InterDigital (IDCC) 10-K 18 Feb 21 2020 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 16, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-33579
Entity Registrant Name	INTERDIGITAL, INC.
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	82-4936666
Entity Address, Address Line One	200 Bellevue Parkway
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	Wilmington
Entity Address, State or Province	DE
Entity Address, Postal Zip Code	19809-3727
City Area Code	302
Local Phone Number	281-3600
Title of 12(b) Security	Common Stock (par value $0.01 per share)
Trading Symbol	IDCC
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,730,267,697
Entity Common Stock, Shares Outstanding		30,828,895
Documents Incorporated by Reference	Portions of the registrant's definitive proxy statement to be filed pursuant to Regulation 14A in connection with the registrant's 2021 annual meeting of shareholders are incorporated by reference into Items 10, 11, 12, 13 and 14 of Part III of this Form 10-K.
Entity Central Index Key	0001405495
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 473,474	$ 745,491
Short-term investments	453,173	179,204
Accounts receivable, less allowances of $0 and $537	16,008	28,272
Prepaid and other current assets	84,224	63,365
Total current assets	1,026,879	1,016,332
PROPERTY AND EQUIPMENT, NET	16,630	10,217
PATENTS, NET	418,343	436,339
DEFERRED TAX ASSETS	80,380	73,168
OTHER NON-CURRENT ASSETS	74,043	76,026
Total non-current assets	589,396	595,750
TOTAL ASSETS	1,616,275	1,612,082
CURRENT LIABILITIES:
Current portion of long-term debt	0	94,170
Accounts payable	10,979	13,393
Accrued compensation and related expenses	32,413	29,162
Deferred revenue	219,935	146,654
Taxes payable	360	51
Dividend payable	10,786	10,746
Other accrued expenses	21,289	11,382
Total current liabilities	295,762	305,558
LONG-TERM DEBT	367,992	350,588
LONG-TERM DEFERRED REVENUE	108,069	123,653
OTHER LONG-TERM LIABILITIES	47,886	46,002
TOTAL LIABILITIES	819,709	825,801
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, 71,389 and 71,268 shares issued and 30,816 and 30,701 shares outstanding	714	712
Additional paid-in capital	738,481	727,402
Retained earnings	1,413,969	1,412,779
Accumulated other comprehensive loss	(184)	(74)
Stockholders' equity before treasury stock	2,152,980	2,140,819
Treasury stock, 40,573 and 40,567 shares of common held at cost	1,379,611	1,379,262
Total InterDigital, Inc. shareholders’ equity	773,369	761,557
Noncontrolling interest	23,197	24,724
Total equity	796,566	786,281
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 1,616,275	$ 1,612,082

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Accounts receivable, less allowances of $0 and $537	$ 0	$ 537
SHAREHOLDERS’ EQUITY:
Preferred stock, par value (in USD per share)	$ 0.10	$ 0.10
Preferred stock, shares authorized (in shares)	14,399,000	14,399,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	71,389,000	71,268,000
Common stock, shares outstanding (in shares)	30,816,000	30,701,000
Treasury stock, shares of common held at cost (in shares)	40,573,000	40,567,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues	$ 358,991	$ 318,924	$ 307,404
OPERATING EXPENSES:
Patent administration and licensing	170,178	154,940	124,081
Development	84,646	74,860	69,698
Selling, general and administrative	48,999	51,289	51,030
Total Operating expenses	303,823	281,089	244,809
Income from operations	55,168	37,835	62,595
INTEREST EXPENSE	(40,799)	(40,955)	(35,956)
OTHER INCOME, NET	16,924	29,062	5,419
Income before income taxes	31,293	25,942	32,058
INCOME TAX BENEFIT (PROVISION)	6,648	(10,991)	27,417
NET INCOME	37,941	14,951	59,475
Net loss attributable to noncontrolling interest	(6,860)	(5,977)	(5,556)
NET INCOME ATTRIBUTABLE TO INTERDIGITAL, INC.	$ 44,801	$ 20,928	$ 65,031
NET INCOME PER COMMON SHARE - BASIC (in usd per share)	$ 1.46	$ 0.66	$ 1.89
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING - BASIC (in usd per share)	30,776	31,546	34,491
NET INCOME PER COMMON SHARE - DILUTED (in usd per share)	$ 1.44	$ 0.66	$ 1.84
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING - DILUTED (in shares)	31,058	31,785	35,307
CASH DIVIDENDS DECLARED PER COMMON SHARE (in usd per share)	$ 1.40	$ 1.40	$ 1.40
Patent licensing royalties
Revenues	$ 346,630	$ 307,431	$ 302,060
Technology solutions
Revenues	11,761	10,518	4,594
Patent sales b
Revenues	$ 600	$ 975	$ 750

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 37,941	$ 14,951	$ 59,475
Unrealized gain (loss) on investments, net of tax	(110)	2,397	61
Comprehensive income	37,831	17,348	59,536
Comprehensive loss attributable to noncontrolling interest	(6,860)	(5,977)	(5,556)
Total comprehensive income attributable to InterDigital, Inc.	$ 44,691	$ 23,325	$ 65,092

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative effect of change in accounting principle	Common Stock	Additional Paid-In Capital	Retained Earnings	Retained EarningsCumulative effect of change in accounting principle	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss)Cumulative effect of change in accounting principle	Treasury Stock	Non-Controlling Interest
Beginning balance (in shares) at Dec. 31, 2017			70,749						36,127
Beginning balance at Dec. 31, 2017	$ 873,148	$ 161,252	$ 707	$ 680,040	$ 1,257,632	$ 161,701	$ (2,083)	$ (449)	$ (1,072,488)	$ 9,340
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income applicable to common shareholders	65,031				65,031
Distribution preference	(2,500)									(2,500)
Net loss attributable to noncontrolling interest	(5,556)									(5,556)
Net change in unrealized gain on short-term investments	61						61
Dividends declared	(47,922)			472	(48,394)
Exercise of Common Stock options and warrants (in shares)			153
Exercise of Common Stock options and warrants	6,723		$ 2	6,721
Issuance of Common Stock, net (in shares)			232
Issuance of Common Stock, net	(8,808)		$ 2	(8,810)
Amortization of unearned compensation	7,089			7,089
Repurchase of Common Stock (in shares)									1,478
Repurchase of Common Stock	(110,505)								$ (110,505)
Ending balance (in shares) at Dec. 31, 2018			71,134						37,605
Ending balance at Dec. 31, 2018	938,013		$ 711	685,512	1,435,970		(2,471)		$ (1,182,993)	1,284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income applicable to common shareholders	20,928				20,928
Proceeds from and increases in noncontrolling interests	29,417									29,417
Net loss attributable to noncontrolling interest	(5,977)									(5,977)
Net change in unrealized gain on short-term investments	2,397						2,397
Dividends declared	(43,718)			401	(44,119)
Exercise of Common Stock options and warrants	2			2
Issuance of Common Stock, net (in shares)			134
Issuance of Common Stock, net	(4,367)		$ 1	(4,368)
Amortization of unearned compensation	7,603			7,603
Repurchase of Common Stock (in shares)									2,962
Repurchase of Common Stock	(196,269)								$ (196,269)
Equity component of debt, net of tax	56,917			56,917
Net convertible note hedge transactions, net of tax	(49,740)			(49,740)
Net warrant transactions	43,416			43,416
Deferred financing costs allocated to equity, net of tax	(1,692)			(1,692)
Reacquisition of equity component of debt due to prepayment, net of tax	(10,649)			(10,649)
Ending balance (in shares) at Dec. 31, 2019			71,268						40,567
Ending balance at Dec. 31, 2019	786,281		$ 712	727,402	1,412,779		(74)		$ (1,379,262)	24,724
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income applicable to common shareholders	44,801				44,801
Proceeds from and increases in noncontrolling interests	5,333									5,333
Net loss attributable to noncontrolling interest	(6,860)									(6,860)
Net change in unrealized gain on short-term investments	(110)						(110)
Dividends declared	$ (43,113)			498	(43,611)
Exercise of Common Stock options and warrants (in shares)	73		49
Exercise of Common Stock options and warrants	$ 1,892		$ 1	1,891
Issuance of Common Stock, net (in shares)			72
Issuance of Common Stock, net	(1,751)		$ 1	(1,752)
Amortization of unearned compensation	10,442			10,442
Repurchase of Common Stock (in shares)									6
Repurchase of Common Stock	(349)								$ (349)
Ending balance (in shares) at Dec. 31, 2020			71,389						40,573
Ending balance at Dec. 31, 2020	$ 796,566		$ 714	$ 738,481	$ 1,413,969		$ (184)		$ (1,379,611)	$ 23,197

Consolidated Statements of Sh_2

Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	1 Months Ended	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per common share (in usd per share)	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 1.40	$ 1.40	$ 1.40

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 37,941	$ 14,951	$ 59,475
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	81,041	77,094	66,108
Non-cash interest expense, net	18,093	18,709	13,509
Non-cash change in fair value	(5,588)	710	3,884
Gain on asset acquisition and sale of a business	0	(22,690)	0
Change in deferred revenue	24,397	(7,749)	6,966
Deferred income taxes	(7,182)	4,123	(45,426)
Share-based compensation	10,442	7,603	7,089
Impairment of long-term investment	0	3,312	200
Loss on extinguishment of debt	0	5,488	0
Loss on disposal of assets	7,539	119	8,323
Other	412	623	(625)
(Increase) decrease in assets:
Receivables	11,354	6,742	31,615
Deferred charges and other assets	(26,256)	(27,206)	(6,065)
Increase (decrease) in liabilities:
Accounts payable	(2,850)	(638)	6,203
Accrued compensation and other expenses	13,815	9,699	254
Accrued taxes payable and other tax contingencies	309	(1,457)	(4,718)
Net cash provided by operating activities	163,467	89,433	146,792
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of short-term investments	(529,559)	(92,436)	(142,555)
Sales of short-term investments	256,726	389,032	399,105
Purchases of property and equipment	(11,793)	(4,509)	(2,576)
Capitalized patent costs	(30,615)	(33,481)	(32,069)
Acquisition of patents	0	0	(2,250)
Acquisition of business, net of cash acquired	0	0	(142,985)
Proceeds from sale of business	910	10,000	0
Long-term investments	4,285	(350)	(6,686)
Net cash (used in) provided by investing activities	(310,046)	268,256	69,984
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from exercise of stock options	1,892	2	6,723
Proceeds from issuance of senior convertible notes	0	400,000	0
Payments on long-term debt	(94,909)	(221,091)	0
Purchase of convertible bond hedge	0	(72,000)	0
Payment for warrant unwind	0	(4,184)	0
Prepayment penalty on long-term debt	0	(10,763)	0
Proceeds from hedge unwind	0	9,038	0
Proceeds from issuance of warrants	0	47,600	0
Payments of debt issuance costs	0	(8,375)	0
Proceeds from noncontrolling interests	5,333	15,666	0
Dividends paid	(43,072)	(44,580)	(48,468)
Taxes withheld upon restricted stock unit vestings	(1,751)	(4,368)	(8,807)
Repurchase of common stock	(349)	(196,269)	(110,505)
Net cash used in financing activities	(132,856)	(89,324)	(161,057)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(279,435)	268,365	55,719
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD	757,098	488,733	433,014
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF PERIOD	$ 477,663	$ 757,098	$ 488,733

Background and Basis of Present

Background and Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BACKGROUND AND BASIS OF PRESENTATION	BACKGROUND AND BASIS OF PRESENTATION InterDigital designs and develops advanced technologies that enable and enhance wireless communications and capabilities. Since our founding in 1972, our engineers have designed and developed a wide range of innovations that are used in digital cellular and wireless products and networks, including 2G, 3G, 4G, 5G and IEEE 802-related products and networks, as well as video processing, coding and display technology. We are a leading contributor of innovation to the wireless communications industry, as well as a leading holder of patents in the video industry. Principles of Consolidation The accompanying consolidated financial statements include all of our accounts and all entities in which we have a controlling interest and/or are required to be consolidated in accordance with the Generally Accepted Accounting Principles in the United States (“GAAP”). All significant intercompany accounts and transactions have been eliminated in consolidation. In determining whether we are the primary beneficiary of a variable interest entity and therefore required to consolidate, we apply a qualitative approach that determines whether we have both the power to direct the economically significant activities of the entity and the obligation to absorb losses of, or the right to receive benefits from, the entity that could potentially be significant to that entity. These considerations impact the way we account for our existing collaborative relationships and other arrangements. We continuously assess whether we are the primary beneficiary of a variable interest entity as changes to existing relationships or future transactions may result in us consolidating or deconsolidating our partner(s) to collaborations and other arrangements. Use of Estimates 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, the disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. If different assumptions were made or different conditions had existed, our financial results could have been materially different. InterDigital has analyzed the impact of the ongoing Coronavirus pandemic (“COVID-19”) on its financial statements as of December 31, 2020. InterDigital has determined that the changes to its significant judgments and estimates as a result of COVID-19 did not have a material impact on its financial statements. The potential impact of COVID-19 will continue to be analyzed going forward. Reclassifications Certain reclassifications have been made to prior year amounts to conform to the current year presentation. Supplemental Cash Flow Information The following table presents additional supplemental cash flow information for the year ended December 31, 2020, 2019 and 2018 (in thousands): FOR THE YEAR ENDED DECEMBER 31, SUPPLEMENTAL CASH FLOW INFORMATION: 2020 2019 2018 Interest paid $ 8,712 $ 7,886 $ 4,740 Income taxes paid, including foreign withholding taxes 26,233 24,229 33,904 Non-cash investing and financing activities: Dividend payable 10,786 10,746 11,627 Increases in noncontrolling interests — 13,750 — Non-cash acquisition of patents 33,300 22,500 — Accrued capitalized patent costs and property and equipment (436) 1,619 (2,789)

Summary of Significant Accounti

Summary of Significant Accounting Policies and New Accounting Guidance	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND NEW ACCOUNTING GUIDANCE	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND NEW ACCOUNTING GUIDANCE Foreign Currency Translation The functional currency of substantially all of the Company's wholly-owned subsidiaries is the U.S. dollar. Certain subsidiaries have monetary assets and liabilities that are denominated in a currency that is different than the functional currency. The gains and losses resulting from this remeasurement and translation of monetary assets denominated in a currency that is different than the functional currency are reflected in the determination of net income (loss). Cash, Cash Equivalents, Restricted Cash and Marketable Securities We classify all highly liquid investment securities with original maturities of three months or less at date of purchase as cash equivalents. Cash that is held for a specific purpose and therefore not available to the Company for immediate or general business use is classified as restricted cash. Our investments are comprised of mutual and exchange traded funds, commercial paper, United States and municipal government obligations and corporate securities. Management determines the appropriate classification of our investments at the time of acquisition and re-evaluates such determination at each balance sheet date. Other-than-Temporary Impairments We review our investment portfolio during each reporting period to determine whether there are identified events or circumstances that would indicate there is a decline in the fair value that is considered to be other-than-temporary. For non-public investments, if there are no identified events or circumstances that would have a significant adverse effect on the fair value of the investment, then the fair value is not estimated. If an investment is deemed to have experienced an other-than-temporary decline below its cost basis, we reduce the carrying amount of the investment to its quoted or estimated fair value, as applicable, and establish a new cost basis for the investment. We charge the impairment to the " Other Income, Net" line of our consolidated statements of income. Intangible Assets Patents We capitalize external costs, such as filing fees and associated attorney fees, incurred to obtain issued patents and patent license rights. We expense costs associated with maintaining and defending patents subsequent to their issuance in the period incurred. We amortize capitalized patent costs for internally generated patents on a straight-line basis over 10 years, which represents the estimated useful lives of the patents. The ten-year estimated useful life for internally generated patents is based on our assessment of such factors as: the integrated nature of the portfolios being licensed, the overall makeup of the portfolio over time, and the length of license agreements for such patents. The estimated useful lives of acquired patents and patent rights, however, have been and will continue to be based on a separate analysis related to each acquisition and may differ from the estimated useful lives of internally generated patents. The average estimated useful life of acquired patents is 9.7 years. We assess the potential impairment to all capitalized net patent costs when events or changes in circumstances indicate that the carrying amount of our patent portfolio may not be recoverable. Goodwill Goodwill is recorded as the difference, if any, between the aggregate consideration paid for an acquisition and the fair value of the net tangible and identified intangible assets acquired under a business combination. We review impairment of goodwill annually on the first day of the fourth quarter. We first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount as a basis for determining whether a quantitative goodwill impairment test is necessary. If we conclude it is more likely than not that the fair value of a reporting unit exceeds its carrying amount, we need not perform the quantitative assessment. If based on the qualitative assessment we believe it is more likely than not that the fair value of a reporting unit is less than its carrying value, a quantitative assessment test is required to be performed. This assessment requires us to compare the fair value of each reporting unit to its carrying value including allocated goodwill. We determine the fair value of our reporting units generally using a combination of the income and market approaches. The income approach is estimated through the discounted cash flow method based on assumptions about future conditions such as future revenue growth rates, new product and technology introductions, gross margins, operating expenses, discount rates, future economic and market conditions, and other assumptions. The market approach estimates the fair value of our equity by utilizing the market comparable method which is based on revenue multiples from comparable companies in similar lines of business. If the carrying value of a reporting unit exceeds the reporting unit’s fair value, a goodwill impairment charge will be recorded for the difference up to the carrying value of goodwill. The Company acquired goodwill from our acquisition of the patent licensing business of Technicolor (the "Technicolor Patent Acquisition") in 2018 and from our acquisition of Hillcrest Laboratories, Inc. (the "Hillcrest product business") in 2016. Refer to Note 5, " Business Combinations and Other Transactions ," for more information regarding these transactions. The carrying value of goodwill as of December 31, 2020 and 2019 was $22.4 million, respectively, which was included within " Other Non-Current Assets " in the consolidated balance sheets. No impairments were recorded during 2020, 2019 or 2018 as a result of our annual goodwill impairment assessment. Other Intangible Assets We capitalize the cost of technology solutions and platforms we acquire or license from third parties when they have a future benefit and the development of these solutions and platforms is substantially complete at the time they are acquired or licensed. Intangible assets consist of acquired patents, existing technology, and trade names. Refer to the above Patents Property and Equipment Property and equipment are stated at cost. Depreciation and amortization of property and equipment are provided using the straight-line method. The estimated useful lives for computer equipment, computer software, engineering and test equipment and furniture and fixtures are generally three five twenty-five Leases In February 2016, the FASB issued ASC 842, which outlines a comprehensive change to the lease accounting model ("ASC840"). The Company adopted ASC 842 on January 1, 2019 using the modified retrospective transition effective date method. We determine if an arrangement is a lease at inception. Operating lease right-of-use assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at commencement date, except short-term leases with an original term of 12 months or less, based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we generally use an incremental borrowing rate based on the estimated rate of interest for collateralized borrowing over a similar term of the lease payments at commencement date. The operating lease right-of-use assets also includes any lease payments made and excludes lease incentives. Lease expense is recognized over the expected term on a straight-line basis. Leases with a lease term of 12 months or less are accounted for using the practical expedient which allows for straight-line rent expense over the remaining term of the lease. Internal-Use Software Costs We capitalize costs associated with software developed for internal use that are incurred during the software development stage. Such costs are limited to expenses incurred after management authorizes and commits to a computer software project, believes that it is more likely than not that the project will be completed, the software will be used to perform the intended function with an estimated service life of two years or more, and the completion of conceptual formulation, design and testing of possible software project alternatives (the preliminary design stage). Costs incurred after final acceptance testing has been successfully completed are expensed. Capitalized computer software costs are amortized over their estimated useful life of three years. All computer software costs capitalized to date relate to the purchase, development and implementation of engineering, accounting and other enterprise software. Impairment of Long-Lived Assets We evaluate long-lived assets for impairment when factors indicate that the carrying value of an asset may not be recoverable. When factors indicate that such assets should be evaluated for possible impairment, we review whether we will be able to realize our long-lived assets by analyzing the projected undiscounted cash flows in measuring whether the asset is recoverable. We did not have any long-lived asset impairments in 2020, 2019 or 2018. Revenue Recognition We adopted ASU No. 2014-09, "Revenue from Contracts with Customers" (ASC 606) effective January 1, 2018. The disclosure below is a description of our revenue recognition accounting policies which were in effect beginning January 1, 2018 under ASC 606. 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 promises to provide any technology updates to the portfolio during the term. In accordance with US GAAP, we use 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 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 consolidated balance sheets. Contract assets due more than twelve months after the balance sheet date are included within 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. Certain patent license agreements contain revenue from non-financial sources in the form of patents received from the customer. 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 license 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. Although we have few static fixed-fee license agreements, we generally satisfy our performance obligations under such agreements 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 of revenue from royalty payments, software licenses, engineering services and product sales. The nature of these contracts and timing of payments vary. We recognize revenue from royalty payments and license agreements using the same methods described above under our policy for recognizing revenue from patent license agreements. We recognize revenue from engineering services using percentage of completion method. 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. Investments in Other Entities We may make strategic investments in companies that have developed or are developing technologies that are complementary to our business. We made an accounting policy election for a measurement alternative for our 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. On a quarterly basis, we monitor items such as our investment’s financial position and liquidity, performance targets, business plans, and cost trends to assess whether there are any triggering events or indicators present that would be indicative of an impairment, or any other observable price changes as indicated above. We do not adjust our investment balance when the investee reports profit or loss. Additionally, other investments may be accounted for under the equity method of accounting. Under this method, we initially record our investment in the stock of an investee at cost, and adjust the carrying amount of the investment to recognize our share of the earnings or losses of the investee after the date of acquisition. The amount of the adjustment is included in the determination of net income, and such amount reflects adjustments similar to those made in preparing consolidated statements including adjustments to eliminate intercompany gains and losses, and to amortize, if appropriate, any difference between our cost and underlying equity in net assets of the investee at the date of investment. The investment is also adjusted to reflect our share of changes in the investee’s capital. Dividends received from an investee reduce the carrying amount of the investment. When there are a series of operating losses by the investee or when other factors indicate that a decrease in value of the investment has occurred which is other than temporary, we recognize an impairment equal to the difference between the fair value and the carrying amount of our investment. The carrying value of our investments in other entities are included within " Other Non-Current Assets " on our consolidated balance sheets. During 2020, 2019 and 2018, we made investments in other entities of $0.2 million, $0.4 million and $6.7 million, respectively. The carrying value of our investments in other entities as of December 31, 2020 and 2019 was $15.5 million and $14.2 million, respectively, the majority of which are accounted for under the measurement alternative for equity investments described above. Collaborative Arrangements We record the elements of our collaboration agreements that represent joint operating activities in accordance with ASC 808, Collaborative Arrangements (“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 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 . Deferred Charges Direct costs of obtaining a contract or fulfilling a contract in a transaction that results in the deferral of revenue may be either expensed as incurred or capitalized, depending on certain criteria. In conjunction with our adoption of ASC 606 effective January 1, 2018, we made a policy election 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. If the amortization period is greater than one year, we capitalize direct costs incurred for the acquisition or fulfillment of a contract through the date of signing if they are directly related to a particular revenue arrangement and are expected to be recovered. The costs are amortized on a straight-line basis over the life of the patent license agreement. For example, from time to time, we use sales agents to assist us in our licensing and/or patent sale activities. In such cases, we may pay a commission. The commission rate varies from agreement to agreement. Commissions are normally paid shortly after our receipt of cash payments associated with the patent license or patent sale agreements. We defer recognition of commission expense and amortize these expenses in proportion to our recognition of the related revenue. Commission expense is included within the " Patent administration and licensing" line of our consolidated statements of income and was immaterial for the years presented. There were no new direct contract costs incurred during 2020, 2019 or 2018. Incremental direct costs incurred related to a debt financing transaction may be capitalized. In connection with our offering of the 2024 Notes and 2020 Notes, defined and discussed in detail within Note 10, " Obligations" , we incurred directly related costs. The initial purchasers' transaction fees and related offering expenses were allocated to the liability and equity components of the debt in proportion to the allocation of proceeds and accounted for as debt issuance costs. The debt issuance costs allocated to the liability component of the debt were capitalized as deferred financing costs and recorded as a direct reduction of the debt. These costs are being amortized over the term of the debt using the effective interest method and are included within the " Interest expense" line of our consolidated statements of income. The costs allocated to the equity component of the debt were recorded as a reduction of the equity component of the debt. The balance of unamortized deferred financing costs as of December 31, 2020 and 2019 was $4.6 million and $5.9 million, respectively. The Company incurred $6.4 million of new debt issuance costs during 2019 in conjunction with the issuance of the 2024 Notes, noting no new debt issuance costs were incurred in 2020 or 2018. Deferred financing expense was $1.2 million, $1.5 million and $1.4 million in 2020, 2019 and 2018, respectively. Research and Development Research and development expenditures are expensed in the period incurred, except certain software development costs that are capitalized between the point in time that technological feasibility of the software is established and when the product is available for general release to customers. We did not have any capitalized software costs related to research and development in any period presented. Research, development and other related costs were approximately $84.6 million, $74.9 million and $69.7 million in 2020, 2019 and 2018, respectively. Compensation Programs We use a variety of compensation programs to attract, retain and motivate our employees, and to align employee compensation more closely with company performance. These programs include, but are not limited to, short-term incentives tied to performance goals, cash awards to inventors for filed patent applications and patent issuances, and long-term incentives in the form of stock option awards, time-based restricted stock unit (“RSU”) awards, performance-based awards and cash awards, noting equity awards are granted pursuant to the terms and conditions of our Equity Plans (as defined in Note 13, " Compensation Plans and Programs "). Our long-term incentives, including equity awards, typically include annual equity and cash award grants with three five three We account for compensation costs associated with share-based compensation based on the fair value of the instruments issued. The estimated value of stock options includes assumptions around expected life, stock volatility and dividends. The expected life of our stock option awards is based on the simplified method as prescribed by Staff Accounting Bulletin Topic 14. In all periods, our policy has been to set the value of RSUs and restricted stock awards equal to the value of our underlying common stock on the date of measurement. For grants with graded vesting, we amortize the associated unrecognized compensation cost using an accelerated method. For grants that cliff vest, we amortize the associated unrecognized compensation cost on a straight-line basis over their vesting term. Income Taxes Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the consolidated statement of income in the period in which the change was enacted. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets if management has determined that it is more likely than not that such assets will not be realized. In addition, the calculation of tax liabilities involves significant judgment in estimating the impact of uncertainties in the application of complex tax laws. We are subject to examinations by the U.S. IRS and other taxing jurisdictions on various tax matters, including challenges to various positions we assert in our filings. In the event that the IRS or another taxing jurisdiction levies an assessment in the future, it is possible the assessment could have a material adverse effect on our consolidated financial condition or results of operations. The financial statement recognition of the benefit for an uncertain tax position is dependent upon the benefit being more likely than not to be sustainable upon audit by the applicable tax authority. If this threshold is met, the tax benefit is then measured and recognized at the largest amount that is greater than 50 percent likely of being realized upon ultimate settlement. In the event that the IRS or another taxing jurisdiction levies an assessment in the future, it is possible the assessment could have a material adverse effect on our consolidated financial condition or results of operations. New Accounting Guidance Accounting Standards Update: Financial Instruments - Credit Losses In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses". This ASU introduces a new accounting model for recognizing credit losses on certain financial instruments and financial assets, including trade receivables, based upon an estimate of current expected credit losses, otherwise known as CECL. The new guidance requires the recognition of an allowance that reflects the current estimate of credit losses expected to be incurred over the life of the financial asset, based not only on historical experience and current conditions, but also on reasonable forecasts. Additionally, ASU No. 2016-13 made several changes to the available-for-sale impairment model. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted. We adopted this guidance as of January 1, 2020 and the adoption did not have a material impact on our consolidated financial statements. Accounting Standards Update: Cloud Computing Arrangements In August 2018, the FASB issued ASU No. 2018-15 “Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract”. The amendments in this ASU align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted. We adopted this guidance on a prospective basis as of January 1, 2020 and the adoption did not have a material impact on our consolidated financial statements. Accounting Standards Update: Collaborative Arrangements In November 2018, the FASB issued ASU No. 2018-18, "Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606". The amendments in this ASU provide guidance on how to assess whether certain transactions between collaborative arrangement participants should be accounted for within the revenue recognition standard. The amendments in this update are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted for entities who have previously adopted the new revenue recognition guidance. We adopted this guidance as of January 1, 2020 and the adoption did not have a material impact on our consolidated financial statements. Accounting Standards Update: Simplifying the Accounting for Income Taxes In December 2019, the FASB issued ASU No. 2019-12, "Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes" ("ASU 2019-12"). The amendments in this ASU are intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020 with early adoption allowed. We have determined that the adoption will not have a material impact on our consolidated financial statements. . Accounting Standards Update: Simplifying the Accounting for Convertible Debt Instruments In August 2020, the FASB issued ASU No. 2020-06, “Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity” (“ASU 2020-06”). The amendments in this ASU are intended to simplify accounting for convertible debt instruments and convertible preferred stock by removing certain accounting models which separate the embedded conversion features from the host contract. ASU 2020-06 also amends certain guidance in ASC 260

