InterDigital (IDCC) 10-K 18 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 16, 2016	Jun. 30, 2015
Entity Information [Line Items]
Entity Registrant Name	INTERDIGITAL, INC.
Entity Central Index Key	1,405,495
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		34,996,183
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 2,026,553,956

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
CURRENT ASSETS:
Cash and cash equivalents	$ 510,207	$ 428,567
Short-term Investments	423,501	275,361
Accounts receivable, less allowances of $1,750	53,868	51,702
Prepaid and other current assets	23,391	32,227
Total current assets	1,010,967	787,857
NON-CURRENT ASSETS:
PROPERTY AND EQUIPMENT, NET	12,148	12,546
PATENTS, NET	277,579	265,540
DEFERRED TAX ASSETS	160,572	125,802
OTHER NON-CURRENT ASSETS, NET	13,219	1,217
Total non-current assets	463,518	405,105
TOTAL ASSETS	1,474,485	1,192,962
CURRENT LIABILITIES:
Long-term Debt, Current Maturities	227,174	0
Accounts payable	19,002	34,654
Accrued compensation and related expenses	26,013	27,089
Deferred revenue	106,229	124,695
Taxes Payable	1,405	0
Dividends Payable	7,068	7,456
Other accrued expenses	13,082	11,275
Total current liabilities	399,973	205,169
LONG-TERM DEBT	259,595	216,206
NON-CURRENT LIABILITIES
LONG-TERM DEFERRED REVENUE	289,039	293,342
OTHER LONG-TERM LIABILITIES	3,983	2,568
TOTAL LIABILITIES	$ 952,590	$ 717,285
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY:
Preferred Stock, $0.10 par value, 0 and 14,399 shares authorized 0 shares issued and outstanding	$ 0	$ 0
Common Stock, $0.01 par value, 100,000 shares authorized, 68,968 and 68,602 shares issued and 45,398 and 45,032 shares outstanding	701	698
Additional paid-in capital	663,073	614,162
Retained earnings	847,033	757,050
Accumulated other comprehensive income	(178)	118
Stockholders' Equity before Treasury Stock	1,510,629	1,372,028
Treasury stock, 23,570 shares of common held at cost	1,000,110	903,700
Total shareholders’ equity	510,519	468,328
Noncontrolling Interest in Variable Interest Entity	11,376	7,349
Total equity	521,895	475,677
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 1,474,485	$ 1,192,962

Balance Sheet Parenthetical (Pa

Balance Sheet Parenthetical (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts		$ 1,654
Common stock, par value		$ 0.01
Common stock, shares authorized		100,000,000
Common stock, shares issued - DEI	70,130,000	69,800,000
Common stock, shares outstanding	35,414,000	36,920,000
Preferred stock, par value		$ 0.10
Preferred stock, shares authorized		14,399,000
Preferred stock, shares issued		0
Preferred stock, shares outstanding		0
Treasury stock, 32,880 and 29,326 shares of common held at cost	34,716,000	32,880,000

Consolidated Statements of Inco

Consolidated Statements of Income Statement - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
REVENUES
Technology Services Revenue	$ 8,947	$ 10,433	$ 61,187
Revenues	441,435	415,821	325,361
REVENUES	432,488	403,389	264,174
Sales Revenue, Goods, Net	0	1,999	0
OPERATING EXPENSES:
Patent administration and licensing	120,401	133,808	143,037
Development Expense	72,702	75,300	64,729
Selling, general and administrative	39,783	37,753	31,295
Repositioning	0	0	1,544
Total Operating Expenses	232,886	246,861	240,605
Income from operations	208,549	168,960	84,756
OTHER INCOME:
Other Nonoperating Income (Expense)	(27,534)	(15,432)	(23,237)
Income before income taxes	181,015	153,528	61,519
INCOME TAX PROVISION	(64,621)	(52,108)	(25,836)
NET INCOME	116,394	101,420	35,683
Net Income (Loss) Attributable to Noncontrolling Interest	(2,831)	(2,922)	(2,482)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 119,225	$ 104,342	$ 38,165
NET INCOME PER COMMON SHARE — BASIC	$ 3.31	$ 2.65	$ 0.93
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING — BASIC	36,048	39,420	41,115
NET INCOME PER COMMON SHARE — DILUTED	$ 3.27	$ 2.62	$ 0.92
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING — DILUTED	36,463	39,879	41,424
Common Stock, Dividends, Per Share, Declared	$ 0.80	$ 0.70	$ 0.40

Consolidated Statements of Cash

Consolidated Statements of Cash Flows Statement - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Accrued Capitalized Patent Costs										$ (20,546)	$ (452)
NET INCOME	$ 33,038	$ 24,520	$ 32,602	$ 29,065	$ 13,790	$ 13,512	$ 78,901	$ (1,861)	$ 116,394	101,420	35,683
Multiple Element Arrangements [Abstract] [Abstract]
Net cash provided by operating activities									114,499	242,013	218,175
Depreciation, Depletion and Amortization									47,793	42,246	33,385
Amortization of Financing Costs and Discounts									20,869	10,325	9,726
Recognition of Deferred Revenue									(163,354)	(163,139)	(174,014)
Increase in deferred revenue									113,962	272,885	209,930
Increase (Decrease) in Deferred Income Taxes									(34,770)	(62,979)	4,861
Share-based Compensation									15,139	18,494	15,940
Restructuring Charges									0	0	1,544
Other than Temporary Impairment Losses, Investments									198	559	21,720
Other Noncash Expense									0	700	0
Other Operating Activities, Cash Flow Statement									238	572	424
Decrease (increase) in assets:
Increase (Decrease) in Receivables									(2,166)	26,128	77,044
Deferred charges and other current assets									8,489	6,156	(9,753)
Increase (decrease) in liabilities:
Increase (Decrease) in Accounts Payable									2,503	(10,396)	14,655
Accrued taxes payable									1,501	(5,635)	3,096
Other accrued expenses									(12,297)	5,853	(24,522)
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchases of short-term investments									643,087	438,157	417,728
Sales of short-term investments									495,201	363,175	443,074
Purchases of property and equipment									3,700	7,095	4,591
Capitalized patent costs									29,766	31,932	34,057
Payments to Acquire Intangible Assets									20,000	26,300	25,013
Payments for (Proceeds from) Long-term Investments									(12,623)	0	0
Net cash used in investing activities									(213,975)	(140,309)	(38,315)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Net proceeds from exercise of stock options									46	402	1,032
Proceeds from Convertible Debt									316,000	0	0
Proceeds from (Payments for) Other Financing Activities									4,500	0	0
Proceeds from Hedge, Financing Activities									(59,376)	0	0
Dividends paid									28,937	23,729	12,354
Proceeds from Issuance of Warrants									42,881	0	0
Payments of debt issuance costs									(9,403)	0	0
Proceeds from Noncontrolling Interests									9,358	5,101	7,652
Excess Tax Benefit from Share-based Compensation, Financing Activities									2,457	0	815
Payments for Repurchase of Common Stock									96,410	152,625	29,134
Net Cash Provided by (Used in) Financing Activities									181,116	(170,851)	(31,989)
Cash and Cash Equivalents, Period Increase (Decrease)									81,640	(69,147)	147,871
CASH AND CASH EQUIVALENTS, END OF PERIOD	510,207				428,567				510,207	428,567	497,714	$ 349,843
Interest Paid									7,988	5,750	5,750
Income taxes paid, including foreign witholding taxes									85,780	114,876	24,961
Dividends Payable	$ 7,068				$ 7,456				7,068	7,456	4,031
Other Significant Noncash Transaction, Value of Consideration Received									24,123	19,250	0
Excess Tax Benefit from Share-based Compensation, Operating Activities									0	$ 1,176	$ 0
Patents [Member]
Accrued Capitalized Patent Costs									$ (18,155)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ (296)	$ 12	$ (878)
Other-than-temporary impairment losses related to available for sale securities, net of income taxes of $0, $65, $0	0	(120)	0
Net Income (Loss) Attributable to Parent	116,394	101,420	35,683
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	119,225	104,342	38,165
Total Comprehensive Income	116,098	101,552	34,805
Net Income (Loss) Attributable to Noncontrolling Interest	(2,831)	(2,922)	(2,482)
Total comprehensive income attributable to InterDigital, Inc.	$ 118,929	$ 104,474	$ 37,287

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Noncontrolling Interest in Variable Interest Entity							$ 0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 38,165
Beginning balance at Dec. 31, 2012	518,705	$ 695	$ 579,852	$ 659,235	$ 864	$ (721,941)
Beginning balance in Shares at Dec. 31, 2012		69,459
Beginning balance Treasury Stock, Shares at Dec. 31, 2012						28,409
NET INCOME	35,683			38,165
Other Comprehensive Income (Loss), Net of Tax	(878)
Proceeds from Noncontrolling Interests	7,652						7,652
Net Income (Loss) Attributable to Noncontrolling Interest	(2,482)						(2,482)
Other-than-temporary impairment losses related to available for sale securities, net of income taxes of $65, $0, $0	0
Total Comprehensive Income	34,805
Dividends	(16,385)		(297)	16,682
Exercise of Common Stock options, shares		49
Exercise of Common Stock options	(1,032)		(1,032)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		106
Issuance of Restricted Common Stock, net value	2,458	$ (1)	(2,459)
Tax benefit from exercise of stock options	815		815
Amortization of unearned compensation			15,940
Treasury Stock, Shares, Acquired						917
Deferred financing costs allocated to equity			2,848
Treasury Stock, Value, Acquired, Cost Method						$ (29,134)
Ending balance at Dec. 31, 2013	533,820	$ 696	598,325	680,718	(14)	$ (751,075)
Ending balance in Shares at Dec. 31, 2013		69,614
Ending balance Treasury Stock, Shares at Dec. 31, 2013						29,326
Noncontrolling Interest in Variable Interest Entity							5,170
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	104,342
NET INCOME	101,420
Other Comprehensive Income (Loss), Net of Tax	132
Proceeds from Noncontrolling Interests	5,101						5,101
Net Income (Loss) Attributable to Noncontrolling Interest	(2,922)						(2,922)
Other-than-temporary impairment losses related to available for sale securities, net of income taxes of $65, $0, $0	120
Total Comprehensive Income	101,552
Dividends	(27,153)		(857)	28,010
Exercise of Common Stock options, shares		21
Exercise of Common Stock options	(402)		(402)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		165
Issuance of Restricted Common Stock, net value	2,738	$ (2)	(2,740)
Tax benefit from exercise of stock options	(1,176)		(1,176)
Amortization of unearned compensation			18,494
Treasury Stock, Shares, Acquired						3,554
Treasury Stock, Value, Acquired, Cost Method						$ (152,625)
Ending balance at Dec. 31, 2014	$ 468,328	$ 698	614,162	757,050	118	$ (903,700)
Ending balance in Shares at Dec. 31, 2014	69,800	69,800
Ending balance Treasury Stock, Shares at Dec. 31, 2014	32,880					32,880
Noncontrolling Interest in Variable Interest Entity	$ 7,349						7,349
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	475,677
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	119,225
NET INCOME	116,394
Other Comprehensive Income (Loss), Net of Tax	(296)
Proceeds from Noncontrolling Interests	9,358						9,358
Distribution preference	(2,500)
Net Income (Loss) Attributable to Noncontrolling Interest	(2,831)						(2,831)
Other-than-temporary impairment losses related to available for sale securities, net of income taxes of $65, $0, $0	0
Total Comprehensive Income	116,098
Dividends	$ 28,548		(694)	29,242
Exercise of Common Stock options, shares	5	5
Exercise of Common Stock options	$ (46)		(46)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		325
Issuance of Restricted Common Stock, net value	(9,846)	$ (3)	(9,849)
Tax benefit from exercise of stock options			2,457
Amortization of unearned compensation			15,139
Payments of Financing Costs						$ (2,430)
Treasury Stock, Shares, Acquired						1,836
Convertible note hedge transactions, net of tax			(38,594)
Issuance of Warrants during period	42,881
Treasury Stock, Value, Acquired, Cost Method						$ (96,410)
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt			38,567
Ending balance at Dec. 31, 2015	$ 510,519	$ 701	$ 663,073	$ 847,033	$ (178)	$ (1,000,110)
Ending balance in Shares at Dec. 31, 2015	70,130	70,130
Ending balance Treasury Stock, Shares at Dec. 31, 2015	34,716					34,716
Noncontrolling Interest in Variable Interest Entity	$ 11,376						$ 11,376
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 521,895

Background

Background	12 Months Ended
	Dec. 31, 2015
BACKGROUND [Abstract]
Business Description and Basis of Presentation [Text Block]	1. BACKGROUND InterDigital designs and develops advanced technologies that enable and enhance wireless communications and capabilities. Since our founding in 1972, we have designed and developed a wide range of innovations that are used in digital cellular and wireless products and networks, including 2G, 3G, 4G and IEEE 802-related products and networks. We are a leading contributor of intellectual property to the wireless communications industry.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies [Text Block]	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation The accompanying consolidated financial statements include all of our accounts and all entities which we have a controlling interest, which 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. Cash and Cash Equivalents We classify all highly liquid investment securities with original maturities of three months or less at date of purchase as cash equivalents. 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. Cash and cash equivalents at December 31, 2015 and 2014 consisted of the following (in thousands): December 31, 2015 2014 Money market and demand accounts $ 333,671 $ 307,995 Commercial paper 176,536 120,572 $ 510,207 $ 428,567 Short-Term Investments At December 31, 2015 and 2014 , all 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 3 years, and we have both the ability and intent to hold the investments until maturity. During 2015 and 2014 , we recorded other-than-temporary impairments of approximately $0.2 million and $0.6 million , respectively. These amounts were included within the realized losses for these periods shown in the table below. Net unrealized gain on short-term investments was $0.1 million at December 31, 2014. Net unrealized loss on short-term investments was $0.3 million and $0.9 million at December 31, 2015 and 2013, respectively. Realized gains and losses for 2015 , 2014 and 2013 were as follows (in thousands): Year Gains Losses Net 2015 $ — $ (309 ) $ (309 ) 2014 $ 48 $ (681 ) $ (633 ) 2013 $ 166 $ (678 ) $ (512 ) Short-term investments as of December 31, 2015 and 2014 consisted of the following (in thousands): December 31, 2015 2014 Commercial paper $ 200,811 $ 86,877 U.S. government agency instruments 183,950 151,618 Corporate bonds and asset backed securities 38,740 36,866 $ 423,501 $ 275,361 At December 31, 2015 and 2014 , $373.7 million and $151.4 million , respectively, of our short-term investments had contractual maturities within one year. The remaining portions of our short-term investments had contractual maturities primarily within two to five years Concentration of Credit Risk and Fair Value of Financial Instruments Financial instruments that potentially subject us to concentration of credit risk consist primarily of cash equivalents, short-term investments and accounts receivable. We place our cash equivalents and short-term investments only in highly rated financial instruments and in United States government instruments. Our accounts receivable are derived principally from patent license and technology solutions agreements. At December 31, 2015 , four licensees comprised 97% of our net accounts receivable balance. At December 31, 2014 , three licensees represented 94% of our net 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 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. Our financial assets are included within short-term investments on our consolidated balance sheets, unless otherwise indicated. Our financial assets that are accounted for at fair value on a recurring basis are presented in the tables below as of December 31, 2015 and December 31, 2014 (in thousands): Fair Value as of December 31, 2015 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 333,671 $ — $ — $ 333,671 Commercial paper (b) — 377,347 — 377,347 U.S. government securities — 183,950 — 183,950 Corporate bonds, asset backed and other securities 183 38,557 — 38,740 $ 333,854 $ 599,854 $ — $ 933,708 _______________ (a) Included within cash and cash equivalents. (b) Includes $176.5 million of commercial paper that is included within cash and cash equivalents. Fair Value as of December 31, 2014 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 307,995 $ — $ — $ 307,995 Commercial paper (b) — 207,449 — 207,449 U.S. government securities — 151,618 — 151,618 Corporate bonds and asset backed securities 671 36,195 — 36,866 $ 308,666 $ 395,262 $ — $ 703,928 _______________ (a) Included within cash and cash equivalents. (b) Includes $120.6 million of commercial paper that is included within cash and cash equivalents. The principal amount, carrying value and related estimated fair value of the Company's long-term debt reported in the Condensed Consolidated Balance Sheets as of December 31, 2015 and December 31, 2014 are as follows (in thousands): December 31, 2015 December 31, 2014 Principal Amount Carrying Value Fair Value Principal Amount Carrying Fair Value Total Long-Term Debt $ 546,000 $ 486,769 $ 533,203 $ 230,000 $ 216,206 $ 255,300 The aggregate fair value of the principal amount of the long-term debt (Level 2 Notes as defined in Note 6 " Obligations ") was calculated using inputs such as actual trade data, benchmark yields, broker/dealer quotes and other similar data, which were obtained from independent pricing vendors, quoted market prices or other sources. As discussed in Note 3, " Significant Events ," we acquired patents as part of the multiple-element arrangements entered into in 2015. We have recorded these patents based on their total estimated fair value of $24.1 million and will amortize them over their estimated useful lives. We estimated the fair value of the patents in each transaction by a combination of an analysis of comparable market transactions (the market approach) and discounted cash flow analysis (the income 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. 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 to five years. Leasehold improvements are amortized over the lesser of their estimated useful lives or their respective lease terms, which are generally five to ten years. Buildings are being depreciated over twenty-five years. Expenditures for major improvements and betterments are capitalized, while minor repairs and maintenance are charged to expense as incurred. Leases meeting certain capital lease criteria are capitalized and the net present value of the related lease payments is recorded as a liability. Amortization of capital leased assets is recorded using the straight-line method over the lesser of the estimated useful lives or the lease terms. Upon the retirement or disposition of property, plant and equipment, the related cost and accumulated depreciation or amortization are removed, and a gain or loss is recorded. 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. 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 Expense (Net) line of our Consolidated Statements of Income. 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 account for our investments using either the cost or equity method of accounting. Under the cost method, we do not adjust our investment balance when the investee reports profit or loss but monitor the investment for an other-than-temporary decline in value. On a quarterly basis, we monitor our investment’s financial position and performance to assess whether there are any triggering events or indicators present that would be indicative of an other-than-temporary impairment of our investment. When assessing whether an other-than-temporary decline in value has occurred, we consider such factors as the valuation placed on the investee in subsequent rounds of financing, the performance of the investee relative to its own performance targets and business plan, and the investee’s revenue and cost trends, liquidity and cash position, including its cash burn rate, and updated forecasts. Under the equity method of accounting, 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 costs of our investments are included within Other Non-Current Assets on our Consolidated Balance Sheets. During 2015, we made investments in two separate entities for a total of $12.6 million . Due to the fact that we do not have significant influence over either organization, we are accounting for these investments using the cost method of accounting. The carrying value of these investments as of December 31, 2015 was $12.6 million . 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 ten 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 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 thus far has been 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. Patents consisted of the following (in thousands, except for useful life data): December 31, 2015 2014 Weighted average estimated useful life (years) 9.9 10.0 Gross patents $ 511,503 $ 455,447 Accumulated amortization (233,924 ) (189,907 ) Patents, net $ 277,579 $ 265,540 Amortization expense related to capitalized patent costs was $44.0 million , $38.4 million and $29.8 million in 2015 , 2014 and 2013 , 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, 2015 is as follows (in thousands): 2016 $ 46,700 2017 43,876 2018 38,594 2019 35,718 2020 30,946 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. Revenue Recognition We derive the vast majority of our revenue from patent licensing. The timing and amount of revenue recognized from each licensee depends upon a variety of factors, including the specific terms of each agreement and the nature of the deliverables and obligations. Such agreements are often complex and include multiple elements. These agreements can include, without limitation, elements related to the settlement of past patent infringement liabilities, up-front and non-refundable license fees for the use of patents and/or know-how, patent and/or know-how licensing royalties on covered products sold by licensees, cross-licensing terms between us and other parties, the compensation structure and ownership of intellectual property rights associated with contractual technology development arrangements, advanced payments and fees for service arrangements and settlement of intellectual property enforcement. For agreements entered into or materially modified prior to 2011, due to the inherent difficulty in establishing reliable, verifiable, and objectively determinable evidence of the fair value of the separate elements of these agreements, the total revenue resulting from such agreements has often been recognized over the performance period. Beginning in January 2011, all new or materially modified agreements are being accounted for under the Financial Accounting Standards Board ("FASB") revenue recognition guidance, "Revenue Arrangements with Multiple Deliverables." This guidance requires consideration to be allocated to each element of an agreement that has stand alone value using the relative fair value method. In other circumstances, such as those agreements involving consideration for past and expected future patent royalty obligations, after consideration of the particular facts and circumstances, the appropriate recording of revenue between periods may require the use of judgment. In all cases, revenue is only recognized after all of the following criteria are met: (1) written agreements have been executed; (2) delivery of technology or intellectual property rights has occurred or services have been rendered; (3) fees are fixed or determinable; and (4) collectibility of fees is reasonably assured. We establish a receivable for payments expected to be received within twelve months from the balance sheet date based on the terms in the license. Our reporting of such payments often results in an increase to both accounts receivable and deferred revenue. Deferred revenue associated with fixed-fee royalty payments is classified on the balance sheet as short-term when it is scheduled to be amortized within twelve months from the balance sheet date. All other deferred revenue is classified as long-term, as amounts to be recognized over the next twelve months are not known. 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 for revenue arrangements with multiple deliverables. We have elected to utilize the leased-based model for revenue recognition, with revenue being recognized over the expected period of benefit to the licensee. 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 when we have obtained a signed agreement, identified a fixed or determinable price and determined that collectibility is reasonably assured. Fixed-Fee Royalty Payments: These are up-front, 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). We recognize revenues related to Fixed-Fee Royalty Payments on a straight-line basis over the effective term of the license. We utilize the straight-line method because we cannot reliably predict in which periods, within the term of a license, the licensee will benefit from the use of our patented inventions. Prepayments: These are up-front, non-refundable royalty payments towards a licensee’s future obligations to us related to its expected sales of covered products in future periods. Our licensees’ obligations to pay royalties typically extend beyond the exhaustion of their Prepayment balance. Once a licensee exhausts its Prepayment balance, we may provide them with the opportunity to make another Prepayment toward future sales or it will be required to make Current Royalty Payments. Current Royalty Payments: These are royalty payments covering a licensee’s obligations to us related to its sales of covered products in the current contractual reporting period. Licensees that either owe us Current Royalty Payments or have Prepayment balances are obligated to 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, it is impractical for us to recognize revenue in the period in which the underlying sales occur, and, in most cases, we recognize revenue in the period in which the royalty report is received and other revenue recognition criteria are met due to the fact that without royalty reports from our licensees, our visibility into our licensees’ sales is very limited. When a licensee is required to gross-up their royalty payment to cover applicable foreign withholding tax requirements, the additional consideration is recorded in revenue. The exhaustion of Prepayments and Current Royalty Payments are often calculated based on related per-unit sales of covered products. From time to time, licensees will not report revenues in the proper period, most often due to legal disputes. When this occurs, the timing and comparability of royalty revenue could be affected. In cases where we receive objective, verifiable evidence that a licensee has discontinued sales of products covered under a patent license agreement with us, we recognize any related deferred revenue balance in the period that we receive such evidence. 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 when there is persuasive evidence of a sales arrangement, fees are fixed or determinable, delivery has occurred and collectibility is reasonably assured. These requirements are generally fulfilled upon closing of the patent sale transaction. Technology Solutions and Engineering Services Technology solutions revenue consists primarily of revenue from royalty payments. We recognize revenue from royalty payments using the same methods described above under our policy for recognizing revenue from patent license agreements. Technology solutions revenues also consist of revenues from software licenses and engineering services. Software license revenues are recognized in accordance with the original and revised guidance for software revenue recognition. When the arrangement with a customer includes significant production, modification, or customization of the software, we recognize the related revenue using the percentage-of-completion method in accordance with the accounting guidance for construction-type and certain production-type contracts. Under this method, revenue and profit are recognized throughout the term of the contract, based on actual labor costs incurred to date as a percentage of the total estimated labor costs related to the contract. Changes in estimates for revenues, costs and profits are recognized in the period in which they are determinable. When such estimates indicate that costs will exceed future revenues and a loss on the contract exists, a provision for the entire loss is recognized at that time. We recognize revenues associated with engineering service arrangements that are outside the scope of the accounting guidance for construction-type and certain production-type contracts on a straight-line basis, unless evidence suggests that the revenue is earned in a different pattern, over the contractual term of the arrangement or the expected period during which those specified services will be performed, whichever is longer. In such cases we often recognize revenue using proportional performance and measure the progress of our performance based on the relationship between incurred labor hours and total estimated labor hours or other measures of progress, if available. Our most significant cost has been labor and we believe both labor hours and labor cost provide a measure of the progress of our services. The effect of changes to total estimated contract costs is recognized in the period such changes are determined. Deferred Charges 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 related to both prepayments and fixed-fee royalty payments and amortize these expenses in proportion to our recognition of the related revenue. In 2015 , 2014 and 2013 , we paid cash commissions of less than $0.1 million , approximately $0.3 million and less than $0.1 million , respectively. Incremental direct costs incurred related to acquisition or origination of a customer contract in a transaction that results in the deferral of revenue may be either expensed as incurred or capitalized. The only eligible costs for deferral are those costs directly related to a particular revenue arrangement. We capitalize those direct costs incurred for the acquisition of a contract through the date of signing, and amortize them on a straight-line basis over the life of the patent license agreement. There were no direct contract origination costs incurred during 2015, 2014, or 2013. Incremental direct costs incurred related to a debt financing transaction may be capitalized. In connection with our offerings of the Notes, discussed in detail within Note 6, 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 to interest expense over the term of the debt using the effective interest method. The costs allocated to the equity component of the debt were recorded as a reduction of the equity component of the debt. There were no debt issuance costs incurred in 2014 or 2013 . Deferred charges are recorded in our Consolidated Balance Sheets within the following captions (in thousands): December 31, 2015 2014 Prepaid and other current assets Deferred commission expense $ 245 $ 342 Deferred contract origination costs — 79 Other non-current assets Deferred commission expense 196 495 Deferred contract origination costs — 79 Long-term debt (including current portion of long-term debt) Deferred financing costs 6,117 1,629 Commission expense was approximately $0.6 million , $0.4 million and $0.3 million in 2015 , 2014 and 2013 , respectively. Commission expense is included within the Patent administration and licensing line of our Consolidated Statements of Income. Deferred contract origination expense recognized in 2015 , 2014 and 2013 was less than $0.1 million in each period and is included within the Patent administration and licensing line of our Consolidated Statements of Income. Deferred financing expense was $2.5 million in 2015 and $1.3 million in both 2014 and 2013 . Deferred financing expense is included within the Other Expense (Net) line of our Consolidated Statements of Income. 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 $72.7 million , $75.3 million and $64.7 million in 2015 , 2014 and 2013 , respectively. Compensation Programs Our compensation programs include, but are not limited to, short-term incentive awards tied to performance goals and cash awards to inventors for filed patent applications and patent issuances, as well as stock option awards, time-based restricted stock unit (“RSU”) awards and performance-based awards under our long-term compensation program ("LTCP"). Our LTCP typically includes annual grants with a three-year vesting period; as a result, in any one year, we are typically accounting for three active LTCP cycles. The aggregate amount of performance compensation expense we record in a period, under both short-term and long-term performance compensation programs, requires the input of subjective assumptions and is a function of our estimated progress toward performance compensation goals at the beginning of the period, and our estimated progress or final assessment o

