payments using the same methods described above under our policy for recognizing revenue from patent license agreements. Technology solutions revenues also consist of revenues from software licenses, engineering services and product sales. The nature of these contracts and timing of payments vary. Patent Sales Our business strategy of monetizing our intellectual property includes the sale of select patent assets. As patent sales executed under this strategy represent a component of our ongoing major or central operations and activities, we will record the related proceeds as revenue. We will recognize the revenue in accordance with the five-step model, generally upon closing of the patent sale transaction. Accounting Standards Update: Leases In February 2016, the FASB issued new guidance related to leases that outlines a comprehensive lease accounting model and supersedes the current lease guidance. The new guidance requires lessees to recognize lease liabilities and corresponding right-of-use assets for all leases with lease terms of greater than 12 months. It also changes the definition of a lease and expands the disclosure requirements of lease arrangements. The new guidance must be adopted using the modified retrospective approach and will be effective for the Company starting in first quarter 2019. Early adoption is permitted. We are in the process of determining the effect the adoption will have on the Company's consolidated financial statements. Accounting Standards Update: Financial Instruments In January 2016, the FASB issued ASU No. 2016-01, "Financial Instruments (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities," which amends certain measurement, presentation, and disclosure requirements for financial instruments. The new guidance must be adopted by means of a cumulative-effect adjustment to the balance sheet in the year of adoption and became effective for the Company starting in first quarter 2018. We adopted this guidance in first quarter 2018, and it did not have a material effect on the Company's consolidated financial results. In conjunction with this adoption, we made an accounting policy election for a measurement alternative for equity investments that do not have readily determinable fair values, specifically related to our strategic investments in other entities. Under the alternative, our strategic investments in other entities without readily determinable fair values are measured at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for an identical or similar investment of the same issuer, if any. As of September 30, 2018 and December 31, 2017, strategic investments in other entities totaled $17.4 million and $19.2 million , respectively. Accounting Standards Update: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued ASU No. 2018-02, "Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," which allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017 (the "Tax Reform Act"). The guidance is effective for fiscal years beginning after December 15, 2018, and early adoption is permitted. We early adopted this guidance in first quarter 2018, and reflected a $0.4 million adjustment to retained earnings during the period. Accounting Standards Update: Improvements to Nonemployee Share-Based Payment Accounting In June 2018, the FASB issued ASU No. 2018-07, "Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting," which is intended to reduce cost and complexity and to improve financial reporting for share-based payments issued to nonemployees. The guidance is effective for fiscal years beginning after December 15, 2018 and early adoption is permitted. We do not expect the adoption of this guidance to have a material effect on the Company's consolidated financial statements.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
INCOME TAXES: [Abstract]
Income Tax Disclosure [Text Block]	. INCOME TAXES In first nine months 2018 , based on the statutory federal tax rate net of discrete federal and state taxes, our effective tax rate was a benefit of 74.4% . The effective tax rate for first nine months 2018 was favorably impacted by provisions contained within the Tax Reform Act, discussed below. We recorded discrete net benefits of $18.4 million from excess tax benefits related to share-based compensation, our sale of a commercial initiative and a benefit from the anticipated filing by the Company of amended tax returns in connection with the Competent Authority Proceeding (as defined and discussed below). The effective rate would have been a benefit of 19.7% not including these discrete net benefits. This is compared to an effective tax rate provision of 19.8% based on the statutory federal tax rate net of discrete federal and state taxes during first nine months 2017 . The effective tax rate for first nine months 2017 included a $12.1 million discrete benefit, primarily related to excess tax benefits from share-based compensation, and a $9.1 million discrete benefit, primarily related to the reversal of uncertain tax positions associated with domestic production activities refund claims. The effective tax rate would have been a provision of 34.2% not including these discrete benefits for first nine months 2017 . During first nine months 2018 and 2017 , we paid approximately $16.5 million and $11.7 million , respectively, of foreign source withholding tax. Additionally, as of September 30, 2018 and December 31, 2017, we have included $0.6 million and $14.9 million , respectively, of foreign source withholding tax within our taxes payable and deferred tax asset balances. These amounts are related to receivables from foreign licensees. On December 22, 2017, the Tax Reform Act was signed into law. The Tax Reform Act significantly revised the U.S. corporate income tax regime by, among other things: lowering the U.S. corporate tax rate from 35% to 21% effective January 1, 2018; imposing a 13.125% tax rate on income that qualifies as Foreign Derived Intangible Income ("FDII"); repealing the deduction for domestic production activities; implementing a territorial tax system; and imposing a repatriation tax on deemed repatriated earnings of foreign subsidiaries. The first nine months 2018 effective tax rate includes a forecasted $16.8 million net benefit related to our income qualifying as FDII. As a result of the Tax Reform Act, we recorded a tax charge of approximately $43.3 million in 2017 due to a re-measurement of deferred tax assets and liabilities, and we do not expect a material repatriation tax liability to be owed. We will continue to monitor as additional guidance is released. The tax charge represents provisional amounts and the Company’s current best estimates. Any adjustments recorded to the provisional amounts through fourth quarter 2018 will be included in net income as an adjustment to tax expense. The provisional amounts incorporate assumptions made based upon our current interpretation of the Tax Reform Act and may change as the Company receives additional clarification and implementation guidance. The effective tax rate reported in any given year will continue to be influenced by a variety of factors, including timing differences between the recognition of book and tax revenue, the level of pre-tax income or loss, the foreign vs. domestic classification of the Company’s customers, and any discrete items that may occur. The Company further notes that its tax positions could be altered by pending IRS regulations that could clarify certain provisions of the Tax Reform Act. As previously disclosed in our 2017 Form 10-K, we have paid foreign taxes, including to those foreign governments that have tax treaties with the U.S., for which we have claimed foreign tax credits against our U.S. tax obligations. On July 24, 2018, the Company received notification that its request for competent authority pertaining to Article 27 (Mutual Agreement Procedure) of the United States-Republic of Korea Income Tax Convention had been reviewed by the Internal Revenue Service and an agreement had been reached (the "Competent Authority Proceeding"). As a result of this agreement, we expect to receive a total refund of approximately $97.4 million , inclusive of interest, a portion of which we have already received. We have recorded in taxes payable as of September 30, 2018 an amount corresponding to the expected total refund. In addition, we have recorded a net tax benefit of $15.7 million in our third quarter 2018 results related to an anticipated refund the Company expects to receive as a result of amending tax returns for tax years covered by this agreement.

Net Income Per Share

Net Income Per Share	9 Months Ended
	Sep. 30, 2018
NET INCOME PER SHARE: [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	NET INCOME PER SHARE Basic Earnings Per Share ("EPS") is calculated by dividing net income available to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur if options or other securities with features that could result in the issuance of common stock were exercised or converted to common stock. The following tables reconcile the numerator and the denominator of the basic and diluted net income per share computation (in thousands, except for per share data): For the Three Months Ended September 30, 2018 2017 Basic Diluted Basic Diluted Numerator: Net income applicable to InterDigital, Inc. $ 21,407 $ 21,407 $ 35,536 $ 35,536 Denominator: Weighted-average shares outstanding: Basic 34,651 34,651 34,709 34,709 Dilutive effect of stock options, RSUs, convertible securities and warrants 956 679 Weighted-average shares outstanding: Diluted 35,607 35,388 Earnings Per Share: Net income: Basic $ 0.62 $ 0.62 $ 1.02 $ 1.02 Dilutive effect of stock options, RSUs, convertible securities and warrants (0.02 ) (0.02 ) Net income: Diluted $ 0.60 $ 1.00 For the Nine Months Ended September 30, 2018 2017 Basic Diluted Basic Diluted Numerator: Net income applicable to InterDigital, Inc. $ 62,038 $ 62,038 $ 121,791 $ 121,791 Denominator: Weighted-average shares outstanding: Basic 34,687 34,687 34,589 34,589 Dilutive effect of stock options, RSUs, convertible securities and warrants 927 1,276 Weighted-average shares outstanding: Diluted 35,614 35,865 Earnings Per Share: Net income: Basic $ 1.79 $ 1.79 $ 3.52 $ 3.52 Dilutive effect of stock options, RSUs, convertible securities and warrants (0.05 ) (0.12 ) Net income: Diluted $ 1.74 $ 3.40 Certain shares of common stock issuable upon the exercise or conversion of certain securities have been excluded from our computation of EPS because the strike price or conversion rate, as applicable, of such securities was greater than the average market price of our common stock and, as a result, the effect of such exercise or conversion would have been anti-dilutive. Set forth below are the securities and the weighted average number of shares of common stock underlying such securities that were excluded from our computation of EPS for the periods presented (in thousands): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Restricted stock units and stock options 78 25 44 18 Convertible securities — — — — Warrants 4,405 4,386 4,404 — Total 4,483 4,411 4,448 18 Convertible Notes During periods in which the average market price of the Company's common stock is above the applicable conversion price of the Company's 1.50% Senior Convertible Notes due 2020 (for purposes of this discussion, the "Convertible Notes") ( $71.74 per share as of September 30, 2018) or above the strike price of our outstanding warrants ( $87.68 per share as of September 30, 2018), the impact of conversion or exercise, as applicable, would be dilutive and such dilutive effect is reflected in diluted EPS. As a result, in periods where the average market price of the Company's common stock is above the conversion price or strike price, as applicable, under the treasury stock method, the Company calculates the number of shares issuable under the terms of the Convertible Notes and the warrants based on the average market price of the stock during the period, and includes that number in the total diluted shares outstanding for the period. See Note 7, " Long-Term Debt ," for additional information about the Convertible Notes and warrants. For the Three Months Ended September 30, 2018 2017 Basic Diluted Basic Diluted Numerator: Net income applicable to InterDigital, Inc. $ 21,407 $ 21,407 $ 35,536 $ 35,536 Denominator: Weighted-average shares outstanding: Basic 34,651 34,651 34,709 34,709 Dilutive effect of stock options, RSUs, convertible securities and warrants 956 679 Weighted-average shares outstanding: Diluted 35,607 35,388 Earnings Per Share: Net income: Basic $ 0.62 $ 0.62 $ 1.02 $ 1.02 Dilutive effect of stock options, RSUs, convertible securities and warrants (0.02 ) (0.02 ) Net income: Diluted $ 0.60 $ 1.00 For the Nine Months Ended September 30, 2018 2017 Basic Diluted Basic Diluted Numerator: Net income applicable to InterDigital, Inc. $ 62,038 $ 62,038 $ 121,791 $ 121,791 Denominator: Weighted-average shares outstanding: Basic 34,687 34,687 34,589 34,589 Dilutive effect of stock options, RSUs, convertible securities and warrants 927 1,276 Weighted-average shares outstanding: Diluted 35,614 35,865 Earnings Per Share: Net income: Basic $ 1.79 $ 1.79 $ 3.52 $ 3.52 Dilutive effect of stock options, RSUs, convertible securities and warrants (0.05 ) (0.12 ) Net income: Diluted $ 1.74 $ 3.40