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION Disaggregated Revenue The following table presents the disaggregation of our revenue for the year ended December 31, 2020, 2019 and 2018 (in thousands): For the Year Ended December 31, 2020 2019 2018 Variable patent royalty revenue $ 26,587 $ 30,428 $ 36,384 Fixed-fee royalty revenue 298,461 257,221 239,347 Current patent royalties a 325,048 287,649 275,731 Non-current patent royalties b 21,582 19,782 26,329 Total patent royalties 346,630 307,431 302,060 Current technology solutions revenue a 11,761 10,518 4,594 Patent sales b 600 975 750 Total revenue $ 358,991 $ 318,924 $ 307,404 a. Recurring revenues are comprised of current patent royalties, inclusive of Dynamic Fixed-Fee Agreement royalties, and current technology solutions revenue. b. Non-recurring revenues are comprised of non-current patent royalties, which primarily include past patent royalties and royalties from static agreements, as well as patent sales. During the year ended December 31, 2020, we recognized $145.8 million of revenue that had been included in deferred revenue as of the beginning of the period. As of December 31, 2020, we had contract assets of $9.7 million and $8.9 million included within " Accounts receivable " and " Other non-current assets " in the consolidated balance sheet, respectively. As of December 31, 2019, we had contract assets of $16.2 million and $10.2 million included within " Accounts receivable " and " Other non-current assets " in the consolidated balance sheet, respectively. Contracted Revenue Based on contracts signed and committed Dynamic Fixed-Fee Agreement payments as of December 31, 2020, we expect to recognize the following amounts of revenue over the term of such contracts (in thousands): Revenue 2021 $ 273,815 2022 236,045 2023 44,469 2024 89 2025 — Thereafter — $ 554,418

Geographic _ Customer Concentra

Geographic / Customer Concentration	12 Months Ended
	Dec. 31, 2020
GEOGRAPHIC CUSTOMER CONCENTRATION [Abstract]
GEOGRAPHIC / CUSTOMER CONCENTRATION	GEOGRAPHIC / CUSTOMER CONCENTRATION The Company’s chief operating decision maker assesses company-wide performance and allocates resources based on consolidated financial information. As such, we have one reportable segment. During 2020, 2019 and 2018, the majority of our revenue was derived from a limited number of licensees based outside of the United States, primarily in Asia. Substantially all of these revenues were paid in U.S. dollars and were not subject to any substantial foreign exchange transaction risk. The table below lists the countries of the headquarters of our licensees and customers and the total revenue derived from each country or region for the periods indicated (in thousands): For the Year Ended December 31, 2020 2019 2018 United States $ 128,238 $ 139,162 $ 119,159 South Korea 111,634 113,189 112,291 China 63,172 11,103 309 Japan 23,694 35,614 29,525 Taiwan 10,059 938 23,326 France 7,773 5,895 277 Sweden 7,573 6,934 6,933 Other Europe 6,848 5,810 5,116 Other Asia — 279 468 Finland — — 10,000 Total $ 358,991 $ 318,924 $ 307,404 During 2020, 2019 and 2018, the following licensees or customers accounted for 10% or more of total revenues: 2020 2019 2018 Apple 31% 35% 36% Samsung 22% 25% 25% Huawei 15% —% —% LG <10% 10% 10%

Business Combinations and Other

Business Combinations and Other Transactions	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
BUSINESS COMBINATIONS AND OTHER TRANSACTIONS	BUSINESS COMBINATIONS AND OTHER TRANSACTIONS Acquisition of Technicolor's Patent Licensing Business On July 30, 2018, we completed our acquisition of the patent licensing business of Technicolor SA ("Technicolor"), a worldwide technology leader in the media and entertainment sector, which we refer to as the Technicolor Patent Acquisition. The Technicolor Patent Acquisition included 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 expanded InterDigital’s technology footprint in the mobile industry, and opens new markets in consumer home electronics, display technology and video. Under the terms of the original agreement, the portfolio was to be supplemented by a jointly funded R&D collaboration. This jointly funded R&D collaboration was terminated in conjunction with the acquisition of Technicolor's Research & Innovation unit (the "R&I Acquisition"), which is discussed below. Members of Technicolor’s licensing, legal and other support teams in offices in Rennes and Paris, France; Princeton, New Jersey, USA; 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. We account for our assumption of Technicolor’s rights and obligations under the Madison Arrangement as a collaborative arrangement. As part of this transaction, we also granted back to Technicolor a perpetual license for patents acquired in the transaction. The Technicolor Patent Acquisition met 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. Under the terms of the original agreement, Technicolor was to 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 was no revenue sharing associated with InterDigital’s mobile industry licensing efforts. As such, we accounted 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. This revenue-sharing arrangement and associated contingent consideration liability were modified in conjunction with the R&I Acquisition, which closed during second quarter 2019. Refer to the discussion below. Additionally, as of the acquisition date, we estimated we would receive payments totaling $20.2 million relating to the transaction from Technicolor. 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 7, " Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities" , for discussion regarding the valuation methodologies used for the contingent consideration liability. The following table summarizes the fair value of consideration transferred and our allocation of that consideration based on the fair values of the assets acquired and liabilities assumed as of the date of acquisition (in thousands): As of 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 $ 154,000 9 - 10 Goodwill (1) 6,388 Total identified intangible assets $ 160,388 Total fair value of consideration transferred $ 157,314 (1) 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 almost all of the goodwill resulting from the Technicolor Patent Acquisition will be deductible for income tax purposes. The amount of revenue and earnings that would have been included in the Company’s consolidated statements of income for the years ended December 31, 2018 had the acquisition date been January 1, 2018 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, 2018. In addition, pro forma adjustments have been made to reflect the impact of the transaction-related costs discussed below. 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, except per share data): For the Year Ended December 31, 2018 (Unaudited) Actual revenue $ 307,404 Supplemental pro forma revenue $ 314,096 Actual earnings $ 65,031 Supplemental pro forma earnings $ 52,754 Actual diluted earnings per share $ 1.84 Supplemental pro forma diluted earnings per share $ 1.49 Acquisition of Technicolor's Research & Innovation Unit On May 31, 2019, we completed the acquisition of the Research & Innovation unit of Technicolor, which we refer to as the R&I Acquisition. The R&I Acquisition expanded the Company’s research capabilities in video coding, Internet of Things (IoT) and smart home, imaging sciences, augmented reality and virtual reality, and artificial intelligence and machine learning technologies. The Technicolor R&I unit was the driving creative force behind the patent portfolio that was acquired in the Technicolor Patent Acquisition discussed above. The R&I Acquisition unit met the definition of an asset acquisition and was accounted for using the cost accumulation and allocation model. There was no cash consideration for the R&I Acquisition. As consideration for the R&I Acquisition, the jointly funded R&D collaboration that was entered into as part of the Technicolor Patent Acquisition was terminated. Technicolor will continue to fund research to be performed by the R&I unit for certain limited projects for a specified time period, subject to renewal. The Company also assumed certain employee-related liabilities, including obligations for certain defined benefit post-retirement plans for the acquired R&I unit employees, which are further discussed below. Additionally, Technicolor agreed to reduce its rights under the revenue-sharing arrangement entered into as part of the Technicolor Patent Acquisition, as further discussed below. The R&I Acquisition resulted in a net gain of approximately $14.2 million, inclusive of the $20.5 million gain from the derecognition of the contingent consideration liability described below, all of which is included within “ Other Income, Net ” in the consolidated statement of income for the year ended December 31, 2019. Contingent Consideration As discussed above, in conjunction with the initial Technicolor Patent Acquisition, Technicolor was to 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 was 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 was originally accounted for as a contingent consideration liability in accordance with ASC 805-30-25, Business Combinations - Contingent Consideration. There are no minimum or maximum payments under the revenue sharing arrangement, and, except in certain circumstances, the arrangement continues through December 31, 2038. 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 was based on the perspective of a market participant and included significant unobservable inputs that are classified as Level 3 inputs within the fair value hierarchy and are discussed further within Note 7, " Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities" . As a result of the R&I Acquisition in second quarter 2019, u nder the amended revenue-sharing arrangement described above, Technicolor will now receive 42.5% of future cash receipts from new licensing efforts from the Madison Arrangement only, subject to certain conditions and hurdles, but will no longer receive revenue-sharing from other licensing efforts in the consumer electronics field outside of the Madison Arrangement. We determined that the initial contingent consideration liability from the Technicolor Patent Acquisition was significantly modified in conjunction with the R&I Acquisition, and, as such, the contingent consideration liability will now be accounted for under ASC 450 - Contingencies under the asset acquisition framework when the liability is deemed probable and estimable. Since the contingent consideration liability arising from the amended revenue-sharing arrangement was not probable and estimable as of the R&I Acquisition date, the carrying value of the previous contingent consideration liability was derecognized, which resulted in a $20.5 million gain during the year ended December 31, 2019 and is included within " Other Income, Net" in the consolidated statement of income for the period. As of December 31, 2020 and 2019, the contingent consideration liability from the amended revenue-sharing arrangement was deemed not probable and estimable and is therefore not reflected within the consolidated financial statements. Defined Benefit Plans In connection with the Technicolor Patent Acquisition and the R&I Acquisition, we assumed certain defined benefit plans which are accounted for in accordance with ASC 715 - Compensation - Retirement Benefits . These plans include a retirement lump sum indemnity plan and jubilee plan, both of which provide benefit payments to employees based upon years of service and compensation levels. As of December 31, 2020 and 2019, the combined accumulated projected benefit obligation related to these plans totaled $7.6 million and $6.2 million, respectively. Service cost and interest cost for the combined plans totaled $0.6 million, $0.1 million and $0.1 million for the years ended December 31, 2020, 2019 and 2018, respectively. The weighted average discount rate and assumed salary increase rate for these plans were 0.44% and 3.0%, respectively. These plans are not required to be funded and were not funded as of December 31, 2020. Expected future benefit payments under these plans as of December 31, 2020 were as follows (in thousands): 2021 $ 229 2022 381 2023 547 2024 297 2025 540 Thereafter 2,699 Madison Arrangement As discussed above, in conjunction with the Technicolor Patent Acquisition, effective July 30, 2018, we 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. 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 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 consolidated statements of income. Cost reimbursements for expenses incurred resulting from fulfilling the duties of the licensing agent are recorded as contra expenses. During the year ended December 31, 2020 and 2019, gross revenues recorded related to the Madison Arrangement were $5.5 million and $13.5 million, respectively, and are reflected within " Patent licensing royalties " in the consolidated statement of income. Net operating expenses related to the Madison Arrangement during the year ended December 31, 2020, 2019, and 2018 were approximately $8.4 million, $12.0 million and $2.8 million, including $2.5 million, $6.3 million, and $0.0 million related to revenue sharing, respectively, and are reflected primarily within " Patent administration and licensing " expenses in the consolidated statement of income. 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 met 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 consolidated balance sheet. This initial fair value measurement was 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. The fair value of the long-term debt as of December 31, 2020 is disclosed within Note 7, " Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities" . Our repayment obligations are contingent upon future royalty revenues generated from the Madison Arrangement and there are no minimum or maximum payments under the arrangement. Under ASC 470, amounts recorded as debt shall be amortized under the interest method. At each reporting period, we will review the discounted expected future cash flows over the life of the obligation. 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 “ Interest expense ” in the consolidated statements of income. The effective interest rate as of the acquisition date was approximately 14.5%. This rate represents the discount rate that equates the estimated future cash flows with the fair value of the debt as of the acquisition date, and is used to compute the amount of interest to be recognized each period based on the estimated life of the future revenue streams. During the year ended December 31, 2020 and 2019, we recognized $3.1 million and $2.7 million of interest expense related to this debt which is included within “ Interest expense ” in the consolidated statements of income. 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 December 31, 2020 and 2019, the Company had $3.1 million and $9.5 million of restricted cash included within the consolidated balance sheet attributable to the Madison Arrangement. Refer to Note 6, " Cash, Cash Equivalents, Restricted Cash and Marketable Securities", for a reconciliation of cash, cash equivalents and restricted cash within the consolidated balance sheets. 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. This commitment expired as of December 31, 2020 and we did not contribute any shortfall funding. Transaction Costs Transaction and integration related costs related to the above transactions for the years ended December 31, 2020, 2019 and 2018 were $2.3 million, $8.4 million and $17.8 million, respectively. The majority of these costs were recorded within “ Patent administration and licensing ” and “ Selling, general and administrative ” expenses in the consolidated statements of income. Hillcrest Product Business On December 20, 2016, we acquired Hillcrest Laboratories, Inc. ("Hillcrest"), a pioneer in sensor processing technology, for approximately $48.0 million in cash, net of $0.4 million cash acquired. The business combination transaction was accounted for using the acquisition method of accounting. On July 19, 2019, we completed the sale of Hillcrest's product business to a subsidiary of CEVA, Inc. In connection with the sale, we received initial proceeds of $10.0 million, with a customary portion of the purchase price placed in escrow to secure potential indemnification claims. As part of the transaction, we retained substantially all of the Hillcrest patent assets that we acquired in 2016. As a result of this transaction, we recorded an $8.5 million gain on sale which is included within " Other Income, Net " in the consolidated statements of income for the year ended December 31, 2019.

Cash, Cash Equivalents, Restric

Cash, Cash Equivalents, Restricted Cash and Marketable Securities	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES	CASH, CASH EQUIVALENTS, RESTRICTED CASH AND MARKETABLE SECURITIES Cash, Cash Equivalents and Restricted Cash Cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, 2020 2019 Money market and demand accounts $ 397,522 $ 757,098 Commercial paper 80,141 — Total cash, cash equivalents and restricted cash $ 477,663 $ 757,098 The following table provides a reconciliation of total cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 within the consolidated balance sheets (in thousands): December 31, 2020 2019 Cash and cash equivalents $ 473,474 $ 745,491 Restricted cash included within prepaid and other current assets 3,108 10,526 Restricted cash included within other non-current assets 1,081 1,081 Total cash, cash equivalents and restricted cash 477,663 757,098 Marketable Securities As of December 31, 2020 and 2019, the majority of our marketable securities have been classified as available-for-sale and are carried at fair value, with unrealized gains and losses reported net-of-tax as a separate component of shareholders’ equity. Substantially all of our investments are investment-grade government and corporate debt securities that have maturities of less than 2 years, and we have both the ability and intent to hold the investments until maturity. We recorded no other-than-temporary impairments during 2020, 2019 or 2018. The gross realized gains and losses on sales of marketable securities were not significant during the years ended December 31, 2020, 2019 and 2018. Marketable securities as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, 2020 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities Commercial paper $ 285,244 $ 5 $ (7) $ 285,242 U.S. government securities 166,195 44 (16) 166,223 Corporate bonds, asset backed and other securities 81,540 314 (5) 81,849 Total available-for-sale securities $ 532,979 $ 363 $ (28) $ 533,314 Reported in: Cash and cash equivalents $ 80,141 Short-term investments 453,173 Total marketable securities $ 533,314 December 31, 2019 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities U.S. government securities $ 105,453 $ 249 $ — $ 105,702 Corporate bonds, asset backed and other securities 73,276 226 — 73,502 Total available-for-sale securities $ 178,729 $ 475 $ — $ 179,204 Reported in: Cash and cash equivalents $ — Short-term investments 179,204 Total marketable securities $ 179,204 As of December 31, 2020 and 2019, $517.4 million and $163.1 million, respectively, of our short-term investments had contractual maturities within one year. The remaining portions of our short-term investments had contractual maturities within one