Significant Agreements

Significant Agreements	12 Months Ended
	Dec. 31, 2015
Variable Interest Entity [Line Items]
Legal Matters and Contingencies [Text Block]	SIGNIFICANT EVENTS Patent License Agreements and Settlement Agreements During second quarter 2015, we entered into a settlement agreement with Arima Communications Corporation ("Arima"). The agreement maintains the existing patent license agreement and resolves all pending payment disputes between the companies. In addition, the agreement resulted in the dismissal of all current litigations and arbitrations between the companies in all jurisdictions. We recognized $27.2 million of past patent royalties related to this settlement. During third quarter 2015, we entered into a new patent license agreement with Sony (the "new Sony PLA"). In addition, we renewed our joint venture with Sony, Convida Wireless, to continue investments in the development of IoT technologies and expanded it to include development efforts in 5G technologies. As discussed more fully in Note 14, " Variable Interest Entities ," Convida Wireless is a variable interest entity and is consolidated within our financial statements. Our agreement with Sony is a multiple-element arrangement for accounting purposes, which includes, among other elements, the new Sony PLA. The new Sony PLA covers the sale by Sony of covered products for the three-year period that commenced on December 1, 2015. In addition, the new Sony PLA covers Sony's covered product sales that occurred during certain prior periods and that were not covered under our prior agreement with Sony. We recognized past sales of $21.8 million from this agreement in third quarter 2015, and are recognizing future revenue from the new Sony PLA on a straight-line basis over its term. A portion of consideration received was in the form of patents. Refer to Note 2, " Summary of Significant Accounting Policies ," for additional information related to the estimates and methods used to determine the fair value of the patents acquired. During fourth quarter 2015, we entered into a new worldwide, non-exclusive, royalty bearing patent license agreement with Kyocera. Our agreement with Kyocera is a multiple-element arrangement for accounting purposes. The agreement covers Kyocera's sale of certain cellular terminal unit products. We recognized $16.4 million of past patent royalties related to this settlement during fourth quarter 2015. A portion of the consideration received was in the form of patents. Refer to Note 2, " Summary of Significant Accounting Policies ," for additional information related to the estimates and methods used to determine the fair value of the patents acquired. Additionally, during fourth quarter 2015, we entered into a settlement agreement with a technology solutions customer. The agreement resolves all pending payment disputes between the parties. We recognized $2.8 million of past technology solutions revenue, $1.8 million of interest income, a $0.5 million reversal of a bad debt reserve and $0.4 million of contra-expenses related to this settlement. Both of the patent license agreements signed during 2015, as discussed above, are multiple-element arrangements for accounting purposes. Consistent with the revenue recognition policy disclosed in Note 2, " Summary of Significant Accounting Policies ," for each agreement, we identified each element of the arrangement, estimated its relative value for purposes of allocating the arrangement consideration and determined when each of those elements should be recognized. Using the accounting guidance applicable to multiple-element revenue arrangements, we allocated the consideration to each element for accounting purposes using our best estimate of the term and value of each element. The development of a number of these inputs and assumptions in the model requires a significant amount of management judgment and is based upon a number of factors, including the assumed royalty rates, sales volumes, discount rate and other relevant factors. Changes in any of a number of these assumptions could have had a substantial impact on the relative fair value assigned to each element for accounting purposes. These inputs and assumptions represent management's best estimates at the time of the transactions. Huawei Arbitration In December 2013, InterDigital and Huawei reached a settlement agreement to enter into binding arbitration to resolve their global patent licensing dispute. Pursuant to their agreement, InterDigital and Huawei initiated an arbitration in April 2014 jointly seeking a determination by an arbitral tribunal of FRAND royalty terms and conditions to be included in a binding worldwide patent license agreement to take effect upon issuance of the arbitration award. An arbitration hearing was held in January 2015, and the arbitration panel delivered a confidential partial award in May 2015 and a confidential final award in July 2015. In July 2015, InterDigital filed a petition in the District Court for the Southern District of New York for an order confirming the arbitration award (the “New York Proceeding”), and Huawei filed an action in the Paris Court of Appeal requesting annulment of the arbitration award (the “Paris Proceeding”). Huawei also filed a motion to stay the New York Proceeding pending the Paris Proceeding. A hearing in the New York Proceeding was held on February 16, 2016. On February 17, 2016, the judge notified the parties that he had rendered a decision on Huawei’s motion to stay the New York Proceeding, finding that the New York Proceeding should be stayed pending the Paris Proceeding, subject to a requirement that Huawei post suitable security, pursuant to Article VI of the New York Convention, in the amount of the final award, together with interest. The stay is subject to revision should circumstances change, and InterDigital can renew its petition for an order confirming the award after the outcome of the Paris Proceeding is determined.. A hearing is scheduled in the Paris Proceeding for March 2016. To date, Huawei has not made any payments under the arbitration award. We will recognize any related revenue in the period in which the amount of revenue is fixed or determinable and collectability is reasonably assured.

Geographic Concentration

Geographic Concentration	12 Months Ended
	Dec. 31, 2015
GEOGRAPHIC CUSTOMER CONCENTRATION [Abstract]
Segment Reporting Disclosure [Text Block]	GEOGRAPHIC / CUSTOMER CONCENTRATION We have one reportable segment. During 2015 and 2014, 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, 2015 2014 2013 Taiwan a $ 218,584 $ 115,955 $ 128,551 South Korea 69,000 144,398 15,334 United States 65,703 53,163 108,728 Japan 53,775 52,194 27,494 Canada 13,151 15,422 36,148 Sweden 6,934 24,530 — Germany 6,712 5,293 4,539 Other Europe 4,807 4,064 3,004 China 2,768 800 1,563 Other Asia 1 2 — Total $ 441,435 $ 415,821 $ 325,361 (a) We are engaged in a legal dispute with Pegatron Corporation ("Pegatron"), our largest Taiwan-based customer, regarding, among other things, the terms of our patent license agreement, and we are the subject of an investigation by the Taiwan Fair Trade Commission. See Note 8, “Litigation and Legal Proceedings,” in these Notes to Condensed Consolidated Financial Statements. During 2015 , 2014 and 2013 , the following licensees or customers accounted for 10% or more of total revenues: 2015 2014 2013 Pegatron a 31 % 18 % 30 % Samsung b 16 % 33 % — % Sony c 14 % < 10% 12 % Intel Mobile Communications GmbH d < 10% < 10% 18 % (a) 2013 revenues include $71.4 million of past patent royalties. As noted above, we are engaged in a legal dispute with Pegatron. See Note 8, “Litigation and Legal Proceedings,” in these Notes to Condensed Consolidated Financial Statements. (b) 2014 revenues include $86.2 million of past patent royalties. (c) 2015 revenues include $21.8 million of past patent royalties (d) 2013 revenues include $53.3 million of past technology solutions revenue. At December 31, 2015, 2014 and 2013, we held $289.7 million , $278.1 million and $215.9 million , respectively, or nearly 100% in each year, of our property and equipment and patents in the United States net of accumulated depreciation and amortization. At each of December 31, 2015, 2014 and 2013, we held less than $0.1 million of property and equipment, net of accumulated depreciation, collectively, in Canada, the United Kingdom and South Korea.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2015
Property and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	5. PROPERTY AND EQUIPMENT December 31, 2015 2014 Computer equipment and software $ 30,066 $ 27,678 Engineering and test equipment 12,321 11,970 Building and improvements 11,356 11,076 Leasehold improvements 7,544 7,406 Furniture and fixtures 1,513 1,292 Land 695 695 Property and equipment, gross 63,495 60,117 Less: accumulated depreciation (51,347 ) (47,571 ) Property and equipment, net $ 12,148 $ 12,546 Depreciation expense was $3.8 million , $3.9 million and $3.6 million in 2015 , 2014 and 2013 , respectively. Depreciation expense included depreciation of computer software costs of $1.4 million , $1.4 million and $1.0 million in 2015 , 2014 and 2013 , respectively. Accumulated depreciation related to computer software costs was $15.6 million and $14.3 million at December 31, 2015 and 2014 , respectively. The net book value of our computer software was $1.2 million and $2.2 million at December 31, 2015 and 2014 , respectively.

Obligations

Obligations	12 Months Ended
	Dec. 31, 2015
OBLIGATIONS: [Abstract]
Long-term Debt [Text Block]	6. OBLIGATIONS December 31, 2015 2014 2.50% Senior Convertible Notes due 2016 $ 230,000 $ 230,000 1.50% Senior Convertible Notes due 2020 316,000 — Less: Unamortized interest discount (53,114 ) (12,165 ) Deferred financing costs (6,117 ) (1,629 ) Total debt obligations 486,769 216,206 Less: Current portion of long-term debt 227,174 — Long-term debt obligations $ 259,595 $ 216,206 There were no capital leases remaining at December 31, 2015 or December 31, 2014 . Maturities of principal of the long-term debt obligations of the Company as of December 31, 2015 are as follows (in thousands): 2016 $ 230,000 2017 — 2018 — 2019 — 2020 316,000 Thereafter — $ 546,000 2016 Senior Convertible Notes and related Note Hedge and Warrant Transactions In April, 2011, we issued $230.0 million in aggregate principal amount of 2.50% Senior Convertible Notes due 2016 (the “2016 Notes”). The 2016 Notes bear interest at a rate of 2.50% per year, payable in cash on March 15 and September 15 of each year, and mature on March 15, 2016, unless earlier converted or repurchased. The 2016 Notes are convertible into cash and, if applicable, shares of our common stock at a current conversion rate of 18.2166 shares of common stock per $1,000 principal amount of 2016 Notes (which is equivalent to a conversion price of approximately $54.90 per share), as adjusted as of January 11, 2016 pursuant to the terms of the Indenture for the 2016 Notes. Commencing on December 15, 2015, the 2016 Notes are convertible in multiples of $1,000 principal amount, at any time prior to 5:00 p.m., New York City time, on the business day immediately preceding March 15, 2016, the maturity date of the 2016 Notes. Upon any conversion, the conversion obligation will be settled in cash up to, and including, the principal amount and, to the extent of any excess over the principal amount, in shares of common stock. The Company may not redeem the 2016 Notes prior to their maturity date. On March 29 and March 30, 2011, in connection with the offering of the 2016 Notes, InterDigital entered into convertible note hedge transactions that cover, subject to customary anti-dilution adjustments, approximately 3.5 million and approximately 0.5 million shares of our common stock, respectively, at an initial strike price that corresponded to the initial conversion price of the 2016 Notes and are exercisable upon conversion of the 2016 Notes. On April 4, 2011, we paid $37.1 million and $5.6 million for the convertible note hedge transactions entered into on March 29 and March 30, 2011, respectively. The aggregate cost of the convertible note hedge transactions was $42.7 million . As described in more detail below, this cost was partially offset by the proceeds from the sale of the warrants described below. On March 29 and March 30, 2011, we sold warrants to acquire, subject to customary anti-dilution adjustments, approximately 3.5 million shares and approximately 0.5 million shares, respectively, of common stock. The warrants have a current strike price of approximately $63.18 per share, as adjusted as of January 11, 2016 in connection with the above-referenced adjustment to the conversion rate of the 2016 Notes. The warrants become exercisable in tranches starting in June 2016. As consideration for the warrants issued on March 29 and March 30, 2011, we received, on April 4, 2011, $27.6 million and $4.1 million , respectively. Accounting Treatment of the 2016 Notes and the related Convertible Note Hedge and Warrant Transactions The offering of the 2016 Notes on March 29, 2011 was for $200.0 million and included an overallotment option that allowed the initial purchaser to purchase up to an additional $30.0 million aggregate principal amount of 2016 Notes. The initial purchaser exercised its overallotment option on March 30, 2011, bringing the total amount of 2016 Notes issued on April 4, 2011 to $230.0 million . In connection with the offering of the 2016 Notes, as discussed above, we entered into convertible note hedge transactions with respect to our common stock. The $42.7 million cost of the convertible note hedge transactions was partially offset by the proceeds from the sale of the warrants described above, resulting in a net cost of $10.9 million . Existing accounting guidance provided that the March 29, 2011 convertible note hedge and warrant contracts be treated as derivative instruments for the period during which the initial purchaser's overallotment option was outstanding. Once the overallotment provision was exercised on March 30, 2011, the March 29 convertible note hedge and warrant contracts were reclassified to equity, as the settlement terms of the Company's note hedge and warrant contracts both provide for net share settlement. There was no material net change in the value of these convertible note hedges and warrants during the one day they were classified as derivatives and the equity components of these instruments will not be adjusted for subsequent changes in fair value. Under current accounting guidance, we bifurcated the proceeds from the offering of the 2016 Notes between the liability and equity components of the debt. On the date of issuance, the liability and equity components were calculated to be approximately $187.0 million and $43.0 million , respectively. The initial $187.0 million liability component was determined based on the fair value of similar debt instruments excluding the conversion feature. The initial $43.0 million ( $28.0 million net of tax) equity component represents the difference between the fair value of the initial $187.0 million in debt and the $230.0 million of gross proceeds. The related initial debt discount of $43.0 million is being amortized using the effective interest method over the life of the 2016 Notes. An effective interest rate of 7% was used to calculate the debt discount on the 2016 Notes. In connection with the above-noted transactions, we incurred $8.0 million of directly related costs. The initial purchaser's 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. We allocated $6.5 million of debt issuance costs to the liability component of the debt, which were capitalized as deferred financing costs. These costs are being amortized to interest expense over the term of the debt using the effective interest method. The remaining $1.5 million of costs allocated to the equity component of the debt were recorded as a reduction of the equity component of the debt. 2020 Senior Convertible Notes and related Note Hedge and Warrant Transactions On March 11, 2015, we issued $316.0 million in aggregate principal amount of 1.50% Senior Convertible Notes due 2020 (the “2020 Notes”). The 2020 Notes bear interest at a rate of 1.50% per year, payable in cash on March 1 and September 1 of each year, commencing September 1, 2015, and mature on March 1, 2020, unless earlier converted or repurchased. The 2020 Notes will be convertible into cash, shares of our common stock or a combination thereof, at our election, at an initial conversion rate of 13.8172 shares of common stock per $1,000 principal amount of 2020 Notes (which is equivalent to an initial conversion price of approximately $72.37 per share). It is our current intent and policy to settle all conversions through combination settlement of cash and shares of common stock, with a specified dollar amount of $1,000 per $1,000 principal amount of the 2020 Notes and any remaining amounts in shares. Prior to 5:00 p.m., New York City time, on the business day immediately preceding December 1, 2019, the 2020 Notes will be convertible only under certain circumstances as set forth in the indenture to the 2020 Notes. Commencing on December 1, 2019, the 2020 Notes will be convertible in multiples of $1,000 principal amount, at any time prior to 5:00 p.m., New York City time, on the second scheduled trading day immediately preceding the maturity date of the 2020 Notes. The Company may not redeem the 2020 Notes prior to their maturity date. On March 5 and March 9, 2015, in connection with the offering of the 2020 Notes, we entered into convertible note hedge transactions that cover approximately 3.8 million and approximately 0.6 million shares of our common stock, respectively, at a strike price that corresponds initially to the initial conversion price of the 2020 Notes and are exercisable upon conversion of the 2020 Notes. The cost of the March 5 and March 9, 2015 convertible note hedge transactions was approximately $51.7 million and approximately $7.7 million , respectively. On March 5 and March 9, 2015, we sold warrants to acquire, subject to customary anti-dilution adjustments, approximately 3.8 million and approximately 0.6 million , respectively, of common stock at an initial strike price of approximately $88.46 per share. The warrants become exercisable in tranches starting in June 2020. As consideration for the warrants issued on March 5 and March 9, 2015, we received approximately $37.3 million and approximately $5.6 million , respectively. We also repurchased 0.8 million shares of our common stock at $53.61 per share, the closing price of the stock on March 5, 2015, from institutional investors through one of the initial purchasers and its affiliate, as our agent, concurrently with the pricing of the offering of the 2020 Notes. Accounting Treatment of the 2020 Notes and related Convertible Note Hedge and Warrant Transactions The offering of the 2020 Notes on March 5, 2015 was for $275.0 million and included an overallotment option that allowed the initial purchasers to purchase up to an additional $41.0 million aggregate principal amount of 2020 Notes. The initial purchasers exercised their overallotment option on March 9, 2015, bringing the total amount of 2020 Notes issued on March 11, 2015 to $316.0 million . In connection with the offering of the 2020 Notes, as discussed above, we entered into convertible note hedge transactions with respect to our common stock. The $59.4 million cost of the convertible note hedge transactions was partially offset by the proceeds from the sale of the warrants described above, resulting in a net cost of $16.5 million . Both the convertible note hedge and warrants were classified as equity. We bifurcated the proceeds from the offering of the 2020 Notes between liability and equity components. On the date of issuance, the liability and equity components were calculated to be approximately $256.7 million and $59.3 million , respectively. The initial $256.7 million liability component was determined based on the fair value of similar debt instruments excluding the conversion feature. The initial $59.3 million ( $38.6 million net of tax) equity component represents the difference between the fair value of the initial $256.7 million in debt and the $316.0 million of gross proceeds. The related initial debt discount of $59.3 million is being amortized using the effective interest method over the life of the 2020 Notes. An effective interest rate of 5.89% was used to calculate the debt discount on the 2020 Notes. In connection with the above-noted transactions, we incurred $9.3 million of directly related costs. The initial purchasers' transaction fees and related offering expenses were allocated to the liability and equity components in proportion to the allocation of proceeds and accounted for as debt and equity issuance costs, respectively. We allocated $7.0 million of debt issuance costs to the liability component, which were capitalized as deferred financing costs. These costs are being amortized to interest expense over the term of the debt using the effective interest method. The remaining $2.4 million of costs allocated to the equity component were recorded as a reduction of the equity component. As described in Note 2, " Summary of Significant Accounting Policies ," in March 2015, as part of their simplification initiative, the FASB issued amendments to guidance for reporting debt issuance costs. According to the revised standard, an entity will recognize debt issuance costs as a direct deduction from the debt liability as opposed to an asset. The following table presents the amount of interest cost recognized for the years ended December 31, 2015 , 2014 and 2013 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, 2015 2014 2013 Contractual coupon interest $ 9,568 $ 5,750 $ 5,750 Accretion of debt discount 18,384 9,022 8,423 Amortization of financing costs 2,485 1,303 1,303 Total $ 30,437 $ 16,075 $ 15,476