Litigation and Legal Proceeding

Litigation and Legal Proceedings	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Litigation and Legal Proceedings	. LITIGATION AND LEGAL PROCEEDINGS ARBITRATIONS AND COURT PROCEEDINGS (OTHER THAN DE DISTRICT COURT ACTIONS RELATED TO USITC PROCEEDINGS) Huawei China Proceedings On February 21, 2012, InterDigital was served with two complaints filed by Huawei Technologies Co., Ltd. in the Shenzhen Intermediate People's Court in China on December 5, 2011. The first complaint named as defendants InterDigital, Inc. and its wholly owned subsidiaries InterDigital Technology Corporation and InterDigital Communications, LLC (now InterDigital Communications, Inc.), and alleged that InterDigital had abused its dominant market position in the market for the licensing of essential patents owned by InterDigital by engaging in allegedly unlawful practices, including differentiated pricing, tying and refusal to deal. The second complaint named as defendants the Company's wholly owned subsidiaries InterDigital Technology Corporation, InterDigital Communications, LLC (now InterDigital Communications, Inc.), InterDigital Patent Holdings, Inc. and IPR Licensing, Inc. and alleged that InterDigital had failed to negotiate on FRAND terms with Huawei. Huawei asked the court to determine the FRAND rate for licensing essential Chinese patents to Huawei and also sought compensation for its costs associated with this matter. On February 4, 2013, the Shenzhen Intermediate People's Court issued rulings in the two proceedings. With respect to the first complaint, the court decided that InterDigital had violated the Chinese Anti-Monopoly Law by (i) making proposals for royalties from Huawei that the court believed were excessive, (ii) tying the licensing of essential patents to the licensing of non-essential patents, (iii) requesting as part of its licensing proposals that Huawei provide a grant-back of certain patent rights to InterDigital and (iv) commencing a USITC action against Huawei while still in discussions with Huawei for a license. Based on these findings, the court ordered InterDigital to cease the alleged excessive pricing and alleged improper bundling of InterDigital's Chinese essential and non-essential patents, and to pay Huawei 20.0 million RMB (approximately $3.2 million) in damages related to attorneys’ fees and other charges, without disclosing a factual basis for its determination of damages. The court dismissed Huawei's remaining allegations, including Huawei's claim that InterDigital improperly sought a worldwide license and improperly sought to bundle the licensing of essential patents on multiple generations of technologies. With respect to the second complaint, the court determined that, despite the fact that the FRAND requirement originates from ETSI's Intellectual Property Rights policy, which refers to French law, InterDigital's license offers to Huawei should be evaluated under Chinese law. Under Chinese law, the court concluded that the offers did not comply with FRAND. The court further ruled that the royalties to be paid by Huawei for InterDigital's 2G, 3G and 4G essential Chinese patents under Chinese law should not exceed 0.019% of the actual sales price of each Huawei product. On March 11, 2013, InterDigital filed notices of appeal with respect to the judgments in both proceedings, seeking reversal of the court’s February 4, 2013 rulings. On October 16, 2013, the Guangdong Province High Court issued a ruling affirming the ruling of the Shenzhen Intermediate People's Court in the second proceeding, and on October 21, 2013, issued a ruling affirming the ruling of the Shenzhen Intermediate People's Court in the first proceeding. InterDigital believes that the decisions are seriously flawed both legally and factually. For instance, in determining a purported FRAND rate, the Chinese courts applied an incorrect economic analysis by evaluating InterDigital’s lump-sum 2007 patent license agreement with Apple (the “2007 Apple PLA”) in hindsight to posit a running royalty rate. Indeed, the ALJ in USITC Inv. No. 337-TA-800 rejected that type of improper analysis. Moreover, the Chinese courts had an incomplete record and applied incorrect facts, including with respect to the now-expired and superseded 2007 Apple PLA, which had been found in an arbitration between InterDigital and Apple to be limited in scope. On April 14, 2014, InterDigital filed a petition for retrial of the second proceeding with the Chinese Supreme People’s Court (“SPC”), seeking dismissal of the judgment or at least a higher, market-based royalty rate for a license to InterDigital’s Chinese standards-essential patents (“SEPs”). The petition for retrial argues, for example, that (1) the lower court improperly determined a Chinese FRAND running royalty rate by using as a benchmark the 2007 Apple lump sum fixed payment license agreement, and looking in hindsight at the unexpectedly successful sales of Apple iPhones to construct an artificial running royalty rate that neither InterDigital nor Apple could have intended and that would have varied significantly depending on the relative success or failure in hindsight of Apple iPhone sales; (2) the 2007 Apple PLA was also an inappropriate benchmark because its scope of product coverage was significantly limited as compared to the license that the court was considering for Huawei, particularly when there are other more comparable license agreements; and (3) if the appropriate benchmarks had been used, and the court had considered the range of royalties offered by other similarly situated SEP holders in the wireless telecommunications industry, the court would have determined a FRAND royalty that was substantially higher than 0.019%, and would have found, consistent with findings of the ALJ’s initial determination in the USITC 337-TA-800 proceeding, that there was no proof that InterDigital’s offers to Huawei violated its FRAND commitments. The SPC held a hearing on October 31, 2014, regarding whether to grant a retrial and requested that both parties provide additional information regarding the facts and legal theories underlying the case. The SPC convened a second hearing on April 1, 2015 regarding whether to grant a retrial. If the retrial is granted, the SPC will likely schedule one or more additional hearings before it issues a decision on the merits of the case. The SPC retrial proceeding was excluded from the dismissal provisions of the August 2016 patent license agreement between Huawei and InterDigital, and a decision in this proceeding is still pending. ZTE China Proceedings On July 10 and 11, 2014, InterDigital was served with two complaints filed by ZTE Corporation in the Shenzhen Intermediate People's Court in China on April 3, 2014. The first complaint names as defendants the Company's wholly owned subsidiaries InterDigital Technology Corporation, InterDigital Communications, Inc., InterDigital Patent Holdings, Inc. and IPR Licensing, Inc. This complaint alleges that InterDigital has failed to comply with its FRAND obligations for the licensing of its Chinese standards-essential patents. ZTE is asking the court to determine the FRAND rate for licensing InterDigital’s standards-essential Chinese patents to ZTE and also seeks compensation for its litigation costs associated with this matter. The second complaint names as defendants InterDigital, Inc. and its wholly owned subsidiaries InterDigital Technology Corporation and InterDigital Communications, Inc. This complaint alleges that InterDigital has a dominant market position in China and the United States in the market for the licensing of essential patents owned by InterDigital, and abused its dominant market position in violation of the Chinese Anti-Monopoly Law by engaging in allegedly unlawful practices, including excessively high pricing, tying, discriminatory treatment, and imposing unreasonable trading conditions. ZTE originally sought relief in the amount of 20.0 million RMB (approximately $2.9 million based on the exchange rate as of September 30, 2018), an order requiring InterDigital to cease the allegedly unlawful conduct and compensation for its litigation costs associated with this matter. On August 7, 2014, InterDigital filed petitions challenging the jurisdiction of the Shenzhen Intermediate People's Court to hear the actions. On August 28, 2014, the court denied InterDigital’s jurisdictional challenge with respect to the anti-monopoly law case. InterDigital filed an appeal of this decision on September 26, 2014. On September 28, 2014, the court denied InterDigital’s jurisdictional challenge with respect to the FRAND case, and InterDigital filed an appeal of that decision on October 27, 2014. On December 18, 2014, the Guangdong High Court issued decisions on both appeals upholding the Shenzhen Intermediate Court’s decisions that it had jurisdiction to hear these cases. On February 10, 2015, InterDigital filed a petition for retrial with the Supreme People’s Court regarding its jurisdictional challenges to both cases. The Shenzhen Court held hearings on the anti-monopoly law case on May 11, 13, 15 and 18, 2015. At the May hearings, ZTE withdrew its claims alleging discriminatory treatment and the imposition of unfair trading conditions and increased its damages claim to 99.8 million RMB (approximately $14.5 million based on the exchange rate as of September 30, 2018). The Shenzhen Court held hearings in the FRAND case on July 29-31, 2015 and held a second hearing on the anti-monopoly law case on October 12, 2015. On September 18, 2018, ZTE independently filed a petition with the Shenzhen Court to withdraw the complaint in its FRAND case against InterDigital, and on September 28, 2018, the Shenzhen Court granted ZTE’s petition and dismissed the FRAND case without prejudice. On October 25, 2018, ZTE independently filed a petition with the Shenzhen Court to withdraw the complaint in its anti-monopoly law case against InterDigital, and on October 26, 2018, the Shenzhen Court granted ZTE’s petition and dismissed the anti-monopoly law case without prejudice. Asustek Actions On April 15, 2015, Asustek Computer Incorporated (“Asus”) filed a complaint in the CA Northern District Court against InterDigital, Inc., and its subsidiaries InterDigital Communications, Inc., InterDigital Technology Corporation, IPR Licensing, Inc., and InterDigital Patent Holdings, Inc. The complaint asserted the following causes of action: violation of Section Two of the Sherman Act, violation of Section 17200 of the California Business and Professions Code, breach of contract resulting from ongoing negotiations, breach of contract leading to and resulting in the parties’ April 2008 patent license agreement (the “2008 Asus PLA”), promissory estoppel, waiver, and fraudulent inducement to contract. Among other allegations, Asus alleged that InterDigital breached its FRAND commitment. As relief, Asus sought a judgment that the 2008 Asus PLA is void or unenforceable, damages in the amount of excess royalties Asus paid under the 2008 Asus PLA plus interest, a judgment setting the proper FRAND terms and conditions for InterDigital’s patent portfolio, an order requiring InterDigital to grant Asus a license on FRAND terms and conditions, and punitive damages and other relief. In response, on May 30, 2015, InterDigital filed an Arbitration Demand with the ICDR. InterDigital claimed that Asus breached the 2008 Asus PLA’s dispute resolution provision by filing its CA Northern District Court lawsuit and sought declaratory relief that it is not liable for any of the claims in Asus’s complaint. On June 2, 2015, InterDigital filed in the CA Northern District Court a motion to compel arbitration on each of Asus’s claims. On August 25, 2015, the court granted InterDigital’s motion for all of Asus’s claims except its claim for breach of contract resulting from ongoing negotiations. Aside from this claim, the court ruled that the issue of arbitrability should be decided by an arbitrator, and stayed the proceedings pending that determination. Asus asserted counterclaims in the arbitration that mirrored its CA Northern District Court claims, except that it did not assert the breach of contract claim that the court determined was not arbitrable and it added a claim of violation of the Delaware Consumer Fraud Act. Asus also contended that its counterclaims were not arbitrable. InterDigital added a claim for breach of the 2008 Asus PLA’s confidentiality provision. On July 14, 2016, Asus filed a motion to lift the stay in the CA Northern District Court proceeding along with a notice of the arbitral tribunal’s decision on arbitrability, informing the court of the arbitrators’ decision that, other than InterDigital’s breach of contract claims and Asus’s fraudulent inducement claim, no other claim or counterclaim is arbitrable. Asus then filed in the CA Northern District Court an amended complaint on August 18, 2016. This amended complaint includes all of the claims in Asus’s first CA Northern District Court complaint except fraudulent inducement and adds a claim of violation of the Delaware Consumer Fraud Act. It seeks the same relief as its first CA Northern District Court complaint, but also seeks a ruling that each of InterDigital’s patents “declared [to standards-setting organizations] to be essential or potentially essential” is unenforceable and any contracts InterDigital entered into in furtherance of its unlawful conduct are void. On September 8, 2016, InterDigital filed its answer and counterclaims to Asus’s amended complaint. It denied Asus’s claims and filed a counterclaim for declaratory judgment that Asus’s tort claims are invalid or preempted as applied under the First Amendment to the U.S. Constitution, the Patent Clause of the U.S. Constitution, and Title 35 of the U.S. Code. On September 28, 2016, Asus answered and denied InterDigital’s counterclaims. On December 16, 2016, the court set a case schedule that includes a May 2019 trial date. With respect to its arbitration counterclaim for fraudulent inducement, Asus stated in its pleadings that it was seeking return of excess royalties (which totaled close to $63 million as of the August 2016 date referenced in the pleadings and had increased with additional royalty payments made by Asus since such time), plus interest, costs and attorneys’ fees. The evidentiary hearing in the arbitration was held in January 2017, and the parties presented oral closing arguments on March 22, 2017. On August 2, 2017, the arbitral tribunal issued its Final Award. The tribunal fully rejected Asus’s counterclaim, finding that InterDigital did not fraudulently induce Asus to enter into the 2008 Asus PLA. Accordingly, the tribunal dismissed Asus’s fraudulent inducement counterclaim in its entirety. The tribunal also dismissed InterDigital’s claims that Asus breached the confidentiality provisions and the dispute resolution provisions of the 2008 Asus PLA. On October 20, 2017, InterDigital and Asus jointly moved to confirm both the tribunal’s Final Award and the Interim Award on Jurisdiction in the CA Northern District. The court confirmed both awards on October 25, 2017. On April 16, 2018, InterDigital filed a motion in the CA Northern District Court proceeding for leave to amend its counterclaims to include a claim of intentional interference with contract. On June 12, 2018, the court denied this motion. On April 17, 2018, the parties served opening expert reports in the CA Northern District Court proceeding. Asus’s damages expert contends that Asus is currently owed damages in the amount of $75.9 million based on its claims that InterDigital charged royalties inconsistent with its FRAND commitments. Those damages, which represent a substantial portion of the royalties paid by Asus through third quarter 2017, do not reflect Asus’s most recent royalty payments. Asus also seeks interest, costs and attorneys’ fees, as well as, in connection with its Sherman Act claim, treble damages. On August 16, 2018, the parties filed motions for summary judgment. InterDigital contends that (1) Asus is judicially estopped from arguing that the 2008 Asus PLA is “non-FRAND” due to Asus’s prior inconsistent positions; (2) issue preclusion prevents Asus from re-litigating issues decided in the arbitration; (3) as a matter of law, Asus cannot void the binding and enforceable 2008 Asus PLA; and (4) Asus’s Sherman Act, promissory estoppel, and California UCL claims fail as a matter of law. For its part, Asus contends that, as a matter of law, InterDigital breached its contractual obligation to license its essential patents on FRAND terms and conditions by engaging in discriminatory licensing practices. The parties filed oppositions on September 13, 2018 and replies on September 27, 2018, and the court held an oral argument on October 11, 2018. These motions remain pending. The Company has not recorded any accrual at September 30, 2018, for contingent losses associated with the CA Northern District Court Proceeding. While a material loss is reasonably possible, the Company cannot estimate the potential range of loss given the range of possible outcomes, as this matter is not at a sufficiently advanced stage to allow for such an estimate. REGULATORY PROCEEDINGS Investigation by National Development and Reform Commission of China On September 23, 2013, counsel for InterDigital was informed by China’s National Development and Reform Commission (“NDRC”) that the NDRC had initiated a formal investigation into whether InterDigital has violated China’s Anti-Monopoly Law (“AML”) with respect to practices related to the licensing of InterDigital’s standards-essential patents to Chinese companies. Companies found to violate the AML may be subject to a cease and desist order, fines and disgorgement of any illegal gains. On March 3, 2014, the Company submitted to NDRC, pursuant to a procedure set out in the AML, a formal application for suspension of the investigation that included proposed commitments by the Company. On May 22, 2014, NDRC formally suspended its investigation of the Company based on the commitments proposed by the Company. The Company’s commitments with respect to the licensing of its patent portfolio for wireless mobile standards to Chinese manufacturers of cellular terminal units (“Chinese Manufacturers”) are as follows: 1. Whenever InterDigital engages with a Chinese Manufacturer to license InterDigital’s patent portfolio for 2G, 3G and 4G wireless mobile standards, InterDigital will offer such Chinese Manufacturer the option of taking a worldwide portfolio license of only its standards-essential wireless patents, and comply with F/RAND principles when negotiating and entering into such licensing agreements with Chinese Manufacturers. 2. As part of its licensing offer, InterDigital will not require that a Chinese Manufacturer agree to a royalty-free, reciprocal cross-license of such Chinese Manufacturer's similarly categorized standards-essential wireless patents. 3. Prior to commencing any action against a Chinese Manufacturer in which InterDigital may seek exclusionary or injunctive relief for the infringement of any of its wireless standards-essential patents, InterDigital will offer such Chinese Manufacturer the option to enter into expedited binding arbitration under fair and reasonable procedures to resolve the royalty rate and other terms of a worldwide license under InterDigital's wireless standards-essential patents. If the Chinese Manufacturer accepts InterDigital's binding arbitration offer or otherwise enters into an agreement with InterDigital on a binding arbitration mechanism, InterDigital will, in accordance with the terms of the arbitration agreement and patent license agreement, refrain from seeking exclusionary or injunctive relief against such company. The commitments contained in item 3 above will expire five years from the effective date of the suspension of the investigation, or May 22, 2019. USITC PROCEEDINGS AND RELATED DELAWARE DISTRICT COURT PROCEEDINGS 2013 USITC Proceeding (337-TA-868) and Related ZTE Delaware District Court Proceeding USITC Proceeding (337-TA-868) On January 2, 2013, the Company’s wholly owned subsidiaries InterDigital Communications, Inc., InterDigital Technology Corporation, IPR Licensing, Inc. and InterDigital Holdings, Inc. filed a complaint with the United States International Trade Commission (the “USITC” or “Commission”) against Samsung Electronics Co., Ltd., Samsung Electronics America, Inc. and Samsung Telecommunications America, LLC, Nokia Corporation and Nokia Inc., Huawei Technologies Co., Ltd., Huawei Device USA, Inc. and FutureWei Technologies, Inc. d/b/a Huawei Technologies (USA) and ZTE Corporation and ZTE (USA) Inc. (collectively, the “337-TA-868 Respondents”), alleging violations of Section 337 of the Tariff Act of 1930 in that they engaged in unfair trade practices by selling for importation into the United States, importing into the United States and/or selling after importation into the United States certain 3G and 4G wireless devices (including WCDMA-, cdma2000- and LTE-capable mobile phones, USB sticks, mobile hotspots, laptop computers and tablets and components of such devices) that infringe one or more of up to seven of InterDigital’s U.S. patents. The complaint also extended to certain WCDMA and cdma2000 devices incorporating Wi-Fi functionality. InterDigital’s complaint with the USITC sought an exclusion order that would bar from entry into the United States infringing 3G or 4G wireless devices (and components), including LTE devices, that are imported by or on behalf of the 337-TA-868 Respondents, and also sought a cease-and-desist order to bar further sales of infringing products that have already been imported into the United States. Certain of the asserted patents were also asserted against Nokia, Huawei and ZTE in earlier pending USITC proceedings (including the Nokia, Huawei and ZTE 2011 USITC Proceeding (337-TA-800) and the Nokia 2007 USITC Proceeding (337-TA-613), as set forth below) and therefore were not asserted against those 337-TA-868 Respondents in this investigation. On December 23, 2013, InterDigital and Huawei reached a settlement agreement to enter into binding arbitration to resolve their global patent licensing disputes. Pursuant to the settlement agreement, InterDigital and Huawei moved to dismiss all litigation matters pending between the parties except the action filed by Huawei in China to set a fair, reasonable and non-discriminatory (“FRAND”) rate for the licensing of InterDigital’s Chinese standards-essential patents (discussed above under “Huawei China Proceedings”), the decision in which InterDigital is permitted to further appeal. As a result, effective February 12, 2014, the Huawei Respondents were terminated from the 337-TA-868 investigation. From February 10 to February 20, 2014, ALJ Essex presided over the evidentiary hearing in this investigation. The patents in issue in this investigation as of the hearing were U.S. Patent Nos. 7,190,966 (the “’966 patent”) and 7,286,847 (the “’847 patent”) asserted against ZTE and Samsung, and U.S. Patent No. 7,941,151 (the “’151 patent”) asserted against ZTE, Samsung and Nokia. On June 3, 2014, InterDigital and Samsung filed a joint motion to terminate the investigation as to Samsung on the basis of settlement. The ALJ granted the joint motion by initial determination issued on June 9, 2014, and the USITC determined not to review the initial determination on June 30, 2014. On June 13, 2014, the ALJ issued an Initial Determination (“ID”) in the 337-TA-868 investigation. In the ID, the ALJ found that no violation of Section 337 had occurred in connection with the importation of 3G/4G devices by ZTE or Nokia, on the basis that the accused devices do not infringe asserted claims 1-6, 8-9, 16-21 or 23-24 of the ’151 patent, claims 1, 3, 6, 8, 9, or 11 of the ’966 patent, or claims 3 or 5 of the ’847 patent. The ALJ also found that claim 16 of the ’151 patent was invalid as indefinite. Among other determinations, the ALJ further determined that InterDigital did not violate any FRAND obligations, a conclusion also reached by the ALJ in the 337-TA-800 investigation, and that Respondents have engaged in patent “hold out.” On June 30, 2014, InterDigital filed a Petition for Review with the USITC seeking review and reversal of certain of the ALJ’s conclusions in the ID. On the same day, Respondents filed a Conditional Petition for Review urging alternative grounds for affirmance of the ID’s finding that Section 337 was not violated and a Conditional Petition for Review with respect to FRAND issues. In June 2014, Microsoft Mobile Oy (“MMO”) was added as a respondent in the investigation. On August 14, 2014, the Commission determined to review in part the June 13, 2014 ID but terminated the investigation with a finding of no violation. On October 10, 2014, InterDigital filed a petition for review with the U.S. Court of Appeals for the Federal Circuit (the “Federal Circuit”), appealing certain of the adverse determinations in the Commission’s August 8, 2014 final determination including those related to the ’966 and ’847 patents. On June 2, 2015, InterDigital moved to voluntarily dismiss the Federal Circuit appeal, because, even if it were to prevail, it did not believe there would be sufficient time following the court’s decision and mandate for the USITC to complete its proceedings on remand such that the accused products would be excluded before the ’966 and ’847 patents expire in June 2016. The court granted the motion and dismissed the appeal on June 18, 2015. Related Delaware District Court Proceeding On January 2, 2013, the Company’s wholly owned subsidiaries InterDigital Communications, Inc., InterDigital Technology Corporation, IPR Licensing, Inc. and InterDigital Holdings, Inc. filed four related district court actions in the Delaware District Court against the 337-TA-868 Respondents. The proceedings against Huawei, Samsung and Nokia were subsequently dismissed, as discussed below. The remaining complaint alleges that ZTE infringes the same patents with respect to the same products alleged in the complaint filed by InterDigital in USITC Proceeding (337-TA-868). The complaint seeks a permanent injunction and compensatory damages in an amount to be determined, as well as enhanced damages based on willful infringement, and recovery of reasonable attorneys’ fees and costs. On January 31, 2013, ZTE filed its answer and counterclaims to InterDigital’s Delaware District Court complaint; ZTE asserted counterclaims for breach of contract, equitable estoppel, waiver of right to enjoin and declarations that InterDigital has not offered ZTE licenses on FRAND terms, declarations seeking the determination of FRAND terms and declarations of noninfringement, invalidity and unenforceability. In addition to the declaratory relief specified in its counterclaims, ZTE seeks specific performance of InterDigital's purported contracts with ZTE and standards-setting organizations, appropriate damages in an amount to be determined at trial, reasonable attorneys’ fees and such other relief as the court may deem appropriate. On March 21, 2013, pursuant to stipulation, the Delaware District Court granted InterDigital leave to file an amended complaint against ZTE to assert allegations of infringement of the ’244 patent. On March 22, 2013, ZTE filed its answer and counterclaims to InterDigital’s amended Delaware District Court complaint. On April 9, 2013, InterDigital filed a motion to dismiss ZTE’s counterclaims relating to its FRAND allegations. On July 12, 2013, the Delaware District Court held a hearing on InterDigital’s motion to dismiss. By order issued the same day, the Delaware District Court granted InterDigital’s motion, dismissing ZTE's counterclaims for equitable estoppel and waiver of the right to injunction or exclusionary relief with prejudice. It further dismissed the counterclaims for breach of contract and declaratory relief related to InterDigital’s FRAND commitments with leave to amend. On August 6, 2013, ZTE filed its answer and amended counterclaims for breach of contract and for declaratory judgment seeking determination of FRAND terms. The counterclaims also continue to seek declarations of noninfringement, invalidity, and unenforceability. On August 30, 2013, InterDigital filed a motion to dismiss the declaratory judgment counterclaim relating to the request for determination of FRAND terms. On May 28, 2014, the court granted InterDigital’s motion and dismissed ZTE's FRAND-related declaratory judgment counterclaim, ruling that such declaratory judgment would serve no useful purpose. On December 30, 2013, InterDigital and Huawei filed a stipulation of dismissal on account of the confidential settlement agreement and agreement to arbitrate their disputes in this action. On the same day, the Delaware District Court granted the stipulation of dismissal and dismissed the action against Huawei. On February 11, 2014, the Delaware District Court judge entered an InterDigital, Nokia, and ZTE stipulated Amended Scheduling Order that bifurcated issues relating to damages, FRAND-related affirmative defenses, and any FRAND-related counterclaims. On August 28, 2014, the court granted in part a motion by InterDigital for summary judgment that the asserted ’151 patent is not unenforceable by reason of inequitable conduct, holding that only one of the references forming the basis of defendants’ allegations would remain in issue, and granted a motion by InterDigital for summary judgment that the asserted claims of the ’966 and ’847 patents are not invalid for lack of enablement. On August 5, 2014, InterDigital and Samsung filed a stipulation of dismissal in light of the parties’ settlement agreement. On the same day, the court granted the stipulation of dismissal and dismissed the action against Samsung with prejudice. By order dated August 28, 2014, MMO was joined in the case against Nokia as a defendant. The ZTE trial addressing infringement and validity of the ’966, ’847, ’244 and ’151 patents was held from October 20 to October 27, 2014. During the trial, the judge determined that further construction of certain claim language of the ’151 patent was required, and the judge decided to hold another trial as to ZTE's infringement of the ’151 patent at a later date. On October 28, 2014, the jury returned a unanimous verdict in favor of InterDigital, finding that the ’966, ’847 and ’244 patents are all valid and infringed by ZTE 3G and 4G cellular devices. The court issued formal judgment to this effect on October 29, 2014. On November 26, 2014, ZTE filed a motion for judgment as a matter of law that the asserted claims of the ’966, ’847 and ’244 patents are not infringed and, in the alternative, for a new trial. InterDigital filed an opposition on December 15, 2014, and ZTE filed a reply on January 7, 2015. The ZTE trial addressing infringement of the ’151 patent was held from April 20 to April 22, 2015. On April 22, 2015, the jury returned a verdict in favor of ZTE, finding that the ’151 patent is not infringed by ZTE 3G and 4G cellular devices. On May 29, 2015, the court entered a new scheduling order for damages and FRAND-related issues, scheduling the ZTE trial related to damages and FRAND-related issues for October 2016. On September 14, 2015, a panel of Administrative Law Judges of the United States Patent and Trademark Office Patent Trial and Appeal Board (the “PTAB”) issued a final written decision in two Inter Partes Review (“IPR”) cases concerning the ’244 patent. These IPR proceedings were commenced on petitions filed by ZTE Corporation and ZTE (USA) Inc. and by Microsoft Corporation, respectively. Specifically, the panel determined that a number of claims of the ’244 patent are unpatentable as obvious. IPR Licensing, Inc. appealed to the Federal Circuit seeking review of the PTAB’s decision. Oral argument in the appeal was heard on April 7, 2017. On April 20, 2017, the Federal Circuit affirmed the PTAB’s decision that most of the challenged claims of the ’244 patent are unpatentable as obvious. However, the court vacated and remanded the PTAB’s obviousness finding as to claim 8, which returned the matter to the PTAB for further proceedings as to that claim. On July 28, 2017, IPR Licensing, Inc., filed a petition for a writ of certiorari with the U.S. Supreme Court seeking to appeal the Federal Circuit decision, arguing that the petition should be held pending the Supreme Court’s decision in Oil States Energy Services, LLC v. Greene’s Energy Group, LLC , which will determine whether the IPR process as a whole is unconstitutional. On October 2, 2017, ZTE filed a re