Concentration of Credit Risk an

Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
CONCENTRATION OF CREDIT RISK AND FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES	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 primarily place our cash equivalents and short-term investments in highly rated financial instruments and in United States government instruments. Our accounts receivable are derived principally from patent license and technology solutions agreements. As of December 31, 2020 and 2019, five and seven licensees comprised 53% and 73%, respectively, of our accounts receivable balance. 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 included within short-term investments on our 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 December 31, 2020 and December 31, 2019 (in thousands): Fair Value as of December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 397,522 $ — $ — $ 397,522 Commercial paper (b) — 285,242 — 285,242 U.S. government securities — 166,223 — 166,223 Corporate bonds, asset backed and other securities — 81,849 — 81,849 $ 397,522 $ 533,314 $ — $ 930,836 Fair Value as of December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 757,098 $ — $ — $ 757,098 U.S. government securities — 105,702 — 105,702 Corporate bonds and asset backed securities — 73,502 — 73,502 $ 757,098 $ 179,204 $ — $ 936,302 _______________ (a) Included within cash and cash equivalents. (b) As of December 31, 2020, $80.1 million of commercial paper was included within cash and cash equivalents. Level 3 Fair Value Measurements Contingent Consideration As discussed further in Note 5, " Business Combinations and Other Transactions ," we completed the Technicolor Patent Acquisition during third quarter 2018. In conjunction with the Technicolor Patent Acquisition, we initially recognized a contingent consideration liability which was 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 through first quarter 2019. 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. During second quarter 2019, we completed the R&I Acquisition. The transaction met the definition of an asset acquisition and was accounted for using the cost accumulation and allocation model. As discussed in Note 5, " Business Combinations and Other Transactions ," as part of this acquisition, Technicolor reduced its rights to the revenue-sharing arrangement that created the initial contingent consideration liability from the Technicolor Patent Acquisition. We determined that the initial contingent consideration liability from the Technicolor Patent Acquisition was significantly modified in conjunction with the R&I Acquisition, and, as such, the contingent consideration liability will now be accounted for under ASC 450 - Contingencies under the asset acquisition framework when the liability is deemed probable and estimable. Since the contingent consideration liability arising from the amended revenue-sharing arrangement was not probable and estimable as of the acquisition date, the carrying value of the previous contingent consideration liability was derecognized, which resulted in a $20.5 million gain which is included within " Other Income, Net " in the consolidated statement of income for the year ended December 31, 2019. Therefore, effective as of the acquisition date of May 31, 2019, the contingent consideration liability was no longer a Level 3 fair value recurring measurement. As of December 31, 2020 and 2019, the contingent consideration liability from the amended revenue-sharing arrangement was deemed not probable and estimable and is therefore not reflected within the consolidated financial statements. Fair Value of Long-Term Debt 2024 Senior Convertible Notes The principal amount, carrying value and related estimated fair value of the Company's senior convertible debt reported in the consolidated balance sheets as of December 31, 2020 and December 31, 2019 was as follows (in thousands). The aggregate fair value of the principal amount of the senior convertible long-term debt is a Level 2 fair value measurement. December 31, 2020 December 31, 2019 Principal Carrying Fair Principal Carrying Fair Senior Convertible Long-Term Debt $ 400,000 $ 343,821 $ 418,760 $ 494,909 $ 423,657 $ 492,969 Technicolor Patent Acquisition Long-term Debt As more fully disclosed in Note 5, " Business Combinations and Other Transactions ," we recognized long-term debt in conjunction with the Technicolor Patent Acquisition. The carrying value and related estimated fair value of the Technicolor Patent Acquisition long-term debt reported in the consolidated balance sheet as of December 31, 2020 and December 31, 2019 was as follows (in thousands). The aggregate fair value of the Technicolor Patent Acquisition long-term debt is a Level 3 fair value measurement. December 31, 2020 December 31, 2019 Carrying Fair Carrying Fair Technicolor Patent Acquisition Long-Term Debt $ 24,171 $ 27,016 $ 21,101 $ 23,305 Non-Recurring Fair Value Measurements Investments in Other Entities As disclosed in Note 2, " Summary of Significant Accounting Policies and New Accounting Guidance ", 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 long-term strategic investments in other entities. Under the alternative, our long-term 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 year ended 2020, we recognized $5.6 million of unrealized gains resulting from observable price changes in orderly transactions of our long-term strategic investments, which was included within “ Other Income, Net ” in the consolidated statement of income. During the year ended December 31, 2019, we recognized a net loss of $2.6 million resulting from the partial impairment of one of our strategic investments partially offset by a gain on sale of a separate strategic investment, which is included within " Other Income, Net " in the consolidated statement of income. During the year ended December 31, 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. Certain of our investments in other entities may be seeking additional financing in the next twelve months or potential exit strategies. We will continue to review and monitor our investments in other entities for any indications of an increase in fair value or impairment. Lease Assets During 2020, we recognized a $1.1 million impairment, comprised of $0.8 million of Property, Plant, and Equipment, and $0.3 million of Operating lease right-of-use asset related to the abandonment of one of our leased properties, which was included within “ Operating Expense ” in the consolidated statement of income. Patents During 2020, we entered into a multi-year, worldwide, non-exclusive, royalty-bearing patent license with Huawei Investment & Holding Co., Ltd. (“Huawei”). A portion of the future consideration for the agreement was in the form of patents. We have determined the estimated fair value of the patents for determining the transaction price for revenue recognition purposes, which was estimated to be $19.3 million utilizing the market approach. The value is amortized as a non-cash expense over the patents' estimated useful lives. Additionally, as previously disclosed, during 2019 and 2018, we entered into patent license agreements with ZTE and Sony, respectively, for which a portion of the consideration was patents. The estimated fair value of the ZTE patents was $14.0 million, and the estimated fair value of the Sony patents was $22.5 million, which are being amortized as a non-cash expense over their estimated useful lives. We estimated the fair value of the patents in the ZTE and Sony transactions utilizing the market approach, and the cost approach, respectively. As noted above, we estimated the fair value of the patents in these transactions using one of, or a combination of, an analysis of comparable market transactions (the market approach), a discounted cash flow analysis (the income approach) and/or by quantifying the amount of money required to replace the future service capability of the assets (the cost approach). For the market approach, judgment was applied as to which market transactions were most comparable to the transaction. For the income approach, the inputs and assumptions used to develop these estimates were based on a market participant perspective and included estimates of projected royalties, discount rates, economic lives and income tax rates, among others. For the cost approach, we utilized the historical cost of assets of similar technologies to determine the estimated replacement cost, including research, development, testing and patent application fees.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT Property and equipment, net is comprised of the following (in thousands): December 31, 2020 2019 Computer equipment and software $ 16,003 $ 11,320 Leasehold improvements 11,076 11,315 Building and improvements 3,548 3,702 Engineering and test equipment 1,183 1,333 Furniture and fixtures 1,051 1,121 Property and equipment, gross 32,861 28,791 Less: accumulated depreciation (16,231) (18,574) Property and equipment, net $ 16,630 $ 10,217

Patents, Goodwill and Other Int

Patents, Goodwill and Other Intangibles Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
PATENTS, GOODWILL AND OTHER INTANGIBLE ASSETS	PATENTS, GOODWILL AND OTHER INTANGIBLE ASSETS Patents As of December 31, 2020 and 2019, patents consisted of the following (in thousands, except for useful life data): December 31, 2020 2019 Weighted average estimated useful life (years) 9.9 9.9 Gross patents $ 945,609 $ 905,814 Accumulated amortization (527,266) (469,475) Patents, net $ 418,343 $ 436,339 Amortization expense related to capitalized patent costs was $74.9 million, $72.3 million and $61.8 million in 2020, 2019 and 2018, respectively. These amounts are recorded within the " Patent administration and licensing" line of our consolidated statements of income. The estimated aggregate amortization expense for the next five years related to our patents balance as of December 31, 2020 is as follows (in thousands): 2021 74,208 2022 69,897 2023 63,890 2024 55,110 2025 51,068 Goodwill The following table shows the change in the carrying amount of our goodwill balance from December 31, 2018 to December 31, 2020, all of which is allocated to our one reportable segment (in thousands): Goodwill balance as of December 31, 2018 $ 22,421 Activity — Goodwill balance as of December 31, 2019 $ 22,421 Activity — Goodwill balance as of December 31, 2020 $ 22,421

Obligations

Obligations	12 Months Ended
	Dec. 31, 2020
OBLIGATIONS: [Abstract]
OBLIGATIONS	OBLIGATIONS Refer to Note 5, " Business Combinations and Other Transactions, " and Note 7, " Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities ," for information regarding the long-term debt initially recognized during 2018 resulting from the Technicolor Patent Acquisition. Long-term debt obligations, excluding the long-term debt resulting from the Technicolor Patent Acquisition, are comprised of the following (in thousands): December 31, 2020 2019 2.00% Senior Convertible Notes due 2024 $ 400,000 $ 400,000 1.50% Senior Convertible Notes due 2020 — 94,909 Less: Unamortized interest discount (51,567) (65,393) Deferred financing costs (4,612) (5,859) Total net carrying amount of Senior Convertible Notes 343,821 423,657 Less: Current portion of long-term debt — 94,170 Long-term net carrying amount of Senior Convertible Notes $ 343,821 $ 329,487 There were no finance leases as of December 31, 2020 or December 31, 2019. Maturities of principal of the long-term debt obligations of the Company as of December 31, 2020, excluding the long-term debt resulting from the Technicolor Patent Acquisition, are as follows (in thousands): 2021 $ — 2022 — 2023 — 2024 400,000 2025 — Thereafter — $ 400,000 2024 Senior Convertible Notes, and Related Note Hedge and Warrant Transactions On June 3, 2019 we issued $400.0 million in aggregate principal amount of 2.00% Senior Convertible Notes due 2024 (the "2024 Notes"). The net proceeds from the issuance of the 2024 Notes, after deducting the initial purchasers' transaction fees and offering expenses, were approximately $391.6 million. The 2024 Notes bear interest at a rate of 2.00% per year, payable in cash on June 1 and December 1 of each year, commencing on December 1, 2019, and mature on June 1, 2024, unless earlier converted or repurchased. The 2024 Notes will be convertible into cash, shares of our common stock or a combination thereof, at our election, at an initial conversion rate of 12.3018 shares of common stock per $1,000 principal amount of 2024 Notes (which is equivalent to an initial conversion price of approximately $81.29 per share), as adjusted pursuant to the terms of the indenture governing the 2024 Notes (the "Indenture"). The conversion rate of the 2024 Notes, and thus the conversion price, may be adjusted in certain circumstances, including in connection with a conversion of the 2024 Notes made following certain fundamental changes and under other circumstances set forth in the Indenture. As of December 31, 2020, we made the irrevocable election to settle all conversions of the 2024 Notes through combination settlements of cash and shares of common stock, with a specified dollar amount of $1,000 per $1,000 principal amount of 2024 Notes and any remaining amounts in shares of common stock. Prior to 5:00 p.m., New York City time, on the business day immediately preceding March 1, 2024, the 2024 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) beginning after September 30, 2019 if the closing sale price of the common stock was more than 130% of the applicable conversion price (approximately $105.68 based on the current conversion price of the 2024 Notes) on each applicable trading day for at least 20 trading days (whether or not consecutive) in the period of the 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter. Commencing on March 1, 2024, the 2024 Notes will be convertible 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 2024 Notes. The Company may not redeem the 2024 Notes prior to their maturity date. If a fundamental change (as defined in the Indenture) occurs, holders may require the Company to purchase all or a portion of their 2024 Notes for cash at a repurchase price equal to 100% of the principal amount of the 2024 Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date. The 2024 Notes are our senior unsecured obligations and rank equally in right of payment with any of our current and any future senior unsecured indebtedness. The 2024 Notes are effectively subordinated to all of our future secured indebtedness to the extent of the value of the related collateral, and the 2024 Notes are structurally subordinated to indebtedness and other liabilities, including trade payables, of our subsidiaries. On May 29 and May 31, 2019, in connection with the offering of the 2024 Notes, we entered into convertible note hedge transactions (collectively, the “2024 Note Hedge Transactions”) that cover, subject to customary anti-dilution adjustments, approximately 4.9 million shares of common stock, in the aggregate, at a strike price that initially corresponds to the initial conversion price of the 2024 Notes, subject to adjustment, and are exercisable upon any conversion of the 2024 Notes. The aggregate cost of the 2024 Note Hedge Transactions was $72.0 million. On May 29 and May 31, 2019, we also entered into privately negotiated warrant transactions (collectively, the “2024 Warrant Transactions” and, together with the 2024 Note Hedge Transactions, the “2024 Call Spread Transactions”), whereby we sold warrants to acquire, subject to customary anti-dilution adjustments, approximately 4.9 million shares of common stock at an initial strike price of approximately $109.43 per share, subject to adjustment. As consideration for the 2024 Warrant Transactions, we received aggregate proceeds of $47.6 million. The net cost of the 2024 Call Spread Transactions was $24.4 million. The net proceeds from the issuance of the 2024 Notes, after deducting fees and offering expenses, were used for the following: (i) $232.7 million was used to repurchase $221.1 million in aggregate principal amount of the 2020 Notes (as defined below) in privately negotiated transactions concurrently with the offering of the 2024 Notes (ii) $19.6 million was used to repurchase shares of common stock at $62.53 per share, the closing price of the stock on May 29, 2019; and (iii) $24.4 million, in addition to the proceeds from the 2024 Warrant Transactions discussed above, was used to fund the cost of the 2024 Call Spread Transactions. Accounting Treatment of the 2024 Notes and Related Convertible Note Hedge and Warrant Transactions The 2024 Call Spread Transactions were classified as equity. The Company bifurcated the proceeds from the offering of the 2024 Notes between liability and equity components. On the date of issuance, the liability and equity components were calculated to be approximately $328.0 million and $72.0 million, respectively. The initial $328.0 million liability component was determined based on the fair value of similar debt instruments excluding the conversion feature. The initial $72.0 million ($56.9 million net of tax) equity component represents the difference between the fair value of the initial $328.0 million in debt and the $400.0 million gross proceeds. The related initial debt discount of $72.0 million is being amortized over the life of the 2024 Notes using the effective interest method. An effective interest rate of 6.25% was used to calculate the debt discount on the 2024 Notes. In connection with the above-noted transactions, the Company incurred approximately $8.4 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 $6.4 million of debt issuance costs to the liability component, which were capitalized as deferred financing costs. These costs are being amortized as interest expense over the term of the debt using the effective interest method. The remaining $1.9 million of costs ($1.7 million net of tax) allocated to the equity component were recorded as a reduction of the equity component. 2020 Senior Convertible Notes, and Related Note Hedge and Warrant Transactions During second quarter 2019, the Company used $232.7 million from the offering of the 2024 Notes to repurchase $221.1 million in aggregate principal amount of the 1.50% Senior Convertible Notes due 2020 (the "2020 Notes") in privately negotiated transactions concurrently with the offering of the 2024 Notes. As a result of the partial repurchase of the 2020 Notes, $94.9 million in aggregate principal amount of the 2020 Notes remain outstanding as of December 31, 2019. On March 1, 2020, the maturity date of the 2020 Notes, the Company repaid in full the remaining $94.9 million of outstanding principal. We recognized a $5.5 million loss on extinguishment of debt during the year ended December 31, 2019 in connection with this repurchase, which was included within " Other Income, Net " in the consolidated statement of income for the period. The loss on extinguishment represents the difference between the calculated fair value of the debt immediately prior to its derecognition and the carrying amount of the debt component, including any unamortized debt discount and issuance costs. The remaining consideration paid for the partial repurchase of the 2020 Notes was allocated to the reacquisition of the equity component, which equaled $13.0 million ($10.6 million net of tax) and was recorded as a reduction of equity during the year ended December 31, 2019. The remaining unamortized debt discount and issuance costs of $3.3 million was amortized throughout the remaining life of the 2020 Notes, up to maturity on March 1, 2020. The following table presents the amount of interest cost recognized for the years ended December 31, 2020, 2019 and 2018 related to the contractual interest coupon, accretion of the debt discount and the amortization of financing costs (in thousands). For the Year Ended December 31, 2020 2019 2018 2024 Notes 2020 Notes Total 2024 Notes 2020 Notes Total 2020 Notes Contractual coupon interest $ 8,000 $ 237 $ 8,237 $ 4,600 $ 2,824 $ 7,424 $ 4,740 Accretion of debt discount 13,157 669 13,826 7,322 7,743 $ 15,065 12,434 Amortization of financing costs 1,176 70 1,246 654 821 1,475 1,390 Total $ 22,333 $ 976 $ 23,309 $ 12,576 $ 11,388 $ 23,964 $ 18,564

Commitments

Commitments	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS	COMMITMENTS Minimum future payments for accounts payable and other purchase commitments, excluding long-term operating leases for office space, as of December 31, 2020 were as follows (in thousands): 2021 $ 16,113 2022 — 2023 — 2024 — 2025 — Thereafter — We are subject to a revenue-sharing arrangement with Technicolor resulting from the Technicolor Patent Acquisition and the R&I Acquisition. We also assumed certain defined benefit plan liabilities in conjunction with these transactions. Refer to Note 5, " Business Combinations and Other Transactions ," for further information. Refer to Note 10, " Obligations ," for details of the Company's long-term debt obligations. Refer to Note 17, " Leases ," for maturities of the Company's operating lease liabilities as of December 31, 2020.

Litigation and Legal Proceeding

Litigation and Legal Proceedings	12 Months Ended
	Dec. 31, 2020
Litigation Settlement [Abstract]
LITIGATION AND LEGAL PROCEEDINGS	LITIGATION AND LEGAL PROCEEDINGS COURT PROCEEDINGS Huawei China Proceeding On January 3, 2019, InterDigital was notified that a civil complaint was filed on January 2, 2019 by Huawei Technologies Co., Ltd. ("Huawei") and certain of its subsidiaries against InterDigital, Inc. and certain of its subsidiaries in the Shenzhen Intermediate People’s Court (the "Shenzhen Court") seeking a determination that the Company had violated an obligation to license their patents that are essential to 3G, 4G and 5G wireless telecommunication standards on fair, reasonable and non-discriminatory terms and conditions. On June 8, 2020, Huawei filed an application with the Shenzhen Court to dismiss the legal proceeding, and on June 9, 2020, the Company filed an application with the IP Tribunal of the China Supreme People's Court (the "SPC") to dismiss the Company's jurisdictional appeal. On July 1, 2020, the SPC dismissed the Company's jurisdictional appeal, and on July 31, 2020, the Shenzhen Court granted Huawei's petition to dismiss the legal proceeding. Accordingly, there are no further proceedings in this matter. Lenovo U.K. Proceeding On August 27, 2019, InterDigital, Inc. and certain of its subsidiaries filed a claim in the High Court against Lenovo Group Limited and certain of its subsidiaries. The claim, as amended, alleges infringement of five of the Company's patents relating to 3G and/or 4G/LTE standards: European Patent (U.K.) Nos. 2,363,008 (the "'008 Patent"); 2,421,318; 2,485,558; 2,557,714; and 3,355,537. On August 26, 2020, the UK Supreme Court handed down its judgment in the combined appeals in the Unwired Planet and Conversant proceedings, finding, among other things, that UK Courts have jurisdiction to determine fair, reasonable and non-discriminatory ("FRAND") royalty terms and conditions (including, where appropriate, that the terms of a FRAND license would be worldwide) and to award a FRAND injunction under a UK patent that has been found valid, essential and infringed against a defendant that does not enter into a license on the terms the UK Court determines to be FRAND. Subsequently, on September 25, 2020 the Court made an Order recording that Lenovo was no longer pursuing its application challenging the jurisdiction of the High Court and that Lenovo would pay the Company's costs in relation to the same. The Court has held case management conferences on October 6, 2020, December 16, 2020, a further disclosure hearing on January 19, 2021 and Pre-Trial Review hearings for the first trial on January 28, 2021 and February, 8 2021. At those hearings, the High Court entered a schedule for the technical and non-technical FRAND proceedings. The first two trials that have been scheduled are technical trials in March 2021 and June 2021 and the non-technical FRAND trial is scheduled in January 2022. The Company was also granted permission at the October 6 hearing to amend its claim to seek declarations that Lenovo is an "unwilling licensee" based on its refusal to submit to the outcome of the FRAND determination by the High Court, and that it is therefore not entitled to enforce the Company's commitments under the ETSI IPR Policy against it. Lenovo has subsequently amended its case to seek a declaration that the Company is an "unwilling licensor" and has denied that it is not entitled to enforce the Company's commitments under the ETSI IPR Policy. On October 27, 2020, the Company filed an application to schedule a trial to determine the issue of whether Lenovo is an "unwilling licensee," and whether Lenovo is able to rely on the Company's commitments under the ETSI IPR Policy against it, prior to the non-technical FRAND trial. The Court held that while the Company was entitled to plead these issues and have them determined, the trial timetable and likely timing of any appeals meant that the determination of the "willingness" issues should be reserved to the non-technical FRAND trial. District of Delaware Patent Proceeding On August 28, 2019, InterDigital, Inc. and certain of its subsidiaries filed a complaint in the United States District Court for the District of Delaware (the "Delaware District Court") against Lenovo Holding Company, Inc. and certain of its subsidiaries alleging that Lenovo infringes eight of InterDigital's U.S. patents—U.S. Patent Nos. 8,085,665 (the "'665 Patent"); 8,199,726 (the "'726 Patent"); 8,427,954 (the "'954 Patent"); 8,619,747; 8,675,612 (the "'612 Patent"); 8,797,873 (the "'873 Patent"); 9,203,580; and 9,456,449 (the "'449 Patent")—by making, using, offering for sale, and/or selling Lenovo wireless devices with 3G and/or 4G LTE capabilities. As relief, InterDigital is seeking: (a) a declaration that InterDigital is not in breach of its relevant FRAND commitments with respect to Lenovo; (b) to the extent Lenovo does not agree to negotiate a worldwide patent license, does not agree to enter into binding international arbitration to set the terms of a FRAND license, and does not agree to be bound by the FRAND terms to be set by the High Court in the separately filed U.K. Proceedings described above, an injunction prohibiting Lenovo from continued infringement; (c) damages, including enhanced damages for willful infringement and supplemental damages; and (d) attorneys’ fees and costs. On July 14, 2020, the Delaware District Court heard the parties' oral arguments regarding Lenovo's motion to dismiss six of the eight patents-at-issue in the case. The Delaware District Court denied Lenovo's motion to dismiss in its entirety, finding in the Company's favor that all of the challenged claims of all six of the challenged patents cover patent-eligible subject matter under Section 101 of the Patent Act. On September 16, 2020, the Delaware District Court entered a schedule for the case, setting a patent jury trial for December 5, 2022. District of Delaware Antitrust Proceeding On April 9, 2020, Lenovo (United States) Inc. and Motorola Mobility LLC filed a complaint in the Delaware District Court against the Company and certain of its subsidiaries. The complaint alleges that the Company defendants have violated Sections 1 and 2 of the Sherman Act in connection with, among other things, their licensing of 3G and 4G standards essential patents ("SEPs"). The complaint further alleges that the Company defendants have violated their commitment to the European Telecommunications Standards Institute ("ETSI") with respect to the licensing of 3G and 4G SEPs on FRAND terms and conditions. The complaint seeks, among other things (i) rulings that the Company defendants have violated Sections 1 and 2 of the Sherman Act and are liable for breach of their ETSI FRAND commitments, (ii) a judgment that the plaintiffs are entitled to a license with respect to the Company's 3G and 4G SEPs on FRAND terms and conditions, and (iii) injunctions against any demand for allegedly excessive royalties or enforcement of the Company defendants' 3G and 4G U.S. SEPs against the plaintiffs or their customers via patent infringement proceedings. On June 22, 2020, the Company filed a motion to dismiss Lenovo's Sherman Act claims with prejudice, and to dismiss Lenovo's breach of contract claim with leave to re-file as a counterclaim in the Company's legal proceeding against Lenovo in the Delaware District Court discussed above. On July 17, 2020, the United States Department of Justice ("DOJ") filed a statement of interest supporting the Company's motion to dismiss Lenovo's antitrust claims. On July 20, 2020, Lenovo filed its response to the Company's motion to dismiss, and ACT | The App Association ("App Association") filed a motion for leave to file an amicus brief in support of Lenovo's antitrust claims. On August 5, 2020, the Company filed its reply in support of its motion to dismiss. Oral argument on the Company's motion to dismiss was held on October 27, 2020. The Delaware District Court has not yet ruled on the motion. China Proceeding On April 10, 2020, Lenovo (Beijing) Ltd. and certain of its affiliates filed a complaint against the Company and certain of its subsidiaries in the Beijing Intellectual Property Court seeking a determination of the FRAND royalty rates payable for the Company's Chinese 3G, 4G and 5G SEPs. The Beijing action remains pending. Xiaomi China Proceeding On August 5, 2020, the Company was informed in writing by Xiaomi Corporation ("Xiaomi") that, on June 3, 2020, Xiaomi Communication Technology Co., Ltd. and certain of its affiliates filed a complaint against the Company and one of its subsidiaries in the Wuhan Intermediate People's Court (the "Wuhan Court") seeking for the Wuhan Court to determine a global FRAND rate for a license to the Company's 3G and/or 4G/LTE SEPs. The Company was informed on September 25, 2020 that the Wuhan Court held an ex parte hearing on or about September 23, 2020 and issued an order that, among other things, enjoins the Company from seeking a preliminary and permanent injunction against Xiaomi and certain of its subsidiaries for infringement of certain of the Company's patents related to 3G and/or 4G/LTE standards in the Company's case in the Delhi High Court discussed below, or elsewhere. The Wuhan Court ordered a fine of up to one million yuan per day if the Company were to violate the order. The Company contends that it has not yet been properly served with Xiaomi's complaint or the Wuhan Court's anti-suit injunction order. On October 13, 2020, the Company filed an application challenging the jurisdiction of the Wuhan Court to take up Xiaomi’s complaint. That jurisdiction challenge remains pending. On September 30, 2020, the Company filed a preliminary conditional response seeking reconsideration of the Wuhan Court's anti-suit injunction, and requested a hearing, which was held on October 16, 2020. The Company filed a post-hearing submission on October 23, 2020. In a decision dated December 4, 2020, the Wuhan Court dismissed the Company’s reconsideration petition. India Proceeding On July 29, 2020, the Company and certain of its subsidiaries filed two patent infringement actions in the Delhi High Court in New Delhi, India (the "Delhi High Court") against Xiaomi and certain of its subsidiaries. The first complaint alleges infringement of five of the Company's patents related to 3G and/or 4G/LTE standards: Indian Patent Nos. 262910; 295912; 298719; 313036; and 320182. The second complaint alleges infringement of three of the Company's patents related to H.265/HEVC standards: Indian Patent Nos. 242248; 299448; and 308108. In these proceedings, the Company is seeking compensatory and punitive damages for Xiaomi's infringement of the asserted patents. The Company is further seeking, among other remedies, interim and permanent injunctive relief to prevent further infringement of the litigated patents in India, unless Xiaomi elects to take a license on terms determined to be FRAND by the Delhi High Court. The Company’s application for interim injunctive relief remains pending. On January 21, 2021, Xiaomi filed its replies to the cellular and HEVC complaints. The Company has filed an application to forfeit or strike those replies as untimely filed. The Company’s application remains pending. On September 29, 2020, the Company filed an anti-anti-suit injunction application against Xiaomi in the Delhi High Court, seeking, among other things, to enjoin Xiaomi from enforcing the Wuhan Court's September 23, 2020 anti-suit injunction order described above. On October 9, 2020, the Delhi High Court granted the Company's motion and issued an ad interim injunction restraining Xiaomi from enforcing the anti-suit injunction order issued by the Wuhan Court, pending further consideration of the Company's application for an anti-anti-suit injunction at a hearing on November 25, 2020. On November 3, 2020, Xiaomi filed an appeal with the appellate division of the Delhi High Court seeking, inter alia, to (i) set aside the October 9 ad interim anti-anti-suit injunction order, (ii) set aside certain subsequent orders of the first instance court and (iii) stay further pursuit of the Company's application for an interim injunction with respect to infringement of the patents in the first suit. That appeal was dismissed on November 6. From November 25, 2020 through December 15, 2020, the Delhi High Court held hearings on the Company’s application for an anti-anti-suit injunction. A decision on the Company’s application remains pending. German Proceeding On October 30, 2020, the Company filed an anti-anti-suit injunction application against Xiaomi in the Munich District Court, seeking to enjoin Xiaomi from continuing to pursue the Wuhan Court's September 23, 2020 anti-suit injunction order described above with respect to Germany. On November 11, 2020, the Munich court granted the Company's motion and issued an ex parte injunction restraining Xiaomi from pursuing the anti-suit injunction. The Company filed penalty requests for non-compliance with said court order. Xiaomi opposed the injunction and requested stay of enforcement, and an oral hearing was held on January 28, 2021. At the hearing, the Munich Court dismissed the request for stay of enforcement. A decision on the opposition and the penalty request will be rendered on February 25, 2021. This decision can then be appealed to the Higher Regional Court Munich. REGULATORY PROCEEDING 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. With the consolidation of China’s antimonopoly enforcement authorities into the State Administration for Market Regulation ("SAMR") in April 2018, SAMR is now responsible for overseeing InterDigital's commitments. OTHER We are party to certain other disputes and legal actions in the ordinary course of business, including arbitrations and legal proceedings with licensees regarding the terms of their agreements and the negotiation thereof. We do not currently believe that these matters, even if adversely adjudicated or settled, would have a material adverse effect on our financial condition, results of operations or cash flows. None of the preceding matters have met the requirements for accrual or disclosure of a potential range as of December 31, 2020.