Commitments

Commitments	12 Months Ended
	Dec. 31, 2015
COMMITMENTS [Abstract]
Commitments Disclosure [Text Block]	COMMITMENTS Leases We have entered into various operating lease agreements. Total rent expense, primarily for office space, was $3.3 million , $3.2 million and $3.3 million in 2015 , 2014 and 2013 , respectively. Minimum future rental payments for operating leases as of December 31, 2015 are as follows (in thousands): 2016 $ 4,186 2017 3,173 2018 2,918 2019 2,872 2020 1,995 Thereafter 7,781

Litigation and Legal Proceeding

Litigation and Legal Proceedings (Notes)	12 Months Ended
	Dec. 31, 2015
4. LITIGATION AND LEGAL PROCEEDINGS [Abstract]
Legal Matters and Contingencies [Text Block]	8. LITIGATION AND LEGAL PROCEEDINGS ARBITRATIONS AND COURT PROCEEDINGS (OTHER THAN DE DISTRICT COURT ACTIONS RELATED TO USITC PROCEEDINGS) Huawei Arbitration On December 23, 2013, InterDigital and Huawei agreed to engage in an expedited binding arbitration to resolve their licensing disputes. Pursuant to their agreement, on April 9, 2014, InterDigital and Huawei initiated an arbitration with the International Court of Arbitration of the International Chamber of Commerce (ICC) jointly seeking a determination by an arbitral tribunal of FRAND royalty terms and conditions to be included in a binding worldwide patent license agreement to take effect upon issuance of the arbitration award. An arbitration hearing was held on January 12-16, 2015. On May 26, 2015, the panel convened by the ICC delivered a confidential partial award. The panel convened by the ICC delivered a confidential final award dated July 14, 2015. On July 9, 2015, InterDigital filed a petition in the District Court for the Southern District of New York for an order confirming the arbitration award (the “New York Proceeding”). On the same day, Huawei filed an action in the Paris Court of Appeal requesting annulment of the arbitration award (the “Paris Proceeding”). On July 24, 2015, Huawei opposed InterDigital’s petition in the New York Proceeding and filed a motion to stay the New York Proceeding pending the Paris Proceeding. On August 14, 2015, InterDigital amended its petition in the New York Proceeding to take into account the issuance of the arbitration panel’s final award. A hearing in the New York Proceeding was held on February 16, 2016. On February 17, 2016, the judge notified the parties that he had rendered a decision on Huawei’s motion to stay the New York Proceeding, finding that the New York Proceeding should be stayed pending the Paris Proceeding, subject to a requirement that Huawei post suitable security, pursuant to Article VI of the New York Convention, in the amount of the final award, together with interest. The stay is subject to revision should circumstances change, and InterDigital can renew its petition for an order confirming the award after the outcome of the Paris Proceeding is determined. Huawei filed its brief seeking annulment in the Paris Proceeding on July 24, 2015. A hearing in the Paris Proceeding is scheduled for March 8, 2016. To date, Huawei has not made any payments under the arbitration award. We will recognize any related revenue in the period in which the amount of revenue is fixed or determinable and collectability is reasonably assured. Huawei China Proceedings On February 21, 2012, InterDigital was served with two complaints filed by Huawei Technologies Co., Ltd. in the Shenzhen Intermediate People's Court in China on December 5, 2011. The first complaint named as defendants InterDigital, Inc. and its wholly owned subsidiaries InterDigital Technology Corporation and InterDigital Communications, LLC (now InterDigital Communications, Inc.), and alleged that InterDigital had abused its dominant market position in the market for the licensing of essential patents owned by InterDigital by engaging in allegedly unlawful practices, including differentiated pricing, tying and refusal to deal. The second complaint named as defendants the Company's wholly owned subsidiaries InterDigital Technology Corporation, InterDigital Communications, LLC (now InterDigital Communications, Inc.), InterDigital Patent Holdings, Inc. and IPR Licensing, Inc. and alleged that InterDigital had failed to negotiate on FRAND terms with Huawei. Huawei asked the court to determine the FRAND rate for licensing essential Chinese patents to Huawei and also sought compensation for its costs associated with this matter. On February 4, 2013, the Shenzhen Intermediate People's Court issued rulings in the two proceedings. With respect to the first complaint, the court decided that InterDigital had violated the Chinese Anti-Monopoly Law by (i) making proposals for royalties from Huawei that the court believed were excessive, (ii) tying the licensing of essential patents to the licensing of non-essential patents, (iii) requesting as part of its licensing proposals that Huawei provide a grant-back of certain patent rights to InterDigital and (iv) commencing a USITC action against Huawei while still in discussions with Huawei for a license. Based on these findings, the court ordered InterDigital to cease the alleged excessive pricing and alleged improper bundling of InterDigital's Chinese essential and non-essential patents, and to pay Huawei 20.0 million RMB (approximately $3.2 million ) in damages related to attorneys’ fees and other charges, without disclosing a factual basis for its determination of damages. The court dismissed Huawei's remaining allegations, including Huawei's claim that InterDigital improperly sought a worldwide license and improperly sought to bundle the licensing of essential patents on multiple generations of technologies. With respect to the second complaint, the court determined that, despite the fact that the FRAND requirement originates from ETSI's Intellectual Property Rights policy, which refers to French law, InterDigital's license offers to Huawei should be evaluated under Chinese law. Under Chinese law, the court concluded that the offers did not comply with FRAND. The court further ruled that the royalties to be paid by Huawei for InterDigital's 2G, 3G and 4G essential Chinese patents under Chinese law should not exceed 0.019% of the actual sales price of each Huawei product. On March 11, 2013, InterDigital filed notices of appeal with respect to the judgments in both proceedings, seeking reversal of the court’s February 4, 2013 rulings. On October 16, 2013, the Guangdong Province High Court issued a ruling affirming the ruling of the Shenzhen Intermediate People's Court in the second proceeding, and on October 21, 2013, issued a ruling affirming the ruling of the Shenzhen Intermediate People's Court in the first proceeding. InterDigital believes that the decisions are seriously flawed both legally and factually. For instance, in determining a purported FRAND rate, the Chinese courts applied an incorrect economic analysis by evaluating InterDigital’s lump-sum patent license agreement with Apple in hindsight to posit a running royalty rate. Indeed, the ALJ in USITC Inv. No. 337-TA-800 rejected that type of improper analysis. Moreover, the Chinese courts had an incomplete record and applied incorrect facts, including with respect to InterDigital’s now-expired license agreement with Apple, which had been found in an arbitration between InterDigital and Apple to be limited in scope. On April 14, 2014, InterDigital filed a petition for retrial of the second proceeding with the Chinese Supreme People’s Court (“SPC”), seeking dismissal of the judgment or at least a higher, market-based royalty rate for a license to InterDigital’s Chinese standards-essential patents (“SEPs”). The petition for retrial argues, for example, that (1) the lower court improperly determined a Chinese FRAND running royalty rate by using as a benchmark the Apple lump sum fixed payment license agreement, and looking in hindsight at the unexpectedly successful sales of Apple iPhones to construct an artificial running royalty rate that neither InterDigital nor Apple could have intended and that would have varied significantly depending on the relative success or failure in hindsight of Apple iPhone sales; (2) the Apple license agreement was also an inappropriate benchmark because its scope of product coverage was significantly limited as compared to the license that the court was considering for Huawei, particularly when there are other more comparable license agreements; and (3) if the appropriate benchmarks had been used, and the court had considered the range of royalties offered by other similarly situated SEP holders in the wireless telecommunications industry, the court would have determined a FRAND royalty that was substantially higher than 0.019%, and would have found, consistent with findings of the ALJ’s initial determination in the USITC 337-TA-800 proceeding, that there was no proof that InterDigital’s offers to Huawei violated its FRAND commitments. The SPC held a hearing on October 31, 2014, regarding whether to grant a retrial and requested that both parties provide additional information regarding the facts and legal theories underlying the case. The SPC convened a second hearing on April 1, 2015 regarding whether to grant a retrial. InterDigital continues to provide additional information to the SPC in support of its petition for retrial. If the retrial is granted, the SPC will likely schedule one or more additional hearings before it issues a decision on the merits of the case. ZTE China Proceedings On July 10 and 11, 2014, InterDigital was served with two complaints filed by ZTE Corporation in the Shenzhen Intermediate People's Court in China on April 3, 2014. The first complaint names as defendants the Company's wholly owned subsidiaries InterDigital Technology Corporation, InterDigital Communications, Inc., InterDigital Patent Holdings, Inc. and IPR Licensing, Inc. This complaint alleges that InterDigital has failed to comply with its FRAND obligations for the licensing of its Chinese standards-essential patents. ZTE is asking the court to determine the FRAND rate for licensing InterDigital’s standards-essential Chinese patents to ZTE and also seeks compensation for its litigation costs associated with this matter. The second complaint names as defendants InterDigital, Inc. and its wholly owned subsidiaries InterDigital Technology Corporation and InterDigital Communications, Inc. This complaint alleges that InterDigital has a dominant market position in China and the United States in the market for the licensing of essential patents owned by InterDigital, and abused its dominant market position in violation of the Chinese Anti-Monopoly Law by engaging in allegedly unlawful practices, including excessively high pricing, tying, discriminatory treatment, and imposing unreasonable trading conditions. ZTE seeks relief in the amount of 20.0 million RMB (approximately $3.1 million based on the exchange rate as of December 31, 2015), an order requiring InterDigital to cease the allegedly unlawful conduct and compensation for its litigation costs associated with this matter. On August 7, 2014, InterDigital filed petitions challenging the jurisdiction of the Shenzhen Intermediate People's Court to hear the actions. On August 28, 2014, the court denied InterDigital’s jurisdictional challenge with respect to the anti-monopoly law case. InterDigital filed an appeal of this decision on September 26, 2014. On September 28, 2014, the court denied InterDigital’s jurisdictional challenge with respect to the FRAND case, and InterDigital filed an appeal of that decision on October 27, 2014. On December 18, 2014, the Guangdong High Court issued decisions on both appeals upholding the Shenzhen Intermediate Court’s decisions that it had jurisdiction to hear these cases. On February 10, 2015, InterDigital filed a petition for retrial with the Supreme People’s Court regarding its jurisdictional challenges to both cases. The Shenzhen Court held hearings on the anti-monopoly law case on May 11, 13, 15 and 18, 2015. At the May hearings, ZTE withdrew its claims alleging discriminatory treatment and the imposition of unfair trading conditions and increased its damages claim to 99.8 million RMB (approximately $15.4 million based on the exchange rate as of December 31, 2015). The Shenzhen Court held hearings in the FRAND case on July 29-31, 2015 and held a second hearing on the anti-monopoly law case on October 12, 2015. It is possible that the court may schedule further hearings in these cases before issuing its decisions. The Company has not recorded any accrual at December 31, 2015 for contingent losses associated with these matters based on its belief that losses, while possible, are not probable in accordance with accounting guidance. Further, any possible range of loss cannot be reasonably estimated at this time. LG Arbitration On March 19, 2012, LG Electronics, Inc. filed a demand for arbitration against the Company’s wholly owned subsidiaries InterDigital Technology Corporation, IPR Licensing, Inc. and InterDigital Communications, LLC (now InterDigital Communications, Inc.) with the American Arbitration Association’s International Centre for Dispute Resolution (“ICDR”), initiating an arbitration in Washington, D.C. LG sought a declaration that it held a continuing license to certain technology owned by InterDigital under the parties’ patent license agreement dated January 1, 2006 (the “2006 LG PLA”). On April 18, 2012, InterDigital filed an Answering Statement objecting to the jurisdiction of the ICDR on the ground that LG’s claims are not arbitrable, and denying all claims made by LG in its demand for arbitration. The issue of whether LG’s claim to arbitrability is wholly groundless was appealed to the Federal Circuit. On June 7, 2013, the Federal Circuit issued an opinion holding that the USITC erred in terminating USITC Proceeding (337-TA-800) as to LG because “there is no plausible argument that the parties’ dispute in this case arose under their patent license agreement” and finding that “LG’s assertion of arbitrability was ‘wholly groundless.’” The Federal Circuit reversed the USITC’s order terminating the USITC proceeding as to LG and remanded to the USITC for further proceedings. On June 25, 2013, the arbitration tribunal granted the parties’ joint request to stay the arbitration pending the exhaustion of all appellate rights from the Federal Circuit’s decision. As noted above, LG filed a petition for a writ of certiorari with the U.S. Supreme Court challenging the Federal Circuit’s ruling on December 31, 2013, and on April 21, 2014, the Supreme Court granted LG’s petition, vacating the underlying Federal Circuit decision and remanding the case to the Federal Circuit with instructions to dismiss the case as moot (in light of InterDigital’s decision to terminate the 337-TA-800 investigation as to LG). On June 9, 2014, the arbitration tribunal lifted the temporary stay at the request of the parties. The arbitration tribunal held an evidentiary hearing on July 20-22, 2015 and a supplemental oral argument on October 19, 2015. On December 29, 2015, the arbitration tribunal issued its final award. Rejecting LG’s arguments, the arbitration tribunal found that LG’s license with respect to 3G products under the 2006 LG PLA had terminated as of December 31, 2010, at the expiration of the 2006 LG PLA’s five-year term, and that only LG’s paid-up license with respect to 2G-only products survived the expiration of the term. On February 5, 2016, InterDigital filed a petition in the District Court for the Southern District of New York for an order confirming the arbitration award. Pegatron Actions In first quarter 2015, we learned that on or about February 3, 2015, Pegatron Corporation (“Pegatron”), one of our licensees, filed a civil suit in Taiwan Intellectual Property Court against InterDigital, Inc. and certain of its subsidiaries alleging breach of the Taiwan Fair Trade Act (the “Pegatron Taiwan Action”). On May 26, 2015, InterDigital, Inc. received a copy of the civil complaint filed by Pegatron in the Taiwan Intellectual Property Court. The complaint named as defendants InterDigital, Inc. as well as InterDigital’s wholly owned subsidiaries InterDigital Technology Corporation and IPR Licensing, Inc. (together, for purposes of this discussion, “InterDigital”). The complaint alleged that InterDigital abused its market power by improperly setting, maintaining or changing the royalties Pegatron is required to pay under their 2008 patent license agreement (the “Pegatron PLA”), and engaging in unreasonable discriminatory treatment and other unfair competition activities in violation of the Taiwan Fair Trade Act. The complaint sought minimum damages in the amount of approximately $52 million , which amount could be expanded during the litigation, and that the court order multiple damages based on its claim that the alleged conduct was intentional. The complaint also sought an order requiring InterDigital to cease enforcing the royalty provisions of the Pegatron PLA, as well as all other conduct that allegedly violates the Fair Trade Act. On June 5, 2015 InterDigital filed an Arbitration Demand with the American Arbitration Association’s International Centre for Dispute Resolution (“ICDR”) seeking declaratory relief denying all of the claims in Pegatron’s Taiwan Action and for breach of contract. On or about June 10, 2015, InterDigital filed a complaint in the United States District Court for the Northern District of California, San Jose Division (the “CA Northern District Court”) seeking a Temporary Restraining Order, Preliminary Injunction, and Permanent Anti-suit Injunction against Pegatron prohibiting Pegatron from prosecuting the Pegatron Taiwan Action. The complaint also seeks specific performance by Pegatron of the dispute resolution procedures set forth in the Pegatron PLA and compelling arbitration of the disputes in the Pegatron Taiwan Action. On June 29, 2015, the court granted InterDigital’s motion for a temporary restraining order and preliminary injunction requiring Pegatron to take immediate steps to dismiss the Taiwan Action without prejudice. On July 1, 2015, InterDigital was informed that Pegatron had withdrawn its complaint in the Taiwan Intellectual Property Court and that the case had been dismissed without prejudice. On August 3, 2015, Pegatron filed an answer and counterclaims to InterDigital’s CA Northern District Court complaint. Pegatron accused InterDigital of violating multiple sections of the Taiwan Fair Trade Act, violating Section Two of the Sherman Act, breaching ETSI, IEEE, and ITU contracts, promissory estoppel (pled in the alternative), violating Section 17200 of the California Business & Professions Code, and violating the Delaware Consumer Fraud Act. These counterclaims stem from Pegatron’s accusation that InterDigital violated FRAND obligations. As relief, Pegatron seeks a declaration regarding the appropriate FRAND terms and conditions for InterDigital’s “declared essential patents,” a declaration that InterDigital’s standard essential patents are unenforceable due to patent misuse, an order requiring InterDigital to grant Pegatron a license on FRAND terms, an order enjoining InterDigital’s alleged ongoing breaches of its FRAND commitments, and damages in the amount of allegedly excess non-FRAND royalties Pegatron has paid to InterDigital, plus interest and treble damages. On August 7, 2015, Pegatron responded to InterDigital’s arbitration demand, disputing the arbitrability of Pegatron’s claims. On September 24, 2015, InterDigital moved to compel arbitration and dismiss Pegatron’s counterclaims or, in the alternative, stay the counterclaims pending the parties’ arbitration. Pegatron’s opposition to this motion was filed on October 22, 2015, and InterDigital’s reply was filed on November 12, 2015. On January 20, 2016, the court granted InterDigital’s motion to compel arbitration of Pegatron’s counterclaims and to stay the counterclaims pending the arbitrators’ determination of their arbitrability. On January 27, 2016, the parties stipulated to stay all remaining aspects of the CA Northern District case pending such an arbitrability determination. On the same day, the court granted the stay and administratively closed the case. Microsoft Sherman Act Delaware Proceedings On August 20, 2015, Microsoft Mobile, Inc. and MMO (collectively “Microsoft”) filed a complaint in the United States District Court for the District of Delaware against InterDigital, Inc., InterDigital Communications, Inc., InterDigital Technology Corporation, InterDigital Patent Holdings, Inc., InterDigital Holdings, Inc., and IPR Licensing, Inc. The complaint alleges that InterDigital has monopolized relevant markets for 3G and 4G cellular technology in violation of Section 2 of the Sherman Act. As relief, Microsoft seeks declaratory judgments that InterDigital has violated Section 2 of the Sherman Act, that “each of InterDigital’s U.S. patents declared by it to be Essential” to the 3G and 4G standards is unenforceable, and that all agreements InterDigital has entered into in furtherance of its alleged unlawful conduct are void. Microsoft also seeks an award of treble damages and the following injunctive relief: requiring InterDigital to grant Microsoft a non-confidential license to its U.S. standards essential patents (“SEPs”) on FRAND terms as determined by a court, requiring InterDigital to disclose to Microsoft the terms of its other SEP licenses, preventing InterDigital from enforcing any exclusion orders it might receive with respect to its SEPs, and requiring InterDigital to re-assign any declared SEPs that it has assigned to controlled entities. On November 4, 2015, InterDigital filed a motion to dismiss and to strike Microsoft’s complaint. InterDigital asserts that Microsoft failed to (i) state a Sherman Act claim, (ii) adequately allege the essential elements of monopoly power and exclusionary conduct, (iii) plead its fraud claims with specificity, and (iv) plead any cognizable antitrust injury. InterDigital also claimed that Microsoft’s complaint is barred by the Noerr-Pennington doctrine and that the court should strike Microsoft’s improper prayers for relief and damages arising prior to the applicable statute of limitations. A hearing on this motion is scheduled for March 1, 2016. REGULATORY PROCEEDINGS Investigation by Taiwan Fair Trade Commission On December 6, 2013, InterDigital received notice from the Taiwan Fair Trade Commission (“TFTC”) that the TFTC had initiated an investigation to examine alleged anti-competitive behavior under Taiwan’s Fair Trade Act (FTA). Companies found to violate the FTA may be ordered to cease and rectify the unlawful conduct, take other necessary corrective action, and/or pay an administrative fine. InterDigital is fully cooperating with the TFTC’s investigation. Investigation by National Development and Reform Commission of China On September 23, 2013, counsel for InterDigital was informed by China’s National Development and Reform Commission (“NDRC”) that the NDRC had initiated a formal investigation into whether InterDigital has violated China’s Anti-Monopoly Law (“AML”) with respect to practices related to the licensing of InterDigital’s standards-essential patents to Chinese companies. Companies found to violate the AML may be subject to a cease and desist order, fines and disgorgement of any illegal gains. On March 3, 2014, the Company submitted to NDRC, pursuant to a procedure set out in the AML, a formal application for suspension of the investigation that included proposed commitments by the Company. On May 22, 2014, NDRC formally suspended its investigation of the Company based on the commitments proposed by the Company. The Company’s commitments with respect to the licensing of its patent portfolio for wireless mobile standards to Chinese manufacturers of cellular terminal units ("Chinese Manufacturers") are as follows: 1. Whenever InterDigital engages with a Chinese Manufacturer to license InterDigital's patent portfolio for 2G, 3G and 4G wireless mobile standards, InterDigital will offer such Chinese Manufacturer the option of taking a worldwide portfolio license of only its standards-essential wireless patents, and comply with F/RAND principles when negotiating and entering into such licensing agreements with Chinese Manufacturers. 2. As part of its licensing offer, InterDigital will not require that a Chinese Manufacturer agree to a royalty-free, reciprocal cross-license of such Chinese Manufacturer's similarly categorized standards-essential wireless patents. 3. Prior to commencing any action against a Chinese Manufacturer in which InterDigital may seek exclusionary or injunctive relief for the infringement of any of its wireless standards-essential patents, InterDigital will offer such Chinese Manufacturer the option to enter into expedited binding arbitration under fair and reasonable procedures to resolve the royalty rate and other terms of a worldwide license under InterDigital's wireless standards-essential patents. If the Chinese Manufacturer accepts InterDigital's binding arbitration offer or otherwise enters into an agreement with InterDigital on a binding arbitration mechanism, InterDigital will, in accordance with the terms of the arbitration agreement and patent license agreement, refrain from seeking exclusionary or injunctive relief against such company. The commitments contained in item 3 above will expire five years from the effective date of the suspension of the investigation, or May 22, 2019. USITC PROCEEDINGS AND RELATED DELAWARE DISTRICT COURT PROCEEDINGS Nokia and ZTE 2013 USITC Proceeding (337-TA-868) and Related Delaware District Court Proceedings USITC Proceeding (337-TA-868) On January 2, 2013, the Company's wholly owned subsidiaries InterDigital Communications, Inc., InterDigital Technology Corporation, IPR Licensing, Inc. and InterDigital Holdings, Inc. filed a complaint with the United States International Trade Commission (the “USITC” or “Commission”) against Samsung Electronics Co., Ltd., Samsung Electronics America, Inc. and Samsung Telecommunications America, LLC, Nokia Corporation and Nokia Inc., Huawei Technologies Co., Ltd., Huawei Device USA, Inc. and FutureWei Technologies, Inc. d/b/a Huawei Technologies (USA) and ZTE Corporation and ZTE (USA) Inc. (collectively, the “337-TA-868 Respondents”), alleging violations of Section 337 of the Tariff Act of 1930 in that they engaged in unfair trade practices by selling for importation into the United States, importing into the United States and/or selling after importation into the United States certain 3G and 4G wireless devices (including WCDMA-, cdma2000- and LTE-capable mobile phones, USB sticks, mobile hotspots, laptop computers and tablets and components of such devices) that infringe one or more of up to seven of InterDigital's U.S. patents. The complaint also extended to certain WCDMA and cdma2000 devices incorporating Wi-Fi functionality. InterDigital's complaint with the USITC sought an exclusion order that would bar from entry into the United States infringing 3G or 4G wireless devices (and components), including LTE devices, that are imported by or on behalf of the 337-TA-868 Respondents, and also sought a cease-and-desist order to bar further sales of infringing products that have already been imported into the United States. Certain of the asserted patents were also asserted against Nokia, Huawei and ZTE in earlier pending USITC proceedings (including the Nokia, Huawei and ZTE 2011 USITC Proceeding (337-TA-800) and the Nokia 2007 USITC Proceeding (337-TA-613), as set forth below) and therefore were not asserted against those 337-TA-868 Respondents in this investigation. On December 23, 2013, InterDigital and Huawei reached a settlement agreement to enter into binding arbitration to resolve their global patent licensing disputes (see "Huawei Arbitration" below). Pursuant to the settlement agreement, InterDigital and Huawei moved to dismiss all litigation matters pending between the parties except the action filed by Huawei in China to set a fair, reasonable and non-discriminatory (“FRAND”) rate for the licensing of InterDigital’s Chinese standards-essential patents (discussed below under “Huawei China Proceedings”), the decision in which InterDigital is permitted to further appeal. As a result, effective February 12, 2014, the Huawei Respondents were terminated from the 337-TA-868 investigation. From February 10 to February 20, 2014, ALJ Essex presided over the evidentiary hearing in this investigation. The patents in issue in this investigation as of the hearing were U.S. Patent Nos. 7,190,966 (the “’966 patent”) and 7,286,847 (the “’847 patent”) asserted against ZTE and Samsung, and U.S. Patent No. 7,941,151 (the “’151 patent”) asserted against ZTE, Samsung and Nokia. On June 3, 2014, InterDigital and Samsung filed a joint motion to terminate the investigation as to Samsung on the basis of settlement. The ALJ granted the joint motion by initial determination issued on June 9, 2014, and the USITC determined not to review the initial determination on June 30, 2014. On June 13, 2014, the ALJ issued an Initial Determination (“ID”) in the 337-TA-868 investigation. In the ID, the ALJ found that no violation of Section 337 had occurred in connection with the importation of 3G/4G devices by ZTE or Nokia, on the basis that the accused devices do not infringe asserted claims 1-6, 8-9, 16-21 or 23-24 of the ’151 patent, claims 1, 3, 6, 8, 9, or 11 of the ’966 patent, or claims 3 or 5 of the ’847 patent. The ALJ also found that claim 16 of the ’151 patent was invalid as indefinite. Among other determinations, the ALJ further determined that InterDigital did not violate any FRAND obligations, a conclusion also reached by the ALJ in the 337-TA-800 investigation, and that Respondents have engaged in patent “hold out.” On June 30, 2014, InterDigital filed a Petition for Review with the USITC seeking review and reversal of certain of the ALJ’s conclusions in the ID. On the same day, Respondents filed a Conditional Petition for Review urging alternative grounds for affirmance of the ID’s finding that Section 337 was not violated and a Conditional Petition for Review with respect to FRAND issues. In June 2014, Microsoft Mobile Oy (“MMO”) was added as a respondent in the investigation. On August 14, 2014, the Commission determined to review in part the June 13, 2014 ID but terminated the investigation with a finding of no violation. On October 10, 2014, InterDigital filed a petition for review with the Federal Circuit, appealing certain of the adverse determinations in the Commission’s August 8, 2014 final determination including those related to the ’966 and ’847 patents. On June 2, 2015, InterDigital moved to voluntarily dismiss the Federal Circuit appeal, because, even if it were to prevail, it did not believe there would be sufficient time following the court’s decision and mandate for the USITC to complete its proceedings on remand such that the accused products would be excluded before the ’966 and ’847 patents expire in June 2016. The court granted the motion and dismissed the appeal on June 18, 2015. Related Delaware District Court Proceedings On January 2, 2013, the Company's wholly owned subsidiaries InterDigital Communications, Inc., InterDigital Technology Corporation, IPR Licensing, Inc. and InterDigital Holdings, Inc. filed four related district court actions in the United States District Court for the District of Delaware (the “Delaware District Court”) against the 337-TA-868 Respondents. These complaints allege that each of the defendants infringes the same patents with respect to the same products alleged in the complaint filed by InterDigital in USITC Proceeding (337-TA-868). The complaints seek permanent injunctions and compensatory damages in an amount to be determined, as well as enhanced damages based on willful infringement, and recovery of reasonable attorneys' fees and costs. On January 24, 2013, Huawei filed its answer and counterclaims to InterDigital's Delaware District Court complaint. Huawei asserted counterclaims for breach of contract, equitable estoppel, waiver of right to enjoin and declarations that InterDigital has not offered or granted Huawei licenses on FRAND terms, declarations seeking the determination of FRAND terms and declarations of noninfringement, invalidity and unenforceability of the asserted patents. In addition to the declaratory relief specified in its counterclaims, Huawei seeks specific performance of InterDigital's purported contracts with Huawei and standards-setting organizations, appropriate damages in an amount to be determined at trial, reasonable attorneys' fees and such other relief as the court may deem appropriate. On January 31, 2013, ZTE filed its answer and counterclaims to InterDigital's Delaware District Court complaint; ZTE asserted counterclaims for breach of contract, equitable estoppel, waiver of right to enjoin and declarations that InterDigital has not offered ZTE licenses on FRAND terms, declarations seeking the determination of FRAND terms and declarations of noninfringement, invalidity and unenforceability. In addition to the declaratory relief specified in its counte