Equity Transactions

Equity Transactions	9 Months Ended
	Sep. 30, 2018
EQUITY TRANSACTIONS: [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	. EQUITY TRANSACTIONS Changes in shareholders’ equity for the nine months ended September 30, 2018 and September 30, 2017 were as follows (in thousands): For the Nine Months Ended September 30, 2018 2017 Balance beginning of period, December 31 $ 855,267 $ 739,709 Cumulative effect of change in accounting principle 161,251 — Net income attributable to InterDigital, Inc. 62,038 121,791 Unrealized (loss) gain on investments, net (904 ) (181 ) Cash dividends declared (36,312 ) (32,966 ) Repurchase of common stock (43,508 ) — Exercise of common stock options 6,362 82 Taxes withheld upon vesting of restricted stock units (8,478 ) (22,235 ) Share-based compensation 4,875 13,901 Total InterDigital, Inc. shareholders’ equity end of period $ 1,000,591 $ 820,101 Noncontrolling Interest Balance beginning of period, December 31 17,881 14,659 Net loss attributable to noncontrolling interest (3,423 ) (2,744 ) Noncontrolling interest 14,458 11,915 Total Equity end of period $ 1,015,049 $ 832,016 Repurchase of Common Stock In June 2014, our Board of Directors authorized a $300 million share repurchase program (the “2014 Repurchase Program”). In June 2015, our Board of Directors authorized a $100 million increase to the program, and in September 2017, our Board of Directors authorized another $100 million increase to the program, bringing the total amount of the 2014 Repurchase Program to $500 million . The Company may repurchase shares under the 2014 Repurchase Program through open market purchases, pre-arranged trading plans or privately negotiated purchases. The table below sets forth the number of shares repurchased and the dollar value of shares repurchased under the 2014 Repurchase Program from inception of the program through third quarter 2018 (in thousands). 2014 Repurchase Program # of Shares Value 2018 549 $ 43,508 2017 107 7,693 2016 1,304 64,685 2015 1,836 96,410 2014 3,554 152,625 Total 7,350 $ 364,921 Dividends Cash dividends on outstanding common stock declared in 2018 and 2017 were as follows (in thousands, except per share data): 2018 Per Share Total Cumulative by Fiscal Year First quarter $ 0.35 $ 12,124 $ 12,124 Second quarter $ 0.35 $ 12,192 $ 24,316 Third quarter 0.35 11,996 36,312 $ 1.05 $ 36,312 2017 Per Share Total Cumulative by Fiscal Year First quarter $ 0.30 $ 10,404 $ 10,404 Second quarter 0.30 10,413 20,817 Third quarter 0.35 12,149 32,966 Fourth quarter 0.35 12,156 45,122 $ 1.30 $ 45,122 In September 2017, we announced that our Board of Directors had approved an increase in the Company’s quarterly cash dividend to $0.35 per share. We currently expect to continue to pay dividends comparable to our quarterly $0.35 per share cash dividend in the future; however, continued payment of cash dividends and changes in the Company's dividend policy will depend on the Company's earnings, financial condition, capital resources and capital requirements, alternative uses of capital, restrictions imposed by any existing debt, economic conditions and other factors considered relevant by our Board of Directors.