Compensation Plans and Programs

Compensation Plans and Programs	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
COMPENSATION PLANS AND PROGRAMS	COMPENSATION PLANS AND PROGRAMS Compensation Programs We use a variety of compensation programs to attract, retain and motivate our employees, and to more closely align employee compensation with company performance. These programs include, but are not limited to, short-term incentive awards tied to performance goals, cash awards to inventors for filed patent applications and patent issuances, and long-term incentives in the form of stock option awards, time-based RSU awards, performance-based awards and cash awards. Our long-term incentives typically include annual time-based RSU grants or cash awards with a three-year vesting period, as well as annual performance-based RSU grants or cash awards with a three three Equity Incentive Plans On June 14, 2017, our shareholders adopted and approved the 2017 Equity Incentive Plan (the "2017 Plan"), under which officers, employees, non-employee directors and consultants can receive share-based awards such as RSUs, restricted stock and stock options as well as other stock or cash awards. From June 2009 through June 14, 2017, we granted such awards pursuant to our 2009 Stock Incentive Plan (the “2009 Plan," and, together with the 2017 Plan, the "Equity Plans"), which was adopted and approved by our shareholders on June 4, 2009, and the material terms of which were re-approved on June 12, 2014. Upon the adoption of the 2017 Plan in June 2017, the 2009 Plan was terminated and all shares remaining available for grant under the 2009 Plan were canceled. The number of shares available for issuance under the 2017 Plan is equal to 2,400,000 shares plus any shares subject to awards granted under the 2009 Plan that, on or after June 14, 2017, expire or otherwise terminate without having been exercised in full, or that are forfeited to or repurchased by us. RSUs and Restricted Stock We may issue RSUs and/or shares of restricted stock to officers, employees, non-employee directors and consultants. Any cancellations of unvested RSUs granted under the Equity Plans will increase the number of shares remaining available for grant under the 2017 Plan. Time-based RSUs vest over periods generally ranging from 1 to 3 years from the date of the grant. Performance-based RSUs generally have a vesting period of between 3 and 5 years. As of December 31, 2020, we had unrecognized compensation cost related to share-based awards of $8.0 million, at current performance accrual rates. For grants with graded vesting, we expect to amortize the associated unrecognized compensation cost using an accelerated method. For grants made that cliff vest, we expect to amortize the associated unrecognized compensation cost as of December 31, 2020, on a straight-line basis generally over a three Vesting of performance-based RSU awards is subject to attainment of specific goals established by the Compensation Committee of the Board of Directors. Depending upon performance achievement against these goals, the number of shares that vest can be anywhere from 0 to 2 times the target number of shares. Information with respect to current RSU activity is summarized as follows (in thousands, except per share amounts): Number of Weighted Balance at December 31, 2019 955 $ 62.40 Granted* 626 46.18 Forfeited (213) 66.11 Vested (103) 65.06 Balance at December 31, 2020 1,265 $ 53.53 * These numbers include less than 0.1 million RSUs credited on unvested RSU awards as dividend equivalents. Dividend equivalents accrue with respect to unvested RSUs when and as cash dividends are paid on the Company's common stock, and vest if and when the underlying RSUs vest. Granted amounts include performance-based RSU awards at their maximum potential payout. During 2020, 2019 and 2018, we granted approximately 0.4 million, 0.3 million and 0.3 million RSUs under the Equity Plans, respectively, with weighted-average grant date fair values of $46.18, $66.19 and $73.75, respectively, assuming target payout for the performance based awards. The total vest date fair value of the RSUs that vested in 2020, 2019 and 2018 was $6.7 million, $12.7 million and $25.2 million, respectively. The weighted average per share grant date fair value of the awards that vested in 2020, 2019 and 2018 was $65.06, $58.84 and $54.75, respectively. Other Equity Grants We may also grant equity awards to non-management Board members and certain consultants. Stock Options The 2009 Plan allowed, and the 2017 Plan allows, for the granting of incentive and non-qualified stock options, as well as other securities. The administrator of the Equity Plans, the Compensation Committee of the Board of Directors, determines the number of options to be granted, subject to certain limitations set forth in the 2017 Plan. Since 2013, both incentive and non-qualified stock options have been granted annually as part of our long-term incentive programs, which have generally vested over three years. During the year ended December 31, 2018, performance-based options were granted for the first time. The number of options which cliff vest, if at all, is anywhere from 0 to 2 times the target number of options subject to the attainment of performance goals measured at the end of the performance period. These performance-based options have a vesting period between three Under the terms of the Equity Plans, the exercise price per share of each option, other than in the event of options granted in connection with a merger or other acquisition, cannot be less than 100% of the fair market value of a share of common stock on the date of grant. Options granted under the Equity Plans are generally exercisable for a period of between 7 to 10 years from the date of grant and may vest on the grant date, another specified date, over a period of time and/or dependent upon the attainment of specified performance goals. We also have approximately 0.1 million options outstanding under a prior stock plan that have an indefinite contractual life. The fair value for option awards is computed using the Black-Scholes pricing model, whose inputs and assumptions are determined as of the date of grant and which require considerable judgment. Expected volatility was based upon a combination of implied and historic volatilities. The weighted-average grant date fair value per option award granted during the years ended December 31, 2020, 2019 and 2018 was $11.46, $13.68, and $24.56, respectively, based upon the assumptions included in the table below: For the Year Ended December 31, 2020 2019 2018 Expected term (in years) 6.5 4.5 7.7 Expected volatility 37.5 % 25.8 % 30.1 % Risk-free interest rate 0.6 % 2.4 % 3.0 % Dividend yield 3.1 % 2.0 % 1.8 % Information with respect to current year stock option activity is summarized as follows (in thousands, except per share amounts): Outstanding Options Weighted Balance at December 31, 2019 825 $ 58.83 Granted* 307 44.63 Forfeited (348) 65.74 Exercised (73) 43.83 Balance at December 31, 2020 711 $ 50.85 * Granted amounts include performance-based option awards at their maximum potential payout. The weighted average remaining contractual life of our outstanding options was 8.3 years as of December 31, 2020. Options with an indefinite contractual life, which were granted between 1983 and 1986 under a prior stock plan, were assigned an original life in excess of 50 years for purposes of calculating the weighted average remaining contractual life. The majority of these options have an exercise price between $9.00 and $11.63. The total intrinsic value of our outstanding options as of December 31, 2020 was $11.2 million. Of the 0.7 million outstanding options as of December 31, 2020, 0.3 million were exercisable with a weighted-average exercise price of $39.84. Options exercisable as of December 31, 2020 had total intrinsic value of $8.4 million and a weighted average remaining contractual life of 8.6 years. The total intrinsic value of stock options exercised during the years ended December 31, 2020, 2019 and 2018 was $1.1 million, $0.1 million and $5.6 million, respectively. In 2020, we recorded cash received from the exercise of options of $1.9 million. Upon option exercise, we issued new shares of stock. As of December 31, 2020, we had unrecognized compensation cost on our unvested stock options of $0.5 million, at current performance accrual rates. As of December 31, 2020 and 2019, we had approximately 0.5 million and 0.3 million options outstanding, respectively, that had exercise prices less than the fair market value of our stock at the respective balance sheet date. These options would have generated cash proceeds to the Company of $16.9 million and $7.6 million, respectively, if they had been fully exercised on those dates. Defined Contribution Plans We have a 401(k) plan (“Savings Plan”) wherein employees can elect to defer compensation within federal limits. We match a portion of employee contributions. Our 401(k) contribution expense was approximately $1.1 million, $1.1 million and $1.3 million for 2020, 2019 and 2018, respectively. At our discretion, we may also make a profit-sharing contribution to our employees’ 401(k) accounts. Additionally, the company contributed $0.2 million, $0.2 million and $0.2 million in 2020, 2019 and 2018, respectively, to other defined contribution plans.

TAXES

TAXES	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
TAXES	TAXES Our income tax provision (benefit) consists of the following components for 2020, 2019 and 2018 (in thousands): 2020 2019 2018 Current Federal $ (26,092) $ (11,436) $ (3,148) State 89 207 239 Foreign source withholding tax 26,229 19,850 25,187 226 8,621 22,278 Deferred Federal (28,692) (21,735) (63,030) State 119 2,457 (1,554) Foreign source withholding tax 21,699 21,648 14,889 (6,874) 2,370 (49,695) Total $ (6,648) $ 10,991 $ (27,417) The deferred tax assets and liabilities were comprised of the following components at December 31, 2020 and 2019 (in thousands): 2020 2019 Total Total Net operating losses $ 140,940 $ 131,501 Deferred revenue, net 26,213 33,131 Tax credit carryforward 27,813 11,744 Stock compensation 4,082 3,307 Patent amortization 22,530 18,522 Depreciation (1,233) 443 Goodwill (2,211) (1,933) Other-than-temporary impairment 441 1,138 Other (673) 785 Other employee benefits 5,857 7,520 Right of use asset (4,684) (4,913) Lease liability 5,382 5,760 224,457 207,005 Less: valuation allowance (144,367) (133,797) Net deferred tax asset $ 80,090 $ 73,208 Note: Included within the balance sheet, but not reflected in the tables are deferred tax assets primarily related to foreign withholding taxes that are expected to be paid within the next twelve months of $0.4 million and $0.1 million as of December 31, 2020 and December 31, 2019, respectively. The following is a reconciliation of income taxes at the federal statutory rate with income taxes recorded by the Company for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Tax at U.S. statutory rate 21.0 % 21.0 % 21.0 % State tax provision (b) 0.6 % 10.2 % (8.9) % Effects of rates different than statutory (2.0) % (2.8) % (1.4) % Change in valuation allowance 28.5 % 23.3 % 8.5 % Research and development tax credits (1.6) % (4.5) % (4.3) % Uncertain tax positions (2.7) % (0.8) % 3.9 % Permanent differences (1.2) % 2.3 % 4.9 % Stock compensation 1.1 % (0.6) % (5.0) % Foreign derived intangible income deduction (c) — % — % (56.3) % Amended return benefit (a) (65.0) % (8.4) % (49.4) % Other 0.1 % 2.7 % 1.5 % Total tax provision (benefit) (21.2) % 42.4 % (85.5) % (a) In 2020, a net discrete benefit of $20.9 million was recorded that primarily relates to the expected amendment of a prior year tax return to utilize a tax asset generated in the current year, as well as the reversal of a tax reserve. (b) In 2019, we determined that we would not be able to utilize our state deferred tax assets for our parent company in Delaware and Pennsylvania, therefore we put a full valuation allowance on these assets. (c) In 2018, the new Foreign Derived Intangible Income ("FDII") deduction that was enacted as part of the TCJA decreased the tax provision by 56.3%. Valuation Allowances and Net Operating Losses We establish a valuation allowance for any portion of our deferred tax assets for which management believes it is more likely than not that we will be unable to utilize the assets to offset future taxes. Given the binary nature of our business, at this time we believe it is more likely than not that the majority of our state net operating losses and net operating losses in certain subsidiaries in France, as well as our non-wholly owned subsidiaries in the United States and United Kingdom will not be utilized; therefore we have maintained a near full valuation allowance against our state, French and United Kingdom net operating losses as of December 31, 2020. All other deferred tax assets are fully benefited. Uncertain Income Tax Positions As of December 31, 2020, 2019 and 2018, we had $3.8 million, $4.5 million and $4.4 million, respectively, of unrecognized tax benefits that, if recognized, would impact the Company's effective tax rate. The total amount of unrecognized tax benefits could change within the next twelve months for a number of reasons including audit settlements, tax examination activities and the recognition and measurement considerations under this guidance. During 2020, we established reserves of $1.1 million uncertainty arising from our ability to generate the full benefit of the amended returns that utilize the current year tax asset. We also reversed reserves of $1.8 million previously established on 2016 research and development and manufacturing deduction credits as a result of the lapsing of the statute of limitations for that tax year. During 2019, we established a reserve of $0.3 million related to an additional deduction related to the issuance cost of convertible debt that is recorded through equity. During 2018, we established a reserve of $1.1 million related to the recognition of the 2006 to 2010 research and development credits and manufacturing deduction credits. The following is a roll forward of our total gross unrecognized tax benefits, which if reversed would impact the effective tax rate, for the fiscal years 2020 through 2018 (in thousands): 2020 2019 2018 Balance as of January 1 $ 4,456 $ 4,352 $ 3,252 Tax positions related to current year: Additions 1,062 402 73 Reductions — — — Tax positions related to prior years: Additions 37 34 1,054 Reductions — — (27) Settlements — — — Lapses in statues of limitations (1,752) (332) — Balance as of December 31 $ 3,803 $ 4,456 $ 4,352 Our policy is to recognize interest and/or penalties related to income tax matters in income tax expense. For certain positions that related to years prior to 2020, we have recorded approximately $0.1 million of accrued interest during 2020 and 2019. The Company and its subsidiaries are subject to United States federal income tax, foreign income and withholding taxes and income taxes from multiple state jurisdictions. Our federal income tax returns for 2006 to the present, with the exception of 2011 and 2012, are currently open and will not close until the respective statutes of limitations have expired. The statutes of limitations generally expire three years following the filing of the return or in some cases three years following the utilization or expiration of net operating loss carry forwards. The statute of limitations applicable to our open federal returns will expire at the end of 2022. Excluding the Korea Competent Authority Proceeding and the Finland Competent Authority Proceeding described in the section below, specific tax treaty procedures remain open for certain jurisdictions for 2014 to the present. Many of our subsidiaries have filed state income tax returns on a separate company basis. To the extent these subsidiaries have unexpired net operating losses, their related state income tax returns remain open. These returns have been open for varying periods, some exceeding ten years. The total amount of state net operating losses is $1.6 billion. In November 2018, the Company received notice that its 2016 U.S. Federal income tax return will be subject to audit. In February 2020, the Company received a no change letter from the IRS indicating the audit is closed. In December 2018, the Company received a notice of proposed assessment related to an ongoing audit of its California tax returns for 2013 through 2015. The Company filed a protest to the California assessment in February 2019 and in October 2020 received notice the audit was withdrawing their claim. In February 2020, the Company was notified their 2016 and 2017 California tax returns are under audit. Foreign Taxes We pay foreign source withholding taxes on patent license royalties when applicable. We apply foreign source withholding tax payments against our United States federal income tax obligations to the extent we have foreign source income to support these credits. In 2020, 2019 and 2018, we paid $25.9 million, $18.8 million and $25.1 million in foreign source withholding taxes, respectively, and applied these payments as credits against our United States federal tax obligation. Between 2014 and 2020, we paid approximately $134.3 million in foreign taxes to foreign governments that have tax treaties with the U.S., for which we have claimed foreign tax credits against our U.S. tax obligations, and for which the tax treaty procedures are still open. It is possible that as a result of tax treaty procedures, the U.S. government may reach an agreement with the related foreign governments that will result in a partial refund of foreign taxes paid with a related reduction in our foreign tax credits. Due to foreign currency fluctuations, any such agreement could result in foreign currency gain or loss. On November 8, 2019, the Company received notification that its request for competent authority pertaining to Article 25 (Mutual Agreement Procedure) of the United States-Republic of Finland Income Tax Convention had been reviewed by the IRS and an agreement has been reached (the “Finland Competent Authority Proceeding”). As a result of this agreement, the Company does not anticipate any tax consequences. On July 24, 2018, the Company received notification that its request for competent authority pertaining to Article 27 (Mutual Agreement 14 Table of Contents Procedure) of the United States-Republic of Korea Income Tax Convention had been reviewed by the IRS and an agreement had been reached (the "Korea Competent Authority Proceeding"). As a result of this agreement, the Company received refunds of $97.4 million, inclusive of interest. In addition, we have recorded a net tax benefit of $14.7 million in our full year 2018. In September 2019, the amended tax returns for tax years covered by this agreement were filed and an additional benefit of $2.2 million was recorded related to the final refund the Company expects to receive.

