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and 71,134 shares issued and 32,060 and 33,529 shares outstanding Common Stock, Value, Outstanding Additional paid-in capital Additional Paid in Capital Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax TOTAL SHAREHOLDERS’ EQUITY Stockholders' Equity before Treasury Stock Treasury stock, 39,190 and 37,605 shares of common held at cost Treasury Stock, Value Total InterDigital, Inc. shareholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interest Noncontrolling Interest in Variable Interest Entity Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY Liabilities and Equity Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Long-term Debt, Unclassified [Abstract] Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Long-term Debt Instruments [Table Text Block] Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Business Acquisition [Line Items] Business Acquisition [Line Items] Actual 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Expenses (ie. legal, filings, etc.) incurred and are directly related to generating license revenue. Development Research and Development Expense Selling, general and administrative Selling, General and Administrative Expense Total Operating Expenses Costs and Expenses Income (loss) from operations Operating Income (Loss) OTHER EXPENSE (NET) Other Operating Income (Expense), Net Income (loss) before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest INCOME TAX BENEFIT Income Tax Expense (Benefit) NET INCOME (LOSS) NET INCOME (LOSS) ATTRIBUTABLE TO INTERDIGITAL, INC. 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[Text Block] Significant Agreements [Text Block] Disclosure of Long Lived Assets Held-for-sale [Table Text Block] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Deferred Revenue, Revenue Recognized Deferred Revenue, Revenue Recognized Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Amount Commitments and Contingencies Disclosure [Abstract] Litigation and Legal Proceedings Legal Matters and Contingencies [Text Block] Leases [Abstract] Leases of Lessee Disclosure [Text Block] Leases of Lessee Disclosure [Text Block] New Accounting Pronouncements and Changes in Accounting Principles [Text Block] New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Reclassifications Reclassification, Policy [Policy Text Block] New Accounting Guidance New Accounting Pronouncements, Policy [Policy Text Block] Equity [Abstract] Treasury stock, 39,190 and 37,605 shares of common held at cost Equity component of the 2020 Notes, net of tax Equity Component of the Notes, Net of Tax [2] equity component of the notes, net of tax [2] Deferred financing costs allocated to equity Stockholders' Equity Attributable to Parent Cumulative Effect on Retained Earnings, before Tax Cumulative Effect on Retained Earnings, before Tax Cumulative Effect on Retained Earnings, Tax Cumulative Effect on Retained Earnings, Tax Adjustments Related to Tax Withholding for Share-based Compensation Tax benefit from share-based compensation Excess Tax Benefit from Share-based Compensation, Operating Activities Net Income (Loss) Attributable to Parent Dividends Dividends Stock Issued During Period, Value, Stock Options Exercised Stock Issued During Period, Value, Stock Options Exercised Repurchase of common stock Payments for Repurchase of Common Stock Convertible note hedge transactions, net of tax Payments for (Proceeds from) Hedge, Financing Activities Noncontrolling Interest, Increase from Business Combination Distribution preference Distribution preference Distribution preference Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Net of Tax Proceeds from Noncontrolling Interests Proceeds from Noncontrolling Interests INCOME TAXES: [Abstract] INCOME TAXES: [Abstract] Income Tax Disclosure [Text Block] Income Tax Disclosure [Text Block] Earnings Per Share [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Restricted Stock Units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Convertible Debt Securities [Member] Convertible Debt Securities [Member] Warrant [Member] Warrant [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Payments of Debt Issuance Costs Payments of Debt Issuance Costs Leases - Schedule of Future Minimum Lease Payments Under ASC 840 [Abstract] Leases - Schedule of Future Minimum Lease Payments Under ASC 840 [Abstract] Operating Leases, Future Minimum Payments Due, Next Twelve Months Operating Leases, Future Minimum Payments Due, Next Twelve Months Operating Leases, Future Minimum Payments, Due in Two Years Operating Leases, Future Minimum Payments, Due in Two Years Operating Leases, Future Minimum Payments, Due in Three Years Operating Leases, Future Minimum Payments, Due in Three Years Operating Leases, Future Minimum Payments, Due in Four Years Operating Leases, Future Minimum Payments, Due in Four Years Operating Leases, Future Minimum Payments, Due in Five Years Operating Leases, Future Minimum Payments, Due in Five Years Operating Leases, Future Minimum Payments, Due Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Business Combination Disclosure [Text Block] Business Combination Disclosure [Text Block] Calculated under Revenue Guidance in Effect before Topic 606 [Member] Calculated under Revenue Guidance in Effect before Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Static Fixed Fee Agreements [Domain] Static Fixed Fee Agreements [Domain] Static Fixed Fee Agreements [Domain] Static Prepayments [Domain] Static Prepayments [Domain] Static Prepayments [Domain] Quarter Lag Reporting [Domain] Quarter Lag Reporting [Domain] Quarter Lag Reporting [Domain] Significant Financing Component [Domain] Significant Financing Component [Domain] Significant Financing Component [Domain] Related Tax Effect and Other Balance Sheet Impact [Domain] Related Tax Effect and Other Balance Sheet Impact [Domain] Related Tax Effect and Other Balance Sheet Impact [Domain] Variable Patent Royalty Revenue [Domain] Variable Patent Royalty Revenue [Domain] Variable Patent Royalty Revenue [Domain] Fixed-Fee Royalty Revenue [Domain] Fixed-Fee Royalty Revenue [Domain] Fixed-Fee Royalty Revenue [Domain] Current Patent Royalties [Domain] Current Patent Royalties [Domain] Current Patent Royalties [Domain] Non Current Patent Royalties [Domain] Non Current Patent Royalties [Domain] Non Current Patent Royalties [Domain] Total Patent Royalties [Member] Total Patent Royalties [Member] Total Patent Royalties [Member] Retained Earnings, Unappropriated [Member] Retained Earnings, Unappropriated [Member] Deferred Tax Asset [Domain] Deferred Tax Asset [Domain] Taxes Payable [Domain] Taxes Payable [Domain] Taxes Payable [Domain] Deferred Revenue [Domain] Deferred Revenue [Domain] Accounting Standards Update 2014-09 [Member] Accounting Standards Update 2014-09 [Member] ASC 605 [Domain] ASC 605 [Domain] ASC 605 [Domain] Revenue from Contract with Customer, Including Assessed Tax Accounts Receivable 606 Revenues, Net of Interest Expense Revenues, Net of Interest Expense Costs and Expenses Operating Income (Loss) Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Net Income Per Common Share, Basic (in usd per share) DEFERRED TAX ASSETS Taxes Payable 606 Deferred Revenue Deferred Revenue Retained earnings Retained Earnings, Unappropriated Revisions [Abstract] Revisions [Abstract] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Adjustments for Error Corrections [Axis] Adjustments for Error Corrections [Axis] Adjustments for Error Correction [Domain] Adjustments for Error Correction [Domain] Restatement [Axis] Restatement [Axis] Restatement [Domain] Restatement [Domain] Error Corrections and Prior Period Adjustments Restatement [Line Items] Error Corrections and Prior Period Adjustments Restatement [Line Items] Accounting Changes and Error Corrections [Text Block] Accounting Changes and Error Corrections [Text Block] CONCENTRATION OF CREDIT RISK AND FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES: [Abstract] CONCENTRATION OF CREDIT RISK AND FAIR VALUE OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES: [Abstract] Concentration Risk [Table] Concentration Risk [Table] Money Market Funds and Demand Deposits [Member] Money Market Funds and Demand Deposits [Member] Accounts that may or may not bear interest and that depositor is entitled to withdraw at anytime without prior notice. Checking and negotiable order of withdrawal (NOW) accounts are the most common forms of demand deposits. Additionally, includes a fund that has underlying investments in short-term money-market instruments, such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and other highly liquid and safe securities and pays money market rates of interest. 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Asset Backed Securities-This category includes information about securities that are primarily serviced by the cash flows of a discrete pool of receivables or other financial assets (such as mortgage loans or credit-card receivables). 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Senior note holders are paid off in full before any payments are made to junior note holders. Convertible notes can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder. 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Receivable, Fair Value Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed Fair Value, Measurement Inputs, Disclosure [Table Text Block] Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block] Deferred Tax Assets Deferred Tax Assets, Net Taxes Payable 606 Deferred Revenue Retained Earnings Previously Reported [Member] Previously Reported [Member] Restatement Adjustment [Member] Restatement Adjustment [Member] Net income per common share, Diluted - As Reported Total comprehensive income attributable to InterDigital, Inc. - As Reported VIE [Abstract] VIE [Abstract] Legal Entity [Axis] Legal 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Basic Earnings Per Share Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Operating Lease, Weighted Average Remaining Lease Term Operating Lease, Weighted Average Remaining Lease Term Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year Operating Lease, Cost Operating Lease, Cost Operating Lease, Right-of-Use Asset Operating Lease, Right-of-Use Asset Operating Lease, Liability, Current Operating Lease, Liability, Current Operating Lease, Liability, Noncurrent Operating Lease, Liability, Noncurrent Operating Lease, Liability Operating Lease, Liability Short-term Lease, Cost Short-term Lease, Cost Variable Lease, Cost Variable Lease, Cost Lessee, Operating Lease, Liability, Payments, Due Year Two Lessee, Operating Lease, Liability, Payments, Due Year Two Lessee, Operating Lease, Liability, Payments, 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transferred Business Combination, Consideration Transferred Less: Transaction-related receivable Net fair value of consideration transferred Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Other current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other Other non-current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets Current liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Long-term debt Other long-term liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities Total net tangible assets and liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Patents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Goodwill Total identified intangible assets Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Intangible Assets, Including Goodwill Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Intangible Assets, Including Goodwill Total fair value of consideration transferred Estimated useful lives Finite-Lived Intangible Asset, Useful Life Additional annualized amortization expense EstimatedAdditionalAmortizationExpenseFromAcquiredIntangibles EstimatedAdditionalAmortizationExpenseFromAcquiredIntangibles