Concentration of Credit Risk an

Concentration of Credit Risk and Fair Value of Financial Assets and Liabilities	9 Months Ended
	Sep. 30, 2018
CONCENTRATION OF CREDIT RISK AND FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES: [Abstract]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block]	. CONCENTRATION OF CREDIT RISK AND FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES Concentration of Credit Risk and Fair Value of Financial Instruments Financial instruments that potentially subject us to concentration of credit risk consist primarily of cash equivalents, short-term investments, and accounts receivable. We place our cash equivalents and short-term investments only in highly rated financial instruments and in United States government instruments. Our accounts receivable and contract assets are derived principally from patent license and technology solutions agreements. As of September 30, 2018 and December 31, 2017 , four and three licensees comprised 64% and 96% of our net accounts receivable balance, respectively. We perform ongoing credit evaluations of our licensees, who generally include large, multinational, wireless telecommunications equipment manufacturers. We believe that the book values of our financial instruments approximate their fair values. Fair Value Measurements We use various valuation techniques and assumptions when measuring the fair value of our assets and liabilities. We utilize market data or assumptions that market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. This guidance established a hierarchy that prioritizes fair value measurements based on the types of input used for the various valuation techniques (market approach, income approach and cost approach). The levels of the hierarchy are described below: Level 1 Inputs — Level 1 includes financial instruments for which quoted market prices for identical instruments are available in active markets. Level 2 Inputs — Level 2 includes financial instruments for which there are inputs other than quoted prices included within Level 1 that are observable for the instrument such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets with insufficient volume or infrequent transactions (less active markets) or model-driven valuations in which significant inputs are observable or can be derived principally from, or corroborated by, observable market data, including market interest rate curves, referenced credit spreads and pre-payment rates. Level 3 Inputs — Level 3 includes financial instruments for which fair value is derived from valuation techniques including pricing models and discounted cash flow models in which one or more significant inputs are unobservable, including the Company’s own assumptions. The pricing models incorporate transaction details such as contractual terms, maturity and, in certain instances, timing and amount of future cash flows, as well as assumptions related to liquidity and credit valuation adjustments of marketplace participants. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of financial assets and financial liabilities and their placement within the fair value hierarchy. We use quoted market prices for similar assets to estimate the fair value of our Level 2 investments. Recurring Fair Value Measurements Our financial assets are generally included within short-term investments on our condensed consolidated balance sheets, unless otherwise indicated. Our financial assets and liabilities that are accounted for at fair value on a recurring basis are presented in the tables below as of September 30, 2018 and December 31, 2017 (in thousands): Fair Value as of September 30, 2018 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 415,614 $ — $ — $ 415,614 Commercial paper (b) — 131,987 — 131,987 U.S. government securities — 328,440 — 328,440 Corporate bonds, asset backed and other securities — 198,251 — 198,251 Total $ 415,614 $ 658,678 $ — $ 1,074,292 Liabilities: Contingent consideration resulting from the Technicolor Acquisition — — 18,616 $ 18,616 Long-term debt resulting from the Technicolor Acquisition — — 18,107 $ 18,107 $ — $ — $ 36,723 $ 36,723 Fair Value as of December 31, 2017 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 417,348 $ — $ — $ 417,348 Commercial paper (b) — 66,132 — 66,132 U.S. government securities — 511,032 — 511,032 Corporate bonds, asset backed and other securities — 163,483 — 163,483 $ 417,348 $ 740,647 $ — $ 1,157,995 ______________________________ (a) Primarily included within cash and cash equivalents. (b) Includes $109.2 million and $15.7 million of commercial paper that is included within cash and cash equivalents as of September 30, 2018 and December 31, 2017, respectively. Level 3 Fair Value Measurements Contingent consideration As discussed further in Note 9, we completed our acquisition of the patent licensing business of Technicolor (the “Technicolor Acquisition”) during third quarter 2018. In conjunction with the Technicolor Acquisition, we recognized a contingent consideration liability which is measured at fair value on a recurring basis using significant unobservable inputs classified as Level 3 measurements within the fair value hierarchy. We utilized a Monte Carlo simulation model to determine the estimated fair value of the contingent consideration liability. A Monte Carlo simulation uses random numbers together with volatility assumptions to generate individual paths, or trials, for variables of interest governed by a Geometric Brownian Motion in a risk-neutral framework. Level 3 significant unobservable inputs include the following: Significant Unobservable Input Ranges Risk-adjusted discount rate for revenue 13.5% - 14.5% Credit risk discount rate 3.9% - 6.7% Revenue volatility 35.0% Projected years of earn out 2018 - 2030 Significant increases or decreases in any of those inputs in isolation could result in a significantly lower or higher fair value measurement. Adjustments to the fair value of contingent consideration are reflected within our condensed consolidated statements of income. Technicolor Acquisition long-term debt We also recognized long-term debt in conjunction with the Technicolor Acquisition as more fully disclosed in Note 9. This long-term debt is measured at fair value on a recurring basis based on the discounted expected future cash flows over the life of the arrangement. Estimating the future cash flows under this arrangement requires several Level 3 significant unobservable inputs, including the following: Significant Unobservable Input Ranges Discount rate for revenue 14.5% Projected term of arrangement 2018 - 2030 Significant increases or decreases in any of those inputs in isolation could result in a significantly lower or higher fair value measurement, and estimates may change which would result in future adjustments to the accretion of the interest expense and the principal amortization of the debt. Adjustments to the fair value of the long-term debt are reflected as interest expense within “Other Expense (Net)” in the condensed consolidated statements of income. The following table provides a reconciliation of the beginning and ending balances of our two Level 3 fair value measurements from December 31, 2017 to September 30, 2018, both of which relate to the Technicolor Acquisition and are discussed further above and within Note 9. As of September 30, 2018, the Level 3 contingent consideration liability is included within "Other long-term liabilities" and the Level 3 long-term debt is included within "Long-term debt" in the condensed consolidated balance sheet. Level 3 Fair Value Measurements Contingent Consideration Liability Technicolor Acquisition Long-term Debt Balance as of December 31, 2017 $ — $ — Technicolor Acquisition - July 30, 2018 18,616 17,717 Reduction for payments — — Interest expense accretion — 390 Changes in fair value recognized in the condensed consolidated statements of income — — Balance as of September 30, 2018 $ 18,616 $ 18,107 Non-Recurring Fair Value Measurements As discussed in Note 1, in conjunction with the adoption of ASU 2016-01 in the first quarter of 2018, we made an accounting policy election to utilize a measurement alternative for equity investments that do not have readily determinable fair values, which applies to our strategic investments in other entities. Under the alternative, our strategic investments in other entities that do not have readily determinable fair values are measured at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for an identical or similar investment of the same issuer. Any adjustments to the carrying value of those investments are considered non-recurring fair value measurements. During third quarter 2018, we recognized an aggregate $8.4 million loss resulting from the sale of our entire ownership interest in one of our strategic investments and the impairment of a separate strategic investment. Fair Value of Senior Convertible Long-Term Debt The principal amount, carrying value and related estimated fair value of the Company's senior convertible debt reported in the condensed consolidated balance sheets as of September 30, 2018 and December 31, 2017 are as follows (in thousands). The table below does not include the Technicolor Acquisition long-term debt that is classified as a Level 3 fair value measurement and is discussed above. September 30, 2018 December 31, 2017 Principal Amount Carrying Value Fair Value Principal Amount Carrying Fair Value Total Senior Convertible Long-Term Debt $ 316,000 $ 295,420 $ 371,300 $ 316,000 $ 285,126 $ 377,029 The aggregate fair value of the principal amount of the senior convertible long-term debt (Level 2 Notes as defined in Note 7 “ Long-Term Debt ”) was calculated using inputs such as actual trade data, benchmark yields, broker/dealer quotes and other similar data, which were obtained from independent pricing vendors, quoted market prices or other sources.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2018
Long-term Debt, Unclassified [Abstract]
Long-term Debt [Text Block]	LONG-TERM DEBT Technicolor Acquisition Long-Term Debt Refer to Note 9 for information regarding the long-term debt recognized during third quarter 2018 resulting from the Technicolor Acquisition. 2020 Senior Convertible Notes, and related Note Hedge and Warrant Transactions On March 11, 2015, we issued $316.0 million in aggregate principal amount of 1.50% Senior Convertible Notes due 2020 (the “2020 Notes”). The 2020 Notes bear interest at a rate of 1.50% per year, payable in cash on March 1 and September 1 of each year, commencing September 1, 2015, and mature on March 1, 2020, unless earlier converted or repurchased. The 2020 Notes will be convertible into cash, shares of our common stock or a combination thereof, at our election, at a current conversion rate of 13.9392 shares of common stock per $1,000 principal amount of 2020 Notes (which is equivalent to a conversion price of approximately $71.74 per share), as adjusted pursuant to the terms of the indenture for the 2020 Notes (the "Indenture"). The conversion rate, and thus the conversion price, may be adjusted under certain circumstances, including in connection with conversions made following certain fundamental changes and under other circumstances set forth in the Indenture. It is our current intent and policy to settle all conversions through combination settlement of cash and shares of common stock, with a specified dollar amount of $1,000 per $1,000 principal amount of the 2020 Notes and any remaining amounts in shares. Prior to 5:00 p.m., New York City time, on the business day immediately preceding December 1, 2019, the 2020 Notes will be convertible only under certain circumstances as set forth in the Indenture , including on any date during any calendar quarter (and only during such calendar quarter) if the closing sale price of our common stock was more than 130% of the applicable conversion price (approximately $93.26 based on the current conversion price) on each applicable trading day for at least 20 trading days in the period of the 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter. Commencing on December 1, 2019, the 2020 Notes will be convertible in multiples of $1,000 principal amount, at any time prior to 5:00 p.m., New York City time, on the second scheduled trading day immediately preceding the maturity date of the 2020 Notes. The Company may not redeem the 2020 Notes prior to their maturity date. On March 5 and March 9, 2015, in connection with the offering of the 2020 Notes, we entered into convertible note hedge transactions that cover approximately 3.8 million and approximately 0.6 million shares of our common stock, respectively, at a strike price that corresponds initially to the initial conversion price of the 2020 Notes and are exercisable upon conversion of the 2020 Notes. The cost of the March 5 and March 9, 2015 convertible note hedge transactions was approximately $51.7 million and approximately $7.7 million , respectively. On March 5 and March 9, 2015, we sold warrants to acquire approximately 3.8 million and approximately 0.6 million , respectively, of common stock, subject to customary anti-dilution adjustments. As of September 30, 2018, the warrants had a strike price of approximately $87.68 per share, as adjusted. The warrants become exercisable and expire in daily tranches over a three and a half month period starting in June 2020. As consideration for the warrants issued on March 5 and March 9, 2015, we received approximately $37.3 million and approximately $5.6 million , respectively. On April 3, 2018, in connection with the reorganization of the Company’s holding company structure, the predecessor company (now known as InterDigital Wireless, Inc., the "Predecessor Company") and the successor company (now known as InterDigital, Inc., the "Successor Company") entered into a First Supplemental Indenture (the “Supplemental Indenture”) to the Indenture with the trustee. The Supplemental Indenture effected certain amendments to the Indenture in connection with the Reorganization, which, among other things, amended the conversion right of the 2020 Notes so that at the effective time of the Reorganization, the holder of each Note outstanding as of the effective time of the Reorganization will have the right to convert, subject to the terms of the Indenture, each $1,000 principal amount of such 2020 Note into the number of shares of the Successor Company’s common stock that a holder of a number of shares of the Predecessor Company’s common stock equal to the conversion rate immediately prior to the effective time of the Reorganization would have been entitled to receive upon the Reorganization. In addition, pursuant to the Supplemental Indenture, the Successor Company guaranteed the Predecessor Company’s obligations under the 2020 Notes and the Indenture. Accounting Treatment of the 2020 Notes and related Convertible Note Hedge and Warrant Transactions The offering of the 2020 Notes on March 5, 2015 was for $275.0 million and included an overallotment option that allowed the initial purchasers to purchase up to an additional $41.0 million aggregate principal amount of 2020 Notes. The initial purchasers exercised their overallotment option on March 9, 2015, bringing the total amount of 2020 Notes issued on March 11, 2015 to $316.0 million . In connection with the offering of the 2020 Notes, as discussed above, InterDigital entered into convertible note hedge transactions with respect to its common stock. The $59.4 million cost of the convertible note hedge transactions was partially offset by the proceeds from the sale of the warrants described above, resulting in a net cost of $16.5 million . Both the convertible note hedge and warrants were classified as equity. The Company bifurcated the proceeds from the offering of the 2020 Notes between liability and equity components. On the date of issuance, the liability and equity components were calculated to be approximately $256.7 million and $59.3 million , respectively. The initial $256.7 million liability component was determined based on the fair value of similar debt instruments excluding the conversion feature. The initial $59.3 million ( $38.6 million net of tax) equity component represents the difference between the fair value of the initial $256.7 million in debt and the $316.0 million of gross proceeds. The related initial debt discount of $59.3 million is being amortized using the effective interest method over the life of the 2020 Notes. An effective interest rate of 5.89% was used to calculate the debt discount on the 2020 Notes. In connection with the above-noted transactions, the Company incurred $9.3 million of directly related costs. The initial purchasers' transaction fees and related offering expenses were allocated to the liability and equity components in proportion to the allocation of proceeds and accounted for as debt and equity issuance costs, respectively. We allocated $7.0 million of debt issuance costs to the liability component, which were capitalized as deferred financing costs. These costs are being amortized to interest expense over the term of the debt using the effective interest method. The remaining $2.4 million of costs allocated to the equity component were recorded as a reduction of the equity component. The following table reflects the carrying value of the 2020 Notes as of September 30, 2018 and December 31, 2017 (in thousands): September 30, 2018 December 31, 2017 Principal $ 316,000 $ 316,000 Less: Unamortized interest discount (18,611 ) (27,863 ) Deferred financing costs (1,969 ) (3,011 ) Net carrying amount of 2020 Notes $ 295,420 $ 285,126 The following table presents the amount of interest cost recognized, which is included within " Other Expense" in our condensed consolidated statements of income, for the three and nine months ended September 30, 2018 and September 30, 2017 relating to the contractual interest coupon, accretion of the debt discount, and the amortization of financing costs (in thousands): For the Three Months Ended September 30, 2018 2017 Contractual coupon interest $ 1,185 $ 1,185 Accretion of debt discount 3,124 2,947 Amortization of deferred financing costs 347 348 Total $ 4,656 $ 4,480