Net Income Per Share

Net Income Per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
NET INCOME PER SHARE	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 table reconciles the numerator and the denominator of the basic and diluted net income per share computation (in thousands, except for per share data): For the Year Ended December 31, 2020 2019 2018 Basic Diluted Basic Diluted Basic Diluted Numerator: Net income applicable to common shareholders $ 44,801 $ 44,801 $ 20,928 $ 20,928 $ 65,031 $ 65,031 Denominator: Weighted-average shares outstanding: Basic 30,776 30,776 31,546 31,546 34,491 34,491 Dilutive effect of stock options, RSUs and convertible securities 282 239 816 Weighted-average shares outstanding: Diluted 31,058 31,785 35,307 Earnings Per Share: Net income: Basic $ 1.46 1.46 $ 0.66 0.66 $ 1.89 1.89 Dilutive effect of stock options, RSUs and convertible securities (0.02) — (0.05) Net income: Diluted $ 1.44 $ 0.66 $ 1.84 Certain shares of common stock issuable upon the exercise or conversion of certain securities have been excluded from our computation of earnings per share because the strike price or conversion rate, as applicable, of such securities was greater than the average market price of our common stock for the years ended December 31, 2020, 2019 and 2018, as applicable, 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 earnings per share for the periods presented (in thousands): For the Year Ended December 31, 2020 2019 2018 Restricted stock units and stock options 146 128 25 Convertible securities 5,143 5,495 — Warrants 5,662 5,495 4,404 Total 10,951 11,118 4,429

Equity Transactions

Equity Transactions	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
EQUITY TRANSACTIONS	EQUITY TRANSACTIONS 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, September 2017, December 2018, and May 2019, our Board of Directors authorized four $100 million increases to the program, respectively, bringing the total amount of the 2014 Repurchase Program to $700 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 total number of shares repurchased and the dollar value of shares repurchased under the 2014 Repurchase Program (in thousands). As of December 31, 2020, there was approximately $71.5 million remaining under the stock repurchase authorization. 2014 Repurchase Program # of Shares Value 2020 6 $ 349 2019 2,962 196,269 2018 1,478 110,505 2017 107 7,693 2016 1,304 64,685 2015 1,836 96,410 2014 3,554 152,625 Total 11,247 $ 628,536 Dividends Cash dividends on outstanding common stock declared in 2020 and 2019 were as follows (in thousands, except per share data): 2020 Per Share Total Cumulative by Fiscal Year First quarter $ 0.35 $ 10,762 $ 10,762 Second quarter 0.35 10,781 21,543 Third quarter 0.35 10,782 32,325 Fourth quarter 0.35 10,786 43,111 $ 1.40 $ 43,111 2019 First quarter $ 0.35 $ 11,180 $ 11,180 Second quarter 0.35 10,895 22,075 Third quarter 0.35 10,897 32,972 Fourth quarter 0.35 10,746 43,718 $ 1.40 $ 43,718 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.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
LEASES	LEASESThe Company enters into operating leases primarily for real estate to support research and development ("R&D") sites and general office space in North America, with additional locations in Europe and Asia. The Company does not currently have any finance leases. Certain of our leases include options to extend the lease at our discretion at the end of the lease term, or terminate the lease early subject to certain conditions and penalties. We do not include any renewal options in our lease terms for calculating our lease liabilities, as the renewal options allow us to maintain operational flexibility and we are not reasonably certain we will exercise these options. At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the specific facts and circumstances present. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable, and, as such, the Company utilizes its incremental borrowing rate as the discount rate based on information available on the lease commencement date. Our incremental borrowing rate represents the rate we would incur to borrow on a collateralized basis over a similar term for an amount equal to the lease payments in a similar economic environment. The table below includes the balances of operating lease right-of-use assets and operating lease liabilities as of December 31, 2020 (in thousands): Balance Sheet Classification December 31, 2020 December 31, 2019 Assets Operating lease receivable - current Prepaid and other current assets $ 817 $ — Operating lease right-of-use assets, net Other Non-current Assets 22,456 24,513 Total Lease Assets $ 23,273 $ 24,513 Liabilities Operating lease liabilities - Current Other accrued expenses $ 3,170 $ 3,437 Operating lease liabilities - Noncurrent Other long-term liabilities 23,043 24,142 Total Lease Liabilities $ 26,213 $ 27,579 The components of lease costs which were included within operating expenses in our consolidated statement of income were as follows (in thousands): For the Year Ended December 31, 2020 2019 Operating lease cost $ 5,442 $ 4,776 Short-term lease cost 726 925 Variable lease cost 1,764 1,502 For the years ended December 31, 2020 and 2019, sublease income was insignificant. Cash paid for amounts included in the measurement of operating lease liabilities for the year ended December 31, 2020 and 2019 was $4.9 million and $5.2 million, respectively, and was included in net cash provided by operating activities in our consolidated statement of cash flows. Operating lease right-of-use assets obtained in exchange for operating lease obligations totaled $2.5 million and $14.4 million during the years ended December 31, 2020 and 2019, respectively. As of December 31, 2020, the weighted average remaining operating lease term was 6.6 years and the weighted average discount rate used to determine the operating lease liabilities was 5.6%. As of December 31, 2020, there have been no leases entered into that have not yet commenced. The maturities of our operating lease liabilities as of December 31, 2020, excluding short-term leases with terms less than 12 months, were as follows (in thousands): Maturity of Operating Lease Liabilities 2021 $ 3,741 2022 5,463 2023 4,727 2024 4,508 2025 3,585 Thereafter 8,795 Total lease payments $ 30,819 Less: Imputed interest (5,423) Present value of lease liabilities $ 25,396

Other Income (Expense), Net

Other Income (Expense), Net	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
OTHER INCOME (EXPENSE), NET	OTHER INCOME (EXPENSE), NET The amounts included in " Other Income, Net " in the consolidated statements of income for the year ended December 31, 2020, 2019 and 2018 were as follows (in thousands): For the Year Ended December 31, 2020 2019 2018 Interest and investment income $ 5,661 $ 13,458 $ 14,590 Gain on asset acquisition and sale of business — 22,690 — Loss on extinguishment of long-term debt — (5,488) — Other income (expense), net 11,263 (1,598) (9,171) Other income, net $ 16,924 $ 29,062 $ 5,419 Refer to Note 5, " Business Combinations and Other Transactions, " for further information regarding the $14.2 million gain resulting from the R&I Acquisition and the $8.5 million gain on sale of our Hillcrest product business during the year ended December 31, 2019. Refer to Note 10, " Obligations, " for further information on the $5.5 million loss on extinguishment of long-term debt recognized during the year ended December 31, 2019. During the year ended December 31, 2020, we recognized $5.6 million of unrealized gains resulting from observable price changes in orderly transactions of our long-term strategic investments. During the year ended December 31, 2019, we recognized a net loss of $2.6 million resulting from the partial impairment of one of our strategic investments partially offset by a gain on sale of a separate strategic investment. During the year ended December 31, 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. These items are included in the " Other income (expense), net " caption in the table above.

Selected Quarterly Results (una

Selected Quarterly Results (unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
SELECTED QUARTERLY RESULTS (UNAUDITED)	SELECTED QUARTERLY RESULTS (UNAUDITED) The table below presents quarterly data for the years ended December 31, 2020 and 2019. (In thousands, except per share amounts, unaudited) 2020 First Second Third Fourth Revenues (a) $ 76,210 $ 104,498 $ 87,493 $ 90,790 Income from operations $ 4,681 $ 31,917 $ 15,430 $ 3,140 Net income (loss) applicable to InterDigital, Inc.'s common shareholders (b) $ 116 $ 22,251 $ 23,784 $ (1,350) Net income (loss) per common share — basic $ — $ 0.72 $ 0.77 $ (0.04) Net income (loss) per common share — diluted $ — $ 0.72 $ 0.76 $ (0.04) 2019 First Second Third Fourth Revenues (c) $ 68,631 $ 75,609 $ 72,523 $ 102,161 Income (loss) from operations $ (150) $ 8,915 $ 3,774 $ 25,296 Net income applicable to InterDigital, Inc.'s common shareholders $ (2,803) $ 7,743 $ 2,234 $ 13,754 Net income (loss) per common share — basic $ (0.09) $ 0.25 $ 0.07 $ 0.44 Net income (loss) per common share — diluted $ (0.09) $ 0.24 $ 0.07 $ 0.44 (a) In 2020, we recognized $21.6 million of non-current patent royalties primarily attributable to the Huawei patent license agreement signed in second quarter 2020. (b) In third quarter 2020, we recognized a net discrete tax benefit of $18.5 million that primarily related to the expected amendment of a prior year tax return to utilize a tax asset generated in the current year, as well as the reversal of a tax reserve. (c) In 2019, we recognized $19.8 million of non-current patent royalties primarily attributable to the Funai, ZTE Corporation, and Innovius LLC patent license agreements, all of which were signed in fourth quarter 2019.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
VARIABLE INTEREST ENTITIES	VARIABLE INTEREST ENTITIES As further discussed below, we are the primary beneficiary of three variable interest entities. As of December 31, 2020, the combined book values of the assets and liabilities associated with these variable interest entities included in our consolidated balance sheet were $62.0 million and $5.8 million, respectively. Assets included $24.5 million of cash and cash equivalents, $2.3 million of accounts receivable and prepaid assets, $35.2 million of patents, net, and $0.0 million of other non-current assets. As of December 31, 2019, the combined book values of the assets and liabilities associated with these variable interest entities included in our consolidated balance sheet were $60.6 million and $5.4 million, respectively. Assets included $18.5 million of cash and cash equivalents, $1.7 million of accounts receivable, $39.3 million of patents, net, and $1.3 million of other non-current assets. Chordant On January 31, 2019, we launched the Company’s Chordant™ business as a standalone company. The spinout of the unit, which now includes an affiliate of Sony as an investor along with the Company, gives Chordant added independence and flexibility in driving into its core operator and smart city markets. Chordant is a variable interest entity and we have determined that we are the primary beneficiary for accounting purposes and consolidate Chordant. For the years ended December 31, 2020 and 2019, we have allocated approximately $1.1 million and $1.5 million, respectively, of Chordant's net loss to noncontrolling interests held by other parties. Convida Wireless Convida Wireless was launched in 2013 and most recently renewed in 2018 to combine Sony's consumer electronics expertise with our pioneering 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 years ended December 31, 2020, 2019 and 2018, we have allocated approximately $5.7 million, $4.5 million and $5.6 million, respectively, of Convida Wireless' net loss to noncontrolling interests held by other parties. Signal Trust for Wireless Innovation During 2013, we announced the establishment of the Signal Trust for Wireless Innovation (the “Trust”), the goal of which was to monetize a patent portfolio primarily related to 3G cellular infrastructure. In response to a request from Signal Trust, in first quarter 2021, we provided our consent, as major beneficiary, to dissolve Signal Trust.” The Trust has been accounted for as a variable interest entity. Based on the terms of the trust agreement, we determined that we are the primary beneficiary for accounting purposes and have included the Trust in our consolidated financial statements. As such, we recorded a $2.4 million charge within the " Patent administration and licensing

Prepaid and Other Current Asset

Prepaid and Other Current Assets	12 Months Ended
	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
PREPAID AND OTHER CURRENT ASSETS	PREPAID AND OTHER CURRENT ASSETS The amounts included in " Prepaid and other current assets " in the consolidated balance sheet as of December 31, 2020, and 2019 were as follows (in thousands): December 31, 2020 2019 Tax receivables $ 69,592 $ 38,021 Prepaid assets 10,899 16,814 Operating lease receivable 817 — Other current assets 2,916 8,530 Total Prepaid and other current assets $ 84,224 $ 63,365

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	Valuation and Qualifying Accounts Balance Beginning of Period Increase/ (Decrease) Reversal of Valuation Allowance Balance End of Period 2020 valuation allowance for deferred tax assets $ 133,797 $ 10,570 (a) $ — $ 144,367 2019 valuation allowance for deferred tax assets $ 125,158 $ 8,639 (a) $ — $ 133,797 2018 valuation allowance for deferred tax assets $ 123,916 $ 1,568 (a) $ (326) $ 125,158 2020 reserve for uncollectible accounts $ 537 $ (537) (b) $ — $ — 2019 reserve for uncollectible accounts $ 693 $ (156) (b) $ — $ 537 2018 reserve for uncollectible accounts $ 456 $ 237 $ — $ 693 (a) The increase was primarily necessary to maintain a full, or near full, valuation allowance against our state deferred tax assets and deferred tax assets for certain subsidiaries in France as well as a non-wholly owned subsidiary in the United States and the United Kingdom. (b) The decrease relates to the write-off of a previously recorded reserve during 2019.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and New Accounting Guidance (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include all of our accounts and all entities in which we have a controlling interest and/or are required to be consolidated in accordance with the Generally Accepted Accounting Principles in the United States (“GAAP”). All significant intercompany accounts and transactions have been eliminated in consolidation. In determining whether we are the primary beneficiary of a variable interest entity and therefore required to consolidate, we apply a qualitative approach that determines whether we have both the power to direct the economically significant activities of the entity and the obligation to absorb losses of, or the right to receive benefits from, the entity that could potentially be significant to that entity. These considerations impact the way we account for our existing collaborative relationships and other arrangements. We continuously assess whether we are the primary beneficiary of a variable interest entity as changes to existing relationships or future transactions may result in us consolidating or deconsolidating our partner(s) to collaborations and other arrangements.
Use of Estimates	Use of EstimatesThe preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. If different assumptions were made or different conditions had existed, our financial results could have been materially different.
Reclassifications	Reclassifications Certain reclassifications have been made to prior year amounts to conform to the current year presentation.
Foreign Currency Transaction	Foreign Currency Translation The functional currency of substantially all of the Company's wholly-owned subsidiaries is the U.S. dollar. Certain subsidiaries have monetary assets and liabilities that are denominated in a currency that is different than the functional currency. The gains and losses resulting from this remeasurement and translation of monetary assets denominated in a currency that is different than the functional currency are reflected in the determination of net income (loss).
Cash, Cash Equivalents, Restricted Cash and Marketable Securities	Cash, Cash Equivalents, Restricted Cash and Marketable Securities We classify all highly liquid investment securities with original maturities of three months or less at date of purchase as cash equivalents. Cash that is held for a specific purpose and therefore not available to the Company for immediate or general business use is classified as restricted cash. Our investments are comprised of mutual and exchange traded funds, commercial paper, United States and municipal government obligations and corporate securities. Management determines the appropriate classification of our investments at the time of acquisition and re-evaluates such determination at each balance sheet date.
Other-than-Temporary Impairments and Impairment of Long-Lived Assets	Other-than-Temporary Impairments We review our investment portfolio during each reporting period to determine whether there are identified events or circumstances that would indicate there is a decline in the fair value that is considered to be other-than-temporary. For non-public investments, if there are no identified events or circumstances that would have a significant adverse effect on the fair value of the investment, then the fair value is not estimated. If an investment is deemed to have experienced an other-than-temporary decline below its cost basis, we reduce the carrying amount of the investment to its quoted or estimated fair value, as applicable, and establish a new cost basis for the investment. We charge the impairment to the " Other Income, Net" line of our consolidated statements of income.
Patents	Intangible Assets Patents We capitalize external costs, such as filing fees and associated attorney fees, incurred to obtain issued patents and patent license rights. We expense costs associated with maintaining and defending patents subsequent to their issuance in the period incurred. We amortize capitalized patent costs for internally generated patents on a straight-line basis over 10 years, which represents the estimated useful lives of the patents. The ten-year estimated useful life for internally generated patents is based on our assessment of such factors as: the integrated nature of the portfolios being licensed, the overall makeup of the portfolio over time, and the length of license agreements for such patents. The estimated useful lives of acquired patents and patent rights, however, have been and will continue to be based on a separate analysis related to each acquisition and may differ from the estimated useful lives of internally generated patents. The average estimated useful life of acquired patents is 9.7 years. We assess the potential impairment to all capitalized net patent costs when events or changes in circumstances indicate that the carrying amount of our patent portfolio may not be recoverable.
Goodwill and Other Intangible Assets	Goodwill Goodwill is recorded as the difference, if any, between the aggregate consideration paid for an acquisition and the fair value of the net tangible and identified intangible assets acquired under a business combination. We review impairment of goodwill annually on the first day of the fourth quarter. We first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount as a basis for determining whether a quantitative goodwill impairment test is necessary. If we conclude it is more likely than not that the fair value of a reporting unit exceeds its carrying amount, we need not perform the quantitative assessment. If based on the qualitative assessment we believe it is more likely than not that the fair value of a reporting unit is less than its carrying value, a quantitative assessment test is required to be performed. This assessment requires us to compare the fair value of each reporting unit to its carrying value including allocated goodwill. We determine the fair value of our reporting units generally using a combination of the income and market approaches. The income approach is estimated through the discounted cash flow method based on assumptions about future conditions such as future revenue growth rates, new product and technology introductions, gross margins, operating expenses, discount rates, future economic and market conditions, and other assumptions. The market approach estimates the fair value of our equity by utilizing the market comparable method which is based on revenue multiples from comparable companies in similar lines of business. If the carrying value of a reporting unit exceeds the reporting unit’s fair value, a goodwill impairment charge will be recorded for the difference up to the carrying value of goodwill. The Company acquired goodwill from our acquisition of the patent licensing business of Technicolor (the "Technicolor Patent Acquisition") in 2018 and from our acquisition of Hillcrest Laboratories, Inc. (the "Hillcrest product business") in 2016. Refer to Note 5, " Business Combinations and Other Transactions ," for more information regarding these transactions. The carrying value of goodwill as of December 31, 2020 and 2019 was $22.4 million, respectively, which was included within " Other Non-Current Assets " in the consolidated balance sheets. No impairments were recorded during 2020, 2019 or 2018 as a result of our annual goodwill impairment assessment. Other Intangible Assets We capitalize the cost of technology solutions and platforms we acquire or license from third parties when they have a future benefit and the development of these solutions and platforms is substantially complete at the time they are acquired or licensed. Intangible assets consist of acquired patents, existing technology, and trade names. Refer to the above Patents
Property and Equipment	Property and Equipment Property and equipment are stated at cost. Depreciation and amortization of property and equipment are provided using the straight-line method. The estimated useful lives for computer equipment, computer software, engineering and test equipment and furniture and fixtures are generally three five twenty-five
Leases	Leases In February 2016, the FASB issued ASC 842, which outlines a comprehensive change to the lease accounting model ("ASC840"). The Company adopted ASC 842 on January 1, 2019 using the modified retrospective transition effective date method.
Internal-Use Software Costs	Internal-Use Software Costs We capitalize costs associated with software developed for internal use that are incurred during the software development stage. Such costs are limited to expenses incurred after management authorizes and commits to a computer software project, believes that it is more likely than not that the project will be completed, the software will be used to perform the intended function with an estimated service life of two years or more, and the completion of conceptual formulation, design and testing of possible software project alternatives (the preliminary design stage). Costs incurred after final acceptance testing has been successfully completed are expensed. Capitalized computer software costs are amortized over their estimated useful life of three years. All computer software costs capitalized to date relate to the purchase, development and implementation of engineering, accounting and other enterprise software.
Revenue Recognition	Revenue Recognition We adopted ASU No. 2014-09, "Revenue from Contracts with Customers" (ASC 606) effective January 1, 2018. The disclosure below is a description of our revenue recognition accounting policies which were in effect beginning January 1, 2018 under ASC 606. 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 promises to provide any technology updates to the portfolio during the term. In accordance with US GAAP, we use 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 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 consolidated balance sheets. Contract assets due more than twelve months after the balance sheet date are included within 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. Certain patent license agreements contain revenue from non-financial sources in the form of patents received from the customer. 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 license 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. Although we have few static fixed-fee license agreements, we generally satisfy our performance obligations under such agreements 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 of revenue from royalty payments, software licenses, engineering services and product sales. The nature of these contracts and timing of payments vary. We recognize revenue from royalty payments and license agreements using the same methods described above under our policy for recognizing revenue from patent license agreements. We recognize revenue from engineering services using percentage of completion method. Patent Sales
Accounts Receivable	Accounts ReceivableAccounts receivable is presented net of allowance for doubtful accounts. Our accounts receivable consists mainly of trade receivables derived from fixed-fee license arrangements, with contractual payment terms and the remaining material amounts of revenue are from variable patent license agreements, with quarterly payments. The provision for doubtful accounts reflects the current estimate of credit losses expected to be incurred over the life of the financial asset, based on historical experience current conditions and reasonable forecasts of future economic conditions. Further, we evaluate the collectability of our accounts receivable and if there is doubt that we will collect the full amount, we will record a reserve specific to that customer’s receivable balance.
Investments in Other Entities	Investments in Other Entities We may make strategic investments in companies that have developed or are developing technologies that are complementary to our business. We made an accounting policy election for a measurement alternative for our 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. On a quarterly basis, we monitor items such as our investment’s financial position and liquidity, performance targets, business plans, and cost trends to assess whether there are any triggering events or indicators present that would be indicative of an impairment, or any other observable price changes as indicated above. We do not adjust our investment balance when the investee reports profit or loss. Additionally, other investments may be accounted for under the equity method of accounting. Under this method, we initially record our investment in the stock of an investee at cost, and adjust the carrying amount of the investment to recognize our share of the earnings or losses of the investee after the date of acquisition. The amount of the adjustment is included in the determination of net income, and such amount reflects adjustments similar to those made in preparing consolidated statements including adjustments to eliminate intercompany gains and losses, and to amortize, if appropriate, any difference between our cost and underlying equity in net assets of the investee at the date of investment. The investment is also adjusted to reflect our share of changes in the investee’s capital. Dividends received from an investee reduce the carrying amount of the investment. When there are a series of operating losses by the investee or when other factors indicate that a decrease in value of the investment has occurred which is other than temporary, we recognize an impairment equal to the difference between the fair value and the carrying amount of our investment. The carrying value of our investments in other entities are included within " Other Non-Current Assets
Collaborative Arrangements	Collaborative Arrangements We record the elements of our collaboration agreements that represent joint operating activities in accordance with ASC 808, Collaborative Arrangements (“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 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 .
Deferred Charges	Deferred Charges Direct costs of obtaining a contract or fulfilling a contract in a transaction that results in the deferral of revenue may be either expensed as incurred or capitalized, depending on certain criteria. In conjunction with our adoption of ASC 606 effective January 1, 2018, we made a policy election 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. If the amortization period is greater than one year, we capitalize direct costs incurred for the acquisition or fulfillment of a contract through the date of signing if they are directly related to a particular revenue arrangement and are expected to be recovered. The costs are amortized on a straight-line basis over the life of the patent license agreement. For example, from time to time, we use sales agents to assist us in our licensing and/or patent sale activities. In such cases, we may pay a commission. The commission rate varies from agreement to agreement. Commissions are normally paid shortly after our receipt of cash payments associated with the patent license or patent sale agreements. We defer recognition of commission expense and amortize these expenses in proportion to our recognition of the related revenue. Commission expense is included within the " Patent administration and licensing" line of our consolidated statements of income and was immaterial for the years presented. There were no new direct contract costs incurred during 2020, 2019 or 2018. Incremental direct costs incurred related to a debt financing transaction may be capitalized. In connection with our offering of the 2024 Notes and 2020 Notes, defined and discussed in detail within Note 10, " Obligations" , we incurred directly related costs. The initial purchasers' transaction fees and related offering expenses were allocated to the liability and equity components of the debt in proportion to the allocation of proceeds and accounted for as debt issuance costs. The debt issuance costs allocated to the liability component of the debt were capitalized as deferred financing costs and recorded as a direct reduction of the debt. These costs are being amortized over the term of the debt using the effective interest method and are included within the " Interest expense"
Research and Development	Research and DevelopmentResearch and development expenditures are expensed in the period incurred, except certain software development costs that are capitalized between the point in time that technological feasibility of the software is established and when the product is available for general release to customers. We did not have any capitalized software costs related to research and development in any period presented.
Compensation Programs	Compensation Programs We use a variety of compensation programs to attract, retain and motivate our employees, and to align employee compensation more closely with company performance. These programs include, but are not limited to, short-term incentives tied to performance goals, cash awards to inventors for filed patent applications and patent issuances, and long-term incentives in the form of stock option awards, time-based restricted stock unit (“RSU”) awards, performance-based awards and cash awards, noting equity awards are granted pursuant to the terms and conditions of our Equity Plans (as defined in Note 13, " Compensation Plans and Programs "). Our long-term incentives, including equity awards, typically include annual equity and cash award grants with three five three We account for compensation costs associated with share-based compensation based on the fair value of the instruments issued. The estimated value of stock options includes assumptions around expected life, stock volatility and dividends. The expected life of our stock option awards is based on the simplified method as prescribed by Staff Accounting Bulletin Topic 14. In all periods, our policy has been to set the value of RSUs and restricted stock awards equal to the value of our underlying common stock on the date of measurement. For grants with graded vesting, we amortize the associated unrecognized compensation cost using an accelerated method. For grants that cliff vest, we amortize the associated unrecognized compensation cost on a straight-line basis over their vesting term.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the consolidated statement of income in the period in which the change was enacted. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets if management has determined that it is more likely than not that such assets will not be realized. In addition, the calculation of tax liabilities involves significant judgment in estimating the impact of uncertainties in the application of complex tax laws. We are subject to examinations by the U.S. IRS and other taxing jurisdictions on various tax matters, including challenges to various positions we assert in our filings. In the event that the IRS or another taxing jurisdiction levies an assessment in the future, it is possible the assessment could have a material adverse effect on our consolidated financial condition or results of operations. The financial statement recognition of the benefit for an uncertain tax position is dependent upon the benefit being more likely than not to be sustainable upon audit by the applicable tax authority. If this threshold is met, the tax benefit is then measured and recognized at the largest amount that is greater than 50 percent likely of being realized upon ultimate settlement. In the event that the IRS or another taxing jurisdiction levies an assessment in the future, it is possible the assessment could have a material adverse effect on our consolidated financial condition or results of operations.
New Accounting Guidance	New Accounting Guidance Accounting Standards Update: Financial Instruments - Credit Losses In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses". This ASU introduces a new accounting model for recognizing credit losses on certain financial instruments and financial assets, including trade receivables, based upon an estimate of current expected credit losses, otherwise known as CECL. The new guidance requires the recognition of an allowance that reflects the current estimate of credit losses expected to be incurred over the life of the financial asset, based not only on historical experience and current conditions, but also on reasonable forecasts. Additionally, ASU No. 2016-13 made several changes to the available-for-sale impairment model. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted. We adopted this guidance as of January 1, 2020 and the adoption did not have a material impact on our consolidated financial statements. Accounting Standards Update: Cloud Computing Arrangements In August 2018, the FASB issued ASU No. 2018-15 “Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract”. The amendments in this ASU align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted. We adopted this guidance on a prospective basis as of January 1, 2020 and the adoption did not have a material impact on our consolidated financial statements. Accounting Standards Update: Collaborative Arrangements In November 2018, the FASB issued ASU No. 2018-18, "Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606". The amendments in this ASU provide guidance on how to assess whether certain transactions between collaborative arrangement participants should be accounted for within the revenue recognition standard. The amendments in this update are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted for entities who have previously adopted the new revenue recognition guidance. We adopted this guidance as of January 1, 2020 and the adoption did not have a material impact on our consolidated financial statements. Accounting Standards Update: Simplifying the Accounting for Income Taxes In December 2019, the FASB issued ASU No. 2019-12, "Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes" ("ASU 2019-12"). The amendments in this ASU are intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020 with early adoption allowed. We have determined that the adoption will not have a material impact on our consolidated financial statements. . Accounting Standards Update: Simplifying the Accounting for Convertible Debt Instruments In August 2020, the FASB issued ASU No. 2020-06, “Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity” (“ASU 2020-06”). The amendments in this ASU are intended to simplify accounting for convertible debt instruments and convertible preferred stock by removing certain accounting models which separate the embedded conversion features from the host contract. ASU 2020-06 also amends certain guidance in ASC 260 on the computation of earnings per share for convertible instruments and contracts on an entity’s own equity. ASU 2020-06 is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years, and early adoption permitted for fiscal years beginning after December 15, 2020. This update permits the use of either the modified retrospective or fully retrospective methods of transition. We will elect to early adopt this standard on a modified retrospective approach as of January 1, 2021. We expect this adoption to increase Long-term debt $50.2 million at January 1, 2021, which is comprised of $51.6 million of unamortized interest discount and the $1.9 million equity component of the deferred financing costs, net catch up amortization of $0.5 million, due to the new standard no longer requires bifurcation of the embedded conversion feature from the host contract. We also expect this adoption to reduce non-cash interest expense starting in 2021 due to the removal of the accretion of the debt discount.
Fair Value Measurements	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.
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.