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	RELATED PARTY TRANSACTIONS In February 2013, we entered into an R&D collaboration agreement with BIO-key International, Inc. ("BIO-key"), and made a direct investment in the company. The R&D collaboration targeted security technology. As part of the agreement, we acquired approximately 4.0 million shares of BIO-key which were initially valued at $0.5 million . During 2014, we sold approximately 1.4 million of such shares, which had been initially valued at approximately $0.2 million . During 2015, we sold our remaining ownership interest, which had been initially valued at approximately $0.3 million . In 2015 and 2014, we paid zero to BIO-key in relation to the collaboration agreement previously discussed. On September 17, 2013, InterDigital announced that it had entered into a development agreement with a wholly owned subsidiary of DDD Group plc ("DDD") regarding its next generation HD and UHD video processing technologies. Under the terms of the development agreement, DDD and InterDigital collaborated on a video technology project. As part of the agreement, we acquired approximately 7.0 million shares of DDD that were initially valued at $0.9 million . In 2015 and 2014, we paid zero to DDD in relation to the development agreement previously discussed.

Compensation Plans and Programs

Compensation Plans and Programs	12 Months Ended
	Dec. 31, 2015
COMPENSATION PLANS AND PROGRAMS [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	COMPENSATION PLANS AND PROGRAMS Compensation Programs We use a variety of compensation programs to both attract and retain 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 and cash awards to inventors for filed patent applications and patent issuances, as well as stock option awards, time-based RSU awards and performance-based awards under the LTCP. Our LTCP typically includes annual grants with a three-year vesting period; as a result, in any one year, we are typically accounting for three active LTCP cycles. We issue new shares of our common stock to satisfy our obligations under the share-based components of these programs from the 2009 Plan discussed below. However, our Board of Directors has the right to authorize the issuance of treasury shares to satisfy such obligations in the future. Stock Plans On June 4, 2009, our shareholders adopted and approved the 2009 Stock Incentive Plan (the “2009 Plan”), under which current or prospective officers and employees and non-employee directors, consultants and advisors can receive share-based awards such as RSUs, restricted stock, stock options and other stock awards. Our shareholders re-approved the material terms of the 2009 Plan on June 12, 2014. We issue the share-based awards authorized under the 2009 Plan through a variety of compensation programs. The following table summarizes changes in the number of equity instruments available for grant (in thousands) under the 2009 Plan for the current year: Available for Grant Balance at December 31, 2014 1,445 RSUs granted (a) (379 ) Options granted (94 ) Options expired and RSUs canceled 431 Balance at December 31, 2015 1,403 (a) RSUs granted include time-based RSUs, performance-based RSUs and dividend equivalents. RSUs and Restricted Stock Under the 2009 Plan, we may issue RSUs and/or shares of restricted stock to current or prospective officers and employees and non-employee directors, consultants and advisors. Any cancellations of outstanding RSUs granted under the 2009 Plan will increase the number of RSUs and/or shares of restricted stock remaining available for grant under the 2009 Plan. The RSUs vest over periods generally ranging from 0 to 3 years from the date of the grant. During 2015 and 2014, we granted approximately 0.3 million and 0.6 million RSUs, respectively, under the 2009 Plan. We have issued less than 0.1 million shares of restricted stock under the 2009 Plan. At December 31, 2015 and 2014, we had unrecognized compensation cost related to share-based awards of $18.1 million and $17.9 million , respectively. For grants made in 2015, 2014 and 2013 that cliff vest, we expect to amortize the associated unrecognized compensation cost at December 31, 2015 on a straight-line basis over a three-year period. 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 against these goals, the payout range for performance-based RSU awards can be anywhere from 0 to 2 times the value of the award. Information with respect to current RSU activity is summarized as follows (in thousands, except per share amounts): Number of Unvested RSUs Weighted Average Per Share Grant Date Fair Value Balance at December 31, 2014 1,902 $ 35.73 Granted* 379 52.06 Forfeited* (62 ) 38.12 Vested* (490 ) 41.29 Balance at December 31, 2015 1,729 $ 37.65 * These numbers include less than 0.1 million RSUs credited on unvested RSU awards as dividend equivalents. Dividend equivalents accrue with respect to unvested RSU awards 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 level of 200%. The total vest date fair value of the RSUs that vested in 2015, 2014 and 2013 was $26.3 million , $7.7 million and $6.5 million , respectively. The weighted average per share grant date fair value of the awards that vested in 2015, 2014 and 2013 was $41.29 , $31.29 and $42.34 , respectively. Other RSU Grants We also grant RSUs to all non-management Board members and, in special circumstances, management personnel outside of the LTCP. Grants of this type are supplemental to any awards granted to management personnel through the LTCP. Stock Options The 2009 Plan allows for the granting of incentive and non-qualified stock options, as well as other securities. The 2009 Plan authorizes the issuance of up to 3.0 million shares of common stock pursuant to incentive stock options. The administrator of the 2009 Plan, initially the Compensation Committee of the Board of Directors, determines the number of options to be granted. Annually, since 2013, both incentive and non-qualified stock options have been granted pursuant to the LTCP under the 2009 Plan. Under the terms of the 2009 Plan, 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. Under the 2009 Plan, options 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 or over a period of time. We also have approximately 0.1 million options outstanding under a prior stock plan that have an indefinite contractual life. Information with respect to current year stock option activity under the above plans is summarized as follows (in thousands, except per share amounts): Outstanding Options Weighted Balance at December 31, 2014 336 $ 24.90 Granted 94 52.85 Canceled (4 ) 44.19 Exercised (5 ) 9.28 Balance at December 31, 2015 421 $ 31.16 The weighted average remaining contractual life of our outstanding options was 12.3 years as of December 31, 2015 . We currently have approximately 0.1 million options outstanding that have an indefinite contractual life. These options were granted between 1983 and 1986 under a prior stock plan. For purposes of calculating the weighted average remaining contractual life, these options were assigned an original life in excess of 50 years. The majority of these options have an exercise price between $8.00 and $11.63 . The total intrinsic value of stock options exercised during the years ended December 31, 2015 , 2014 and 2013 was $0.2 million , $0.3 million and $1.0 million , respectively. The total intrinsic value of our options outstanding at December 31, 2015 was $7.9 million . In 2015 , we recorded cash received from the exercise of options of less than $0.1 million . Upon option exercise, we issued new shares of stock. At both December 31, 2015 and 2014 , we had approximately 0.3 million options outstanding that had exercise prices less than the fair market value of our stock at each balance sheet date. These options would have generated cash proceeds to the Company of $8.2 million and $8.4 million , respectively, if they had been fully exercised on those dates. 401(k) 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 contribution expense was approximately $1.0 million for each of 2015 , 2014 and 2013 . At our discretion, we may also make a profit-sharing contribution to our employees’ 401(k) accounts.

Income Taxes (Notes)

Income Taxes (Notes)	12 Months Ended
	Dec. 31, 2015
INCOME TAXES: [Abstract]
Income Tax Disclosure [Text Block]	. TAXES Our income tax provision consists of the following components for 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Current Federal $ 42,181 $ 49,049 $ (6,093 ) State 415 2,499 225 Foreign source withholding tax 55,276 70,703 23,269 97,872 122,251 17,401 Deferred Federal (89,026 ) (121,937 ) (18,727 ) State 554 (437 ) 2,614 Foreign source withholding tax 55,221 52,231 24,548 (33,251 ) (70,143 ) 8,435 Total $ 64,621 $ 52,108 $ 25,836 The deferred tax assets and liabilities were comprised of the following components at December 31, 2015 and 2014 (in thousands): 2015 Federal State Foreign Total Net operating losses $ — $ 81,965 $ 140 $ 82,105 Deferred revenue, net 94,203 8 22,473 116,684 Stock compensation 8,147 1,452 — 9,599 Patent amortization 21,217 — — 21,217 Depreciation 929 (64 ) — 865 Other-than-temporary impairment 494 46 — 540 Other accrued liabilities 7,416 509 — 7,925 Other employee benefits 1,888 141 — 2,029 134,294 84,057 22,613 240,964 Less: valuation allowance — (81,893 ) — (81,893 ) Net deferred tax asset $ 134,294 $ 2,164 $ 22,613 $ 159,071 2014 Federal State Foreign Total Net operating losses $ — $ 71,837 $ 4 $ 71,841 Deferred revenue, net 50,575 41 22,657 73,273 Stock compensation 10,567 1,751 — 12,318 Patent amortization 18,337 — — 18,337 Depreciation 1,110 29 — 1,139 Other accrued liabilities 1,097 (28 ) — 1,069 Other-than-temporary impairment 10,010 154 — 10,164 Other employee benefits 8,784 668 — 9,452 100,480 74,452 22,661 197,593 Less: valuation allowance — (71,731 ) — (71,731 ) Net deferred tax asset $ 100,480 $ 2,721 $ 22,661 $ 125,862 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, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Tax at U.S. statutory rate 35.0 % 35.0 % 35.0 % State tax provision 0.5 % 0.1 % 4.1 % Change in federal and state valuation allowance — % — % 0.4 % Research and development tax credits (1.2 )% (4.7 )% — % Uncertain tax positions — % 0.9 % — % Permanent differences 1.2 % 1.5 % 3.5 % Settlement with taxing authorities 0.1 % 1.1 % — % Other 0.1 % 0.1 % (1.1 )% Total tax provision 35.7 % 34.0 % 41.9 % 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. We believe it is more likely than not that the majority of our state deferred tax assets will not be utilized; therefore we have maintained a near full valuation allowance against our state deferred tax assets as of December 31, 2015 . All other deferred tax assets are fully benefited. We recognize excess tax benefits associated with share-based compensation to shareholders’ equity only when realized. When assessing whether excess tax benefits relating to share-based compensation have been realized, we follow the with and without approach excluding any indirect effects of the excess tax deductions. Under the approach, excess tax benefits related to share-based compensation are not deemed to be realized until after the utilization of all other tax benefits available to the Company. During 2015, we realized $2.5 million of tax windfalls and accordingly recorded a corresponding credit to additional paid-in capital. During 2014, we recorded a shortfall of $1.2 million and recorded a corresponding debit to additional paid-in capital. We had sufficient windfall benefits previously recorded in additional paid-in capital to offset the shortfall in 2014. During 2013, we realized $0.8 million of such excess tax benefits for federal purposes, and accordingly recorded a corresponding credit to additional paid-in capital. As of December 31, 2015 and 2014, we had $12.3 million and $12.2 million , respectively, of state unrealized tax benefits associated with share-based compensation. These state tax benefits will be accounted for as a credit to additional paid-in capital, if and when realized, rather than a reduction of the provision for income taxes. Uncertain Income Tax Positions As of December 31, 2015, 2014 and 2013, we had $1.5 million , $1.4 million and zero , respectively, of unrecognized tax benefits. 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 2015, the reserve was increased for interest and penalty on previously recognized reserves, and we also established a reserve of $0.1 million related to the recognition of the 2015 research and development credit. During 2014, we established a reserve of $0.7 million related to the recognition of a gross benefit for research and development credits. We also recorded $0.7 million of unrecognized tax benefits related to certain deductions that may not be allowed by the Internal Revenue Code. 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 2013 through 2015 (in thousands): 2015 2014 2013 Balance as of January 1 $ 1,361 $ — $ — Tax positions related to current year: Additions 141 95 — Reductions — — — Tax positions related to prior years: Additions — 1,266 — Reductions (33 ) — — Settlements — — — Lapses in statues of limitations — — — Balance as of December 31 $ 1,469 $ 1,361 $ — Our policy is to recognize interest and/or penalties related to income tax matters in income tax expense. Because we had zero unrecognized tax benefits as of December 31, 2013, we also had zero accrued interest as of the same date. For certain positions that related to years prior to 2015, we have recorded less than $0.1 million of accrued interest during 2015 and 2014. 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 2010 to the present 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 2019. The 2015 return is expected to be filed by September 15, 2016 and the statute of limitations will expire three years from the date it is filed. Specific tax treaty procedures remain open for certain jurisdictions for 2006, 2007 and 2008. 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 $1.5 billion . The U.S. Internal Revenue Service ("IRS") has concluded their audit of tax years 2010 through 2012 and the refund, related to research and development tax credits, was being reviewed by the Joint Committee on Taxation, as all refund claims in excess of $5.0 million are reviewed. Subsequent to December 31, 2015, we received notice from the Joint Committee on Taxation that its review was concluded with no changes. We expect to receive the refund amount as filed. Additionally, we will reverse our reserve for unrecognized tax benefits of $0.6 million in first quarter 2016. We are under audit by one state for tax years 2012 through 2013. Currently we do not expect any material adjustments to our previous tax filings as a result of this audit. No other federal, state or foreign audits are in process. The IRS examination for 2011 was closed in 2014 resulting in no changes. A state audit for the years 2002 to 2008 was concluded in 2014 resulting in a $2.5 million settlement. Additional periods, 2010 to 2012, were resolved in 2015 resulting in a $0.4 million settlement. Foreign Taxes We pay foreign source withholding taxes on patent license royalties and state taxes 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 2015 , 2014 and 2013 , we paid $55.3 million , $70.7 million and $23.3 million in foreign source withholding taxes, respectively, and applied these payments as credits against our United States federal tax obligation. Between 2006 and 2015, we paid approximately $295.1 million in foreign taxes for which we have claimed foreign tax credits against our U.S. tax obligations. 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 both foreign currency fluctuations and differences in the interest rate charged by the U.S. government compared to the interest rates, if any, used by the foreign governments, any such agreement could result in interest expense and/or foreign currency gain or loss.