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2018
Variable Interest Entities [Abstract]
Equity Method Investments and Joint Ventures Disclosure [Text Block]	VARIABLE INTEREST ENTITIES As further discussed below, we are the primary beneficiary of two variable interest entities. As of September 30, 2018 , the combined book values of the assets and liabilities associated with these variable interest entities included in our condensed consolidated balance sheet were $29.4 million and $3.0 million , respectively. Assets included $12.1 million of cash and cash equivalents, $1.3 million of accounts receivable, $13.4 million of patents, net, and $2.5 million of other non-current assets. As of December 31, 2017 , the combined book values of the assets and liabilities associated with these variable interest entities included in our condensed consolidated balance sheet were $34.4 million and $0.2 million , respectively. Assets included $23.3 million of cash and cash equivalents and $11.1 million of patents, net. We recognized $10.0 million of non-current patent royalties during the nine months ended September 30, 2018 related to a patent license agreement signed by the Signal Trust for Wireless Innovation (the “Signal Trust”). Convida Wireless In September 2015, we renewed and expanded our joint venture with Sony, Convida Wireless, to include 5G technologies. Convida Wireless was launched in 2013 to combine Sony's consumer electronics expertise with our pioneering Internet of Things (“IoT”) expertise to drive IoT communications and connectivity. Based on the terms of the agreement, the parties will contribute funding and resources for additional research and platform development, which we will perform. SCP IP Investment LLC, an affiliate of Stephens Inc., is a minority investor in Convida Wireless. Convida Wireless is a variable interest entity. Based on our provision of research and platform development services to Convida Wireless, we have determined that we remain the primary beneficiary for accounting purposes and will continue to consolidate Convida Wireless. For the three months ended September 30, 2018 and 2017 , we have allocated approximately $1.3 million and $0.8 million , respectively, of Convida Wireless's net loss to noncontrolling interests held by other parties. For the nine months ended September 30, 2018 and 2017 , we have allocated approximately $3.4 million and $2.7 million , respectively, of Convida Wireless's net loss to noncontrolling interests held by other parties. Signal Trust for Wireless Innovation During 2013, we announced the establishment of the Signal Trust, the goal of which is to monetize a large InterDigital patent portfolio related to cellular infrastructure. The more than 500 patents and patent applications transferred from InterDigital to the Signal Trust focus primarily on 3G and LTE technologies, and were developed by InterDigital's engineers and researchers over more than a decade, with a number of the innovations contributing to the worldwide standards process. InterDigital is the primary beneficiary of the Signal Trust. The distributions from the Signal Trust will support continued research related to cellular wireless technologies. A small portion of the proceeds from the Signal Trust will be used to fund, through the Signal Foundation for Wireless Innovation, scholarly analysis of intellectual property rights and the technological, commercial and creative innovations they facilitate. The Signal Trust is a variable interest entity. Based on the terms of the trust agreement, we have determined that we are the primary beneficiary for accounting purposes and must consolidate the Signal Trust.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	9. BUSINESS COMBINATIONS Technicolor Acquisition On July 30, 2018, we completed our acquisition of the patent licensing business of Technicolor, a worldwide technology leader in the media and entertainment sector, which we refer to as the Technicolor Acquisition. The final transaction includes the acquisition by InterDigital of approximately 18,000 patents and applications, across a broad range of technologies, including approximately 3,000 worldwide video coding patents and applications. The acquisition of Technicolor’s portfolio greatly expands InterDigital’s technology footprint in the mobile industry, and opens new markets in consumer home electronics, display technology and video. The portfolio will also be supplemented by jointly funded R&D collaboration, which will bring together the efforts of hundreds of engineers in InterDigital Labs and Technicolor Research and Innovation (“R&I”). Members of Technicolor’s licensing, legal and other support teams in offices in Rennes and Issy-les-Moulineaux, France; Princeton, New Jersey, and other locations joined InterDigital’s team of more than 300 R&D and other staff in locations around the world. In addition, we have assumed Technicolor’s rights and obligations under a joint licensing program with Sony Corporation (“Sony”) relating to digital televisions and standalone computer display monitors (the “Madison Arrangement”), including Technicolor's role as sole licensing agent for the Madison Arrangement. As part of this transaction, we also granted back to Technicolor a perpetual license for patents acquired in the transaction. With respect to patents generated through the jointly funded R&D efforts, we will own the patents, and Technicolor will receive a license back to the patents resulting from the targeted research conducted by its R&I team. The Technicolor Acquisition meets the definition of a business combination, and as such was accounted for using the acquisition method of accounting. Under the terms of the agreement, in third quarter 2018, we paid Technicolor $158.9 million in cash, inclusive of $15.9 million of cash acquired, yielding net cash consideration of $143.0 million . We funded this payment with cash on hand. Technicolor will receive 42.5% of all of InterDigital's future cash receipts (net of estimated operating expenses) from InterDigital’s new licensing efforts in the consumer electronics field; there will be no revenue sharing associated with InterDigital’s mobile industry licensing efforts. We account for the portion of the future cash receipts owed to Technicolor relating to patents existing as of the date of the acquisition as a contingent consideration liability, which was valued at $18.6 million as of the acquisition date. See below for further discussion of the contingent consideration liability. Additionally, we estimate we will receive payments totaling $20.2 million relating to the transaction from Technicolor, of which $8.5 million is included within "Prepaid and other current assets" and the remaining balance is included within "Other non-current assets" in the condensed consolidated balance sheet. We account for our assumption of Technicolor’s rights and obligations under the Madison Arrangement as a collaborative arrangement. We allocated the fair value of consideration transferred to identifiable assets acquired and liabilities assumed based on their estimated fair values as of the acquisition date. We recorded the excess of the fair value of consideration transferred over the net values of these assets and liabilities as goodwill. We estimated the fair value of the intangible assets in this transaction through a combination of a discounted cash flow analysis (the income approach) and an analysis of comparable market transactions (the market approach). For the income approach, we based the inputs and assumptions used to develop these estimates on a market participant perspective and included estimates of projected revenues, discount rates, economic lives and income tax rates, among others, and all of these estimates require significant management judgment. For the market approach, we applied judgment to identify the most comparable market transactions to this transaction. Refer to Note 6 for discussion regarding the valuation methodologies used for the contingent consideration liability. The following table summarizes the fair value of consideration transferred and our preliminary allocation of that consideration based on the estimated fair values of the assets acquired and liabilities assumed as of the date of acquisition: As of July 30, 2018 Cash $ 158,898 Contingent consideration liability 18,616 $ 177,514 ` Less: Transaction-related receivable (20,200 ) Net fair value of consideration transferred $ 157,314 Allocation: Estimated useful life (Years) Net tangible assets and liabilities: Restricted cash $ 15,913 Other current assets 5,600 Other non-current assets 3,116 Current liabilities (6,219 ) Long-term debt (17,717 ) Other long-term liabilities (3,767 ) Total net tangible assets and liabilities $ (3,074 ) Identified intangible assets: Patents (1) $ 154,000 9 - 10 Goodwill (2) 6,388 Total identified intangible assets $ 160,388 Total fair value of consideration transferred $ 157,314 (1) We expect $16.4 million of additional annualized amortization expense from patents acquired in the Technicolor Acquisition. (2) Goodwill consists of expected synergies resulting from the combination of our and Technicolor’s patent licensing businesses in the increasingly complementary areas of mobile and video technology. We expect that the majority of the goodwill resulting from the Technicolor Acquisition will be deductible for income tax purposes. The following table shows the change in the carrying amount of our goodwill balance from December 31, 2017 to September 30, 2018, all of which is allocated to our one reportable segment: Goodwill balance as of December 31, 2017 $ 16,033 Technicolor Acquisition 6,388 Goodwill balance as of September 30, 2018 $ 22,421 Since the date of closing, the Technicolor Acquisition resulted in $1.9 million of revenue and $4.6 million of pre-tax losses that were included in our condensed consolidated statements of income for the three and nine months ended September 30, 2018. Transaction-related one-time costs for the three and nine months ended September 30, 2018 were $5.4 million and $9.2 million , respectively, the majority of which were recorded within “Selling, general and administrative” expenses in the condensed consolidated statements of income. The amount of revenue and earnings that would have been included in the Company’s condensed consolidated statement of income for the three and nine months ended September 30, 2018 and 2017 had the acquisition date been January 1, 2017 are reflected in the table below. These amounts have been calculated after applying the Company's accounting policies and adjusting the results to reflect additional interest expense as well as amortization that would have been charged assuming the fair value adjustments to amortizable intangible assets had been recorded as of January 1, 2017. In addition, pro forma adjustments have been made to reflect the impact of the transaction-related costs discussed above. These unaudited pro forma combined results of operations have been prepared for comparative purposes only, and they do not purport to be indicative of the results of operations that actually would have resulted had the acquisition occurred on the date indicated, or that may result in the future. The amounts in the table are unaudited (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Actual revenue $ 75,079 $ 97,325 $ 232,078 $ 327,634 Supplemental pro forma revenue $ 76,034 $ 100,391 $ 238,761 $ 335,229 Actual earnings $ 21,407 $ 35,536 $ 62,038 $ 121,791 Supplemental pro forma earnings $ 22,539 $ 29,621 $ 54,404 $ 97,303 Actual diluted earnings per share $ 0.60 $ 1.00 $ 1.74 $ 3.40 Supplemental pro forma diluted earnings per share $ 0.63 $ 0.84 $ 1.53 $ 2.71 Contingent Consideration As discussed above, in conjunction with the Technicolor Acquisition, Technicolor will receive 42.5% of all of InterDigital's future cash receipts (net of estimated operating expenses) from InterDigital's new licensing efforts in the consumer electronics field; there will be no revenue sharing associated with InterDigital’s mobile industry licensing efforts. The portion of the future cash receipts relating to patents existing as of the date of the acquisition will be accounted for as a contingent consideration liability in accordance with ASC 805-30-25, Business Combinations - Contingent Consideration. The revenue sharing arrangement continues through December 31, 2038, and there are no minimum or maximum payments under the arrangement. The estimated acquisition date fair value of the contingent consideration liability of $18.6 million was determined utilizing a Monte Carlo simulation model. This initial fair value measurement is based on the perspective of a market participant and includes significant unobservable inputs that are classified as Level 3 inputs within the fair value hierarchy and are discussed further within Note 6. The contingent consideration is subject to re-measurement each reporting period until it has been fully paid, and any adjustments to the fair value of the contingent consideration are reflected within the condensed consolidated statements of income. Madison Arrangement As discussed above, in conjunction with the Technicolor Acquisition, effective July 30, 2018, we have assumed Technicolor’s rights and obligations under the Madison Arrangement, which commenced in 2015. The Madison Arrangement falls under the scope of ASC 808, Collaborative Arrangements (“ASC 808”). Significant Accounting Policy - Collaborative Arrangements We record the elements of our collaboration agreements that represent joint operating activities in accordance with ASC 808. Accordingly, the elements of our collaboration agreements that represent activities in which both parties are active participants, and to which both parties are exposed to the significant risks and rewards that are dependent on the commercial success of the activities, are recorded as collaborative arrangements. Generally, the classification of a transaction under a collaborative arrangement is determined based on the nature and contractual terms of the arrangement along with the nature of the operations of the participants. For transactions that are deemed to be a collaborative arrangement under ASC 808, costs incurred and revenues generated on sales to third parties will be reported in our condensed consolidated statement of operations on a gross basis if the Company is deemed to be the principal in the transaction, or on a net basis if the Company is instead deemed to be the agent in the transaction, consistent with the guidance in ASC 606-10-55-36, Revenue From Contracts with Customers - Principal Agent Considerations . Under the Madison Arrangement, Technicolor and Sony combined portions of their respective digital TV (“DTV”) and computer display monitor (“CDM”) patent portfolios and created a combined licensing opportunity to DTV and CDM manufacturers. Per an Agency and Management Services Agreement (“AMSA”) entered into upon the creation of the Madison Arrangement, Technicolor was initially appointed as sole licensing agent of the arrangement, and InterDigital has now assumed that role. As licensing agent, we are responsible for making decisions regarding the prosecution and maintenance of the combined patent portfolio and the licensing and enforcement of the combined patent portfolio in the field of use of DTVs and CDMs on an exclusive basis during the term of the AMSA in exchange for an agent fee. We were deemed to be the principal in this collaborative arrangement under ASC 808, and, as such, in accordance with ASC 606-10-55-36 Revenue From Contracts with Customers - Principal Agent Considerations , we record revenues generated on sales to third parties and costs incurred on a gross basis in the condensed consolidated statements of income. Therefore, we recognize all royalties from customers as revenue and payments to Sony for its royalty share as operating expenses within the condensed consolidated statements of income. Cost reimbursements for expenses incurred resulting from fulfilling the duties of the licensing agent are recorded as contra expenses. Amounts attributable to transactions arising from the Madison Arrangement between participants were not material during the three and nine months ended September 30, 2018. Long-term debt An affiliate of CPPIB Credit Investments Inc. ("CPPIB Credit"), a wholly owned subsidiary of Canada Pension Plan Investment Board, is a third-party investor in the Madison Arrangement. CPPIB Credit has made certain payments to Technicolor and Sony and has agreed to contribute cash to fund certain capital reserve obligations under the arrangement in exchange for a percentage of future revenues, specifically through September 11, 2030 in regard to the Technicolor patents. Upon our assumption of Technicolor’s rights and obligations under the Madison Arrangement, our relationship with CPPIB Credit meets the criteria in ASC 470-10-25 - Sales of Future Revenues or Various Other Measures of Income (“ASC 470”), which relates to cash received from an investor in exchange for a specified percentage or amount of revenue or other measure of income of a particular product line, business segment, trademark, patent, or contractual right for a defined period. Under this guidance, we recognized the fair value of our contingent obligation to CPPIB Credit, as of the acquisition date, as long-term debt in our condensed consolidated balance sheet. This initial fair value measurement is based on the perspective of a market participant and includes significant unobservable inputs which are classified as Level 3 inputs within the fair value hierarchy and are discussed further within Note 6. At each subsequent reporting period, we will measure the long-term debt at fair value based on the discounted expected future cash flows over the life of the obligation. Our repayment obligations are contingent upon future royalty revenues generated from the Madison Arrangement. Under ASC 470, amounts recorded as debt shall be amortized under the interest method. The Company made an accounting policy election to utilize the catch-up method when there is a change in the estimated future cash flows, whereby we will adjust the carrying amount of the debt to the present value of the revised estimated future cash flows, discounted at the original effective interest rate, with a corresponding adjustment recognized as interest expense within “Other Expense (Net)” in the condensed consolidated statements of income. As of September 30, 2018, the effective interest rate was approximately 12%. This rate represents the discount rate that equates the estimated future cash flows with the fair value of the debt, and is used to compute the amount of interest to be recognized each period. Any future payments made to CPPIB Credit, or additional proceeds received from CPPIB Credit, will decrease or increase the long-term debt balance accordingly. Restricted cash Under the Madison Arrangement, the parties reserve cash in bank accounts to fund our activities to manage the portfolios. These accounts are custodial accounts for which the funds are restricted for this purpose. As of September 30, 2018, the Company had $15.9 million of restricted cash included within the condensed consolidated balance sheet attributable to the Madison Arrangement. The following table provides a reconciliation of cash, cash equivalents and restricted cash as of September 30, 2018 and 2017 and December 31, 2017 and 2016: September 30, December 31, 2018 2017 2017 2016 Cash and cash equivalents $ 508,829 $ 283,557 $ 433,014 $ 404,074 Restricted cash included within prepaid and other current assets 15,942 — — — Total cash, cash equivalents and restricted cash $ 524,771 $ 283,557 $ 433,014 $ 404,074 Commitments To receive consent from both Sony and CPPIB Credit to assume the rights and responsibilities of Technicolor under the Madison Arrangement, we committed to contributing cash to fund shortfalls in the Madison Arrangement, up to a maximum of $25.0 million, through 2020. A shortfall funding is only required in the scenario in which the restricted cash is not sufficient to fund current obligations. In the event that we fund a shortfall, any surplus cash resulting from subsequent royalty receipts would be used to repay our shortfall funding plus 25% interest in advance of distributions of royalties to either Sony or CPPIB Credit, assuming they have not participated in the funding of the shortfall. As of September 30, 2018, we have not contributed any shortfall funding.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reclassifications	Reclassifications Certain reclassifications have been made to prior year amounts to conform to the current year presentation.
New Accounting Guidance	New Accounting Guidance Accounting Standards Update: Revenue Recognition In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, "Revenue from Contracts with Customers (Topic 606)" ("ASC 606") which superseded most prior revenue recognition guidance, including industry-specific guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from an entity’s contracts with customers. We adopted the requirements of the new standard as of January 1, 2018 using the modified retrospective transition method applied to those contracts that were not completed as of January 1, 2018. Accordingly, all periods prior to January 1, 2018 are presented in accordance with ASC Topic 605, "Revenue Recognition" (“ASC 605”). The adoption of the new guidance affected our recognition of revenue from both our fixed-fee and per-unit license agreements. For accounting purposes under this new guidance, we separate our fixed-fee license agreements into two categories: (i) those agreements that provide rights, over the term of the license, to future technologies that are highly interdependent or highly interrelated to the technologies provided at the inception of the agreement (“Dynamic Fixed-Fee Agreements”) and (ii) those agreements that do not provide for rights to such future technologies (“Static Fixed-Fee Agreements”). Under our previous accounting practices, after the fair value allocation between the past and future components of the agreement, we recognized the future components of revenue from all fixed-fee license agreements on a straight-line basis over the term of the related license agreement. As a result of our adoption of the new guidance, we will continue to recognize revenue from Dynamic Fixed-Fee Agreements on a straight-line basis over the term of the related license agreement, while we expect to recognize most or all of the revenue from Static Fixed-Fee Agreements in the quarter the license agreement is signed. We will not recognize any ongoing revenue from Static Fixed-Fee Agreements already in existence at the time the guidance was adopted. Additionally, in the event a significant financing component is determined to exist in any of our agreements, we will recognize more or less revenue and corresponding interest expense or income, as appropriate. In addition, under our previous accounting practices, we recognized revenue from our per-unit license agreements in the period in which we received the related royalty report, generally one quarter in arrears from the period in which the underlying sales occurred (i.e. on a "quarter-lag"). We are now required to record per-unit royalty revenue in the same period in which the licensee’s underlying sales occur. Because we generally do not receive the per-unit licensee royalty reports for sales during a given quarter within the time frame necessary to adequately review the reports and include the actual amounts in our quarterly results for such quarter, we accrue the related revenue based on estimates of our licensees’ underlying sales, subject to certain constraints on our ability to estimate such amounts. As a result of accruing revenue for the quarter based on such estimates, adjustments will be required in the following quarter to true-up revenue to the actual amounts reported by our licensees. In addition, to the extent we receive non-refundable prepayments related to per-unit license agreements that do not provide rights over the term of the license to future technologies that are highly interdependent or highly interrelated to the technologies provided at the inception of the agreement, we will recognize such prepayments as revenue in the period in which all remaining revenue recognition criteria have been met. Finally, under our previous accounting practices, we established a receivable, and any related deferred tax asset for foreign withholding taxes, for payments expected to be received within twelve months from the balance sheet date, based on the terms of the license agreement. Our reporting of such payments resulted in increases to: accounts receivable and deferred revenue; and deferred tax assets and taxes payable. Under ASC 606, we will only recognize those amounts as they become due. Timing of revenue recognition may differ significantly from the timing of invoicing to customers. Contract assets are included in accounts receivable and represent unbilled amounts expected to be received from customers in future periods, where the revenue recognized to date (or cumulative adjustments to retained earnings in the initial period of adopting ASC 606) exceeds the amount billed, and right to payment is subject to the underlying contractual terms. Contract assets are classified as long-term assets if the payments are expected to be received more than one year from the reporting date.

