v2.4.1.9

Summary of Significant Accounting Policies Income Tax (Details) (USD $) | 12 Months Ended | 108 Months Ended | 96 Months Ended
--- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2014 | Dec. 31, 2013
Income Tax Contingency [Line Items] |  |  |  |  |
Income taxes paid, including foreign witholding taxes | $ 114,876,000 us-gaap_IncomeTaxesPaid | $ 24,961,000 us-gaap_IncomeTaxesPaid | $ 116,871,000 us-gaap_IncomeTaxesPaid |  |
Income Tax Expense (Benefit) | 52,108,000 us-gaap_IncomeTaxExpenseBenefit | 25,836,000 us-gaap_IncomeTaxExpenseBenefit | 136,830,000 us-gaap_IncomeTaxExpenseBenefit |  |
Unrecognized Tax Benefits | 5,700,000 us-gaap_ForeignIncomeTaxExpenseBenefitContinuingOperations |  |  |  |
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions | 1,266,000 us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions | 0 us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions | 0 us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions |  |
Unrecognized Tax Benefits | 5,700,000 us-gaap_TaxCreditCarryforwardAmount |  |  | 5,700,000 us-gaap_TaxCreditCarryforwardAmount |
Unrecognized Tax Benefits, Period Increase (Decrease) | 700,000 us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease |  |  |  |
Foreign Tax Authority [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Income taxes paid, including foreign witholding taxes | 70,700,000 us-gaap_IncomeTaxesPaid / us-gaap_IncomeTaxAuthorityAxis = us-gaap_ForeignCountryMember | 23,300,000 us-gaap_IncomeTaxesPaid / us-gaap_IncomeTaxAuthorityAxis = us-gaap_ForeignCountryMember | 3,600,000 us-gaap_IncomeTaxesPaid / us-gaap_IncomeTaxAuthorityAxis = us-gaap_ForeignCountryMember | 239,800,000 us-gaap_IncomeTaxesPaid / us-gaap_IncomeTaxAuthorityAxis = us-gaap_ForeignCountryMember |
Foreign Tax Authority [Member] | Tax Period 2006-2013 [Member] [Domain] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Income taxes paid, including foreign witholding taxes |  |  |  |  | 239,800,000 us-gaap_IncomeTaxesPaid / us-gaap_IncomeTaxAuthorityAxis = us-gaap_ForeignCountryMember / us-gaap_TaxPeriodAxis = idcc_TaxPeriod20062013MemberDomain
Research and Development Arrangement [Member] |  |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |  |
Income Tax Expense (Benefit) | $ 900,000 us-gaap_IncomeTaxExpenseBenefit / us-gaap_IncomeTaxAuthorityAxis = us-gaap_ResearchAndDevelopmentArrangementMember |  |  |  |

X
- Definition Amount of current and deferred foreign income tax expense (benefit) attributable to income (loss) from continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Subparagraph 1 -Article 4 + Details
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- Definition The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585 + Details
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- Definition The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Carryforwards -URI http://asc.fasb.org/extlink&oid=6506874 + Details
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- Definition Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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