v2.4.1.9

Geographic Concentration (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	$ 86,121,000us-gaap_Revenues	$ 77,622,000us-gaap_Revenues	$ 194,234,000us-gaap_Revenues	$ 57,844,000us-gaap_Revenues	$ 99,683,000us-gaap_Revenues	$ 110,623,000us-gaap_Revenues	$ 67,692,000us-gaap_Revenues	$ 47,363,000us-gaap_Revenues	$ 415,821,000us-gaap_Revenues	$ 325,361,000us-gaap_Revenues	$ 663,063,000us-gaap_Revenues
Pegatron [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity-Wide Revenues, Major Customer, Percentage									0.18	0.3	< 10%
Intel Corporation [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity-Wide Revenues, Major Customer, Percentage									0	0	0.57
Intel Mobile Communications GmbH [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity-Wide Revenues, Major Customer, Percentage									< 10%	0.18	< 10%
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									138,000,000us-gaap_Revenues / us-gaap_MajorCustomersAxis = idcc_SamsungElectronicsLtdMember
Entity-Wide Revenues, Major Customer, Percentage									0.33	0	0.15
Sony Corporation of America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Entity-Wide Revenues, Major Customer, Percentage									< 10%	0.12	< 10%
KOREA
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									144,398,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_KR	15,334,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_KR	118,078,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_KR
JAPAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									52,194,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_JP	27,494,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_JP	39,558,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_JP
SWEDEN
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									24,530,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_SE	0us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_SE	0us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_SE
CANADA
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									15,422,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_CA	36,148,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_CA	40,667,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_CA
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	100,000us-gaap_NoncurrentAssets / us-gaap_StatementGeographicalAxis = idcc_CanadaUKandSouthKoreaDomain				100,000us-gaap_NoncurrentAssets / us-gaap_StatementGeographicalAxis = idcc_CanadaUKandSouthKoreaDomain				100,000us-gaap_NoncurrentAssets / us-gaap_StatementGeographicalAxis = idcc_CanadaUKandSouthKoreaDomain	100,000us-gaap_NoncurrentAssets / us-gaap_StatementGeographicalAxis = idcc_CanadaUKandSouthKoreaDomain	100,000us-gaap_NoncurrentAssets / us-gaap_StatementGeographicalAxis = idcc_CanadaUKandSouthKoreaDomain
TAIWAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									115,955,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_TW	128,551,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_TW	40,394,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_TW
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									53,163,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_US	108,728,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_US	406,950,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_US
UNITED STATES | Property and Equipment [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Long-Lived Assets in Entity's Country of Domicile	278,100,000us-gaap_NoncurrentAssets / us-gaap_PropertyPlantAndEquipmentByTypeAxis = idcc_PropertyPlantAndEquipmentAndPatentsNetMember / us-gaap_StatementGeographicalAxis = country_US				215,900,000us-gaap_NoncurrentAssets / us-gaap_PropertyPlantAndEquipmentByTypeAxis = idcc_PropertyPlantAndEquipmentAndPatentsNetMember / us-gaap_StatementGeographicalAxis = country_US				278,100,000us-gaap_NoncurrentAssets / us-gaap_PropertyPlantAndEquipmentByTypeAxis = idcc_PropertyPlantAndEquipmentAndPatentsNetMember / us-gaap_StatementGeographicalAxis = country_US	215,900,000us-gaap_NoncurrentAssets / us-gaap_PropertyPlantAndEquipmentByTypeAxis = idcc_PropertyPlantAndEquipmentAndPatentsNetMember / us-gaap_StatementGeographicalAxis = country_US	185,400,000us-gaap_NoncurrentAssets / us-gaap_PropertyPlantAndEquipmentByTypeAxis = idcc_PropertyPlantAndEquipmentAndPatentsNetMember / us-gaap_StatementGeographicalAxis = country_US
GERMANY
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									5,293,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_DE	4,539,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_DE	3,470,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_DE
CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries									800,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_CN	1,563,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_CN	9,246,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = country_CN
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									4,064,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = idcc_OtherEuropeDomain	3,004,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = idcc_OtherEuropeDomain	4,700,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = idcc_OtherEuropeDomain
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									2,000us-gaap_Revenues / us-gaap_StatementGeographicalAxis = idcc_OtherAsiaDomain	0us-gaap_Revenues / us-gaap_StatementGeographicalAxis = idcc_OtherAsiaDomain	0us-gaap_Revenues / us-gaap_StatementGeographicalAxis = idcc_OtherAsiaDomain
Past Infringement [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Litigation Settlement, Amount					36,400,000us-gaap_LitigationSettlementAmount / idcc_RoyaltyRevenueAxis = idcc_PastInfringementMember
Past Infringement [Member] | Pegatron [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Litigation Settlement, Amount							23,500,000us-gaap_LitigationSettlementAmount / us-gaap_MajorCustomersAxis = idcc_PegatronMember / idcc_RoyaltyRevenueAxis = idcc_PastInfringementMember			71,400,000us-gaap_LitigationSettlementAmount / us-gaap_MajorCustomersAxis = idcc_PegatronMember / idcc_RoyaltyRevenueAxis = idcc_PastInfringementMember
Past Infringement [Member] | Technology Solutions Customer [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Litigation Settlement, Amount						51,600,000us-gaap_LitigationSettlementAmount / us-gaap_MajorCustomersAxis = idcc_TechnologySolutionsCustomerMember / idcc_RoyaltyRevenueAxis = idcc_PastInfringementMember				53,300,000us-gaap_LitigationSettlementAmount / us-gaap_MajorCustomersAxis = idcc_TechnologySolutionsCustomerMember / idcc_RoyaltyRevenueAxis = idcc_PastInfringementMember
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									$ 86,200,000us-gaap_Revenues / us-gaap_MajorCustomersAxis = idcc_SamsungElectronicsLtdMember / idcc_RoyaltyRevenueAxis = idcc_PastInfringementMember

X

- Definition

Percent of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

+ References

No definition available.

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X

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

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- Definition

Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 41

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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