Net Income Per Share (Tables)

Net Income Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
NET INCOME PER SHARE: [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	NET INCOME PER SHARE Basic Earnings Per Share ("EPS") is calculated by dividing net income available to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur if options or other securities with features that could result in the issuance of common stock were exercised or converted to common stock. The following tables reconcile the numerator and the denominator of the basic and diluted net income per share computation (in thousands, except for per share data): For the Three Months Ended September 30, 2018 2017 Basic Diluted Basic Diluted Numerator: Net income applicable to InterDigital, Inc. $ 21,407 $ 21,407 $ 35,536 $ 35,536 Denominator: Weighted-average shares outstanding: Basic 34,651 34,651 34,709 34,709 Dilutive effect of stock options, RSUs, convertible securities and warrants 956 679 Weighted-average shares outstanding: Diluted 35,607 35,388 Earnings Per Share: Net income: Basic $ 0.62 $ 0.62 $ 1.02 $ 1.02 Dilutive effect of stock options, RSUs, convertible securities and warrants (0.02 ) (0.02 ) Net income: Diluted $ 0.60 $ 1.00 For the Nine Months Ended September 30, 2018 2017 Basic Diluted Basic Diluted Numerator: Net income applicable to InterDigital, Inc. $ 62,038 $ 62,038 $ 121,791 $ 121,791 Denominator: Weighted-average shares outstanding: Basic 34,687 34,687 34,589 34,589 Dilutive effect of stock options, RSUs, convertible securities and warrants 927 1,276 Weighted-average shares outstanding: Diluted 35,614 35,865 Earnings Per Share: Net income: Basic $ 1.79 $ 1.79 $ 3.52 $ 3.52 Dilutive effect of stock options, RSUs, convertible securities and warrants (0.05 ) (0.12 ) Net income: Diluted $ 1.74 $ 3.40 Certain shares of common stock issuable upon the exercise or conversion of certain securities have been excluded from our computation of EPS because the strike price or conversion rate, as applicable, of such securities was greater than the average market price of our common stock and, as a result, the effect of such exercise or conversion would have been anti-dilutive. Set forth below are the securities and the weighted average number of shares of common stock underlying such securities that were excluded from our computation of EPS for the periods presented (in thousands): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Restricted stock units and stock options 78 25 44 18 Convertible securities — — — — Warrants 4,405 4,386 4,404 — Total 4,483 4,411 4,448 18 Convertible Notes During periods in which the average market price of the Company's common stock is above the applicable conversion price of the Company's 1.50% Senior Convertible Notes due 2020 (for purposes of this discussion, the "Convertible Notes") ( $71.74 per share as of September 30, 2018) or above the strike price of our outstanding warrants ( $87.68 per share as of September 30, 2018), the impact of conversion or exercise, as applicable, would be dilutive and such dilutive effect is reflected in diluted EPS. As a result, in periods where the average market price of the Company's common stock is above the conversion price or strike price, as applicable, under the treasury stock method, the Company calculates the number of shares issuable under the terms of the Convertible Notes and the warrants based on the average market price of the stock during the period, and includes that number in the total diluted shares outstanding for the period. See Note 7, " Long-Term Debt ," for additional information about the Convertible Notes and warrants. For the Three Months Ended September 30, 2018 2017 Basic Diluted Basic Diluted Numerator: Net income applicable to InterDigital, Inc. $ 21,407 $ 21,407 $ 35,536 $ 35,536 Denominator: Weighted-average shares outstanding: Basic 34,651 34,651 34,709 34,709 Dilutive effect of stock options, RSUs, convertible securities and warrants 956 679 Weighted-average shares outstanding: Diluted 35,607 35,388 Earnings Per Share: Net income: Basic $ 0.62 $ 0.62 $ 1.02 $ 1.02 Dilutive effect of stock options, RSUs, convertible securities and warrants (0.02 ) (0.02 ) Net income: Diluted $ 0.60 $ 1.00 For the Nine Months Ended September 30, 2018 2017 Basic Diluted Basic Diluted Numerator: Net income applicable to InterDigital, Inc. $ 62,038 $ 62,038 $ 121,791 $ 121,791 Denominator: Weighted-average shares outstanding: Basic 34,687 34,687 34,589 34,589 Dilutive effect of stock options, RSUs, convertible securities and warrants 927 1,276 Weighted-average shares outstanding: Diluted 35,614 35,865 Earnings Per Share: Net income: Basic $ 1.79 $ 1.79 $ 3.52 $ 3.52 Dilutive effect of stock options, RSUs, convertible securities and warrants (0.05 ) (0.12 ) Net income: Diluted $ 1.74 $ 3.40

Equity Transactions Shareholder

Equity Transactions Shareholders Equity Rollforward (Tables)	9 Months Ended
	Sep. 30, 2018
EQUITY TRANSACTIONS: [Abstract]
Schedule of Stockholders Equity [Table Text Block]	Changes in shareholders’ equity for the nine months ended September 30, 2018 and September 30, 2017 were as follows (in thousands): For the Nine Months Ended September 30, 2018 2017 Balance beginning of period, December 31 $ 855,267 $ 739,709 Cumulative effect of change in accounting principle 161,251 — Net income attributable to InterDigital, Inc. 62,038 121,791 Unrealized (loss) gain on investments, net (904 ) (181 ) Cash dividends declared (36,312 ) (32,966 ) Repurchase of common stock (43,508 ) — Exercise of common stock options 6,362 82 Taxes withheld upon vesting of restricted stock units (8,478 ) (22,235 ) Share-based compensation 4,875 13,901 Total InterDigital, Inc. shareholders’ equity end of period $ 1,000,591 $ 820,101 Noncontrolling Interest Balance beginning of period, December 31 17,881 14,659 Net loss attributable to noncontrolling interest (3,423 ) (2,744 ) Noncontrolling interest 14,458 11,915 Total Equity end of period $ 1,015,049 $ 832,016

Concentration of Credit Risk _2

Concentration of Credit Risk and Fair Value of Financial Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
CONCENTRATION OF CREDIT RISK AND FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES: [Abstract]
Fair Value, Measurement Inputs, Disclosure [Table Text Block]	Our financial assets and liabilities that are accounted for at fair value on a recurring basis are presented in the tables below as of September 30, 2018 and December 31, 2017 (in thousands): Fair Value as of September 30, 2018 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 415,614 $ — $ — $ 415,614 Commercial paper (b) — 131,987 — 131,987 U.S. government securities — 328,440 — 328,440 Corporate bonds, asset backed and other securities — 198,251 — 198,251 Total $ 415,614 $ 658,678 $ — $ 1,074,292 Liabilities: Contingent consideration resulting from the Technicolor Acquisition — — 18,616 $ 18,616 Long-term debt resulting from the Technicolor Acquisition — — 18,107 $ 18,107 $ — $ — $ 36,723 $ 36,723 Fair Value as of December 31, 2017 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 417,348 $ — $ — $ 417,348 Commercial paper (b) — 66,132 — 66,132 U.S. government securities — 511,032 — 511,032 Corporate bonds, asset backed and other securities — 163,483 — 163,483 $ 417,348 $ 740,647 $ — $ 1,157,995 ______________________________ (a) Primarily included within cash and cash equivalents.

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Long-term Debt, Unclassified [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	The following table reflects the carrying value of the 2020 Notes as of September 30, 2018 and December 31, 2017 (in thousands): September 30, 2018 December 31, 2017 Principal $ 316,000 $ 316,000 Less: Unamortized interest discount (18,611 ) (27,863 ) Deferred financing costs (1,969 ) (3,011 ) Net carrying amount of 2020 Notes $ 295,420 $ 285,126 The following table presents the amount of interest cost recognized, which is included within " Other Expense" in our condensed consolidated statements of income, for the three and nine months ended September 30, 2018 and September 30, 2017 relating to the contractual interest coupon, accretion of the debt discount, and the amortization of financing costs (in thousands): For the Three Months Ended September 30, 2018 2017 Contractual coupon interest $ 1,185 $ 1,185 Accretion of debt discount 3,124 2,947 Amortization of deferred financing costs 347 348 Total $ 4,656 $ 4,480

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following table summarizes the fair value of consideration transferred and our preliminary allocation of that consideration based on the estimated fair values of the assets acquired and liabilities assumed as of the date of acquisition: As of July 30, 2018 Cash $ 158,898 Contingent consideration liability 18,616 $ 177,514 ` Less: Transaction-related receivable (20,200 ) Net fair value of consideration transferred $ 157,314 Allocation: Estimated useful life (Years) Net tangible assets and liabilities: Restricted cash $ 15,913 Other current assets 5,600 Other non-current assets 3,116 Current liabilities (6,219 ) Long-term debt (17,717 ) Other long-term liabilities (3,767 ) Total net tangible assets and liabilities $ (3,074 ) Identified intangible assets: Patents (1) $ 154,000 9 - 10 Goodwill (2) 6,388 Total identified intangible assets $ 160,388 Total fair value of consideration transferred $ 157,314 (1) We expect $16.4 million of additional annualized amortization expense from patents acquired in the Technicolor Acquisition. (2) Goodwill consists of expected synergies resulting from the combination of our and Technicolor’s patent licensing businesses in the increasingly complementary areas of mobile and video technology. We expect that the majority of the goodwill resulting from the Technicolor Acquisition will be deductible for income tax purposes.