Background and Basis of Prese_2

Background and Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of supplemental cash flow information	The following table presents additional supplemental cash flow information for the year ended December 31, 2020, 2019 and 2018 (in thousands): FOR THE YEAR ENDED DECEMBER 31, SUPPLEMENTAL CASH FLOW INFORMATION: 2020 2019 2018 Interest paid $ 8,712 $ 7,886 $ 4,740 Income taxes paid, including foreign withholding taxes 26,233 24,229 33,904 Non-cash investing and financing activities: Dividend payable 10,786 10,746 11,627 Increases in noncontrolling interests — 13,750 — Non-cash acquisition of patents 33,300 22,500 — Accrued capitalized patent costs and property and equipment (436) 1,619 (2,789)

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Schedule of disaggregation of revenue	The following table presents the disaggregation of our revenue for the year ended December 31, 2020, 2019 and 2018 (in thousands): For the Year Ended December 31, 2020 2019 2018 Variable patent royalty revenue $ 26,587 $ 30,428 $ 36,384 Fixed-fee royalty revenue 298,461 257,221 239,347 Current patent royalties a 325,048 287,649 275,731 Non-current patent royalties b 21,582 19,782 26,329 Total patent royalties 346,630 307,431 302,060 Current technology solutions revenue a 11,761 10,518 4,594 Patent sales b 600 975 750 Total revenue $ 358,991 $ 318,924 $ 307,404 a. Recurring revenues are comprised of current patent royalties, inclusive of Dynamic Fixed-Fee Agreement royalties, and current technology solutions revenue. b. Non-recurring revenues are comprised of non-current patent royalties, which primarily include past patent royalties and royalties from static agreements, as well as patent sales.
Schedule of contracted revenue	Based on contracts signed and committed Dynamic Fixed-Fee Agreement payments as of December 31, 2020, we expect to recognize the following amounts of revenue over the term of such contracts (in thousands): Revenue 2021 $ 273,815 2022 236,045 2023 44,469 2024 89 2025 — Thereafter — $ 554,418

Geographic _ Customer Concent_2

Geographic / Customer Concentration (Tables)	12 Months Ended
	Dec. 31, 2020
GEOGRAPHIC CUSTOMER CONCENTRATION [Abstract]
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas	The table below lists the countries of the headquarters of our licensees and customers and the total revenue derived from each country or region for the periods indicated (in thousands): For the Year Ended December 31, 2020 2019 2018 United States $ 128,238 $ 139,162 $ 119,159 South Korea 111,634 113,189 112,291 China 63,172 11,103 309 Japan 23,694 35,614 29,525 Taiwan 10,059 938 23,326 France 7,773 5,895 277 Sweden 7,573 6,934 6,933 Other Europe 6,848 5,810 5,116 Other Asia — 279 468 Finland — — 10,000 Total $ 358,991 $ 318,924 $ 307,404
Schedule of Revenue by Major Customers by Reporting Segments	During 2020, 2019 and 2018, the following licensees or customers accounted for 10% or more of total revenues: 2020 2019 2018 Apple 31% 35% 36% Samsung 22% 25% 25% Huawei 15% —% —% LG <10% 10% 10%

Business Combinations and Oth_2

Business Combinations and Other Transactions (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Summary of fair value of consideration transfer	The following table summarizes the fair value of consideration transferred and our allocation of that consideration based on the fair values of the assets acquired and liabilities assumed as of the date of acquisition (in thousands): As of 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 $ 154,000 9 - 10 Goodwill (1) 6,388 Total identified intangible assets $ 160,388 Total fair value of consideration transferred $ 157,314
Schedule of Pro Forma Information	The amounts in the table are unaudited (in thousands, except per share data): For the Year Ended December 31, 2018 (Unaudited) Actual revenue $ 307,404 Supplemental pro forma revenue $ 314,096 Actual earnings $ 65,031 Supplemental pro forma earnings $ 52,754 Actual diluted earnings per share $ 1.84 Supplemental pro forma diluted earnings per share $ 1.49
Schedule of expected benefit payments	Expected future benefit payments under these plans as of December 31, 2020 were as follows (in thousands): 2021 $ 229 2022 381 2023 547 2024 297 2025 540 Thereafter 2,699

Cash, Cash Equivalents, Restr_2

Cash, Cash Equivalents, Restricted Cash and Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	Cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, 2020 2019 Money market and demand accounts $ 397,522 $ 757,098 Commercial paper 80,141 — Total cash, cash equivalents and restricted cash $ 477,663 $ 757,098 The following table provides a reconciliation of total cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 within the consolidated balance sheets (in thousands): December 31, 2020 2019 Cash and cash equivalents $ 473,474 $ 745,491 Restricted cash included within prepaid and other current assets 3,108 10,526 Restricted cash included within other non-current assets 1,081 1,081 Total cash, cash equivalents and restricted cash 477,663 757,098
Restrictions on Cash and Cash Equivalents	Cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, 2020 2019 Money market and demand accounts $ 397,522 $ 757,098 Commercial paper 80,141 — Total cash, cash equivalents and restricted cash $ 477,663 $ 757,098 The following table provides a reconciliation of total cash, cash equivalents and restricted cash as of December 31, 2020 and 2019 within the consolidated balance sheets (in thousands): December 31, 2020 2019 Cash and cash equivalents $ 473,474 $ 745,491 Restricted cash included within prepaid and other current assets 3,108 10,526 Restricted cash included within other non-current assets 1,081 1,081 Total cash, cash equivalents and restricted cash 477,663 757,098
Schedule of Marketable Securities	Marketable securities as of December 31, 2020 and 2019 consisted of the following (in thousands): December 31, 2020 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities Commercial paper $ 285,244 $ 5 $ (7) $ 285,242 U.S. government securities 166,195 44 (16) 166,223 Corporate bonds, asset backed and other securities 81,540 314 (5) 81,849 Total available-for-sale securities $ 532,979 $ 363 $ (28) $ 533,314 Reported in: Cash and cash equivalents $ 80,141 Short-term investments 453,173 Total marketable securities $ 533,314 December 31, 2019 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities U.S. government securities $ 105,453 $ 249 $ — $ 105,702 Corporate bonds, asset backed and other securities 73,276 226 — 73,502 Total available-for-sale securities $ 178,729 $ 475 $ — $ 179,204 Reported in: Cash and cash equivalents $ — Short-term investments 179,204 Total marketable securities $ 179,204

Concentration of Credit Risk _2

Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities at Fair Value on Recurring Basis	Our financial assets and liabilities that are accounted for at fair value on a recurring basis are presented in the tables below as of December 31, 2020 and December 31, 2019 (in thousands): Fair Value as of December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 397,522 $ — $ — $ 397,522 Commercial paper (b) — 285,242 — 285,242 U.S. government securities — 166,223 — 166,223 Corporate bonds, asset backed and other securities — 81,849 — 81,849 $ 397,522 $ 533,314 $ — $ 930,836 Fair Value as of December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 757,098 $ — $ — $ 757,098 U.S. government securities — 105,702 — 105,702 Corporate bonds and asset backed securities — 73,502 — 73,502 $ 757,098 $ 179,204 $ — $ 936,302 _______________ (a) Included within cash and cash equivalents. (b) As of December 31, 2020, $80.1 million of commercial paper was included within cash and cash equivalents.
Schedule of Aggregate Fair Value	The principal amount, carrying value and related estimated fair value of the Company's senior convertible debt reported in the consolidated balance sheets as of December 31, 2020 and December 31, 2019 was as follows (in thousands). The aggregate fair value of the principal amount of the senior convertible long-term debt is a Level 2 fair value measurement. December 31, 2020 December 31, 2019 Principal Carrying Fair Principal Carrying Fair Senior Convertible Long-Term Debt $ 400,000 $ 343,821 $ 418,760 $ 494,909 $ 423,657 $ 492,969 December 31, 2020 December 31, 2019 Carrying Fair Carrying Fair Technicolor Patent Acquisition Long-Term Debt $ 24,171 $ 27,016 $ 21,101 $ 23,305

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment, net is comprised of the following (in thousands): December 31, 2020 2019 Computer equipment and software $ 16,003 $ 11,320 Leasehold improvements 11,076 11,315 Building and improvements 3,548 3,702 Engineering and test equipment 1,183 1,333 Furniture and fixtures 1,051 1,121 Property and equipment, gross 32,861 28,791 Less: accumulated depreciation (16,231) (18,574) Property and equipment, net $ 16,630 $ 10,217

Patents, Goodwill and Other I_2

Patents, Goodwill and Other Intangibles Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	As of December 31, 2020 and 2019, patents consisted of the following (in thousands, except for useful life data): December 31, 2020 2019 Weighted average estimated useful life (years) 9.9 9.9 Gross patents $ 945,609 $ 905,814 Accumulated amortization (527,266) (469,475) Patents, net $ 418,343 $ 436,339
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The estimated aggregate amortization expense for the next five years related to our patents balance as of December 31, 2020 is as follows (in thousands): 2021 74,208 2022 69,897 2023 63,890 2024 55,110 2025 51,068
Schedule of Goodwill	The following table shows the change in the carrying amount of our goodwill balance from December 31, 2018 to December 31, 2020, all of which is allocated to our one reportable segment (in thousands): Goodwill balance as of December 31, 2018 $ 22,421 Activity — Goodwill balance as of December 31, 2019 $ 22,421 Activity — Goodwill balance as of December 31, 2020 $ 22,421

Obligations (Tables)

Obligations (Tables)	12 Months Ended
	Dec. 31, 2020
OBLIGATIONS: [Abstract]
Schedule of Debt	Long-term debt obligations, excluding the long-term debt resulting from the Technicolor Patent Acquisition, are comprised of the following (in thousands): December 31, 2020 2019 2.00% Senior Convertible Notes due 2024 $ 400,000 $ 400,000 1.50% Senior Convertible Notes due 2020 — 94,909 Less: Unamortized interest discount (51,567) (65,393) Deferred financing costs (4,612) (5,859) Total net carrying amount of Senior Convertible Notes 343,821 423,657 Less: Current portion of long-term debt — 94,170 Long-term net carrying amount of Senior Convertible Notes $ 343,821 $ 329,487
Schedule of Maturities of Long-term Debt	Maturities of principal of the long-term debt obligations of the Company as of December 31, 2020, excluding the long-term debt resulting from the Technicolor Patent Acquisition, are as follows (in thousands): 2021 $ — 2022 — 2023 — 2024 400,000 2025 — Thereafter — $ 400,000
Schedule of Interest Cost	The following table presents the amount of interest cost recognized for the years ended December 31, 2020, 2019 and 2018 related to the contractual interest coupon, accretion of the debt discount and the amortization of financing costs (in thousands). For the Year Ended December 31, 2020 2019 2018 2024 Notes 2020 Notes Total 2024 Notes 2020 Notes Total 2020 Notes Contractual coupon interest $ 8,000 $ 237 $ 8,237 $ 4,600 $ 2,824 $ 7,424 $ 4,740 Accretion of debt discount 13,157 669 13,826 7,322 7,743 $ 15,065 12,434 Amortization of financing costs 1,176 70 1,246 654 821 1,475 1,390 Total $ 22,333 $ 976 $ 23,309 $ 12,576 $ 11,388 $ 23,964 $ 18,564

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Payments For Accounts Payable and Other Purchase Commitments	Minimum future payments for accounts payable and other purchase commitments, excluding long-term operating leases for office space, as of December 31, 2020 were as follows (in thousands): 2021 $ 16,113 2022 — 2023 — 2024 — 2025 — Thereafter —

Compensation Plans and Progra_2

Compensation Plans and Programs (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Schedule of RSU Award Vesting	Information with respect to current RSU activity is summarized as follows (in thousands, except per share amounts): Number of Weighted Balance at December 31, 2019 955 $ 62.40 Granted* 626 46.18 Forfeited (213) 66.11 Vested (103) 65.06 Balance at December 31, 2020 1,265 $ 53.53 * These numbers include less than 0.1 million RSUs credited on unvested RSU awards as dividend equivalents. Dividend equivalents accrue with respect to unvested RSUs when and as cash dividends are paid on the Company's common stock, and vest if and when the underlying RSUs vest. Granted amounts include performance-based RSU awards at their maximum potential payout.
Schedule of Weighted Average Option Assumptions	The weighted-average grant date fair value per option award granted during the years ended December 31, 2020, 2019 and 2018 was $11.46, $13.68, and $24.56, respectively, based upon the assumptions included in the table below: For the Year Ended December 31, 2020 2019 2018 Expected term (in years) 6.5 4.5 7.7 Expected volatility 37.5 % 25.8 % 30.1 % Risk-free interest rate 0.6 % 2.4 % 3.0 % Dividend yield 3.1 % 2.0 % 1.8 %
Schedule of Stock Option Activity	Information with respect to current year stock option activity is summarized as follows (in thousands, except per share amounts): Outstanding Options Weighted Balance at December 31, 2019 825 $ 58.83 Granted* 307 44.63 Forfeited (348) 65.74 Exercised (73) 43.83 Balance at December 31, 2020 711 $ 50.85 * Granted amounts include performance-based option awards at their maximum potential payout.

TAXES (Tables)

TAXES (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	Our income tax provision (benefit) consists of the following components for 2020, 2019 and 2018 (in thousands): 2020 2019 2018 Current Federal $ (26,092) $ (11,436) $ (3,148) State 89 207 239 Foreign source withholding tax 26,229 19,850 25,187 226 8,621 22,278 Deferred Federal (28,692) (21,735) (63,030) State 119 2,457 (1,554) Foreign source withholding tax 21,699 21,648 14,889 (6,874) 2,370 (49,695) Total $ (6,648) $ 10,991 $ (27,417)
Schedule of Deferred Tax Assets and Liabilities	The deferred tax assets and liabilities were comprised of the following components at December 31, 2020 and 2019 (in thousands): 2020 2019 Total Total Net operating losses $ 140,940 $ 131,501 Deferred revenue, net 26,213 33,131 Tax credit carryforward 27,813 11,744 Stock compensation 4,082 3,307 Patent amortization 22,530 18,522 Depreciation (1,233) 443 Goodwill (2,211) (1,933) Other-than-temporary impairment 441 1,138 Other (673) 785 Other employee benefits 5,857 7,520 Right of use asset (4,684) (4,913) Lease liability 5,382 5,760 224,457 207,005 Less: valuation allowance (144,367) (133,797) Net deferred tax asset $ 80,090 $ 73,208 Note: Included within the balance sheet, but not reflected in the tables are deferred tax assets primarily related to foreign withholding taxes that are expected to be paid within the next twelve months of $0.4 million and $0.1 million as of December 31, 2020 and December 31, 2019, respectively.
Schedule of Effective Income Tax Rate Reconciliation	The following is a reconciliation of income taxes at the federal statutory rate with income taxes recorded by the Company for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Tax at U.S. statutory rate 21.0 % 21.0 % 21.0 % State tax provision (b) 0.6 % 10.2 % (8.9) % Effects of rates different than statutory (2.0) % (2.8) % (1.4) % Change in valuation allowance 28.5 % 23.3 % 8.5 % Research and development tax credits (1.6) % (4.5) % (4.3) % Uncertain tax positions (2.7) % (0.8) % 3.9 % Permanent differences (1.2) % 2.3 % 4.9 % Stock compensation 1.1 % (0.6) % (5.0) % Foreign derived intangible income deduction (c) — % — % (56.3) % Amended return benefit (a) (65.0) % (8.4) % (49.4) % Other 0.1 % 2.7 % 1.5 % Total tax provision (benefit) (21.2) % 42.4 % (85.5) % (a) In 2020, a net discrete benefit of $20.9 million was recorded that primarily relates to the expected amendment of a prior year tax return to utilize a tax asset generated in the current year, as well as the reversal of a tax reserve. (b) In 2019, we determined that we would not be able to utilize our state deferred tax assets for our parent company in Delaware and Pennsylvania, therefore we put a full valuation allowance on these assets. (c) In 2018, the new Foreign Derived Intangible Income ("FDII") deduction that was enacted as part of the TCJA decreased the tax provision by 56.3%.
Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible	The following is a roll forward of our total gross unrecognized tax benefits, which if reversed would impact the effective tax rate, for the fiscal years 2020 through 2018 (in thousands): 2020 2019 2018 Balance as of January 1 $ 4,456 $ 4,352 $ 3,252 Tax positions related to current year: Additions 1,062 402 73 Reductions — — — Tax positions related to prior years: Additions 37 34 1,054 Reductions — — (27) Settlements — — — Lapses in statues of limitations (1,752) (332) — Balance as of December 31 $ 3,803 $ 4,456 $ 4,352

Net Income Per Share (Tables)

Net Income Per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Numerator and the Denominator of the Basic and Diluted	The following table reconciles the numerator and the denominator of the basic and diluted net income per share computation (in thousands, except for per share data): For the Year Ended December 31, 2020 2019 2018 Basic Diluted Basic Diluted Basic Diluted Numerator: Net income applicable to common shareholders $ 44,801 $ 44,801 $ 20,928 $ 20,928 $ 65,031 $ 65,031 Denominator: Weighted-average shares outstanding: Basic 30,776 30,776 31,546 31,546 34,491 34,491 Dilutive effect of stock options, RSUs and convertible securities 282 239 816 Weighted-average shares outstanding: Diluted 31,058 31,785 35,307 Earnings Per Share: Net income: Basic $ 1.46 1.46 $ 0.66 0.66 $ 1.89 1.89 Dilutive effect of stock options, RSUs and convertible securities (0.02) — (0.05) Net income: Diluted $ 1.44 $ 0.66 $ 1.84
Schedule of Excluded from Computation of EPS	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 earnings per share for the periods presented (in thousands): For the Year Ended December 31, 2020 2019 2018 Restricted stock units and stock options 146 128 25 Convertible securities 5,143 5,495 — Warrants 5,662 5,495 4,404 Total 10,951 11,118 4,429

Equity Transactions (Tables)

Equity Transactions (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of Shares Repurchased	2014 Repurchase Program # of Shares Value 2020 6 $ 349 2019 2,962 196,269 2018 1,478 110,505 2017 107 7,693 2016 1,304 64,685 2015 1,836 96,410 2014 3,554 152,625 Total 11,247 $ 628,536
Schedule of Cash Dividends	Cash dividends on outstanding common stock declared in 2020 and 2019 were as follows (in thousands, except per share data): 2020 Per Share Total Cumulative by Fiscal Year First quarter $ 0.35 $ 10,762 $ 10,762 Second quarter 0.35 10,781 21,543 Third quarter 0.35 10,782 32,325 Fourth quarter 0.35 10,786 43,111 $ 1.40 $ 43,111 2019 First quarter $ 0.35 $ 11,180 $ 11,180 Second quarter 0.35 10,895 22,075 Third quarter 0.35 10,897 32,972 Fourth quarter 0.35 10,746 43,718 $ 1.40 $ 43,718

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of operating lease right-of-use assets and operating lease liabilities	The table below includes the balances of operating lease right-of-use assets and operating lease liabilities as of December 31, 2020 (in thousands): Balance Sheet Classification December 31, 2020 December 31, 2019 Assets Operating lease receivable - current Prepaid and other current assets $ 817 $ — Operating lease right-of-use assets, net Other Non-current Assets 22,456 24,513 Total Lease Assets $ 23,273 $ 24,513 Liabilities Operating lease liabilities - Current Other accrued expenses $ 3,170 $ 3,437 Operating lease liabilities - Noncurrent Other long-term liabilities 23,043 24,142 Total Lease Liabilities $ 26,213 $ 27,579
Schedule of lease costs	The components of lease costs which were included within operating expenses in our consolidated statement of income were as follows (in thousands): For the Year Ended December 31, 2020 2019 Operating lease cost $ 5,442 $ 4,776 Short-term lease cost 726 925 Variable lease cost 1,764 1,502
Schedule of maturities operating lease liabilities	The maturities of our operating lease liabilities as of December 31, 2020, excluding short-term leases with terms less than 12 months, were as follows (in thousands): Maturity of Operating Lease Liabilities 2021 $ 3,741 2022 5,463 2023 4,727 2024 4,508 2025 3,585 Thereafter 8,795 Total lease payments $ 30,819 Less: Imputed interest (5,423) Present value of lease liabilities $ 25,396

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Schedule of Other Income Expense, Net	The amounts included in " Other Income, Net " in the consolidated statements of income for the year ended December 31, 2020, 2019 and 2018 were as follows (in thousands): For the Year Ended December 31, 2020 2019 2018 Interest and investment income $ 5,661 $ 13,458 $ 14,590 Gain on asset acquisition and sale of business — 22,690 — Loss on extinguishment of long-term debt — (5,488) — Other income (expense), net 11,263 (1,598) (9,171) Other income, net $ 16,924 $ 29,062 $ 5,419

Selected Quarterly Results (u_2

Selected Quarterly Results (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The table below presents quarterly data for the years ended December 31, 2020 and 2019. (In thousands, except per share amounts, unaudited) 2020 First Second Third Fourth Revenues (a) $ 76,210 $ 104,498 $ 87,493 $ 90,790 Income from operations $ 4,681 $ 31,917 $ 15,430 $ 3,140 Net income (loss) applicable to InterDigital, Inc.'s common shareholders (b) $ 116 $ 22,251 $ 23,784 $ (1,350) Net income (loss) per common share — basic $ — $ 0.72 $ 0.77 $ (0.04) Net income (loss) per common share — diluted $ — $ 0.72 $ 0.76 $ (0.04) 2019 First Second Third Fourth Revenues (c) $ 68,631 $ 75,609 $ 72,523 $ 102,161 Income (loss) from operations $ (150) $ 8,915 $ 3,774 $ 25,296 Net income applicable to InterDigital, Inc.'s common shareholders $ (2,803) $ 7,743 $ 2,234 $ 13,754 Net income (loss) per common share — basic $ (0.09) $ 0.25 $ 0.07 $ 0.44 Net income (loss) per common share — diluted $ (0.09) $ 0.24 $ 0.07 $ 0.44 (a) In 2020, we recognized $21.6 million of non-current patent royalties primarily attributable to the Huawei patent license agreement signed in second quarter 2020. (b) In third quarter 2020, we recognized a net discrete tax benefit of $18.5 million that primarily related to the expected amendment of a prior year tax return to utilize a tax asset generated in the current year, as well as the reversal of a tax reserve. (c) In 2019, we recognized $19.8 million of non-current patent royalties primarily attributable to the Funai, ZTE Corporation, and Innovius LLC patent license agreements, all of which were signed in fourth quarter 2019.

