v2.4.1.9

Obligations (Details) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Apr. 04, 2011
Debt Instrument [Line Items] |  |  |  |  |
Amortization of Financing Costs | $ 1,303,000 us-gaap_AmortizationOfFinancingCosts | $ 1,303,000 us-gaap_AmortizationOfFinancingCosts | $ 1,303,000 us-gaap_AmortizationOfFinancingCosts |  |
Senior Notes | 230,000,000 us-gaap_SeniorNotes | 230,000,000 us-gaap_SeniorNotes |  |  | 230,000,000 us-gaap_SeniorNotes
Debt Instrument, Unamortized Discount | (12,165,000)us-gaap_DebtInstrumentUnamortizedDiscount | (21,187,000)us-gaap_DebtInstrumentUnamortizedDiscount |  |  |
Long-term Debt | 217,835,000 us-gaap_LongTermDebt | 208,813,000 us-gaap_LongTermDebt |  |  |
Long-term Debt, Current Maturities | 0 us-gaap_DebtCurrent | 0 us-gaap_DebtCurrent |  |  |
Long-term debt obligations | 217,835,000 us-gaap_LongTermDebtNoncurrent | 208,813,000 us-gaap_LongTermDebtNoncurrent |  |  |
Land and Building Carrying Amount | 12,546,000 us-gaap_PropertyPlantAndEquipmentNet | 9,535,000 us-gaap_PropertyPlantAndEquipmentNet |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months | 0 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths |  |  |  |
2013 - Long Term Debt Maturities | 230,000,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo |  |  |  |
2014 - Long Term Debt Maturities | 0 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree |  |  |  |
2015 - Long Term Debt Maturities | 0 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour |  |  |  |
2016 - Long Term Debt Maturities | 0 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive |  |  |  |
Thereafter - Long Term Debt Maturities | 0 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive |  |  |  |
Total debt obligations | 230,000,000 us-gaap_DebtInstrumentCarryingAmount |  |  |  |
Balance Sheet by Location [Domain] | Convertible Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Payments of Debt Issuance Costs |  |  |  | $ 8,000,000 us-gaap_PaymentsOfDebtIssuanceCosts / us-gaap_BalanceSheetLocationAxis = idcc_BalanceSheetByLocationDomain / us-gaap_LongtermDebtTypeAxis = us-gaap_ConvertibleDebtMember |

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- Definition Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 8 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 8 -Article 9 + Details
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