Basis of Presentation - Account

Basis of Presentation - Accounting Standards Update (Details) - USD ($) $ in Millions	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Equity Method Investments	$ 17.4		$ 19.2
ASU 2018-02 [Domain]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 0.4

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with Customer, Asset, Net		$ 24,700
Accounts Receivable 606	$ 29,769	61,514	$ 216,293
Taxes Payable 606	(98,022)	(6,226)	(14,881)
Deferred Revenue	(269,662)	(257,239)	(616,813)
Retained earnings	(1,436,171)	(1,410,342)	(1,249,091)
DEFERRED TAX ASSETS	60,056	32,383	$ 84,582
Accounts Receivable [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with Customer, Asset, Net	22,000
Accounts Receivable 606		(154,779)
Deferred Tax Asset [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
DEFERRED TAX ASSETS		(52,199)
Taxes Payable [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Taxes Payable 606		(8,655)
Deferred Revenue [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue		(359,574)
Retained Earnings, Unappropriated [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings		161,251
Other Noncurrent Assets [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with Customer, Asset, Net	$ 5,500
Static Fixed Fee Agreements [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606		6,000
Taxes Payable 606		0
Deferred Revenue		(99,466)
Retained earnings		105,466
DEFERRED TAX ASSETS		0
Static Prepayments [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606		0
Taxes Payable 606		0
Deferred Revenue		(85,146)
Retained earnings		85,146
DEFERRED TAX ASSETS		0
Quarter Lag Reporting [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606		10,948
Taxes Payable 606		0
Deferred Revenue		0
Retained earnings		10,948
DEFERRED TAX ASSETS		0
Significant Financing Component [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606		0
Taxes Payable 606		0
Deferred Revenue		(3,235)
Retained earnings		3,235
DEFERRED TAX ASSETS		0
Related Tax Effect and Other Balance Sheet Impact [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606		(171,727)
Taxes Payable 606		(8,655)
Deferred Revenue		(171,727)
Retained earnings		(43,544)
DEFERRED TAX ASSETS		$ (52,199)

Basis of Presentation - Cumulat

Basis of Presentation - Cumulative Effect Recognized on Initial Application of the New Guidance (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 75,079	$ 97,325	$ 232,078	$ 327,634
Accounts Receivable 606	29,769		29,769		$ 61,514	$ 216,293
Costs and Expenses	62,159	56,450	173,328	171,843
Operating Income (Loss)	12,920	40,875	58,750	155,791
OTHER EXPENSE (NET)	(13,953)	(2,187)	(25,136)	(7,331)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(1,033)	38,688	33,614	148,460
INCOME TAX BENEFIT (PROVISION)	21,143	(3,963)	25,001	(29,413)
Net income	20,110	34,725	58,615	119,047
Net loss attributable to noncontrolling interest	(1,297)	(811)	(3,423)	(2,744)
Net Income (Loss) Attributable to Parent	$ 21,407	$ 35,536	$ 62,038	$ 121,791
Net Income Per Common Share, Basic (in usd per share)	$ 0.62	$ 1.02	$ 1.79	$ 3.52
NET INCOME PER COMMON SHARE — DILUTED (in usd per share)	$ 0.60	$ 1	$ 1.74	$ 3.40
DEFERRED TAX ASSETS	$ 60,056		$ 60,056		32,383	84,582
OTHER NON-CURRENT ASSETS	63,877		63,877			37,963
Taxes Payable 606	(98,022)		(98,022)		(6,226)	(14,881)
Deferred Revenue	(269,662)		(269,662)		(257,239)	(616,813)
Retained earnings	(1,436,171)		(1,436,171)		(1,410,342)	(1,249,091)
Accounts Receivable [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606					(154,779)
Deferred Tax Asset [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
DEFERRED TAX ASSETS					(52,199)
Taxes Payable [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Taxes Payable 606					(8,655)
Deferred Revenue [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred Revenue					(359,574)
Variable Patent Royalty Revenue [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	13,645	$ 10,081	26,322	$ 37,338
Fixed-Fee Royalty Revenue [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	60,272	73,653	178,207	220,083
Current Patent Royalties [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	73,917	83,734	204,529	257,421
Non Current Patent Royalties [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	128	8,832	25,489	56,692
Total Patent Royalties [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	74,045	92,566	230,018	314,113
Technology solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,034	$ 4,759	2,060	$ 13,521
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	91,343		286,925
Accounts Receivable 606	235,848		235,848			216,293
Operating Income (Loss)	29,184		113,597
OTHER EXPENSE (NET)	(9,960)		(12,132)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	19,224		101,465
INCOME TAX BENEFIT (PROVISION)	14,467		9,394
Net income	33,691		110,859
Net loss attributable to noncontrolling interest	(1,297)		(3,423)
Net Income (Loss) Attributable to Parent	$ 34,988		$ 114,282
Net Income Per Common Share, Basic (in usd per share)	$ 1.01		$ 3.29
NET INCOME PER COMMON SHARE — DILUTED (in usd per share)	$ 0.98		$ 3.21
DEFERRED TAX ASSETS	$ 106,154		$ 106,154			84,582
OTHER NON-CURRENT ASSETS	58,377		58,377			37,963
Taxes Payable 606	(114,460)		(114,460)			(14,881)
Deferred Revenue	(611,478)		(611,478)			(616,813)
Retained earnings	(1,324,594)		(1,324,594)			$ (1,249,091)
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Variable Patent Royalty Revenue [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	8,403		25,856
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Fixed-Fee Royalty Revenue [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	80,581		238,288
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Current Patent Royalties [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	88,984		264,144
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Non Current Patent Royalties [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	128		15,489
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Total Patent Royalties [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	89,112		279,633
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Technology solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	2,231		7,292
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606	206,079		206,079
DEFERRED TAX ASSETS	46,098		46,098
OTHER NON-CURRENT ASSETS	(5,500)		(5,500)
Taxes Payable 606	(16,438)		(16,438)
Deferred Revenue	341,816		341,816
Retained earnings	(111,577)		(111,577)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	16,264		54,847
Costs and Expenses	0		0
Operating Income (Loss)	16,264		54,847
OTHER EXPENSE (NET)	3,993		13,004
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	20,257		67,851
INCOME TAX BENEFIT (PROVISION)	(6,676)		(15,607)
Net income	13,581		52,244
Net loss attributable to noncontrolling interest	0		0
Net Income (Loss) Attributable to Parent	$ 13,581		$ 52,244
Net Income Per Common Share, Basic (in usd per share)	$ 0.39		$ 1.50
NET INCOME PER COMMON SHARE — DILUTED (in usd per share)	$ 0.38		$ 1.47
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Variable Patent Royalty Revenue [Domain] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ (5,242)		$ (466)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Fixed-Fee Royalty Revenue [Domain] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	20,309		60,081
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Current Patent Royalties [Domain] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	15,067		59,615
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Non Current Patent Royalties [Domain] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0		(10,000)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Total Patent Royalties [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	15,067		49,615
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Technology solutions | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 1,197		$ 5,232
Static Fixed Fee Agreements [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606					6,000
DEFERRED TAX ASSETS					0
Taxes Payable 606					0
Deferred Revenue					(99,466)
Retained earnings					105,466
Static Prepayments [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606					0
DEFERRED TAX ASSETS					0
Taxes Payable 606					0
Deferred Revenue					(85,146)
Retained earnings					85,146
Quarter Lag Reporting [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606					10,948
DEFERRED TAX ASSETS					0
Taxes Payable 606					0
Deferred Revenue					0
Retained earnings					10,948
Significant Financing Component [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606					0
DEFERRED TAX ASSETS					0
Taxes Payable 606					0
Deferred Revenue					(3,235)
Retained earnings					3,235
Related Tax Effect and Other Balance Sheet Impact [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable 606					(171,727)
DEFERRED TAX ASSETS					(52,199)
Taxes Payable 606					(8,655)
Deferred Revenue					(171,727)
Retained earnings					$ (43,544)

Basis of Presentation - Disaggr

Basis of Presentation - Disaggregated Revenue (Details) - USD ($) number in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 75,079	$ 97,325	$ 232,078	$ 327,634
Increase/(Decrease) in Disaggregated Revenue	$ (22,246)		(95,556)
Deferred Revenue, Revenue Recognized			$ 54,100
Percentage Increase/(Decrease) in Disaggregated Revenue	0.00%		0.00%
Variable Patent Royalty Revenue [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 13,645	10,081	$ 26,322	37,338
Increase/(Decrease) in Disaggregated Revenue	$ 3,564		$ (11,016)
Percentage Increase/(Decrease) in Disaggregated Revenue	0.00%		0.00%
Fixed-Fee Royalty Revenue [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 60,272	73,653	$ 178,207	220,083
Increase/(Decrease) in Disaggregated Revenue	$ (13,381)		$ (41,876)
Percentage Increase/(Decrease) in Disaggregated Revenue	0.00%		0.00%
Current Patent Royalties [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 73,917	83,734	$ 204,529	257,421
Increase/(Decrease) in Disaggregated Revenue	$ (9,817)		$ (52,892)
Percentage Increase/(Decrease) in Disaggregated Revenue	0.00%		0.00%
Non Current Patent Royalties [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 128	8,832	$ 25,489	56,692
Increase/(Decrease) in Disaggregated Revenue	$ (8,704)		$ (31,203)
Percentage Increase/(Decrease) in Disaggregated Revenue	0.00%		0.00%
Total Patent Royalties [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 74,045	92,566	$ 230,018	314,113
Increase/(Decrease) in Disaggregated Revenue	$ (18,521)		$ (84,095)
Percentage Increase/(Decrease) in Disaggregated Revenue	0.00%		0.00%
Technology solutions
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 1,034	$ 4,759	$ 2,060	$ 13,521
Increase/(Decrease) in Disaggregated Revenue	$ (3,725)		$ (11,461)
Percentage Increase/(Decrease) in Disaggregated Revenue	0.00%		0.00%

Basis of Presentation - Details

Basis of Presentation - Details (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jan. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with Customer, Asset, Net		$ 24.7
Accounts Receivable [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with Customer, Asset, Net	$ 22
Other Noncurrent Assets [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with Customer, Asset, Net	$ 5.5

Basis of Presentation - Remaini

Basis of Presentation - Remaining Performance Obligation (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Deferred Revenue, Revenue Recognized	$ 54,100
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	60,272
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	237,339
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	236,089
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	169,039
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 85,228

Significant Agreements Assets H

Significant Agreements Assets Held For Sale (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Long Lived Assets Held-for-sale [Line Items]
Gain (Loss) on Disposition of Assets	$ (8,176)	$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Jan. 31, 2018
Income Tax Contingency [Line Items]
Effective Income Tax Rate, Continuing Operations			74.40%	(19.80%)
Estimated Annual Effective Tax Rate			19.70%	34.20%
INCOME TAX BENEFIT (PROVISION)	$ 21,143	$ (3,963)	$ 25,001	$ (29,413)
Income taxes paid, including foreign withholding taxes			24,459	29,173
Taxes payable	98,022		98,022			$ 14,881	$ 6,226
Tax Adjustments, Settlements, and Unusual Provisions						$ 43,300
Stock Compensation Plan [Member]
Income Tax Contingency [Line Items]
INCOME TAX BENEFIT (PROVISION)	(18,400)			(12,100)
Uncertain tax position [Member]
Income Tax Contingency [Line Items]
INCOME TAX BENEFIT (PROVISION)				(9,100)
Foreign Country [Member]
Income Tax Contingency [Line Items]
Income taxes paid, including foreign withholding taxes			16,500	$ 11,700
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority	15,700		15,700
Estimated Tax Refund	$ 97,400		$ 97,400
Scenario, Forecast [Member]
Income Tax Contingency [Line Items]
INCOME TAX BENEFIT (PROVISION)					$ (16,800)

Net Income Per Share (Details)

Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 09, 2015	Mar. 05, 2015
Earnings Per Share, Basic & Dilutive, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Attributable to Parent	$ 21,407,000	$ 35,536,000	$ 62,038,000	$ 121,791,000
Weighted Average Number of Shares Outstanding, Basic (in shares)	34,651	34,709	34,687	34,589
Weighted Average Number Diluted Shares Outstanding Adjustment	956	679	927	1,276
Weighted Average Number of Shares Outstanding, Diluted (in shares)	35,607	35,388	35,614	35,865
Dilutive Securities, Efffect on Basic Earnings Per Share [2]	$ (0.02)	$ (0.02)	$ (0.05)	$ (0.12)
Net Income Per Common Share, Basic (in usd per share)	$ 0.62	$ 1.02	$ 1.79	$ 3.52
NET INCOME PER COMMON SHARE — DILUTED (in usd per share)	$ 0.60	$ 1	$ 1.74	$ 3.40
Convertible Debt Securities [Member]
Earnings Per Share, Basic & Dilutive, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0	0	0
Warrant [Member]
Earnings Per Share, Basic & Dilutive, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,405	4,386	4,404	0
Convertible Debt [Member] | Convertible Notes 2020 [Member]
Earnings Per Share, Basic & Dilutive, by Common Class, Including Two Class Method [Line Items]
Debt Instrument, Convertible, Conversion Price	$ 71.74		$ 71.74
Equity [Member] | Convertible Debt [Member]
Earnings Per Share, Basic & Dilutive, by Common Class, Including Two Class Method [Line Items]
Class of Warrant or Right, Outstanding					600	3,800
Warrant Option Strike Price	$ 87.68		$ 87.68

Net Income Per Share Antidiluti

Net Income Per Share Antidilutive Securities Excluded from Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0	0	0
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,405	4,386	4,404	0
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	78	25	44	18

Litigation and Legal Proceedi_2

Litigation and Legal Proceedings (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Legal Gain (Loss) Contingencies [Line Items]
Deferred revenue	$ 134,197	$ 307,142

Equity Transactions (Details)