Prepaid and Other Current Ass_2

Prepaid and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Prepaid and Other Current Assets	The amounts included in " Prepaid and other current assets " in the consolidated balance sheet as of December 31, 2020, and 2019 were as follows (in thousands): December 31, 2020 2019 Tax receivables $ 69,592 $ 38,021 Prepaid assets 10,899 16,814 Operating lease receivable 817 — Other current assets 2,916 8,530 Total Prepaid and other current assets $ 84,224 $ 63,365

Background and Basis of Prese_3

Background and Basis of Presentation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid	$ 8,712	$ 7,886	$ 4,740
Income taxes paid, including foreign withholding taxes	26,233	24,229	33,904
Non-cash investing and financing activities:
Dividend payable	10,786	10,746	11,627
Increases in noncontrolling interests	0	13,750	0
Non-cash acquisition of patents	33,300	22,500	0
Accrued capitalized patent costs and property and equipment	$ (436)	$ 1,619	$ (2,789)

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and New Accounting Guidance - Cash, Cash Equivalents, Restricted Cash and Marketable Securities (Details)	Dec. 31, 2020
Maximum
Debt Securities, Available-for-sale [Line Items]
Contractual maturities	2 years

Summary of Significant Accoun_4

Summary of Significant Accounting Policies and New Accounting Guidance - Goodwill and Other Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Goodwill	$ 22,421,000	$ 22,421,000	$ 22,421,000
Goodwill impairment	$ 0	$ 0	$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies and New Accounting Guidance - Patents (Details)	12 Months Ended
	Dec. 31, 2020
Developed Technology Rights
Finite-Lived Intangible Assets [Line Items]
Weighted average estimated useful life (years)	10 years
Patents Purchased
Finite-Lived Intangible Assets [Line Items]
Weighted average estimated useful life (years)	9 years 8 months 12 days

Summary of Significant Accoun_6

Summary of Significant Accounting Policies and New Accounting Guidance - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2020
Building
Property, Plant and Equipment [Line Items]
Useful lives	25 years
Minimum | Machinery and Equipment
Property, Plant and Equipment [Line Items]
Useful lives	3 years
Minimum | Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful lives	5 years
Maximum | Machinery and Equipment
Property, Plant and Equipment [Line Items]
Useful lives	5 years
Maximum | Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful lives	10 years

Summary of Significant Accoun_7

Summary of Significant Accounting Policies and New Accounting Guidance - Internal Use Software Costs (Details) - Software Development	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Useful lives	3 years
Minimum
Property, Plant and Equipment [Line Items]
Useful lives	2 years

Summary of Significant Accoun_8

Summary of Significant Accounting Policies and New Accounting Guidance - Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Provision for doubtful accounts	$ 0	$ 537

Summary of Significant Accoun_9

Summary of Significant Accounting Policies and New Accounting Guidance - Investment in Other Entities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Investments in other entities	$ 0.2	$ 0.4	$ 6.7
Carrying value of investments in other entities	$ 15.5	$ 14.2

Summary of Significant Accou_10

Summary of Significant Accounting Policies and New Accounting Guidance - Deferred Charges (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Unamortized deferred financing costs	$ 4,600,000	$ 5,900,000
Debt issuance costs	$ 6,400,000	$ 0	$ 0

Summary of Significant Accou_11

Summary of Significant Accounting Policies and New Accounting Guidance - Research and Development (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Development	$ 84,646	$ 74,860	$ 69,698

Summary of Significant Accou_12

Summary of Significant Accounting Policies and New Accounting Guidance - Compensation Programs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, tax windfalls	$ 0.2	$ 0.2	$ 1.8
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years

Summary of Significant Accou_13

Summary of Significant Accounting Policies and New Accounting Guidance - New Accounting Guidance (Details) - USD ($) $ in Thousands	Jan. 01, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Net catch up amortization		$ 18,093	$ 18,709	$ 13,509
Senior Convertible Long-Term Debt
Debt Instrument [Line Items]
Unamortized discount		$ 51,567	$ 65,393
Senior Convertible Long-Term Debt | Subsequent Event
Debt Instrument [Line Items]
Unamortized discount	$ 51,600
Senior Convertible Long-Term Debt | Accounting Standards Update 2020-06 | Subsequent Event
Debt Instrument [Line Items]
Long-term debt	50,200
Debt issuance costs equity component	1,900
Net catch up amortization	$ 500

Revenue Recognition - Schedule

Revenue Recognition - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenue	$ 90,790	$ 87,493	$ 104,498	$ 76,210	$ 102,161	$ 72,523	$ 75,609	$ 68,631	$ 358,991	$ 318,924	$ 307,404
Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Total revenue											307,404
Patent licensing royalties
Disaggregation of Revenue [Line Items]
Total revenue									346,630	307,431	302,060
Patent licensing royalties | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Total revenue											302,060
Patent licensing royalties | Current revenue
Disaggregation of Revenue [Line Items]
Total revenue									325,048	287,649
Patent licensing royalties | Current revenue | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Total revenue											275,731
Patent licensing royalties | Non-current revenue
Disaggregation of Revenue [Line Items]
Total revenue									21,582	19,782
Patent licensing royalties | Non-current revenue | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Total revenue											26,329
Technology solutions
Disaggregation of Revenue [Line Items]
Total revenue									11,761	10,518	4,594
Technology solutions | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Total revenue											4,594
Patent sales b
Disaggregation of Revenue [Line Items]
Total revenue									600	975	750
Patent sales b | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Total revenue											750
Variable patent royalty revenue
Disaggregation of Revenue [Line Items]
Total revenue									26,587	30,428
Variable patent royalty revenue | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Total revenue											36,384
Fixed-fee royalty revenue
Disaggregation of Revenue [Line Items]
Total revenue									$ 298,461	$ 257,221
Fixed-fee royalty revenue | Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Total revenue											$ 239,347

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue recognized that had been included in deferred revenue as of the beginning of the period	$ 145.8
Contract asset, current	9.7	$ 16.2
Non-current contract asset	$ 8.9	$ 10.2

Revenue Recognition - Schedul_2

Revenue Recognition - Schedule of Contracted Revenue (Details) $ in Thousands	Dec. 31, 2020USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 554,418
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	$ 273,815
Revenue remaining performance obligation expected timing of satisfaction period	1 year
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	$ 236,045
Revenue remaining performance obligation expected timing of satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 44,469
Revenue remaining performance obligation expected timing of satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 89
Revenue remaining performance obligation expected timing of satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 0
Revenue remaining performance obligation expected timing of satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 0
Revenue remaining performance obligation expected timing of satisfaction period

Geographic _ Customer Concent_3

Geographic / Customer Concentration - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Revenue from External Customer [Line Items]
Number of reportable segments | segment	1
United States | Long Lived Assets | Geographic Concentration Risk
Revenue from External Customer [Line Items]
Concentration risk	95.00%	95.00%	95.00%
United States | Property Plant and Equipment and Patents, net
Revenue from External Customer [Line Items]
Long-lived assets	$ 435	$ 446.6	$ 464.6
Canada and Europe
Revenue from External Customer [Line Items]
Long-lived assets	$ 23.1

Geographic _ Customer Concent_4

Geographic / Customer Concentration - Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from External Customer [Line Items]
Actual revenue	$ 90,790	$ 87,493	$ 104,498	$ 76,210	$ 102,161	$ 72,523	$ 75,609	$ 68,631	$ 358,991	$ 318,924	$ 307,404
United States
Revenue from External Customer [Line Items]
Actual revenue									128,238	139,162	119,159
South Korea
Revenue from External Customer [Line Items]
Actual revenue									111,634	113,189	112,291
China
Revenue from External Customer [Line Items]
Actual revenue									63,172	11,103	309
Japan
Revenue from External Customer [Line Items]
Actual revenue									23,694	35,614	29,525
Taiwan
Revenue from External Customer [Line Items]
Actual revenue									10,059	938	23,326
France
Revenue from External Customer [Line Items]
Actual revenue									7,773	5,895	277
Sweden
Revenue from External Customer [Line Items]
Actual revenue									7,573	6,934	6,933
Other Europe
Revenue from External Customer [Line Items]
Actual revenue									6,848	5,810	5,116
Other Asia
Revenue from External Customer [Line Items]
Actual revenue									0	279	468
Finland
Revenue from External Customer [Line Items]
Actual revenue									$ 0	$ 0	$ 10,000

Geographic _ Customer Concent_5

Geographic / Customer Concentration - Schedule of Revenue by Major Customers by Reporting Segments (Details) - Customer Concentration Risk - Revenue	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Apple
Revenue from External Customer [Line Items]
Accounts receivable percentage	31.00%	35.00%	36.00%
Samsung
Revenue from External Customer [Line Items]
Accounts receivable percentage	22.00%	25.00%	25.00%
Huawei
Revenue from External Customer [Line Items]
Accounts receivable percentage	15.00%	0.00%	0.00%
LG
Revenue from External Customer [Line Items]
Accounts receivable percentage	10.00%	10.00%	10.00%

Business Combinations and Oth_3

Business Combinations and Other Transactions (Details) videoCodingPatentAndApplication in Thousands, patentAndApplication in Thousands	Jul. 19, 2019USD ($)	May 31, 2019USD ($)	Jul. 30, 2018USD ($)	Dec. 20, 2016USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jul. 30, 2018patentAndApplication	Jul. 30, 2018videoCodingPatentAndApplication	Jul. 30, 2018staff	Jul. 30, 2018
Business Acquisition [Line Items]
Acquisition of business, net of cash acquired													$ 0	$ 0	$ 142,985,000
Goodwill					$ 22,421,000				$ 22,421,000				$ 22,421,000	$ 22,421,000	22,421,000
Assumed salary increase rate					0.44%				3.00%				0.44%	3.00%
Net operating expenses					$ 3,140,000	$ 15,430,000	$ 31,917,000	$ 4,681,000	$ 25,296,000	$ 3,774,000	$ 8,915,000	$ (150,000)	$ 55,168,000	$ 37,835,000	62,595,000
Cash and cash equivalents					3,100,000				9,500,000				3,100,000	9,500,000
Other commitment					25,000,000								25,000,000
Proceeds from sale of business	$ 10,000,000												910,000	10,000,000	0
Gain on disposition of business	$ 8,500,000													8,500,000
Technicolor Patent and R&I Acquisition
Business Acquisition [Line Items]
2020					229,000								229,000
2021					381,000								381,000
2022					547,000								547,000
2023					297,000								297,000
2024					540,000								540,000
Thereafter					$ 2,699,000								$ 2,699,000
Technicolor Patent Acquisition Long-Term Debt
Business Acquisition [Line Items]
Number of patents (more than)																18	3
Number of staff from acquisition | staff																		300
Payments to acquire business			$ 158,898,000
Cash acquired			15,913,000
Acquisition of business, net of cash acquired			143,000,000
Percentage of voting interests acquired		42.50%																	42.50%
Contingent consideration liability			18,616,000
Transaction-related receivable			(20,200,000)
Acquisition consideration			177,514,000
Fair value of consideration transferred			157,314,000
Other current assets			5,600,000
Other non-current assets			3,116,000
Current liabilities			(6,219,000)
Long-term debt			(17,717,000)
Other long-term liabilities			(3,767,000)
Total net tangible assets and liabilities			(3,074,000)
Goodwill			6,388,000
Total identified intangible assets			160,388,000
Gain on contingent consideration														20,500,000
Effective interest rate as of acquisition date					14.50%								14.50%
Interest debt expense													$ 3,100,000	2,700,000
Transaction and integration related costs													2,300,000	8,400,000	17,800,000
R&I Acquisition
Business Acquisition [Line Items]
Payments to acquire business		$ 0
Gain on asset acquisition														14,200,000
Gain on contingent consideration														20,500,000
Accumulated projected benefit obligation					$ 7,600,000				$ 6,200,000				7,600,000	6,200,000
Service cost													$ 600,000	$ 100,000	100,000
Hillcrest Products Business
Business Acquisition [Line Items]
Acquisition of business, net of cash acquired				$ 48,000,000
Cash acquired from acquisition				$ 400,000
Patents
Business Acquisition [Line Items]
Weighted average estimated useful life (years)													9 years 10 months 24 days	9 years 10 months 24 days
Patents | Technicolor Patent Acquisition Long-Term Debt
Business Acquisition [Line Items]
Patents			$ 154,000,000
Minimum | Patents | Technicolor Patent Acquisition Long-Term Debt
Business Acquisition [Line Items]
Weighted average estimated useful life (years)			9 years
Maximum | Patents | Technicolor Patent Acquisition Long-Term Debt
Business Acquisition [Line Items]
Weighted average estimated useful life (years)			10 years
Madison Arrangement | Technicolor Patent Acquisition Long-Term Debt
Business Acquisition [Line Items]
Net operating expenses													$ 8,400,000	$ 12,000,000	2,800,000
Madison Arrangement | Patent licensing royalties | Technicolor Patent Acquisition Long-Term Debt
Business Acquisition [Line Items]
Madison Arrangement revenue													5,500,000	13,500,000
Patent administration and licensing | Madison Arrangement | Technicolor Patent Acquisition Long-Term Debt
Business Acquisition [Line Items]
Net operating expenses													$ 2,500,000	$ 6,300,000	$ 0

Business Combinations and Oth_4

Business Combinations and Other Transactions - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Actual revenue	$ 90,790	$ 87,493	$ 104,498	$ 76,210	$ 102,161	$ 72,523	$ 75,609	$ 68,631	$ 358,991	$ 318,924	$ 307,404
Actual earnings	$ (1,350)	$ 23,784	$ 22,251	$ 116	$ 13,754	$ 2,234	$ 7,743	$ (2,803)	$ 44,801	$ 20,928	$ 65,031
Actual diluted earnings per share (in usd per share)	$ (0.04)	$ 0.76	$ 0.72	$ 0	$ 0.44	$ 0.07	$ 0.24	$ (0.09)	$ 1.44	$ 0.66	$ 1.84
Technicolor Patent Acquisition Long-Term Debt
Business Acquisition [Line Items]
Supplemental pro forma revenue											$ 314,096
Supplemental pro forma earnings											$ 52,754
Supplemental proforma earnings per share - diluted (in usd per share)											$ 1.49

Cash, Cash Equivalents, Restr_3

Cash, Cash Equivalents, Restricted Cash and Marketable Securities - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and restricted cash	$ 477,663	$ 757,098	$ 488,733	$ 433,014
Money market and demand accounts
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and restricted cash	397,522	757,098
Commercial paper
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and restricted cash	$ 80,141	$ 0

Cash, Cash Equivalents, Restr_4

Cash, Cash Equivalents, Restricted Cash and Marketable Securities - Reconciliation of Total Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 473,474	$ 745,491
Restricted cash included within prepaid and other current assets	3,108	10,526
Restricted cash included within other non-current assets	1,081	1,081
Total cash, cash equivalents and restricted cash	$ 477,663	$ 757,098	$ 488,733	$ 433,014

Cash, Cash Equivalents, Restr_5

Cash, Cash Equivalents, Restricted Cash and Marketable Securities - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Other than temporary impairment losses, investments	$ 0	$ 0	$ 0
Short-term investments with contractual maturities within one year	$ 517,400,000	$ 163,100,000
Minimum
Debt Securities, Available-for-sale [Line Items]
Contractual maturities	1 year
Maximum
Debt Securities, Available-for-sale [Line Items]
Contractual maturities	2 years

Cash, Cash Equivalents, Restr_6

Cash, Cash Equivalents, Restricted Cash and Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Restricted Cash and Cash Equivalents Items [Line Items]
Cost	$ 532,979	$ 178,729
Gross Unrealized Gains	363	475
Gross Unrealized Losses	(28)	0
Fair Value	533,314	179,204
Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Fair Value	80,141	0
Short-term investments
Restricted Cash and Cash Equivalents Items [Line Items]
Fair Value	453,173	179,204
Commercial paper
Restricted Cash and Cash Equivalents Items [Line Items]
Cost	285,244
Gross Unrealized Gains	5
Gross Unrealized Losses	(7)
Fair Value	285,242
U.S. government securities
Restricted Cash and Cash Equivalents Items [Line Items]
Cost	166,195	105,453
Gross Unrealized Gains	44	249
Gross Unrealized Losses	(16)	0
Fair Value	166,223	105,702
Corporate bonds, asset backed and other securities
Restricted Cash and Cash Equivalents Items [Line Items]
Cost	81,540	73,276
Gross Unrealized Gains	314	226
Gross Unrealized Losses	(5)	0
Fair Value	$ 81,849	$ 73,502

Concentration of Credit Risk _3

Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Impairment of long-term strategic investments	$ 5.6
Net loss on sale of investments	(5.6)	$ 2.6	$ 8.4
Lease asset impairment	1.1
Operating lease, property, plant and equipment, impairment loss	0.8
Operating lease, ROU asset, impairment loss	$ 0.3
Technicolor Patent Acquisition Long-Term Debt
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Contingent consideration liability		$ 20.5
Seven Largest Licensees | Accounts Receivable | Customer Concentration Risk
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Accounts receivable percentage	53.00%	73.00%
ZTE Corporation | Patents
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair value of patents	$ 19.3
Sony Corporation of America | Patents
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair value of patents		$ 14
LG | Patents
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair value of patents			$ 22.5

Concentration of Credit Risk _4

Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities - Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	$ 533,314	$ 179,204
Total	930,836	936,302
Money market and demand accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	397,522	757,098
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	285,242
U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	166,223	105,702
Corporate bonds, asset backed and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	81,849	73,502
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	397,522	757,098
Fair Value, Inputs, Level 1 | Money market and demand accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	397,522	757,098
Fair Value, Inputs, Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0
Fair Value, Inputs, Level 1 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	0	0
Fair Value, Inputs, Level 1 | Corporate bonds, asset backed and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	0	0
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	533,314	179,204
Fair Value, Inputs, Level 2 | Money market and demand accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Fair Value, Inputs, Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	285,242
Fair Value, Inputs, Level 2 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	166,223	105,702
Fair Value, Inputs, Level 2 | Corporate bonds, asset backed and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	81,849	73,502
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	0
Fair Value, Inputs, Level 3 | Money market and demand accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Fair Value, Inputs, Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0
Fair Value, Inputs, Level 3 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	0	0
Fair Value, Inputs, Level 3 | Corporate bonds, asset backed and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities	$ 0	$ 0

Concentration of Credit Risk _5

Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities - Fair Value of Long-Term Debt (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Technicolor Patent Acquisition Long-Term Debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Carrying Value	$ 24,171,000	$ 21,101,000
Fair Value	27,016,000	23,305,000
Senior Convertible Long-Term Debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Principal Amount	400,000,000	494,909,000
Carrying Value	343,821,000	423,657,000
Fair Value	$ 418,760,000	$ 492,969,000

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Computer equipment and software	$ 16,003	$ 11,320
Engineering and test equipment	1,183	1,333
Building and improvements	3,548	3,702
Leasehold improvements	11,076	11,315
Furniture and fixtures	1,051	1,121
Property and equipment, gross	32,861	28,791
Less: accumulated depreciation	(16,231)	(18,574)
Property and equipment, net	16,630	10,217
Depreciation expense	$ 5,300	$ 3,900	$ 3,700

Patents, Goodwill and Other I_3

Patents, Goodwill and Other Intangibles Assets - Patents (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Patents, net	$ 418,343	$ 436,339
Patents
Finite-Lived Intangible Assets [Line Items]
Weighted average estimated useful life (years)	9 years 10 months 24 days	9 years 10 months 24 days
Gross patents	$ 945,609	$ 905,814
Accumulated amortization	(527,266)	(469,475)
Patents, net	$ 418,343	$ 436,339

Patents, Goodwill and Other I_4

Patents, Goodwill and Other Intangibles Assets - Amortization Expense (Details) - Patents - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 74,900	$ 72,300	$ 61,800
2021	74,208
2022	69,897
2023	63,890
2024	55,110
2025	$ 51,068