Equity Transactions (Notes)

Equity Transactions (Notes)	12 Months Ended
	Dec. 31, 2015
EQUITY TRANSACTIONS: [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	EQUITY TRANSACTIONS Repurchase of Common Stock In May 2012, our Board of Directors authorized a share repurchase program, which was then expanded in June 2012 to increase the amount of the program from $100 million to $200 million (the "2012 Repurchase Program"). Of the $200 million authorized under the 2012 Repurchase Program, $106.8 million was utilized prior to the termination of the program in June 2014. In June 2014, our Board of Directors authorized a new share repurchase program, which was expanded in June 2015 to increase the amount of the program from $300 million to $400 million (the “2014 Repurchase Program"). We 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 for the periods presented the number of shares repurchased and the dollar value of shares repurchased under the 2012 Repurchase Program and the 2014 Repurchase Program, in thousands. 2012 Repurchase Program 2014 Repurchase Program Total Both Programs # of Shares Value # of Shares Value # of Shares Value 2015 — $ — 1,836 $ 96,410 1,836 $ 96,410 2014 — — 3,554 152,625 3,554 152,625 2013 917 29,135 — — 917 29,135 Prior to 2013 2,552 77,694 — — 2,552 77,694 Total 3,469 $ 106,829 5,390 $ 249,035 8,859 $ 355,864 Dividends Cash dividends on outstanding common stock declared in 2015 and 2014 were as follows (in thousands, except per share data): 2015 Per Share Total Cumulative by Fiscal Year First quarter $ 0.20 $ 7,232 $ 7,232 Second quarter 0.20 7,243 14,475 Third quarter 0.20 7,183 21,658 Fourth quarter 0.20 7,068 28,726 $ 0.80 $ 28,726 2014 First quarter $ 0.10 $ 3,954 $ 3,954 Second quarter 0.20 8,033 11,987 Third quarter 0.20 7,666 19,653 Fourth quarter 0.20 7,500 27,153 $ 0.70 $ 27,153 In June 2014, we announced that our Board of Directors had approved a 100% increase in the Company's quarterly cash dividend, to $0.20 per share. We currently expect to continue to pay dividends comparable to our quarterly $0.20 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. Common Stock Warrants On March 29, 2011 and March 30, 2011, we entered into privately negotiated warrant transactions with Barclays Bank PLC through its agent, Barclays Capital Inc., whereby we sold to Barclays Bank PLC warrants to acquire, subject to customary anti-dilution adjustments, approximately 3.5 million and approximately 0.5 million shares of our common stock, respectively, at a strike price of approximately $63.18 per share, subject to adjustment, as updated. The warrants become exercisable in tranches starting in June 2016. In consideration for the warrants issued on March 29, 2011 and March 30, 2011, we received $27.6 million and $4.1 million , respectively, on April 4, 2011. On March 5 and March 9, 2015, we sold warrants to acquire, subject to customary anti-dilution adjustments, approximately 3.8 million and approximately 0.6 million , respectively, of common stock at an initial strike price of approximately $88.46 per share. The warrants become exercisable in tranches starting in June 2020. As consideration for the warrants issued on March 5 and March 9, 2015, we received approximately $37.3 million and approximately $5.6 million , respectively.

Selected Quarterly Results

Selected Quarterly Results	12 Months Ended
	Dec. 31, 2015
SELECTED QUARTERLY RESULTS (Unaudited) [Abstract]
Quarterly Financial Information [Text Block]	SELECTED QUARTERLY RESULTS (UNAUDITED) The table below presents quarterly data for the years ended December 31, 2015 and 2014 : First Second Third Fourth (In thousands, except per share amounts, unaudited) 2015 Revenues $ 110,378 $ 118,551 $ 100,408 $ 112,098 Net income applicable to InterDigital, Inc.'s common shareholders $ 29,065 $ 32,602 $ 24,520 $ 33,038 Net income per common share — basic $ 0.79 $ 0.91 $ 0.68 $ 0.93 Net income per common share — diluted $ 0.78 $ 0.89 $ 0.68 $ 0.92 2014 Revenues (a) $ 57,844 $ 194,234 $ 77,622 $ 86,121 Net income applicable to InterDigital, Inc.'s common shareholders $ (1,861 ) $ 78,901 $ 13,512 $ 13,790 Net income per common share — basic $ (0.05 ) $ 1.95 $ 0.34 $ 0.37 Net income per common share — diluted $ (0.05 ) $ 1.93 $ 0.34 $ 0.36 (a) In second quarter 2014, we recognized $119.9 million of past patent royalties primarily due to new patent license agreements.

Subsequent Event (Notes)

Subsequent Event (Notes)	12 Months Ended
	Dec. 31, 2015
Subsequent Event [Line Items]
Subsequent Events [Text Block]	15. SUBSEQUENT EVENTS We anticipate a severance charge in the range of $1.5 million to $2.0 million during first quarter 2016 related to ongoing efforts to optimize our cost

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Notes to Financial Statements [Abstract]
Reclassifications [Text Block]	Reclassifications Certain reclassifications have been made to prior year amounts to conform to the current year presentation.
Consolidation, Variable Interest Entity, Policy [Policy Text Block]	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. 14. VARIABLE INTEREST ENTITIES As further discussed below, we are the primary beneficiary of two variable interest entities. As of December 31, 2015, the combined book values of the assets and liabilities associated with these variable interest entities included in our Consolidated Balance Sheet were $24.2 million and $0.8 million , respectively. Assets included $19.0 million of cash and cash equivalents and $5.2 million of patents, net. As of December 31, 2014, the combined book values of the assets and liabilities associated with these variable interest entities included in our Consolidated Balance Sheet were $15.3 million and $0.4 million , respectively. Assets included $11.4 million of cash and cash equivalents and $3.9 million of patents, net. The impact of consolidating these variable interest entities on our Consolidated Statements of Income was not significant. Convida Wireless On September 26, 2015, we renewed and expanded our joint venture with Sony, Convida Wireless, to include 5G technologies. Convida Wireless was launched in 2013 to combine Sony's consumer electronics expertise with our pioneering 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, 2015, 2014 and 2013, we have allocated approximately $2.8 million , $2.9 million and $2.5 million , respectively, of Convida Wireless' net loss to noncontrolling interests held by other parties. Signal Trust for Wireless Innovation On October 17, 2013, we announced the establishment of the Signal Trust for Wireless Innovation ("Signal Trust"), the goal of which is to monetize a large patent portfolio related to cellular infrastructure. The more than 500 patents and patent applications transferred from InterDigital to the Signal Trust focus primarily on 3G and LTE technologies, and were developed by InterDigital's engineers and researchers over more than a decade, with a number of the innovations contributed to the worldwide standards process. InterDigital is the primary beneficiary of the Signal Trust. The distributions from the Signal Trust will support continued research related to cellular wireless technologies. A small portion of the proceeds from the Signal Trust will be used to fund, through the newly formed Signal Foundation for Wireless Innovation, scholarly analysis of intellectual property rights and the technological, commercial and creative innovations they facilitate. The Signal Trust is a variable interest entity. Based on the terms of the Trust Agreement, we have determined that we are the primary beneficiary for accounting purposes and must consolidate the Signal Trust.
Consolidation, Policy [Policy Text Block]	Principles of Consolidation The accompanying consolidated financial statements include all of our accounts and all entities which we have a controlling interest, which 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.
Use of Estimates, Policy [Policy Text Block]	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.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents We classify all highly liquid investment securities with original maturities of three months or less at date of purchase as cash equivalents. 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. Cash and cash equivalents at December 31, 2015 and 2014 consisted of the following (in thousands): December 31, 2015 2014 Money market and demand accounts $ 333,671 $ 307,995 Commercial paper 176,536 120,572 $ 510,207 $ 428,567
Marketable Securities, Available-for-sale Securities, Policy [Policy Text Block]	Short-Term Investments At December 31, 2015 and 2014 , all 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 3 years, and we have both the ability and intent to hold the investments until maturity. During 2015 and 2014 , we recorded other-than-temporary impairments of approximately $0.2 million and $0.6 million , respectively. These amounts were included within the realized losses for these periods shown in the table below. Net unrealized gain on short-term investments was $0.1 million at December 31, 2014. Net unrealized loss on short-term investments was $0.3 million and $0.9 million at December 31, 2015 and 2013, respectively. Realized gains and losses for 2015 , 2014 and 2013 were as follows (in thousands): Year Gains Losses Net 2015 $ — $ (309 ) $ (309 ) 2014 $ 48 $ (681 ) $ (633 ) 2013 $ 166 $ (678 ) $ (512 ) Short-term investments as of December 31, 2015 and 2014 consisted of the following (in thousands): December 31, 2015 2014 Commercial paper $ 200,811 $ 86,877 U.S. government agency instruments 183,950 151,618 Corporate bonds and asset backed securities 38,740 36,866 $ 423,501 $ 275,361 At December 31, 2015 and 2014 , $373.7 million and $151.4 million , respectively, of our short-term investments had contractual maturities within one year. The remaining portions of our short-term investments had contractual maturities primarily within two to five years
Fair Value of Financial Instruments, Policy [Policy Text Block]	Concentration of Credit Risk and Fair Value of Financial Instruments Financial instruments that potentially subject us to concentration of credit risk consist primarily of cash equivalents, short-term investments and accounts receivable. We place our cash equivalents and short-term investments only in highly rated financial instruments and in United States government instruments. Our accounts receivable are derived principally from patent license and technology solutions agreements. At December 31, 2015 , four licensees comprised 97% of our net accounts receivable balance. At December 31, 2014 , three licensees represented 94% of our net 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 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. Our financial assets are included within short-term investments on our consolidated balance sheets, unless otherwise indicated. Our financial assets that are accounted for at fair value on a recurring basis are presented in the tables below as of December 31, 2015 and December 31, 2014 (in thousands): Fair Value as of December 31, 2015 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 333,671 $ — $ — $ 333,671 Commercial paper (b) — 377,347 — 377,347 U.S. government securities — 183,950 — 183,950 Corporate bonds, asset backed and other securities 183 38,557 — 38,740 $ 333,854 $ 599,854 $ — $ 933,708 _______________ (a) Included within cash and cash equivalents. (b) Includes $176.5 million of commercial paper that is included within cash and cash equivalents. Fair Value as of December 31, 2014 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 307,995 $ — $ — $ 307,995 Commercial paper (b) — 207,449 — 207,449 U.S. government securities — 151,618 — 151,618 Corporate bonds and asset backed securities 671 36,195 — 36,866 $ 308,666 $ 395,262 $ — $ 703,928 _______________ (a) Included within cash and cash equivalents. (b) Includes $120.6 million of commercial paper that is included within cash and cash equivalents. The principal amount, carrying value and related estimated fair value of the Company's long-term debt reported in the Condensed Consolidated Balance Sheets as of December 31, 2015 and December 31, 2014 are as follows (in thousands): December 31, 2015 December 31, 2014 Principal Amount Carrying Value Fair Value Principal Amount Carrying Fair Value Total Long-Term Debt $ 546,000 $ 486,769 $ 533,203 $ 230,000 $ 216,206 $ 255,300 The aggregate fair value of the principal amount of the long-term debt (Level 2 Notes as defined in Note 6 " Obligations ") was calculated using inputs such as actual trade data, benchmark yields, broker/dealer quotes and other similar data, which were obtained from independent pricing vendors, quoted market prices or other sources. As discussed in Note 3, " Significant Events ," we acquired patents as part of the multiple-element arrangements entered into in 2015. We have recorded these patents based on their total estimated fair value of $24.1 million and will amortize them over their estimated useful lives. We estimated the fair value of the patents in each transaction by a combination of an analysis of comparable market transactions (the market approach) and discounted cash flow analysis (the income 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.
Property, Plant and Equipment, Policy [Policy Text Block]	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 to five years. Leasehold improvements are amortized over the lesser of their estimated useful lives or their respective lease terms, which are generally five to ten years. Buildings are being depreciated over twenty-five years. Expenditures for major improvements and betterments are capitalized, while minor repairs and maintenance are charged to expense as incurred. Leases meeting certain capital lease criteria are capitalized and the net present value of the related lease payments is recorded as a liability. Amortization of capital leased assets is recorded using the straight-line method over the lesser of the estimated useful lives or the lease terms. Upon the retirement or disposition of property, plant and equipment, the related cost and accumulated depreciation or amortization are removed, and a gain or loss is recorded.
Internal Use Software, Policy [Policy Text Block]	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 or Disposal of Long-Lived Assets, Policy [Policy Text Block]	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 Expense (Net) line of our Consolidated Statements of Income. 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 recorded approximately $0.2 million of long-lived asset impairments in 2015 . We did not have any long-lived asset impairments in 2014 or 2013 .
Equity and Cost Method Investments, Policy [Policy Text Block]	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 account for our investments using either the cost or equity method of accounting. Under the cost method, we do not adjust our investment balance when the investee reports profit or loss but monitor the investment for an other-than-temporary decline in value. On a quarterly basis, we monitor our investment’s financial position and performance to assess whether there are any triggering events or indicators present that would be indicative of an other-than-temporary impairment of our investment. When assessing whether an other-than-temporary decline in value has occurred, we consider such factors as the valuation placed on the investee in subsequent rounds of financing, the performance of the investee relative to its own performance targets and business plan, and the investee’s revenue and cost trends, liquidity and cash position, including its cash burn rate, and updated forecasts. Under the equity method of accounting, 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 costs of our investments are included within Other Non-Current Assets on our Consolidated Balance Sheets. During 2015, we made investments in two separate entities for a total of $12.6 million . Due to the fact that we do not have significant influence over either organization, we are accounting for these investments using the cost method of accounting. The carrying value of these investments as of December 31, 2015 was $12.6 million .
Intangible Assets, Finite-Lived, Policy [Policy Text Block]	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 ten 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 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 thus far has been 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. Patents consisted of the following (in thousands, except for useful life data): December 31, 2015 2014 Weighted average estimated useful life (years) 9.9 10.0 Gross patents $ 511,503 $ 455,447 Accumulated amortization (233,924 ) (189,907 ) Patents, net $ 277,579 $ 265,540 Amortization expense related to capitalized patent costs was $44.0 million , $38.4 million and $29.8 million in 2015 , 2014 and 2013 , 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, 2015 is as follows (in thousands): 2016 $ 46,700 2017 43,876 2018 38,594 2019 35,718 2020 30,946
Goodwill and Intangible Assets, Intangible Assets, Indefinite-Lived, Policy [Policy Text Block]	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.
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition We derive the vast majority of our revenue from patent licensing. The timing and amount of revenue recognized from each licensee depends upon a variety of factors, including the specific terms of each agreement and the nature of the deliverables and obligations. Such agreements are often complex and include multiple elements. These agreements can include, without limitation, elements related to the settlement of past patent infringement liabilities, up-front and non-refundable license fees for the use of patents and/or know-how, patent and/or know-how licensing royalties on covered products sold by licensees, cross-licensing terms between us and other parties, the compensation structure and ownership of intellectual property rights associated with contractual technology development arrangements, advanced payments and fees for service arrangements and settlement of intellectual property enforcement. For agreements entered into or materially modified prior to 2011, due to the inherent difficulty in establishing reliable, verifiable, and objectively determinable evidence of the fair value of the separate elements of these agreements, the total revenue resulting from such agreements has often been recognized over the performance period. Beginning in January 2011, all new or materially modified agreements are being accounted for under the Financial Accounting Standards Board ("FASB") revenue recognition guidance, "Revenue Arrangements with Multiple Deliverables." This guidance requires consideration to be allocated to each element of an agreement that has stand alone value using the relative fair value method. In other circumstances, such as those agreements involving consideration for past and expected future patent royalty obligations, after consideration of the particular facts and circumstances, the appropriate recording of revenue between periods may require the use of judgment. In all cases, revenue is only recognized after all of the following criteria are met: (1) written agreements have been executed; (2) delivery of technology or intellectual property rights has occurred or services have been rendered; (3) fees are fixed or determinable; and (4) collectibility of fees is reasonably assured. We establish a receivable for payments expected to be received within twelve months from the balance sheet date based on the terms in the license. Our reporting of such payments often results in an increase to both accounts receivable and deferred revenue. Deferred revenue associated with fixed-fee royalty payments is classified on the balance sheet as short-term when it is scheduled to be amortized within twelve months from the balance sheet date. All other deferred revenue is classified as long-term, as amounts to be recognized over the next twelve months are not known. 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 for revenue arrangements with multiple deliverables. We have elected to utilize the leased-based model for revenue recognition, with revenue being recognized over the expected period of benefit to the licensee. 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 when we have obtained a signed agreement, identified a fixed or determinable price and determined that collectibility is reasonably assured. Fixed-Fee Royalty Payments: These are up-front, 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). We recognize revenues related to Fixed-Fee Royalty Payments on a straight-line basis over the effective term of the license. We utilize the straight-line method because we cannot reliably predict in which periods, within the term of a license, the licensee will benefit from the use of our patented inventions. Prepayments: These are up-front, non-refundable royalty payments towards a licensee’s future obligations to us related to its expected sales of covered products in future periods. Our licensees’ obligations to pay royalties typically extend beyond the exhaustion of their Prepayment balance. Once a licensee exhausts its Prepayment balance, we may provide them with the opportunity to make another Prepayment toward future sales or it will be required to make Current Royalty Payments. Current Royalty Payments: These are royalty payments covering a licensee’s obligations to us related to its sales of covered products in the current contractual reporting period. Licensees that either owe us Current Royalty Payments or have Prepayment balances are obligated to 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, it is impractical for us to recognize revenue in the period in which the underlying sales occur, and, in most cases, we recognize revenue in the period in which the royalty report is received and other revenue recognition criteria are met due to the fact that without royalty reports from our licensees, our visibility into our licensees’ sales is very limited. When a licensee is required to gross-up their royalty payment to cover applicable foreign withholding tax requirements, the additional consideration is recorded in revenue. The exhaustion of Prepayments and Current Royalty Payments are often calculated based on related per-unit sales of covered products. From time to time, licensees will not report revenues in the proper period, most often due to legal disputes. When this occurs, the timing and comparability of royalty revenue could be affected. In cases where we receive objective, verifiable evidence that a licensee has discontinued sales of products covered under a patent license agreement with us, we recognize any related deferred revenue balance in the period that we receive such evidence. 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 when there is persuasive evidence of a sales arrangement, fees are fixed or determinable, delivery has occurred and collectibility is reasonably assured. These requirements are generally fulfilled upon closing of the patent sale transaction. Technology Solutions and Engineering Services Technology solutions revenue consists primarily of revenue from royalty payments. We recognize revenue from royalty payments using the same methods described above under our policy for recognizing revenue from patent license agreements. Technology solutions revenues also consist of revenues from software licenses and engineering services. Software license revenues are recognized in accordance with the original and revised guidance for software revenue recognition. When the arrangement with a customer includes significant production, modification, or customization of the software, we recognize the related revenue using the percentage-of-completion method in accordance with the accounting guidance for construction-type and certain production-type contracts. Under this method, revenue and profit are recognized throughout the term of the contract, based on actual labor costs incurred to date as a percentage of the total estimated labor costs related to the contract. Changes in estimates for revenues, costs and profits are recognized in the period in which they are determinable. When such estimates indicate that costs will exceed future revenues and a loss on the contract exists, a provision for the entire loss is recognized at that time. We recognize revenues associated with engineering service arrangements that are outside the scope of the accounting guidance for construction-type and certain production-type contracts on a straight-line basis, unless evidence suggests that the revenue is earned in a different pattern, over the contractual term of the arrangement or the expected period during which those specified services will be performed, whichever is longer. In such cases we often recognize revenue using proportional performance and measure the progress of our performance based on the relationship between incurred labor hours and total estimated labor hours or other measures of progress, if available. Our most significant cost has been labor and we believe both labor hours and labor cost provide a measure of the progress of our services. The effect of changes to total estimated contract costs is recognized in the period such changes are determined.
Deferred Charges, Policy [Policy Text Block]	Deferred Charges 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 related to both prepayments and fixed-fee royalty payments and amortize these expenses in proportion to our recognition of the related revenue. In 2015 , 2014 and 2013 , we paid cash commissions of less than $0.1 million , approximately $0.3 million and less than $0.1 million , respectively. Incremental direct costs incurred related to acquisition or origination of a customer contract in a transaction that results in the deferral of revenue may be either expensed as incurred or capitalized. The only eligible costs for deferral are those costs directly related to a particular revenue arrangement. We capitalize those direct costs incurred for the acquisition of a contract through the date of signing, and amortize them on a straight-line basis over the life of the patent license agreement. There were no direct contract origination costs incurred during 2015, 2014, or 2013. Incremental direct costs incurred related to a debt financing transaction may be capitalized. In connection with our offerings of the Notes, discussed in detail within Note 6, 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 to interest expense over the term of the debt using the effective interest method. The costs allocated to the equity component of the debt were recorded as a reduction of the equity component of the debt. There were no debt issuance costs incurred in 2014 or 2013 . Deferred charges are recorded in our Consolidated Balance Sheets within the following captions (in thousands): December 31, 2015 2014 Prepaid and other current assets Deferred commission expense $ 245 $ 342 Deferred contract origination costs — 79 Other non-current assets Deferred commission expense 196 495 Deferred contract origination costs — 79 Long-term debt (including current portion of long-term debt) Deferred financing costs 6,117 1,629 Commission expense was approximately $0.6 million , $0.4 million and $0.3 million in 2015 , 2014 and 2013 , respectively. Commission expense is included within the Patent administration and licensing line of our Consolidated Statements of Income. Deferred contract origination expense recognized in 2015 , 2014 and 2013 was less than $0.1 million in each period and is included within the Patent administration and licensing line of our Consolidated Statements of Income. Deferred financing expense was $2.5 million in 2015 and $1.3 million in both 2014 and 2013 . Deferred financing expense is included within the Other Expense (Net) line of our Consolidated Statements of Income.
Research and Development Expense, Policy [Policy Text Block]	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 $72.7 million , $75.3 million and $64.7 million in 2015 , 2014 and 2013 , respectively.
Compensation Related Costs, Policy [Policy Text Block]	Compensation Programs Our compensation programs include, but are not limited to, short-term incentive awards tied to performance goals and cash awards to inventors for filed patent applications and patent issuances, as well as stock option awards, time-based restricted stock unit (“RSU”) awards and performance-based awards under our long-term compensation program ("LTCP"). Our LTCP typically includes annual grants with a three-year vesting period; as a result, in any one year, we are typically accounting for three active LTCP cycles. The aggregate amount of performance compensation expense we record in a period, under both short-term and long-term performance compensation programs, requires the input of subjective assumptions and is a function of our estimated progress toward performance compensation goals at the beginning of the period, and our estimated progress or final assessment of progress toward performance compensation goals at the end of the period. Our estimated progress toward goals under performance equity grants is based on a meeting a minimum confidence level in accordance with ASC 718. Achievement rates can vary by performance cycle and from period to period, resulting in variability in our compensation expense. We account for compensation costs associated with share-based transactions based on the fair value of the instruments issued, net of any estimated award forfeitures. This requires us to make subjective assumptions around the value of the equity at the time of issuance and the expected forfeiture rates, which in both cases are generally based on historical experience. At December 31, 2015, 2014 and 2013, we have estimated the forfeiture rates for outstanding RSUs to be between 0% and 25% over their lives of one to three years, depending upon the type of grant and the specific terms of the award issued. The estimated value of stock options includes assumptions around expected life, stock volatility, and dividends. The expected life of our stock option awards are 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. In 2006, we adopted the short-cut method to establish the historical additional paid-in-capital pool (“APIC Pool”) related to the tax effects of employee share-based compensation. Any positive balance would be available to absorb tax shortfalls (which occur when the tax deductions resulting from share-based compensation are less than the related book expense) recognized subsequent to the adoption of the stock-based compensation guidance.
Income Tax, Policy [Policy Text Block]	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 that includes the enactment date. 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 Internal Revenue Service (“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 benefi t for a 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. Between 2006 and 2015, we paid approximately $295.1 million in foreign taxes for which we have claimed foreign tax credits against our U.S. tax obligations. 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 and offsetting reduction in our foreign tax credits. Due to both foreign currency fluctuations and differences in the interest rate charged by the U.S. government compared to the interest rates, if any, used by the foreign governments, any such agreement could result in net interest expense and/or foreign currency gain or loss. During 2015, we estimated a research and development credit for the 2015 period that resulted in an approximately $2.1 million tax benefit net of any unrecognized tax benefits. During 2014, we completed the research and development credit studies for the periods from 2010 to 2013 and amended our United States federal income tax returns for the periods from 2010 through 2012 to claim the research and development credit for those periods. After all periods were amended and the 2013 federal income tax return was filed, we recognized a net benefit after consideration of any unrecognized tax benefits from the tax credits in the amount of $5.7 million . Additionally, in 2014, we recognized a benefit after consideration of any unrecognized tax benefits of $0.9 million for the estimated research and development credit for 2014. In addition, in 2014, we recorded $0.7 million of unrecognized tax benefits related to other matters.
Earnings Per Share, Policy [Policy Text Block]	Net Income Per Common 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, 2015 2014 2013 Basic Diluted Basic Diluted Basic Diluted Numerator: Net income applicable to common shareholders $ 119,225 $ 119,225 $ 104,342 $ 104,342 $ 38,165 $ 38,165 Denominator: Weighted-average shares outstanding: Basic 36,048 36,048 39,420 39,420 41,115 41,115 Dilutive effect of stock options, RSUs and convertible securities 415 459 309 Weighted-average shares outstanding: Diluted 36,463 39,879 41,424 Earnings Per Share: Net income: Basic $ 3.31 3.31 $ 2.65 2.65 $ 0.93 0.93 Dilutive effect of stock options, RSUs and convertible securities (0.04 ) (0.03 ) (0.01 ) Net income: Diluted $ 3.27 $ 2.62 $ 0.92 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 less than the average market price of our common stock for the years ended December 31, 2015 , 2014 and 2013 , 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, 2015 2014 2013 Restricted stock units and stock options 211 75 79 Convertible securities 7,656 4,130 4,130 Warrants 7,656 4,130 4,130 Total 15,523 8,335 8,339
New Accounting Pronouncement or Change in Accounting Principle, Description	New Accounting Guidance Accounting Standards Update: Balance Sheet Classification of Deferred Taxes In November 2015, as part of their simplification initiative, the FASB issued amendments to guidance for reporting deferred taxes. According to the revised standard, an entity will be required to present deferred tax assets and deferred tax liabilities as noncurrent in a classified balance sheet. Under current guidance, entities separate deferred tax assets and deferred tax liabilities as current or noncurrent based on the classification of the related asset or liability for financial reporting. The guidance is effective for interim and annual periods beginning on or after December 15, 2016 but early adoption is permitted. We elected to early adopt this guidance effective fourth quarter 2015, and we retrospectively applied the change within our Consolidated Balance Sheets included in this Annual Report on Form 10-K. The impact of this change to our December 31, 2014 Consolidated Balance Sheet was a reduction of $54.0 million to current deferred tax assets and a corresponding increase of $54.0 million to noncurrent deferred tax assets. Accounting Standards Update: Debt Issuance Costs In March 2015, as part of their simplification initiative, the FASB issued amendments to guidance for reporting debt issuance costs. According to the revised standard, an entity will recognize debt issuance costs as a direct deduction from the debt liability as opposed to an asset. The costs will continue to be amortized and included within interest expense in the entity's financial statements. The guidance is effective for interim and annual periods beginning on or after December 15, 2015 but early adoption is permitted. We elected to early adopt this guidance effective first quarter 2015, and we retrospectively applied the change within our Consolidated Balance Sheets included in this Annual Report on Form 10-K. The impact of this change to our December 31, 2014 Consolidated Balance Sheet was a reduction of $1.3 million and a reduction of $0.3 million to Prepaid and other current assets and Other non-current assets, respectively, and a corresponding $1.6 million reduction to Long-term debt. Accounting Standards Update: Consolidation In February 2015, the FASB issued ASU No. 2015-2, “Consolidation (Topic 820): Amendments to the Consolidation Analysis.” ASU 2015-2 provides a revised consolidation model for all reporting entities to use in evaluating whether they should consolidate certain legal entities. All legal entities will be subject to reevaluation under this revised consolidation model. The revised consolidation model, among other things, (i) modifies the evaluation of whether limited partnerships and similar legal entities are voting interest entities, or VIEs, (ii) eliminates the presumption that a general partner should consolidate a limited partnership and (iii) modifies the consolidation analysis of reporting entities that are involved with VIEs through fee arrangements and related party relationships. ASU 2015-2 is effective for fiscal years, and interim reporting periods within those fiscal years, beginning after December 15, 2015. We are still evaluating what impact, if any, this ASU will have on our consolidated financial position, results of operations or cash flows. Accounting Standards Update: Revenue Recognition In May 2014, the FASB issued guidance on revenue from contracts with customers that will supersede most current revenue recognition guidance, including industry-specific guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance provides a five-step analysis of transactions to determine when and how revenue is recognized. Other major provisions include capitalization of certain contract costs, consideration of time value of money in the transaction price, and allowing estimates of variable consideration to be recognized before contingencies are resolved in certain circumstances. The guidance also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from an entity’s contracts with customers. The guidance is effective for the interim and annual periods beginning on or after December 15, 2017 (early adoption is permitted as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within those annual periods). The guidance permits the use of either a retrospective or cumulative effect transition method. We have not yet selected a transition method. We are currently evaluating the effect that adopting this guidance will have on our financial position, results of operations and cash flows.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Notes to Financial Statements [Abstract]
Schedule of Cash and Cash Equivalents [Table Text Block]	Cash and cash equivalents at December 31, 2015 and 2014 consisted of the following (in thousands): December 31, 2015 2014 Money market and demand accounts $ 333,671 $ 307,995 Commercial paper 176,536 120,572 $ 510,207 $ 428,567
Realized Gain (Loss) on Investments [Table Text Block]	ized gains and losses for 2015 , 2014 and 2013 were as follows (in thousands): Year Gains Losses Net 2015 $ — $ (309 ) $ (309 ) 2014 $ 48 $ (681 ) $ (633 ) 2013 $ 166 $ (678 ) $ (512 ) Short-ter
Available-for-sale Securities [Table Text Block]	Short-term investments as of December 31, 2015 and 2014 consisted of the following (in thousands): December 31, 2015 2014 Commercial paper $ 200,811 $ 86,877 U.S. government agency instruments 183,950 151,618 Corporate bonds and asset backed securities 38,740 36,866 $ 423,501 $ 275,361
Fair Value, Measurement Inputs, Disclosure [Table Text Block]	Fair Value Measurements We use various valuation techniques and assumptions when measuring 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. Our financial assets are included within short-term investments on our consolidated balance sheets, unless otherwise indicated. Our financial assets that are accounted for at fair value on a recurring basis are presented in the tables below as of December 31, 2015 and December 31, 2014 (in thousands): Fair Value as of December 31, 2015 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 333,671 $ — $ — $ 333,671 Commercial paper (b) — 377,347 — 377,347 U.S. government securities — 183,950 — 183,950 Corporate bonds, asset backed and other securities 183 38,557 — 38,740 $ 333,854 $ 599,854 $ — $ 933,708 _______________ (a) Included within cash and cash equivalents. (b) Includes $176.5 million of commercial paper that is included within cash and cash equivalents. Fair Value as of December 31, 2014 Level 1 Level 2 Level 3 Total Assets: Money market and demand accounts (a) $ 307,995 $ — $ — $ 307,995 Commercial paper (b) — 207,449 — 207,449 U.S. government securities — 151,618 — 151,618 Corporate bonds and asset backed securities 671 36,195 — 36,866 $ 308,666 $ 395,262 $ — $ 703,928 _______________ (a) Included within cash and cash equivalents. (b) Includes $120.6 million of commercial pap
Schedule of Finite-Lived Intangible Assets by Major Class [Table Text Block]	Patents consisted of the following (in thousands, except for useful life data): December 31, 2015 2014 Weighted average estimated useful life (years) 9.9 10.0 Gross patents $ 511,503 $ 455,447 Accumulated amortization (233,924 ) (189,907 ) Patents, net $ 277,579 $ 265,540
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	The estimated aggregate amortization expense for the next five years related to our patents balance as of December 31, 2015 is as follows (in thousands): 2016 $ 46,700 2017 43,876 2018 38,594 2019 35,718 2020 30,946
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block]	Deferred charges are recorded in our Consolidated Balance Sheets within the following captions (in thousands): December 31, 2015 2014 Prepaid and other current assets Deferred commission expense $ 245 $ 342 Deferred contract origination costs — 79 Other non-current assets Deferred commission expense 196 495 Deferred contract origination costs — 79 Long-term debt (including current portion of long-term debt) Deferred financing costs 6,117 1,629
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	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, 2015 2014 2013 Basic Diluted Basic Diluted Basic Diluted Numerator: Net income applicable to common shareholders $ 119,225 $ 119,225 $ 104,342 $ 104,342 $ 38,165 $ 38,165 Denominator: Weighted-average shares outstanding: Basic 36,048 36,048 39,420 39,420 41,115 41,115 Dilutive effect of stock options, RSUs and convertible securities 415 459 309 Weighted-average shares outstanding: Diluted 36,463 39,879 41,424 Earnings Per Share: Net income: Basic $ 3.31 3.31 $ 2.65 2.65 $ 0.93 0.93 Dilutive effect of stock options, RSUs and convertible securities (0.04 ) (0.03 ) (0.01 ) Net income: Diluted $ 3.27 $ 2.62 $ 0.92

