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