Patents, Goodwill and Other I_5

Patents, Goodwill and Other Intangibles Assets - Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)segment
Goodwill and Intangible Assets Disclosure [Abstract]
Number of reportable segments | segment	1
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 22,421
Activity	0
Goodwill, ending balance	$ 22,421

Obligations - Schedules of Debt

Obligations - Schedules of Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2019	Jun. 03, 2019
Debt Instrument [Line Items]
Long-term debt, gross	$ 400,000
Current portion of long-term debt	0	$ 94,170
Long-term net carrying amount of Senior Convertible Notes	367,992	350,588
2021	0
2022	0
2023	0
2024	400,000
2025	0
Thereafter	0
Long-term debt, gross	400,000
Senior Convertible Long-Term Debt
Debt Instrument [Line Items]
Unamortized interest discount	(51,567)	(65,393)
Deferred financing costs	(4,612)	(5,859)
Total net carrying amount of Senior Convertible Notes	343,821	423,657
Current portion of long-term debt	0	94,170
Long-term net carrying amount of Senior Convertible Notes	343,821	329,487
Contractual coupon interest	8,237	7,424
Accretion of debt discount	13,826	15,065
Amortization of financing costs	1,246	1,475	$ 1,400
Total	23,309	23,964
Senior Convertible Long-Term Debt | Convertible Notes 2024
Debt Instrument [Line Items]
Long-term debt, gross	400,000	400,000
Deferred financing costs					$ (1,700)
Long-term debt, gross	400,000	400,000
Contractual coupon interest	8,000	4,600
Accretion of debt discount	13,157	7,322
Amortization of financing costs	1,176	654
Total	$ 22,333	12,576
Debt instrument interest rate stated percentage	2.00%				2.00%
Senior Convertible Long-Term Debt | Convertible Notes 2020
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	94,909
Long-term debt, gross	0	94,909
Contractual coupon interest	237	2,824	4,740
Accretion of debt discount	669	7,743	12,434
Amortization of financing costs	70	821	1,390
Total	$ 976	$ 11,388	$ 18,564
Debt instrument interest rate stated percentage	1.50%			1.50%

Obligations - Narrative (Detail

Obligations - Narrative (Details) $ / shares in Units, shares in Millions	Mar. 01, 2020USD ($)	Jun. 03, 2019USD ($)day$ / shares	May 31, 2019USD ($)$ / sharesshares	May 31, 2019USD ($)$ / sharesshares	Jun. 30, 2019USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jun. 30, 2020USD ($)	May 29, 2019USD ($)$ / shares
Debt Instrument [Line Items]
Class of warrant or right, exercise price of warrants or rights (in dollars per share) | $ / shares			$ 109.43	$ 109.43
Proceeds from issuance of warrants			$ 47,600,000			$ 0	$ 47,600,000	$ 0
Call spread transactions net			24,400,000	$ 24,400,000
Use of proceeds repayment of long term debt			$ 232,700,000	232,700,000
Repayments of long-term debt				$ 221,100,000		94,909,000	221,091,000	0
Use of proceeds repurchases of common stock										$ 19,600,000
Use of proceeds repurchases of common stock (in dollars per share) | $ / shares										$ 62.53
Debt issuance costs gross						6,400,000	0	0
Long-term debt, gross						400,000,000
Loss on extinguishment of debt						0	5,488,000	$ 0
Adjustments to additional paid in capital equity component of convertible debt, subsequent adjustments							10,649,000
Senior Convertible Long-Term Debt
Debt Instrument [Line Items]
Debt face amount						400,000,000	494,909,000
Debt issuance costs net						$ 4,612,000	5,859,000
Senior Convertible Long-Term Debt | Convertible Notes 2024
Debt Instrument [Line Items]
Debt face amount		$ 400,000,000
Debt instrument interest rate stated percentage		2.00%				2.00%
Proceeds from debt net of issuance costs		$ 391,600,000
Debt instrument convertible conversion ratio		12.3018
Debt conversion converted instrument amount		$ 1,000				$ 1,000
Debt instrument convertible conversion price (in dollars per share) | $ / shares		$ 81.29
Debt instrument convertible threshold percentage of stock price trigger		130.00%
Debt instrument convertible stock price trigger (in dollars per share) | $ / shares		$ 105.68
Debt instrument convertible threshold trading days | day		20
Debt instrument convertible threshold consecutive trading days | day		30
Debt instrument redemption price percentage		100.00%
Convertible note hedge (in shares) | shares			4.9	4.9
Convertible note hedge			$ 72,000,000	$ 72,000,000
Class of warrant or right number of securities called by warrants or rights (in shares) | shares			4.9	4.9
Debt instrument convertible carrying amount of liability component		$ 328,000,000
Debt instrument convertible carrying amount of equity component net of tax		$ 56,900,000
Debt instrument interest rate effective percentage		6.25%
Debt issuance costs gross		$ 8,400,000
Deferred finance costs own-share lending arrangement issuance costs gross		6,400,000
Debt issuance costs net		1,700,000
Proceeds from issuance of debt					$ 232,700,000
Debt instrument convertible carrying amount of equity component		$ 72,000,000
Long-term debt, gross						$ 400,000,000	400,000,000
Senior Convertible Long-Term Debt | Convertible Notes 2020
Debt Instrument [Line Items]
Debt instrument interest rate stated percentage					1.50%	1.50%
Repurchased debt									$ 221,100,000
Long-term debt, gross						$ 0	94,909,000
Repayments of debt	$ 94,900,000
Loss on extinguishment of debt							5,500,000
Adjustments to additional paid in capital equity component of convertible debt subsequent adjustments before tax							13,000,000
Adjustments to additional paid in capital equity component of convertible debt, subsequent adjustments							$ 10,600,000
Unamortized debt discount and issuance costs						$ 3,300,000

Commitments (Details)

Commitments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
2021	$ 16,113
2022	0
2023	0
2024	0
2025	0
Thereafter	$ 0

Litigation and Legal Proceedi_2

Litigation and Legal Proceedings (Details)	Aug. 05, 2020CNY (¥)	Jul. 29, 2020patent	Jul. 14, 2020patent	Aug. 28, 2019patent	Aug. 27, 2019patent
Xiaomi
Loss Contingencies [Line Items]
Court fine per day | ¥	¥ 1,000,000,000,000
Pending Litigation | U.K. Proceedings
Loss Contingencies [Line Items]
Number of patents alleged infringement					5
Pending Litigation | District Of Delaware Proceedings
Loss Contingencies [Line Items]
Number of patents alleged infringement			8	8
Number of patents alleged infringement dismissed			6
Pending Litigation | India Proceedings
Loss Contingencies [Line Items]
Number of patents alleged infringement		2
Pending Litigation | India Proceedings One
Loss Contingencies [Line Items]
Number of patents alleged infringement		5
Pending Litigation | India Proceedings Two
Loss Contingencies [Line Items]
Number of patents alleged infringement		3

Compensation Plans and Progra_3

Compensation Plans and Programs - Narrative (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Jun. 14, 2017shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs credited on unvested RSU awards as dividend equivalents (in shares) | shares	100,000
Number of RSUs granted under the equity plans (in shares) | shares	626,000
Weighted-average grant date fair values (in usd per share) | $ / shares	$ 46.18	$ 66.19	$ 73.75
Fair value of RSUs vested	$ 6,700	$ 12,700	$ 25,200
Vested weighted-average grant date fair value of awards (in usd per share) | $ / shares	$ 65.06	$ 58.84	$ 54.75
Number of minimum exercise price per share options	100.00%
Number of outstanding options (in shares) | shares	711,000	825,000
Weighted-average fair value granted (in usd per share) | $ / shares	$ 11.46	$ 13.68	$ 24.56
Outstanding options intrinsic value	$ 11,200
Number of outstanding exercisable options (in shares) | shares	300,000
Weighted-average exercise price (in usd per share) | $ / shares	$ 39.84
Outstanding options intrinsic value	$ 8,400
Weighted-average remaining contractual life (in years)	8 years 7 months 6 days
Exercised stock options intrinsic value	$ 1,100	$ 100	$ 5,600
Proceeds from exercise of stock options	$ 1,892	$ 2	6,723
Outstanding options (in shares) | shares	500,000	300,000
Proceeds from stock options if exercised	$ 16,900	$ 7,600
Award Date Between 1983 and 1986
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average remaining contractual life of outstanding options (in years)	8 years 3 months 18 days
Lower range limit exercise price (in usd per share) | $ / shares	$ 9
Upper range limit exercise price (in usd per share) | $ / shares	$ 11.63
Savings Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan cost	$ 1,100	1,100	1,300
Other Defined Contribution Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan cost	$ 200	$ 200	$ 200
2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares) | shares				2,400,000
Prior than 2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of outstanding options (in shares) | shares	100,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Multiple of target number of shares	0
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Multiple of target number of shares	2
Proceeds from exercise of stock options	$ 1,900
Time-based Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Time-based Restricted Stock Units (RSUs) | Minimum | 2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Time-based Restricted Stock Units (RSUs) | Maximum | 2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance Based Restricted Stock Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance Based Restricted Stock Units | Minimum | 2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance Based Restricted Stock Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Performance Based Restricted Stock Units | Maximum | 2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Restricted Stock Units RSU and or Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to share-based awards at current performance accrual rates	$ 8,000
Restricted Stock Units RSU and or Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Restricted Stock Units RSU and or Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of RSUs granted under the equity plans (in shares) | shares	400,000	300,000	300,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Unrecognized compensation cost related to share-based awards at current performance accrual rates	$ 500
Expected term (in years)	6 years 6 months	4 years 6 months	7 years 8 months 12 days
Stock Options | Award Date Between 1983 and 1986
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	50 years
Stock Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Multiple of target number of shares		0
Exercisable period	7 years
Stock Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Multiple of target number of shares		2
Exercisable period	10 years

Compensation Plans and Progra_4

Compensation Plans and Programs - Schedule of RSU Award Vesting (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Unvested RSUs
Beginning balance (in shares)	955
RSUs granted (in shares)	626
RSUs forfeited (in shares)	(213)
RSUs vested (in shares)	(103)
Ending balance (in shares)	1,265	955
Weighted Average Per Share Grant Date Fair Value
Beginning balance (in usd per share)	$ 62.40
RSUs granted (in usd per share)	46.18	$ 66.19	$ 73.75
RSUs forfeited (in usd per share)	66.11
RSUs vested (in usd per share)	65.06	58.84	$ 54.75
Ending balance (in usd per share)	$ 53.53	$ 62.40

Compensation Plans and Progra_5

Compensation Plans and Programs - Schedule of Weighted Average Option Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 6 months	4 years 6 months	7 years 8 months 12 days
Expected volatility	37.50%	25.80%	30.10%
Risk-free interest rate	0.60%	2.40%	3.00%
Dividend yield	3.10%	2.00%	1.80%

Compensation Plans and Progra_6

Compensation Plans and Programs - Schedule of Stock Option Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Outstanding Options
Beginning balance (in shares) | shares	825
Granted (in shares) | shares	307
Forfeited (in shares) | shares	(348)
Exercised (in shares) | shares	(73)
Ending balance (in shares) | shares	711
Weighted Average Exercise Price
Beginning balance (in usd per share) | $ / shares	$ 58.83
Granted (in usd per share) | $ / shares	44.63
Forfeited (in usd per share) | $ / shares	65.74
Exercised (in usd per share) | $ / shares	43.83
Ending balance (in usd per share) | $ / shares	$ 50.85

TAXES (Details)

TAXES (Details) - USD ($) $ in Thousands	12 Months Ended			84 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jul. 24, 2018
Income Tax Contingency [Line Items]
Federal	$ (26,092)	$ (11,436)	$ (3,148)
State	89	207	239
Foreign source withholding tax	26,229	19,850	25,187
Current Income Tax Expense (Benefit)	226	8,621	22,278
Federal	(28,692)	(21,735)	(63,030)
State	119	2,457	(1,554)
Foreign source withholding tax	21,699	21,648	14,889
Deferred income taxes	(6,874)	2,370	(49,695)
Total	$ (6,648)	$ 10,991	$ (27,417)
Net operating losses					$ 140,940	$ 131,501
Deferred revenue, net					26,213	33,131
Tax credit carryforward					27,813	11,744
Stock compensation					4,082	3,307
Patent amortization					22,530	18,522
Depreciation					(1,233)	443
Goodwill					(2,211)	(1,933)
Other-than-temporary impairment					441	1,138
Other					(673)	785
Other employee benefits					5,857	7,520
Right of use asset					(4,684)	(4,913)
Lease liability					5,382	5,760
Gross deferred tax asset					224,457	207,005
Less: valuation allowance					(144,367)	(133,797)
Net deferred tax asset					80,090	73,208
Foreign tax withholding					400	100
Tax at U.S. statutory rate	21.00%	21.00%	21.00%
State tax provision	0.60%	10.20%	(8.90%)
Effects of rates different than statutory	(2.00%)	(2.80%)	(1.40%)
Change in valuation allowance	28.50%	23.30%	8.50%
Research and development tax credits	(1.60%)	(4.50%)	(4.30%)
Uncertain tax positions	(2.70%)	(0.80%)	3.90%
Permanent differences	(1.20%)	2.30%	4.90%
Stock compensation	1.10%	(0.60%)	(5.00%)
Foreign derived intangible income deduction	0	0	(0.563)
Amended return benefit	(65.00%)	(8.40%)	(49.40%)
Other	0.10%	2.70%	1.50%
Total tax provision (benefit)	(21.20%)	42.40%	(85.50%)
Net discrete benefit	$ 20,900
Unrecognized tax benefits that would impact effective tax rate	3,803	$ 4,352	$ 4,352	$ 3,803	3,803	4,456
Additions related to additional deduction		300
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance	4,456	4,352	3,252
Additions, tax positions related to current year	1,062	402	73
Reductions, tax positions related to current year	0	0	0
Additions, tax positions related to prior years	37	34	1,054
Reductions, tax positions related to prior years	0	0	(27)
Settlements, tax positions related to prior years	0	0	0
Lapses in statues of limitations	(1,752)	(332)	0
Unrecognized tax benefits, ending balance	3,803	4,456	4,352	3,803
Income tax penalties and accrued interest					100	$ 100
Income taxes paid, including foreign withholding taxes	26,233	24,229	33,904
Income tax benefit	6,648	(10,991)	27,417
State
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
State net operating losses					$ 1,600,000
Foreign
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Income taxes paid, including foreign withholding taxes	$ 25,900	$ 18,800	25,100
Foreign | Foreign Governments With U.S. Tax Treaties
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Income taxes paid, including foreign withholding taxes				$ 134,300
United States-Republic Of Korea Income Tax Convention
Income Tax Contingency [Line Items]
Total			14,700
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Income tax refund							$ 2,200	$ 97,400
Income tax benefit			$ (14,700)

Net Income Per Share - Numerato

Net Income Per Share - Numerator and Denominator of Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net income applicable to common shareholders	$ (1,350)	$ 23,784	$ 22,251	$ 116	$ 13,754	$ 2,234	$ 7,743	$ (2,803)	$ 44,801	$ 20,928	$ 65,031
Denominator:
Weighted-average shares outstanding: basic (in shares)									30,776	31,546	34,491
Dilutive effect of stock options, RSUs, convertible securities (in shares)									282	239	816
Weighted-average shares outstanding: diluted (in shares)									31,058	31,785	35,307
Earnings Per Share:
Net income per common share: basic (in USD per share)	$ (0.04)	$ 0.77	$ 0.72	$ 0	$ 0.44	$ 0.07	$ 0.25	$ (0.09)	$ 1.46	$ 0.66	$ 1.89
Dilutive effect of stock options, RSUs, and convertible securities (in USD per share)									(0.02)	0	(0.05)
Net income per common share: diluted (in USD per share)	$ (0.04)	$ 0.76	$ 0.72	$ 0	$ 0.44	$ 0.07	$ 0.24	$ (0.09)	$ 1.44	$ 0.66	$ 1.84

Net Income Per Share - Antidilu

Net Income Per Share - Antidilutive Securities Excluded from Earnings Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	10,951	11,118	4,429
Restricted stock units and stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	146	128	25
Convertible securities
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	5,143	5,495	0
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	5,662	5,495	4,404

Equity Transactions - Narrative

Equity Transactions - Narrative (Details) - USD ($)	1 Months Ended			12 Months Ended
	May 31, 2019	Sep. 30, 2017	Jun. 30, 2015	Dec. 31, 2018	Dec. 31, 2020	Jun. 30, 2014
Equity [Abstract]
Share repurchase program authorized amount					$ 700,000,000	$ 300,000,000
Increase in share repurchase program authorized amount	$ 100,000,000	$ 100,000,000	$ 100,000,000	$ 100,000,000
Remaining authorized repurchase amount					$ 71,500,000

Equity Transactions - Share Rep

Equity Transactions - Share Repurchases (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended							84 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2020
Accelerated Share Repurchases [Line Items]
Stock repurchased during period (in shares)								11,247
Stock repurchased during period								$ 628,536
2014 Repurchase Program
Accelerated Share Repurchases [Line Items]
Stock repurchased during period (in shares)	6	2,962	1,478	107	1,304	1,836	3,554
Stock repurchased during period	$ 349	$ 196,269	$ 110,505	$ 7,693	$ 64,685	$ 96,410	$ 152,625

Equity Transactions - Dividends

Equity Transactions - Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Cash dividends declared per common share (in usd per share)	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35					$ 1.40	$ 1.40	$ 1.40
Cash Dividend		$ 10,786	$ 10,782	$ 10,781	$ 10,762	$ 10,746	$ 10,897	$ 10,895	$ 11,180	$ 21,543	$ 22,075	$ 32,325	$ 32,972	$ 43,111	$ 43,718

Leases - Operating Lease Right-

Leases - Operating Lease Right-of-use Assets and Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Operating lease right-of-use assets, net	$ 23,273	$ 24,513
Liabilities
Operating lease liabilities - Current	3,170	3,437
Operating lease liabilities - Noncurrent	23,043	24,142
Total Lease Liabilities	$ 26,213	$ 27,579
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherAccruedLiabilitiesCurrent	us-gaap:OtherAccruedLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Prepaid and other current assets
Assets
Operating lease right-of-use assets, net	$ 817	$ 0
Other Non-current Assets
Assets
Operating lease right-of-use assets, net	$ 22,456	$ 24,513

Leases - Schedule of Lease Cost

Leases - Schedule of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 5,442	$ 4,776
Short-term lease cost	726	925
Variable lease cost	$ 1,764	$ 1,502

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Measurement of operating lease liabilities	$ 4.9	$ 5.2
Operating lease right-of-use assets	$ 2.5	$ 14.4
Weighted average remaining operating lease term	6 years 7 months 6 days
Operating lease liabilities percentage	5.60%

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 3,741
2022	5,463
2023	4,727
2024	4,508
2025	3,585
Thereafter	8,795
Total lease payments	30,819
Less: Imputed interest	(5,423)
Present value of lease liabilities	$ 25,396

Other Income (Expense), Net - O

Other Income (Expense), Net - Other Income (Expense), Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Expenses [Abstract]
Interest and investment income	$ 5,661	$ 13,458	$ 14,590
Gain on asset acquisition and sale of business	0	22,690	0
Loss on extinguishment of long-term debt	0	(5,488)	0
Other income (expense), net	11,263	(1,598)	(9,171)
Other income, net	$ 16,924	$ 29,062	$ 5,419

Other Income (Expense), Net - N

Other Income (Expense), Net - Narrative (Details) - USD ($) $ in Thousands	Jul. 19, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Gain on disposition of business	$ 8,500		$ 8,500
Loss on extinguishment of debt		$ 0	5,488	$ 0
Gain (loss) on sale of investments		$ 5,600	(2,600)	$ (8,400)
R&I Acquisition
Business Acquisition [Line Items]
Gain on asset acquisition			$ 14,200

Selected Quarterly Results (u_3

Selected Quarterly Results (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 90,790	$ 87,493	$ 104,498	$ 76,210	$ 102,161	$ 72,523	$ 75,609	$ 68,631	$ 358,991	$ 318,924	$ 307,404
Income (loss) from operations	3,140	15,430	31,917	4,681	25,296	3,774	8,915	(150)	55,168	37,835	62,595
Net income applicable to InterDigital, Inc.'s common shareholders	$ (1,350)	$ 23,784	$ 22,251	$ 116	$ 13,754	$ 2,234	$ 7,743	$ (2,803)	$ 44,801	$ 20,928	$ 65,031
NET INCOME PER COMMON SHARE - BASIC (in usd per share)	$ (0.04)	$ 0.77	$ 0.72	$ 0	$ 0.44	$ 0.07	$ 0.25	$ (0.09)	$ 1.46	$ 0.66	$ 1.89
Net income per share — diluted (in usd per share)	$ (0.04)	$ 0.76	$ 0.72	$ 0	$ 0.44	$ 0.07	$ 0.24	$ (0.09)	$ 1.44	$ 0.66	$ 1.84
Net discrete tax benefit		$ 18,500
Patent licensing royalties
Effect of Fourth Quarter Events [Line Items]
Revenues									$ 346,630	$ 307,431	$ 302,060
Patent licensing royalties | Non-current revenue
Effect of Fourth Quarter Events [Line Items]
Revenues									$ 21,582	$ 19,782

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)variable_interest_entity	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Variable Interest Entity [Line Items]
Assets	$ 1,616,275	$ 1,612,082
Liabilities	819,709	825,801
Cash and cash equivalents	473,474	745,491
Patents, net	418,343	436,339
Other non-current assets	74,043	76,026
Accounts receivable, less allowances of $0 and $537	16,008	28,272
Noncontrolling interests	(6,860)	(5,977)	$ (5,556)
Patent administration and licensing	170,178	154,940	124,081
Chordant
Variable Interest Entity [Line Items]
Noncontrolling interests	1,100	1,500
Convida
Variable Interest Entity [Line Items]
Noncontrolling interests	$ 5,700	4,500	$ 5,600
Primary Beneficiary
Variable Interest Entity [Line Items]
Number of variable interest entities | variable_interest_entity	3
Assets	$ 62,000	60,600
Liabilities	5,800	5,400
Cash and cash equivalents	24,500	18,500
Accounts receivable and prepaid assets	2,300
Patents, net	35,200	39,300
Other non-current assets	0	1,300
Accounts receivable, less allowances of $0 and $537		$ 1,700
Primary Beneficiary | Trust
Variable Interest Entity [Line Items]
Patent administration and licensing	$ 2,400

Prepaid and Other Current Ass_3

Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Tax receivables	$ 69,592	$ 38,021
Prepaid assets	10,899	16,814
Operating lease receivable	817	0
Other current assets	2,916	8,530
Total Prepaid and other current assets	$ 84,224	$ 63,365

Valuation and Qualifying Acco_2

Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance for Deferred Tax Assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Period	$ 133,797	$ 125,158	$ 123,916
Increase/ (Decrease)	10,570	8,639	1,568
Reversal of Valuation Allowance	0	0	(326)
Balance End of Period	144,367	133,797	125,158
Uncollectable Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Period	537	693	456
Increase/ (Decrease)	(537)	(156)	237
Reversal of Valuation Allowance	0	0	0
Balance End of Period	$ 0	$ 537	$ 693