Geographic Concentration (Table

Geographic Concentration (Tables)	12 Months Ended
	Dec. 31, 2015
GEOGRAPHIC CUSTOMER CONCENTRATION [Abstract]
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]	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, 2015 2014 2013 Taiwan a $ 218,584 $ 115,955 $ 128,551 South Korea 69,000 144,398 15,334 United States 65,703 53,163 108,728 Japan 53,775 52,194 27,494 Canada 13,151 15,422 36,148 Sweden 6,934 24,530 — Germany 6,712 5,293 4,539 Other Europe 4,807 4,064 3,004 China 2,768 800 1,563 Other Asia 1 2 — Total $ 441,435 $ 415,821 $ 325,361 (a) We are engaged in a legal dispute with Pegatron Corporation ("Pegatron"), our largest Taiwan-based customer, regarding, among other things, the terms of our patent license agreement, and we are the subject of an investigation by the Taiwan Fair Trade Commission. See Note 8, “Litigation and Legal Proceedings,” in these Notes to Condensed Consolidated Financial Statements. D
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	ing 2015 , 2014 and 2013 , the following licensees or customers accounted for 10% or more of total revenues: 2015 2014 2013 Pegatron a 31 % 18 % 30 % Samsung b 16 % 33 % — % Sony c 14 % < 10% 12 % Intel Mobile Communications GmbH d < 10% < 10% 18 % (a) 2013 revenues include $71.4 million of past patent royalties. As noted above, we are engaged in a legal dispute with Pegatron. See Note 8, “Litigation and Legal Proceedings,” in these Notes to Condensed Consolidated Financial Statements. (b) 2014 revenues include $86.2 million of past patent royalties. (c) 2015 revenues include $21.8 million of past patent royalties (d) 2013 revenues include $53.3 million of past technology solutions revenue. At December 31, 2015, 2014 and 2013, we held $289.7 million , $278.1 million and $215.9 million , respectively, or nearly 100% in each year, of our property and equipment and patents in the United States net of accumulated depreciation and amortization. At each of December 31, 2015, 2014 and 2013, we held less than $0.1 million of property and equipment, net of accumulated depreciation, collectively, in Canada, the United Kingdom and South Korea.

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]	December 31, 2015 2014 Computer equipment and software $ 30,066 $ 27,678 Engineering and test equipment 12,321 11,970 Building and improvements 11,356 11,076 Leasehold improvements 7,544 7,406 Furniture and fixtures 1,513 1,292 Land 695 695 Property and equipment, gross 63,495 60,117 Less: accumulated depreciation (51,347 ) (47,571 ) Property and equipment, net $ 12,148 $ 12,546

Obligations (Tables)

Obligations (Tables)	12 Months Ended
	Dec. 31, 2015
OBLIGATIONS: [Abstract]
Schedule of Debt [Table Text Block]	December 31, 2015 2014 2.50% Senior Convertible Notes due 2016 $ 230,000 $ 230,000 1.50% Senior Convertible Notes due 2020 316,000 — Less: Unamortized interest discount (53,114 ) (12,165 ) Deferred financing costs (6,117 ) (1,629 ) Total debt obligations 486,769 216,206 Less: Current portion of long-term debt 227,174 — Long-term debt obligations $ 259,595 $ 216,206
Schedule of Maturities of Long-term Debt [Table Text Block]	Maturities of principal of the long-term debt obligations of the Company as of December 31, 2015 are as follows (in thousands): 2016 $ 230,000 2017 — 2018 — 2019 — 2020 316,000 Thereafter — $ 546,000
Schedule of Long-term Debt Instruments [Table Text Block]	2020 Senior Convertible Notes and related Note Hedge and Warrant Transactions On March 11, 2015, we issued $316.0 million in aggregate principal amount of 1.50% Senior Convertible Notes due 2020 (the “2020 Notes”). The 2020 Notes bear interest at a rate of 1.50% per year, payable in cash on March 1 and September 1 of each year, commencing September 1, 2015, and mature on March 1, 2020, unless earlier converted or repurchased. The 2020 Notes will be convertible into cash, shares of our common stock or a combination thereof, at our election, at an initial conversion rate of 13.8172 shares of common stock per $1,000 principal amount of 2020 Notes (which is equivalent to an initial conversion price of approximately $72.37 per share). It is our current intent and policy to settle all conversions through combination settlement of cash and shares of common stock, with a specified dollar amount of $1,000 per $1,000 principal amount of the 2020 Notes and any remaining amounts in shares. Prior to 5:00 p.m., New York City time, on the business day immediately preceding December 1, 2019, the 2020 Notes will be convertible only under certain circumstances as set forth in the indenture to the 2020 Notes. Commencing on December 1, 2019, the 2020 Notes will be convertible in multiples of $1,000 principal amount, at any time prior to 5:00 p.m., New York City time, on the second scheduled trading day immediately preceding the maturity date of the 2020 Notes. The Company may not redeem the 2020 Notes prior to their maturity date. On March 5 and March 9, 2015, in connection with the offering of the 2020 Notes, we entered into convertible note hedge transactions that cover approximately 3.8 million and approximately 0.6 million shares of our common stock, respectively, at a strike price that corresponds initially to the initial conversion price of the 2020 Notes and are exercisable upon conversion of the 2020 Notes. The cost of the March 5 and March 9, 2015 convertible note hedge transactions was approximately $51.7 million and approximately $7.7 million , respectively. On March 5 and March 9, 2015, we sold warrants to acquire, subject to customary anti-dilution adjustments, approximately 3.8 million and approximately 0.6 million , respectively, of common stock at an initial strike price of approximately $88.46 per share. The warrants become exercisable in tranches starting in June 2020. As consideration for the warrants issued on March 5 and March 9, 2015, we received approximately $37.3 million and approximately $5.6 million , respectively. We also repurchased 0.8 million shares of our common stock at $53.61 per share, the closing price of the stock on March 5, 2015, from institutional investors through one of the initial purchasers and its affiliate, as our agent, concurrently with the pricing of the offering of the 2020 Notes. Accounting Treatment of the 2020 Notes and related Convertible Note Hedge and Warrant Transactions The offering of the 2020 Notes on March 5, 2015 was for $275.0 million and included an overallotment option that allowed the initial purchasers to purchase up to an additional $41.0 million aggregate principal amount of 2020 Notes. The initial purchasers exercised their overallotment option on March 9, 2015, bringing the total amount of 2020 Notes issued on March 11, 2015 to $316.0 million . In connection with the offering of the 2020 Notes, as discussed above, we entered into convertible note hedge transactions with respect to our common stock. The $59.4 million cost of the convertible note hedge transactions was partially offset by the proceeds from the sale of the warrants described above, resulting in a net cost of $16.5 million . Both the convertible note hedge and warrants were classified as equity. We bifurcated the proceeds from the offering of the 2020 Notes between liability and equity components. On the date of issuance, the liability and equity components were calculated to be approximately $256.7 million and $59.3 million , respectively. The initial $256.7 million liability component was determined based on the fair value of similar debt instruments excluding the conversion feature. The initial $59.3 million ( $38.6 million net of tax) equity component represents the difference between the fair value of the initial $256.7 million in debt and the $316.0 million of gross proceeds. The related initial debt discount of $59.3 million is being amortized using the effective interest method over the life of the 2020 Notes. An effective interest rate of 5.89% was used to calculate the debt discount on the 2020 Notes. In connection with the above-noted transactions, we incurred $9.3 million of directly related costs. The initial purchasers' transaction fees and related offering expenses were allocated to the liability and equity components in proportion to the allocation of proceeds and accounted for as debt and equity issuance costs, respectively. We allocated $7.0 million of debt issuance costs to the liability component, which were capitalized as deferred financing costs. These costs are being amortized to interest expense over the term of the debt using the effective interest method. The remaining $2.4 million of costs allocated to the equity component were recorded as a reduction of the equity component. As described in Note 2, " Summary of Significant Accounting Policies ," in March 2015, as part of their simplification initiative, the FASB issued amendments to guidance for reporting debt issuance costs. According to the revised standard, an entity will recognize debt issuance costs as a direct deduction from the debt liability as opposed to an asset. The following table presents the amount of interest cost recognized for the years ended December 31, 2015 , 2014 and 2013 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, 2015 2014 2013 Contractual coupon interest $ 9,568 $ 5,750 $ 5,750 Accretion of debt discount 18,384 9,022 8,423 Amortization of financing costs 2,485 1,303 1,303 Total $ 30,437 $ 16,075 $ 15,476

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2015
COMMITMENTS [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	Minimum future rental payments for operating leases as of December 31, 2015 are as follows (in thousands): 2016 $ 4,186 2017 3,173 2018 2,918 2019 2,872 2020 1,995 Thereafter 7,781