Equity Transactions (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended				51 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2015	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2018	Mar. 09, 2015	Mar. 05, 2015	Jun. 30, 2014
Class of Stock [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax											$ 161,251	$ 0
CASH DIVIDENDS DECLARED PER COMMON SHARE (in usd per share)	$ 0.35	$ 0.35		$ 0.35	$ 0.35	$ 0.30	$ 0.30				$ 1.05	$ 0.95	$ 1.30
Noncontrolling interest	$ 14,458			$ 17,881	$ 11,915						$ 14,458	$ 11,915	$ 17,881	$ 14,659			$ 14,458
Net loss attributable to noncontrolling interest	(1,297)				(811)						(3,423)	(2,744)
Equity Transactions [Roll Forward]
Balance as of December 31, 2011			$ 855,267	820,101			$ 739,709		$ 855,267	$ 739,709	855,267	739,709	739,709
NET INCOME	21,407				35,536						62,038	121,791
Unrealized (loss) gain on investments, net of tax	467				(94)						(904)	(181)
Adjustments Related to Tax Withholding for Share-based Compensation											8,478	22,235
Balance as of September 30, 2012	1,000,591			855,267	820,101						1,000,591	820,101	855,267	$ 739,709			1,000,591
Dividends, Common Stock, Cash	11,996	$ 12,192	$ 12,124	12,156	12,149	$ 10,413	$ 10,404		$ 24,316	$ 20,817	36,312	32,966	45,122
Proceeds from Issuance of Warrants								$ 5,600
Proceeds from Stock Options Exercised											6,362	82
Share-based compensation											4,875	13,901
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 1,015,049			$ 873,148	$ 832,016						$ 1,015,049	$ 832,016	$ 873,148				$ 1,015,049
Convertible Debt [Member] | Equity [Member]
Equity Transactions [Roll Forward]
Class of Warrant or Right, Outstanding																		600	3,800
Warrant Option Strike Price	$ 87.68										$ 87.68						$ 87.68
Note Warrant2 [Member]
Equity Transactions [Roll Forward]
Proceeds from Issuance of Warrants								$ 37,300
2014 Repurchase Program [Domain]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount	$ 500,000										$ 500,000						$ 500,000			$ 300,000
Treasury Stock Acquired, Repurchase Authorization	100							100
Stock Repurchased During Period, Shares											549		107	1,304	1,836	3,554	7,350
Equity Transactions [Roll Forward]
Stock Repurchased During Period, Value											$ 43,508		$ 7,693	$ 64,685	$ 96,410	$ 152,625	$ 364,921

Equity Transactions Equity Roll

Equity Transactions Equity Rollforward (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended				51 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2015	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2018	Jun. 30, 2014
Class of Stock [Line Items]
Proceeds from Issuance of Warrants								$ 5,600
CASH DIVIDENDS DECLARED PER COMMON SHARE (in usd per share)	$ 0.35	$ 0.35		$ 0.35	$ 0.35	$ 0.30	$ 0.30				$ 1.05	$ 0.95	$ 1.30
Dividends, Common Stock, Cash	$ 11,996	$ 12,192	$ 12,124	$ 12,156	$ 12,149	$ 10,413	$ 10,404		$ 24,316	$ 20,817	$ 36,312	$ 32,966	$ 45,122
Stockholders' Equity Attributable to Parent	1,000,591			855,267	820,101						1,000,591	820,101	855,267	$ 739,709			$ 1,000,591
Adjustments Related to Tax Withholding for Share-based Compensation											(8,478)	(22,235)
Net Income (Loss) Attributable to Parent	21,407				35,536						62,038	121,791
Unrealized (loss) gain on investments, net of tax	467				(94)						(904)	(181)
Cash dividends declared											(36,312)	(32,966)
Repurchase of common stock											(43,508)	0
Proceeds from Stock Options Exercised											6,362	82
Share-based compensation											4,875	13,901
Net loss attributable to noncontrolling interest	(1,297)				(811)						(3,423)	(2,744)
Noncontrolling interest	14,458			17,881	11,915						14,458	11,915	17,881	$ 14,659			14,458
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,015,049			$ 873,148	$ 832,016						1,015,049	$ 832,016	$ 873,148				1,015,049
2014 Repurchase Program [Domain]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount	$ 500,000										$ 500,000						$ 500,000	$ 300,000
Stock Repurchased During Period, Shares											549		107	1,304	1,836	3,554	7,350
Stock Repurchased During Period, Value											$ 43,508		$ 7,693	$ 64,685	$ 96,410	$ 152,625	$ 364,921

Equity Transactions Adjustments

Equity Transactions Adjustments for Tax Withholding (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Class of Stock [Line Items]
Adjustments Related to Tax Withholding for Share-based Compensation	$ (8,478)	$ (22,235)

Concentration of Credit Risk _3

Concentration of Credit Risk and Fair Value of Financial Assets and Liabilities (Details)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Concentration Risk [Line Items]
Concentration Risk, Percentage	64.00%	96.00%
Concentration Risk, Customer	four	three

Concentration of Credit Risk _4

Concentration of Credit Risk and Fair Value of Financial Assets and Liabilities Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 1,074,292	$ 1,157,995
Contingent consideration liability	18,616
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	18,107
Senior Notes	295,420	285,126
Commercial Paper	109,200	15,700
LONG-TERM DEBT	313,527	285,126
Long-term Debt, Fair Value	371,300	377,029
Other Liabilities, Fair Value Disclosure	36,723
Money Market Funds and Demand Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	415,614	417,348
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	131,987	66,132
US Government and Government Agencies and Authorities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	328,440	511,032
Corporate Bonds and Asset Backed Securities [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	198,251	163,483
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	415,614	417,348
Contingent consideration liability	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	0
Other Liabilities, Fair Value Disclosure	0
Fair Value, Inputs, Level 1 [Member] | Money Market Funds and Demand Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	415,614	417,348
Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | US Government and Government Agencies and Authorities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Corporate Bonds and Asset Backed Securities [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	658,678	740,647
Contingent consideration liability	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	0
Other Liabilities, Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member] | Money Market Funds and Demand Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	131,987	66,132
Fair Value, Inputs, Level 2 [Member] | Corporate Bonds and Asset Backed Securities [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	198,251	163,483
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Contingent consideration liability	18,616
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	18,107
Other Liabilities, Fair Value Disclosure	36,723
Fair Value, Inputs, Level 3 [Member] | Money Market Funds and Demand Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | US Government and Government Agencies and Authorities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Corporate Bonds and Asset Backed Securities [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 0	$ 0

Concentration of Credit Risk _5

Concentration of Credit Risk and Fair Value of Financial Assets and Liabilities Significant Unobservable Inputs (Details) - Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2018
Revenue Volatility [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.350
Discount Rate for Revenue [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.145
Credit Risk Discount Rate [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.039
Credit Risk Discount Rate [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.067
RiskAdjustedDiscountRateForRevenue [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.135
RiskAdjustedDiscountRateForRevenue [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.145

Long-Term Debt (Details)

Long-Term Debt (Details) $ / shares in Units, shares in Thousands	3 Months Ended			9 Months Ended		12 Months Ended				51 Months Ended
	Sep. 30, 2018USD ($)$ / shares	Sep. 30, 2017USD ($)	Jun. 30, 2015USD ($)	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares	Sep. 30, 2018USD ($)$ / sharesshares	Mar. 31, 2015USD ($)	Mar. 11, 2015USD ($)	Mar. 09, 2015shares	Mar. 05, 2015USD ($)shares	Jun. 30, 2014USD ($)
Debt Instrument [Line Items]
Interest Expense, Debt, Excluding Amortization		$ 1,185,000			$ 3,555,000
Accretion of Discount		2,947,000			8,710,000
Amortization of Financing Costs		348,000			1,043,000
Proceeds from Issuance of Warrants			$ 5,600,000
Senior Notes	$ 295,420,000			$ 295,420,000		$ 285,126,000				$ 295,420,000
Debt Instrument, Convertible, Stock Price Trigger | $ / shares				$ 93.26
Debt Instrument, Interest Rate, Effective Percentage												5.89%
Interest Expense		$ 4,480,000			$ 13,308,000
Long-term Debt, Fair Value	371,300,000			$ 371,300,000		377,029,000				371,300,000
Note Warrant2 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Warrants			37,300,000
Convertible Note Hedge 2 [Member]
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities			7,700,000
Convertible Note Hedge [Member]
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities			59,400,000
Convertible Note Hedge 1 [Member]
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities			51,700,000
Convertible Note/ Hedge Warrant, net [Member]
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities			16,500,000
Convertible Note Overallotment [Member]
Debt Instrument [Line Items]
Senior Notes														$ 41,000,000
Convertible Debt [Member]
Debt Instrument [Line Items]
Senior Notes	316,000,000			316,000,000		316,000,000				316,000,000
Payments of Debt Issuance Costs			(9,300,000)
Convertible Debt [Member] | Convertible Notes 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	316,000,000			316,000,000		316,000,000				316,000,000
Interest Expense, Debt, Excluding Amortization	1,185,000			3,555,000
Accretion of Discount	3,124,000			9,252,000
Amortization of Financing Costs	347,000			1,042,000
Senior Notes	295,420,000			295,420,000		285,126,000				295,420,000
Debt Instrument, Unamortized Discount	(18,611,000)			(18,611,000)		(27,863,000)				(18,611,000)
Deferred financing costs	$ (1,969,000)			$ (1,969,000)		$ (3,011,000)				$ (1,969,000)
Debt Conversion, Converted Instrument, Amount			1,000
Debt Instrument, Convertible, Conversion Price | $ / shares	$ 71.74			$ 71.74						$ 71.74
Debt Instrument, Interest Rate, Stated Percentage												1.50%
Debt Instrument, Convertible, Conversion Ratio				13.9392
Interest Expense	$ 4,656,000			$ 13,849,000
Convertible Notes 2020 [Member] | Convertible Notes 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount											$ 316,000,000
Convertible Debt 1 [Member]
Debt Instrument [Line Items]
Senior Notes														$ 275,000,000
Equity Component [Domain] | Convertible Debt [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs			(2,400,000)
Balance Sheet by Location [Domain] | Convertible Debt [Member]
Debt Instrument [Line Items]
Senior Notes												$ 256,700,000
Other Noncurrent Liabilities [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs			$ (7,000,000)
Equity [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Senior Notes												59,300,000
Senior Convertible Notes [Equity net of tax]												$ 38,600,000
Class of Warrant or Right, Outstanding | shares													600	3,800
Warrant Option Strike Price | $ / shares	$ 87.68			$ 87.68						$ 87.68
2014 Repurchase Program [Domain]
Debt Instrument [Line Items]
Stock Repurchase Program, Authorized Amount	$ 500,000,000			$ 500,000,000						$ 500,000,000					$ 300,000,000
Stock Repurchased During Period, Shares | shares				549		107	1,304	1,836	3,554	7,350
Stock Repurchased During Period, Value				$ 43,508,000		$ 7,693,000	$ 64,685,000	$ 96,410,000	$ 152,625,000	$ 364,921,000

Variable Interest Entities (Det

Variable Interest Entities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 29,400		$ 29,400		$ 34,400
Net loss attributable to noncontrolling interest	(1,297)	$ (811)	(3,423)	$ (2,744)
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	3,000		3,000		200
Cash and Cash Equivalents [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	12,100		12,100		23,300
Accounts Receivable [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	1,300		1,300
Patents [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 13,400		$ 13,400		$ 11,100

Business Combinations - Narrati

Business Combinations - Narrative (Details) - USD ($) $ in Thousands	Jul. 30, 2018	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual		$ 1,900
Cash			$ 158,900
Contingent consideration liability		18,616	18,616
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual		4,600
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed		5,400	9,200
Restricted Cash		$ 15,942	$ 15,942	$ 0	$ 0	$ 0
Technicolor
Business Acquisition [Line Items]
Cash	$ 158,898
Cash and cash equivalents	15,913
Contingent consideration liability	18,616
Business Combination, Acquired Receivable, Fair Value	$ 20,200

Business Combinations - Fair Va

Business Combinations - Fair Value of Consideration Transferred and Preliminary Allocation (Details) - USD ($) $ in Thousands	Jul. 30, 2018	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed		$ 5,400	$ 9,200
Cash			158,900
Contingent consideration liability		18,616	18,616
Long-term debt		(18,107)	(18,107)
Goodwill		$ 22,421	$ 22,421	$ 16,033
Additional annualized amortization expense	$ 16,400
Technicolor
Business Acquisition [Line Items]
Cash	158,898
Contingent consideration liability	18,616
Consideration transferred	177,514
Less: Transaction-related receivable	(20,200)
Net fair value of consideration transferred	157,314
Cash and cash equivalents	15,913
Other current assets	5,600
Other non-current assets	3,116
Current liabilities	(6,219)
Long-term debt	(17,717)
Other long-term liabilities	(3,767)
Total net tangible assets and liabilities	(3,074)
Patents	154,000
Goodwill	6,388
Total identified intangible assets	160,388
Total fair value of consideration transferred	$ 157,314
Technicolor | Minimum [Member]
Business Acquisition [Line Items]
Estimated useful lives	9 years
Technicolor | Maximum [Member]
Business Acquisition [Line Items]
Estimated useful lives	10 years
Prepaid Expenses and Other Current Assets [Member] | Technicolor
Business Acquisition [Line Items]
Less: Transaction-related receivable	$ 8,500

Business Combinations - Change

Business Combinations - Change in Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Goodwill [Roll Forward]
Goodwill balance as of December 31, 2017	$ 16,033
Goodwill balance as of September 30, 2018	22,421
Technicolor
Goodwill [Roll Forward]
Technicolor Acquisition	$ 6,388

Business Combinations - Pro For

Business Combinations - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Actual revenue	$ 75,079	$ 97,325	$ 232,078	$ 327,634
Supplemental pro forma revenue	76,034	100,391	238,761	335,229
Actual earnings	21,407	35,536	62,038	121,791
Supplemental pro forma earnings	$ 22,539	$ 29,621	$ 54,404	$ 97,303
Actual diluted earnings per share (in usd per share)	$ 0.60	$ 1	$ 1.74	$ 3.40
Supplemental pro forma diluted earnings per share (in usd per share)	$ 0.63	$ 0.84	$ 1.53	$ 2.71

Restricted Cash (Details)

Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 508,829	$ 433,014	$ 283,557	$ 404,074
Restricted Cash	15,942	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 524,771	$ 433,014	$ 283,557	$ 404,074