Compensation Plans and Progra28

Compensation Plans and Programs (Tables)	12 Months Ended
	Dec. 31, 2015
COMPENSATION PLANS AND PROGRAMS [Abstract]
Schedule of RSU Award Vesting	10. COMPENSATION PLANS AND PROGRAMS Compensation Programs We use a variety of compensation programs to both attract and retain 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 and cash awards to inventors for filed patent applications and patent issuances, as well as stock option awards, time-based RSU awards and performance-based awards under the LTCP. Our LTCP typically includes annual grants with a three-year vesting period; as a result, in any one year, we are typically accounting for three active LTCP cycles. We issue new shares of our common stock to satisfy our obligations under the share-based components of these programs from the 2009 Plan discussed below. However, our Board of Directors has the right to authorize the issuance of treasury shares to satisfy such obligations in the future. Stock Plans On June 4, 2009, our shareholders adopted and approved the 2009 Stock Incentive Plan (the “2009 Plan”), under which current or prospective officers and employees and non-employee directors, consultants and advisors can receive share-based awards such as RSUs, restricted stock, stock options and other stock awards. Our shareholders re-approved the material terms of the 2009 Plan on June 12, 2014. We issue the share-based awards authorized under the 2009 Plan through a variety of compensation programs. The following table summarizes changes in the number of equity instruments available for grant (in thousands) under the 2009 Plan for the current year: Available for Grant Balance at December 31, 2014 1,445 RSUs granted (a) (379 ) Options granted (94 ) Options expired and RSUs canceled 431 Balance at December 31, 2015 1,403 (a) RSUs granted include time-based RSUs, performance-based RSUs and dividend equivalents. RSUs and Restricted Stock Under the 2009 Plan, we may issue RSUs and/or shares of restricted stock to current or prospective officers and employees and non-employee directors, consultants and advisors. Any cancellations of outstanding RSUs granted under the 2009 Plan will increase the number of RSUs and/or shares of restricted stock remaining available for grant under the 2009 Plan. The RSUs vest over periods generally ranging from 0 to 3 years from the date of the grant. During 2015 and 2014, we granted approximately 0.3 million and 0.6 million RSUs, respectively, under the 2009 Plan. We have issued less than 0.1 million shares of restricted stock under the 2009 Plan. At December 31, 2015 and 2014, we had unrecognized compensation cost related to share-based awards of $18.1 million and $17.9 million , respectively. For grants made in 2015, 2014 and 2013 that cliff vest, we expect to amortize the associated unrecognized compensation cost at December 31, 2015 on a straight-line basis over a three-year period. 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 against these goals, the payout range for performance-based RSU awards can be anywhere from 0 to 2 times the value of the award. Information with respect to current RSU activity is summarized as follows (in thousands, except per share amounts): Number of Unvested RSUs Weighted Average Per Share Grant Date Fair Value Balance at December 31, 2014 1,902 $ 35.73 Granted* 379 52.06 Forfeited* (62 ) 38.12 Vested* (490 ) 41.29 Balance at December 31, 2015 1,729 $ 37.65 * These numbers include less than 0.1 million RSUs credited on unvested RSU awards as dividend equivalents. Dividend equivalents accrue with respect to unvested RSU awards 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 level of 200%. The total vest date fair value of the RSUs that vested in 2015, 2014 and 2013 was $26.3 million , $7.7 million and $6.5 million , respectively. The weighted average per share grant date fair value of the awards that vested in 2015, 2014 and 2013 was $41.29 , $31.29 and $42.34 , respectively. Other RSU Grants We also grant RSUs to all non-management Board members and, in special circumstances, management personnel outside of the LTCP. Grants of this type are supplemental to any awards granted to management personnel through the LTCP. Stock Options The 2009 Plan allows for the granting of incentive and non-qualified stock options, as well as other securities. The 2009 Plan authorizes the issuance of up to 3.0 million shares of common stock pursuant to incentive stock options. The administrator of the 2009 Plan, initially the Compensation Committee of the Board of Directors, determines the number of options to be granted. Annually, since 2013, both incentive and non-qualified stock options have been granted pursuant to the LTCP under the 2009 Plan. Under the terms of the 2009 Plan, 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. Under the 2009 Plan, options 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 or over a period of time. We also have approximately 0.1 million options outstanding under a prior stock plan that have an indefinite contractual life. Information with respect to current year stock option activity under the above plans is summarized as follows (in thousands, except per share amounts): Outstanding Options Weighted Balance at December 31, 2014 336 $ 24.90 Granted 94 52.85 Canceled (4 ) 44.19 Exercised (5 ) 9.28 Balance at December 31, 2015 421 $ 31.16 The weighted average remaining contractual life of our outstanding options was 12.3 years as of December 31, 2015 . We currently have approximately 0.1 million options outstanding that have an indefinite contractual life. These options were granted between 1983 and 1986 under a prior stock plan. For purposes of calculating the weighted average remaining contractual life, these options were assigned an original life in excess of 50 years. The majority of these options have an exercise price between $8.00 and $11.63 . The total intrinsic value of stock options exercised during the years ended December 31, 2015 , 2014 and 2013 was $0.2 million , $0.3 million and $1.0 million , respectively. The total intrinsic value of our options outstanding at December 31, 2015 was $7.9 million . In 2015 , we recorded cash received from the exercise of options of less than $0.1 million . Upon option exercise, we issued new shares of stock. At both December 31, 2015 and 2014 , we had approximately 0.3 million options outstanding that had exercise prices less than the fair market value of our stock at each balance sheet date. These options would have generated cash proceeds to the Company of $8.2 million and $8.4 million , respectively, if they had been fully exercised on those dates. 401(k) 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 contribution expense was approximately $1.0 million for each of 2015 , 2014 and 2013 . At our discretion, we may also make a profit-sharing contribution to our employees’ 401(k) accounts.
Schedule of Equity Instruments Available for Grant [Table Text Block]	The following table summarizes changes in the number of equity instruments available for grant (in thousands) under the 2009 Plan for the current year: Available for Grant Balance at December 31, 2014 1,445 RSUs granted (a) (379 ) Options granted (94 ) Options expired and RSUs canceled 431 Balance at December 31, 2015 1,403 (a) RSUs granted include time-based RSUs, performance-based RSUs and dividend equivalents.
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	Information with respect to current year stock option activity under the above plans is summarized as follows (in thousands, except per share amounts): Outstanding Options Weighted Balance at December 31, 2014 336 $ 24.90 Granted 94 52.85 Canceled (4 ) 44.19 Exercised (5 ) 9.28 Balance at December 31, 2015 421 $ 31.16

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
TAXES [Abstract]
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	Our income tax provision consists of the following components for 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Current Federal $ 42,181 $ 49,049 $ (6,093 ) State 415 2,499 225 Foreign source withholding tax 55,276 70,703 23,269 97,872 122,251 17,401 Deferred Federal (89,026 ) (121,937 ) (18,727 ) State 554 (437 ) 2,614 Foreign source withholding tax 55,221 52,231 24,548 (33,251 ) (70,143 ) 8,435 Total $ 64,621 $ 52,108 $ 25,836 The d
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	The deferred tax assets and liabilities were comprised of the following components at December 31, 2015 and 2014 (in thousands): 2015 Federal State Foreign Total Net operating losses $ — $ 81,965 $ 140 $ 82,105 Deferred revenue, net 94,203 8 22,473 116,684 Stock compensation 8,147 1,452 — 9,599 Patent amortization 21,217 — — 21,217 Depreciation 929 (64 ) — 865 Other-than-temporary impairment 494 46 — 540 Other accrued liabilities 7,416 509 — 7,925 Other employee benefits 1,888 141 — 2,029 134,294 84,057 22,613 240,964 Less: valuation allowance — (81,893 ) — (81,893 ) Net deferred tax asset $ 134,294 $ 2,164 $ 22,613 $ 159,071	2014 Federal State Foreign Total Net operating losses $ — $ 71,837 $ 4 $ 71,841 Deferred revenue, net 50,575 41 22,657 73,273 Stock compensation 10,567 1,751 — 12,318 Patent amortization 18,337 — — 18,337 Depreciation 1,110 29 — 1,139 Other accrued liabilities 1,097 (28 ) — 1,069 Other-than-temporary impairment 10,010 154 — 10,164 Other employee benefits 8,784 668 — 9,452 100,480 74,452 22,661 197,593 Less: valuation allowance — (71,731 ) — (71,731 ) Net deferred tax asset $ 100,480 $ 2,721 $ 22,661 $ 125,862
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	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, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Tax at U.S. statutory rate 35.0 % 35.0 % 35.0 % State tax provision 0.5 % 0.1 % 4.1 % Change in federal and state valuation allowance — % — % 0.4 % Research and development tax credits (1.2 )% (4.7 )% — % Uncertain tax positions — % 0.9 % — % Permanent differences 1.2 % 1.5 % 3.5 % Settlement with taxing authorities 0.1 % 1.1 % — % Other 0.1 % 0.1 % (1.1 )% Total tax provision 35.7 % 34.0 % 41.9 %
Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block]	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 2013 through 2015 (in thousands): 2015 2014 2013 Balance as of January 1 $ 1,361 $ — $ — Tax positions related to current year: Additions 141 95 — Reductions — — — Tax positions related to prior years: Additions — 1,266 — Reductions (33 ) — — Settlements — — — Lapses in statues of limitations — — — Balance as of December 31 $ 1,469 $ 1,361 $ —

Equity Transactions (Tables)

Equity Transactions (Tables)	12 Months Ended
	Dec. 31, 2015
EQUITY TRANSACTIONS: [Abstract]
Dividends Declared [Table Text Block]	2015 Per Share Total Cumulative by Fiscal Year First quarter $ 0.20 $ 7,232 $ 7,232 Second quarter 0.20 7,243 14,475 Third quarter 0.20 7,183 21,658 Fourth quarter 0.20 7,068 28,726 $ 0.80 $ 28,726 2014 First quarter $ 0.10 $ 3,954 $ 3,954 Second quarter 0.20 8,033 11,987 Third quarter 0.20 7,666 19,653 Fourth quarter 0.20 7,500 27,153 $ 0.70 $ 27,153

Selected Quarterly Results (Tab

Selected Quarterly Results (Tables)	12 Months Ended
	Dec. 31, 2015
SELECTED QUARTERLY RESULTS (Unaudited) [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	The table below presents quarterly data for the years ended December 31, 2015 and 2014 : First Second Third Fourth (In thousands, except per share amounts, unaudited) 2015 Revenues $ 110,378 $ 118,551 $ 100,408 $ 112,098 Net income applicable to InterDigital, Inc.'s common shareholders $ 29,065 $ 32,602 $ 24,520 $ 33,038 Net income per common share — basic $ 0.79 $ 0.91 $ 0.68 $ 0.93 Net income per common share — diluted $ 0.78 $ 0.89 $ 0.68 $ 0.92 2014 Revenues (a) $ 57,844 $ 194,234 $ 77,622 $ 86,121 Net income applicable to InterDigital, Inc.'s common shareholders $ (1,861 ) $ 78,901 $ 13,512 $ 13,790 Net income per common share — basic $ (0.05 ) $ 1.95 $ 0.34 $ 0.37 Net income per common share — diluted $ (0.05 ) $ 1.93 $ 0.34 $ 0.36

Background (Details)

Background (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
BACKGROUND [Abstract]
Repositioning	$ 0	$ 0	$ 1,544

Background Repositioning (Detai

Background Repositioning (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 0	$ 0	$ 1,544

Summary of Significant Accoun34

Summary of Significant Accounting Policies Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments	$ 198	$ 559	$ 21,720
Short-term Investments	423,501	275,361
Assets, Fair Value Disclosure, Recurring	933,708	703,928
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	373,700	151,400
Cash and Cash Equivalents, at Carrying Value	510,207	428,567	497,714	$ 349,843
Other Comprehensive Income (Loss), Net of Tax	(296)	132	$ (878)
Fair Value, Inputs, Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets, Fair Value Disclosure, Recurring	333,854	308,666
Corporate Bonds and Asset Backed Securities [Domain]
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments		36,866
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments	200,811	86,877
Cash and Cash Equivalents, at Carrying Value	176,536	120,572
Money Market Funds and Demand Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 333,671	$ 307,995

Summary of Significant Accoun35

Summary of Significant Accounting Policies Realized Gain (Loss) on Short-Term Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Available-for-sale Securities, Gross Realized Gains	$ 0	$ 48	$ 166
Available-for-sale Securities, Gross Realized Losses	(309)	(681)	(678)
Available-for-sale Securities, Gross Realized Gain (Loss)	$ (309)	$ (633)	$ (512)

Summary of Significant Accoun36

Summary of Significant Accounting Policies Short-Term Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments	$ 198	$ 559	$ 21,720
Other Comprehensive Income (Loss), Net of Tax	(296)	132	$ (878)
Short-term Investments	423,501	275,361
Assets, Fair Value Disclosure, Recurring	933,708	703,928
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value	373,700	151,400
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments	183,950	151,618
Corporate Bonds and Asset Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments	38,740
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments	$ 200,811	86,877
Corporate Bonds and Asset Backed Securities [Domain]
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments		$ 36,866

Summary of Significant Accoun37

Summary of Significant Accounting Policies Fair Value Measurements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2015	Apr. 04, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	$ 486,769	$ 216,206		$ 230,000
Concentration Risk, Additional Characteristic	four	three
Concentration Risk, Percentage	97.00%	94.00%
Assets, Fair Value Disclosure, Recurring	$ 933,708	$ 703,928
Commercial Paper	176,500	120,600
Long-term Debt, Excluding Current Maturities	259,595	216,206
Long-term Debt, Fair Value	533,203	255,300
Investment Owned, at Fair Value			$ 24,100
Money Market Funds and Demand Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	333,671	307,995
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	377,347	207,449
US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	183,950	151,618
Corporate Bonds and Asset Backed Securities [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	38,740
Corporate Bond Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		36,866
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	333,854	308,666
Fair Value, Inputs, Level 1 [Member] | Money Market Funds and Demand Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	333,671	307,995
Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 1 [Member] | Corporate Bonds and Asset Backed Securities [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	183
Fair Value, Inputs, Level 1 [Member] | Corporate Bond Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		671
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	599,854	395,262
Fair Value, Inputs, Level 2 [Member] | Money Market Funds and Demand Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	377,347	207,449
Fair Value, Inputs, Level 2 [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	183,950	151,618
Fair Value, Inputs, Level 2 [Member] | Corporate Bonds and Asset Backed Securities [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	38,557
Fair Value, Inputs, Level 2 [Member] | Corporate Bond Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		36,195
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Money Market Funds and Demand Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Fair Value, Inputs, Level 3 [Member] | Corporate Bonds and Asset Backed Securities [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0
Fair Value, Inputs, Level 3 [Member] | Corporate Bond Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		0
Convertible Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	$ 546,000	$ 230,000

Summary of Significant Accoun38

Summary of Significant Accounting Policies Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2015
Building [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	25 years
Minimum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	3 years
Minimum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	5 years
Maximum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	5 years
Maximum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	10 years

Summary of Significant Accoun39

Summary of Significant Accounting Policies Internal-Use Software Costs (Details)	12 Months Ended
	Dec. 31, 2015
Software Development [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	2 years

Summary of Significant Accoun40

Summary of Significant Accounting Policies Investment in Other Entities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Cost and Equity method Investments [Line Items]
Payments for (Proceeds from) Long-term Investments	$ 12,623	$ 0	$ 0

Summary of Significant Accoun41

Summary of Significant Accounting Policies Patents (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Current - Future Amortization Expense	$ 277,579	$ 265,540
Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Weighted-Average Useful Life	10 years
Patents Purchased [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Weighted-Average Useful Life	9 years 8 months 15 days
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Weighted-Average Useful Life	9 years 11 months	10 years
Finite-Lived Patents, Gross	$ 511,503	$ 455,447
Finite-Lived Intangible Assets, Accumulated Amortization	(233,924)	(189,907)
Finite-Lived Intangible Assets, Net	46,700
Current - Future Amortization Expense	277,579	265,540
2013 - Future Amortization Expense	43,876
2014 - Future Amortization Expense	38,594
2015 - Future Amortization Expense	35,718
2016 - Future Amortization Expense	30,946
Finite-Lived Intangible Assets, Amortization Expense	$ 44,000	$ 38,400	$ 29,800

Summary of Significant Accoun42

Summary of Significant Accounting Policies Deferred Charges (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Deferred Charges [Line Items]
Payments for Commissions		$ 100	$ 300	$ 100
Contract Revenue Cost		100	100	100
Payments of Debt Issuance Costs		9,403	0	0
Sales Commissions and Fees		600	400	300
Amortization of Financing Costs		2,485	1,303	$ 1,303
Deferred Finance Costs, Gross		6,117	1,629
Deferred Sales Commission Current [Member]
Deferred Charges [Line Items]
Other Deferred Costs, Net		245	342
Deferred Contract Revenue Costs Current [Member]
Deferred Charges [Line Items]
Other Deferred Costs, Net		0	79
Deferred Sales Commission Non-Current [Member]
Deferred Charges [Line Items]
Other Deferred Costs, Net		196	495
Deferred Contract Revenue Costs Non-Current [Member]
Deferred Charges [Line Items]
Other Deferred Costs, Net		$ 0	$ 79
Convertible Debt [Member]
Deferred Charges [Line Items]
Payments of Debt Issuance Costs	$ 9,300
Convertible Debt [Member] | Other Long-term Liabilities [Member]
Deferred Charges [Line Items]
Payments of Debt Issuance Costs	$ 7,000
Convertible Debt [Member] | Equity [Member]
Deferred Charges [Line Items]
Payments of Debt Issuance Costs					$ (1,500)

Summary of Significant Accoun43

Summary of Significant Accounting Policies Research and Development (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Research and Development [Abstract]
Development Expense	$ 72,702	$ 75,300	$ 64,729

Summary of Significant Accoun44

Summary of Significant Accounting Policies Compensation Programs (Details)	12 Months Ended
	Dec. 31, 2015
Minimum [Member]
Forfeiture Rate [Line Items]
Forfeiture Rate	0.00%
Maximum [Member]
Forfeiture Rate [Line Items]
Forfeiture Rate	25.00%

Summary of Significant Accoun45

Summary of Significant Accounting Policies Impairment of Long-Lived Assets (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Long-Lived Assets to be Disposed of	$ 0.2

Summary of Significant Accoun46

Summary of Significant Accounting Policies Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended			120 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Income Tax Contingency [Line Items]
Income taxes paid, including foreign witholding taxes	$ 85,780	$ 114,876	$ 24,961
Income Tax Expense (Benefit)	64,621	52,108	25,836
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	0	1,266	0
Unrecognized Tax Benefits	5,700			$ 5,700
Unrecognized Tax Benefits, Period Increase (Decrease)	700
Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Income taxes paid, including foreign witholding taxes	55,300	70,700	$ 23,300
Foreign Tax Authority [Member] | Tax Period 2006-2013 [Member] [Domain]
Income Tax Contingency [Line Items]
Income taxes paid, including foreign witholding taxes				295,100
ForeignGovenmentswithUSTaxTreaties [Domain] | Tax Period 2006-2013 [Member] [Domain]
Income Tax Contingency [Line Items]
Income taxes paid, including foreign witholding taxes				$ 196,500
Research and Development Arrangement [Member]
Income Tax Contingency [Line Items]
Income Tax Expense (Benefit)	$ 2,100	$ 900

Summary of Significant Accoun47

Summary of Significant Accounting Policies Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									$ 119,225,000	$ 104,342,000	$ 38,165,000
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING — BASIC									36,048	39,420	41,115
Weighted Average Number Diluted Shares Outstanding Adjustment									415	459	309
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING — DILUTED									36,463	39,879	41,424
NET INCOME PER COMMON SHARE — BASIC	$ 0.93	$ 0.68	$ 0.91	$ 0.79	$ 0.37	$ 0.34	$ 1.95	$ (0.05)	$ 3.31	$ 2.65	$ 0.93
Dilutive Securities, Effect on Basic Earnings Per Share									$ (0.04)	$ 0.03	$ (0.01)
NET INCOME PER COMMON SHARE — DILUTED	$ 0.92	$ 0.68	$ 0.89	$ 0.78	$ 0.36	$ 0.34	$ 1.93	$ (0.05)	$ 3.27	$ 2.62	$ 0.92
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									7,656	4,130	4,130
Warrant [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Class of Warrant or Right, Outstanding	7,656				4,130				7,656	4,130	4,130
Employee Stock Option [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									211	75	79

Summary of Significant Accoun48

Summary of Significant Accounting Policies New Accounting Guidance (Details) $ in Millions	Dec. 31, 2014USD ($)
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 54
Deferred Tax Asset [Domain]
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	54
Prepaid Expenses and Other Current Assets [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	1.3
Other Noncurrent Assets [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	0.3
Long-term Debt, Type [Domain]
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 1.6

Significant Agreements Litigati

Significant Agreements Litigation Settlement (Details) - Past Infringement [Member] $ in Millions	12 Months Ended
	Dec. 31, 2013USD ($)
Pegatron [Member]
Litigation Settlement, Amount	$ 71.4
Technology Solutions Customer [Member]
Litigation Settlement, Amount	$ 53.3

Significant Agreements Signific

Significant Agreements Significant Events (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues	$ 112,098	$ 100,408	$ 118,551	$ 110,378	$ 86,121	$ 77,622	$ 194,234	$ 57,844	$ 441,435	$ 415,821	$ 325,361
Samsung Electronics, Ltd. [Member] | Past Infringement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues									$ 86,200

Significant Agreements Revenue

Significant Agreements Revenue Agreements (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues	$ 112,098	$ 100,408	$ 118,551	$ 110,378	$ 86,121	$ 77,622	$ 194,234	$ 57,844	$ 441,435	$ 415,821	$ 325,361
Arima Communications Corporation [Member] | Past Infringement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues									27,200
Samsung Electronics, Ltd. [Member] | Past Infringement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues									86,200
Sony Corporation of America [Member] | Past Infringement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues									21,800
Kyocera [Member] | Past Infringement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues									16,400
Technology Solutions Customer [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Interest Income (Expense), Net									1,800
Allowance for Loan and Lease Loss, Recovery of Bad Debts									500
Technology Solutions Customer [Member] | Past Infringement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenues									$ 2,800

Geographic Concentration (Detai

Geographic Concentration (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	$ 112,098	$ 100,408	$ 118,551	$ 110,378	$ 86,121	$ 77,622	$ 194,234	$ 57,844	$ 441,435	$ 415,821	$ 325,361
Pegatron [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity-Wide Revenues, Major Customer, Percentage									0.31	0.18	0.3
Intel Mobile Communications GmbH [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity-Wide Revenues, Major Customer, Percentage									< 10%	< 10%	0.18
Samsung Electronics, Ltd. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity-Wide Revenues, Major Customer, Percentage									0.16	0.33	0
Sony Corporation of America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity-Wide Revenues, Major Customer, Percentage									0.14	< 10%	0.12
KOREA
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									$ 69,000	$ 144,398	$ 15,334
JAPAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									53,775	52,194	27,494
SWEDEN
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									6,934	24,530	0
CANADA
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									13,151	15,422	36,148
Canada, UK, and South Korea [Domain]
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Long-Lived Assets in Entity's Country of Domicile	100				100				100	100	100
TAIWAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									218,584	115,955	128,551
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									65,703	53,163	108,728
UNITED STATES | Property Plant and Equipment and Patents, net [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Long-Lived Assets in Entity's Country of Domicile	$ 289,700				$ 278,100				289,700	278,100	215,900
GERMANY
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									6,712	5,293	4,539
CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									2,768	800	1,563
Other Europe [Domain]
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									4,807	4,064	3,004
Other Asia [Domain]
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									1	$ 2	0
Past Infringement [Member] | Pegatron [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Litigation Settlement, Amount											71,400
Past Infringement [Member] | Technology Solutions Customer [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Litigation Settlement, Amount											$ 53,300
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									2,800
Past Infringement [Member] | Samsung Electronics, Ltd. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									86,200
Past Infringement [Member] | Sony Corporation of America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									$ 21,800

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Land	$ 695	$ 695
Building and improvements	11,356	11,076
Engineering and test equipment	12,321	11,970
Computer Equipment And Software Gross	30,066	27,678
Furniture and fixtures	1,513	1,292
Leasehold improvements	7,544	7,406
Property and equipment, gross	63,495	60,117
Less: accumulated depreciation	(51,347)	(47,571)
Property and equipment, net	12,148	12,546
Depreciation	3,800	3,900	$ 3,600
Capitalized Computer Software, Amortization	1,400	1,400	$ 1,000
Capitalized Computer Software, Accumulated Amortization	15,600	14,300
Capitalized Computer Software, Net	1,200	$ 2,200
Sale Leaseback Transaction, Historical Cost	4,500
Sale Leaseback Transaction, Net Book Value	$ 1,100
Building [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	25 years
Minimum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	3 years
Minimum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	5 years
Maximum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	5 years
Maximum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful Life, Minimum	10 years

Obligations (Details)

Obligations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2015	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Debt Instrument [Line Items]
Payments for (Proceeds from) Hedge, Financing Activities		$ (38,594)
Payments of Debt Issuance Costs			$ 9,403	$ 0	$ 0
Amortization of Financing Costs			2,485	1,303	$ 1,303
Debt Instrument, Unamortized Discount			53,114	12,165
Deferred Finance Costs, Gross			(6,117)	(1,629)
Long-term Debt			486,769	216,206
Long-term Debt, Current Maturities			(227,174)	0
LONG-TERM DEBT			259,595	216,206
Land and Building Carrying Amount			12,148	12,546
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months			230,000
2013 - Long Term Debt Maturities			0
2014 - Long Term Debt Maturities			0
2015 - Long Term Debt Maturities			0
2016 - Long Term Debt Maturities			316,000
Thereafter - Long Term Debt Maturities			0
Total debt obligations			546,000
Convertible Debt [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs	$ 9,300
Balance Sheet by Location [Domain] | Convertible Debt [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs						$ 8,000
Convertible Notes 2016 [Member] | Convertible Notes 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			230,000	230,000
Convertible Notes 2020 [Member] | Convertible Notes 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 316,000		$ 316,000	$ 0
2014 Repurchase Program [Domain]
Debt Instrument [Line Items]
Accelerated Share Repurchases, Initial Price Paid Per Share		$ 53.61

Obligations Senior Convertible

Obligations Senior Convertible Note, Note Hedge and Warrant Transaction (Details) $ / shares in Units, shares in Thousands	1 Months Ended	3 Months Ended		9 Months Ended	12 Months Ended				34 Months Ended
	Apr. 24, 2012USD ($)	Mar. 31, 2015USD ($)	Mar. 31, 2011USD ($)	Sep. 30, 2015USD ($)$ / sharesshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares	Dec. 31, 2013USD ($)shares	Dec. 31, 2011USD ($)	Dec. 31, 2011shares	Mar. 11, 2015USD ($)$ / shares	Mar. 09, 2015shares	Mar. 05, 2015USD ($)$ / sharesshares	Apr. 04, 2011USD ($)$ / shares	Mar. 30, 2011shares	Mar. 29, 2011USD ($)$ / warrantshares
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities					$ 4,500,000	$ 0	$ 0
Proceeds from Issuance of Warrants					$ 42,881,000	$ 0	$ 0
Stock Repurchased During Period, Shares | shares					1,836	3,554	917		2,552
Senior Notes					$ 486,769,000	$ 216,206,000							$ 230,000,000
Payments for (Proceeds from) Hedge, Financing Activities				$ (38,594,000)
Payments of Debt Issuance Costs					9,403,000	0	$ 0
Debt Instrument, Interest Rate, Effective Percentage													7.00%
Interest Expense, Debt, Excluding Amortization					9,568,000	5,750,000	5,750,000
Accretion of debt discount					(18,384,000)	(9,022,000)	(8,423,000)
Amortization of Financing Costs					2,485,000	1,303,000	1,303,000
Senior Convertible Note, Note Hedge, and Warrant Transaction Interest Expense					30,437,000	16,075,000	15,476,000
Convertible Note Hedge 1 [Member]
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities	$ 37,100,000	$ 51,700,000
Convertible Note Hedge 2 [Member]
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities	5,600,000	7,700,000
Convertible Note Hedge [Member]
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities	$ 42,700,000	59,400,000
Convertible Note/ Hedge Warrant, net [Member]
Debt Instrument [Line Items]
Proceeds from (Payments for) Other Financing Activities		16,500,000					$ 10,900,000
Note Warrant [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Warrants			$ 27,600,000
Note Warrant2 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Warrants		37,300,000	$ 4,100,000
Class of Warrant or Right [Domain]
Debt Instrument [Line Items]
Proceeds from Issuance of Warrants		5,600,000
Convertible Debt [Member]
Debt Instrument [Line Items]
Senior Notes					$ 546,000,000	$ 230,000,000
Payments of Debt Issuance Costs		$ 9,300,000
Convertible Debt [Member] | Convertible Notes 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage													2.50%
Debt Instrument, Convertible, Conversion Ratio							18.2166
Debt Conversion, Converted Instrument, Amount							$ 1,000
Debt Instrument, Convertible, Conversion Price | $ / shares													$ 54.90
Convertible Debt [Member] | Convertible Notes 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage										1.50%
Debt Instrument, Convertible, Conversion Ratio		13.8172
Debt Conversion, Converted Instrument, Amount		$ 1,000
Debt Instrument, Convertible, Conversion Price | $ / shares										$ 72.37
Convertible Debt 1 [Member]
Debt Instrument [Line Items]
Senior Notes												$ 275,000,000			$ 200,000,000
Convertible Note Overallotment [Member]
Debt Instrument [Line Items]
Senior Notes												$ 41,000,000			$ 30,000,000
Equity [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Class of Warrant or Right, Outstanding | shares											600	3,800		500	3,500
Warrant Option Strike Price | $ / shares												$ 88.46
Derivative, Price Risk Option Strike Price | $ / warrant															63.18
Senior Notes										$ 59,300,000			$ 43,000,000
Senior Convertible Notes [Equity net of tax]													28,000,000
Payments of Debt Issuance Costs								$ (1,500,000)
Payments of Financing Costs				$ (2,430,000)
Balance Sheet by Location [Domain] | Convertible Debt [Member]
Debt Instrument [Line Items]
Senior Notes										$ 256,700,000
Payments of Debt Issuance Costs								8,000,000
other long-term assets [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Payments of Debt Issuance Costs								$ 6,500,000
Other Long-term Liabilities [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Senior Notes													$ 187,000,000
Payments of Debt Issuance Costs		$ 7,000,000
2014 Repurchase Program [Domain]
Debt Instrument [Line Items]
Accelerated Share Repurchases, Initial Price Paid Per Share | $ / shares				$ 53.61
Repurchases related to 2020 Notes [Member] | 2014 Repurchase Program [Domain]
Debt Instrument [Line Items]
Stock Repurchased During Period, Shares | shares				800

Commitments (Details)

Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Leases, Income Statement [Abstract]
Operating Leases, Rent Expense	$ 3,300	$ 3,200	$ 3,300
2012 - Operating leases	4,186
2013 - Operating leases	3,173
Operating Leases, Future Minimum Payments, Due in Three Years	2,918
2015 - Operating leases	2,872
2016 - Operating leases	1,995
Thereafter - Operating leases	$ 7,781

Litigation and Legal Proceedi57

Litigation and Legal Proceedings (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
China, Yuan Renminbi | Huawei [Domain]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	$ 20
China, Yuan Renminbi | ZTE [Domain] | ReliefSought1 [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	20
China, Yuan Renminbi | ZTE [Domain] | ReliefSought2 [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	99.8
United States of America, Dollars | Huawei [Domain]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	3.2
United States of America, Dollars | ZTE [Domain] | ReliefSought1 [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	3.1
United States of America, Dollars | ZTE [Domain] | ReliefSought2 [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value	$ 15.4

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2013	Mar. 31, 2013
BIO-key [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party		$ 0
Investment Owned, Balance, Shares		1.4		4
Investment Owned, at Fair Value	$ 300,000	$ 200,000		$ 500,000
DDD [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 0	$ 0
Investment Owned, Balance, Shares			7
Investment Owned, at Fair Value			$ 900,000

Compensation Plans and Progra59

Compensation Plans and Programs (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award and Other Compensation Benefits [Line Items] [Line Items]
Stock Issued During Period, Shares, Share-based Compensation, Forfeited	(62)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 38.12
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(490)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,729	1,902
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 52.85
Equity Available for Grant [Roll Forward]
Equity Instruments Available for Grant as of December 31, 2010	1,445
RSUs granted	379
Options Expired and RSUs cancelled	431
Equity Instruments Available for Grant as of December 31, 2011	1,403	1,445
Number of Shares Authorized	3,000
Minimum Exercise Price Per Share Options	100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	12 years 4 months
Stock Options, Outstanding [Roll Forward]
Outstanding Options, as of December 31, 2010	336
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period	(4)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	(5)
Outstanding Options, as of December 31, 2011	421	336
Weighted Average Excercise Price, as of December 31, 2010	$ 24.90
Cancellations in Period, Weighted Average Exercise Price	44.19
Exercises in Period, Weighted Average Exercise Price	9.28
Weighted Average Exercise Price, as of December 31, 2011	31.16	$ 24.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	8
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 11.63
Intrinsic Value of Stock Options Exercised During Period	$ 200	$ 300	$ 1,000
Stock Options, Outstanding, Intrinsic Value	7,900
Proceeds from Stock Options Exercised	46	402	1,032
Excess Tax Benefit from Share-based Compensation, Financing Activities	2,457	0	815
Vested in Period, Total Fair Value	$ 26,300	$ 7,700	$ 6,500
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	300	300
Proceeds From Stock Options If Exercised	$ 8,200	$ 8,400
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
RSUs granted	(379)
RSUs, Grants in Period, Weighted Average Grant Date Fair Value	$ 52.06	$ 31.29	$ 42.34
RSUs, Vested in Period, Weighted Average Grant Date Fair Value	$ 41.29
Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights	100
Share-based Compensation	$ 15,139	$ 18,494	$ 15,940
Other than Temporary Impairment Losses, Investments	198	559	21,720
Other Postretirement Benefit Expense	$ 1,000	$ 1,000	$ 1,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value	$ 37.65	$ 35.73
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	(94)
Stock Options Outstaning which have an Indefinite Contractual Term [Member]
Stock Options, Outstanding [Roll Forward]
Outstanding Options, as of December 31, 2011	100
Cash from stock options [Member]
Stock Options, Outstanding [Roll Forward]
Proceeds from Stock Options Exercised	$ 100
Restricted Stock Units (RSU) and/or Restricted Stock [Member]
Equity Available for Grant [Roll Forward]
RSUs granted	300	600
Stock Options, Outstanding [Roll Forward]
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	100
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 18,100	$ 17,900
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
RSUs granted	(300)	(600)
Prior Plan [Domain] | Stock Options Outstaning which have an Indefinite Contractual Term [Member]
Stock Options, Outstanding [Roll Forward]
Outstanding Options, as of December 31, 2011	100

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended			120 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Income Tax Contingency [Line Items]
Additions	$ 141	$ 95	$ 0
Excess Tax Benefit from Share-based Compensation, Operating Activities	0	1,176	0
Excess Tax Benefit from Share-based Compensation, Financing Activities	2,457	0	815
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation		(1,176)	815
Federal	42,181	49,049	(6,093)
State	415	2,499	225
Foreign source withholding tax	55,276	70,703	23,269
Current Income Tax Expense (Benefit)	97,872	122,251	17,401
Federal	(89,026)	(121,937)	(18,727)
State	554	(437)	2,614
Foreign source withholding tax	55,221	52,231	24,548
Deferred income taxes	$ (33,251)	$ (70,143)	$ 8,435
Income Tax Expense (Benefit)	35.70%	34.00%	41.90%
Net operating losses	$ 208,549	$ 168,960	$ 84,756
Deferred Tax Assets, Operating Loss Carryforwards	82,105	71,841		$ 82,105
Deferred revenue, net	116,684	73,273		116,684
Stock compensation	9,599	12,318		9,599
Patent amortization	21,217	18,337		21,217
Deferred Tax Asset Depreciation	865	1,139		865
Deferred Tax Asset OTTI	540	10,164		540
Other accrued liabilities	7,925	1,069		7,925
Other employee benefits	2,029	9,452		2,029
Deferred Tax Assets Net Before Deducting Valuation Allowance	240,964	197,593		240,964
Less: valuation allowance	81,893	71,731		81,893
Net deferred tax asset	$ 159,071	$ 125,862		159,071
Tax at U.S. statutory rate	35.00%	35.00%	35.00%
State	0.50%	0.10%	4.10%
Change in federal and state valuation allowance	0.00%	0.00%	0.40%
Adjustment to tax credits	(1.20%)	(4.70%)	(0.00%)
Adjustments to uncertain tax positions	0.00%	0.90%	0.00%
Permanent differences	1.20%	1.50%	3.50%
Settlement with taxing authorities	0.10%	1.10%	0.00%
Other	0.10%	0.10%	(1.10%)
Unrecognized Tax Benefits		$ 0
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 100	700		100
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	0	0	$ 0
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	0	1,266	0
Liability for Uncertain Tax Positions, Noncurrent Balance as of December 31, 2010	1,361	0	0
Unrecognized Tax Benefits, Period Increase (Decrease)	700
Reductions	0	0	0
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	33	0	0
Settlements	0	0	0
Lapses in statues of limitations	0	0	0
Liability for Uncertain Tax Positions, Noncurrent Balance as of December 31, 2011	1,469	1,361	0	1,469
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	100	0		100
Income taxes paid, including foreign witholding taxes	85,780	114,876	24,961
Taxes Payable	1,405	0		1,405
Federal
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	0	0		0
Deferred revenue, net	94,203	50,575		94,203
Stock compensation	8,147	10,567		8,147
Patent amortization	21,217	18,337		21,217
Deferred Tax Asset Depreciation	929	1,110		929
Deferred Tax Asset OTTI	494	10,010		494
Other accrued liabilities	7,416	1,097		7,416
Other employee benefits	1,888	8,784		1,888
Deferred Tax Assets Net Before Deducting Valuation Allowance	134,294	100,480		134,294
Less: valuation allowance	0	0		0
Net deferred tax asset	134,294	100,480		134,294
State
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	81,965	71,837		81,965
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	1,500,000			1,500,000
Deferred revenue, net	8	41		8
Stock compensation	1,452	1,751		1,452
Patent amortization	0	0		0
Deferred Tax Asset Depreciation	(64)	29		(64)
Deferred Tax Asset OTTI	46	154		46
Other accrued liabilities	509	(28)		509
Other employee benefits	141	668		141
Deferred Tax Assets Net Before Deducting Valuation Allowance	84,057	74,452		84,057
Less: valuation allowance	81,893	71,731		81,893
Net deferred tax asset	2,164	2,721		2,164
Unrecognized Tax Benefits	12,300	12,200		12,300
New York State Division of Taxation and Finance [Member]
Income Tax Contingency [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions	400	2,500
Foreign
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	140	4		140
Deferred revenue, net	22,473	22,657		22,473
Stock compensation	0	0		0
Patent amortization	0	0		0
Deferred Tax Asset Depreciation	0	0		0
Deferred Tax Asset OTTI	0	0		0
Other accrued liabilities	0	0		0
Other employee benefits	0	0		0
Deferred Tax Assets Net Before Deducting Valuation Allowance	22,613	22,661		22,613
Less: valuation allowance	0	0		0
Net deferred tax asset	22,613	22,661		22,613
Income taxes paid, including foreign witholding taxes	$ 55,300	$ 70,700	$ 23,300
Tax Period 2006-2013 [Member] [Domain] | Foreign
Income Tax Contingency [Line Items]
Income taxes paid, including foreign witholding taxes				295,100
Tax Period 2006-2013 [Member] [Domain] | ForeignGovenmentswithUSTaxTreaties [Domain]
Income Tax Contingency [Line Items]
Income taxes paid, including foreign witholding taxes				$ 196,500

Equity Transactions Share Repur

Equity Transactions Share Repurchases (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended									6 Months Ended		8 Months Ended	9 Months Ended		12 Months Ended			26 Months Ended	34 Months Ended
	Dec. 31, 2015USD ($)$ / shares	Sep. 30, 2015USD ($)$ / shares	Jun. 30, 2015USD ($)$ / shares	Mar. 31, 2015USD ($)$ / shares	Dec. 31, 2014USD ($)$ / shares	Sep. 30, 2014USD ($)$ / shares	Jun. 30, 2014USD ($)$ / shares	Mar. 31, 2014USD ($)$ / shares	Mar. 31, 2011USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Dec. 31, 2012USD ($)shares	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)$ / sharesshares	Jun. 30, 2014USD ($)	Dec. 31, 2011shares	Mar. 09, 2015shares	Mar. 05, 2015$ / sharesshares	Jun. 30, 2012USD ($)	Mar. 30, 2011shares	Mar. 29, 2011$ / warrantshares	Mar. 31, 2009USD ($)
Accelerated Share Repurchases [Line Items]
Stock Repurchased During Period, Shares | shares															1,836	3,554	917		2,552
Stock Repurchased During Period, Value												$ 77,694			$ 96,410	$ 152,625	$ 29,135
Common Stock, Dividends, Per Share, Declared | $ / shares	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.10							$ 0.80	$ 0.70	$ 0.40
Dividends, Common Stock, Cash	$ 7,068	$ 7,183	$ 7,243	$ 7,232	$ 7,500	$ 7,666	$ 8,033	$ 3,954		$ 14,475	$ 11,987		$ 21,658	$ 19,653	$ 28,726	$ 27,153
Proceeds from Issuance of Warrants															$ 42,881	$ 0	$ 0
Note Warrant [Member]
Accelerated Share Repurchases [Line Items]
Proceeds from Issuance of Warrants									$ 27,600
Note Warrant2 [Member]
Accelerated Share Repurchases [Line Items]
Proceeds from Issuance of Warrants				37,300					$ 4,100
Class of Warrant or Right [Domain]
Accelerated Share Repurchases [Line Items]
Proceeds from Issuance of Warrants				$ 5,600
2012 Repurchase Program [Domain]
Accelerated Share Repurchases [Line Items]
Stock Repurchased During Period, Shares | shares												2,552			0	0	917
Stock Repurchased During Period, Value												$ 77,694			$ 0	$ 0	$ 29,135	$ 106,800
2014 Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Stock Repurchased During Period, Shares | shares												0			1,836	3,554	0
Stock Repurchased During Period, Value												$ 0			$ 96,410	$ 152,625	$ 0
2014 Repurchase Program [Domain]
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount			$ 400,000				$ 300,000			$ 400,000	$ 300,000							$ 300,000
2012 Repurchase Program [Domain]
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount																						$ 200,000
2009 Repurchase Program [Domain]
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount																									$ 100,000
Equity [Member] | Convertible Debt [Member]
Accelerated Share Repurchases [Line Items]
Class of Warrant or Right, Outstanding | shares																				600	3,800		500	3,500
Derivative, Price Risk Option Strike Price | $ / warrant																								63.18
Warrant Option Strike Price | $ / shares																					$ 88.46

Selected Quarterly Results (Det

Selected Quarterly Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effect of Fourth Quarter Events [Line Items]
Restructuring Charges									$ 0	$ 0	$ 1,544
Other than Temporary Impairment Losses, Investments									198	559	21,720
Sales Revenue, Goods, Net									0	1,999	0
Revenues	$ 112,098	$ 100,408	$ 118,551	$ 110,378	$ 86,121	$ 77,622	$ 194,234	$ 57,844	441,435	415,821	325,361
NET INCOME	$ 33,038	$ 24,520	$ 32,602	$ 29,065	$ 13,790	$ 13,512	$ 78,901	$ (1,861)	$ 116,394	$ 101,420	$ 35,683
NET INCOME PER COMMON SHARE — BASIC	$ 0.93	$ 0.68	$ 0.91	$ 0.79	$ 0.37	$ 0.34	$ 1.95	$ (0.05)	$ 3.31	$ 2.65	$ 0.93
NET INCOME PER COMMON SHARE — DILUTED	$ 0.92	$ 0.68	$ 0.89	$ 0.78	$ 0.36	$ 0.34	$ 1.93	$ (0.05)	$ 3.27	$ 2.62	$ 0.92
Past Infringement [Member]
Effect of Fourth Quarter Events [Line Items]
Royalty Revenue							$ 119,900
Pegatron [Member] | Past Infringement [Member]
Effect of Fourth Quarter Events [Line Items]
Litigation Settlement, Amount											$ 71,400
Technology Solutions Customer [Member] | Past Infringement [Member]
Effect of Fourth Quarter Events [Line Items]
Litigation Settlement, Amount											$ 53,300
Revenues									$ 2,800

VIE (Details)

VIE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest	$ (2,831)	$ (2,922)	$ (2,482)
Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	24,200	15,300
Cash and Cash Equivalents [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	19,000	11,400
Patents [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	5,200	3,900
Liabilities, Total [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 800	$ 400

Subsequent Event (Details)

Subsequent Event (Details) - Subsequent Event [Member] $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Minimum [Member]
Subsequent Event [Line Items]
Severance Costs	$ 1.5
Maximum [Member]
Subsequent Event [Line Items]
Severance Costs	$ 2