v2.4.1.9

Significant Agreements Significant Events (Details) (USD $) In Thousands, unless otherwise specified	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
Significant Events [Abstract]
Revenues	$ 86,121us-gaap_Revenues	$ 77,622us-gaap_Revenues	$ 194,234us-gaap_Revenues	$ 57,844us-gaap_Revenues	$ 99,683us-gaap_Revenues	$ 110,623us-gaap_Revenues	$ 67,692us-gaap_Revenues	$ 47,363us-gaap_Revenues	$ 415,821us-gaap_Revenues	$ 325,361us-gaap_Revenues	$ 663,063us-gaap_Revenues
Samsung Electronics, Ltd. [Member]
Significant Events [Abstract]
Revenues									138,000us-gaap_Revenues / us-gaap_MajorCustomersAxis = idcc_SamsungElectronicsLtdMember
Samsung Electronics, Ltd. [Member] | Past Infringement [Member]
Significant Events [Abstract]
Revenues									86,200us-gaap_Revenues / us-gaap_MajorCustomersAxis = idcc_SamsungElectronicsLtdMember / idcc_RoyaltyRevenueAxis = idcc_PastInfringementMember
Samsung Electronics, Ltd. [Member] | Recurring Revenue [Domain]
Significant Events [Abstract]
Revenues									51,800us-gaap_Revenues / us-gaap_MajorCustomersAxis = idcc_SamsungElectronicsLtdMember / idcc_RoyaltyRevenueAxis = idcc_RecurringRevenueDomain
Fujitsu and another customer [Domain]
Significant Events [Abstract]
Revenues									48,100us-gaap_Revenues / us-gaap_MajorCustomersAxis = idcc_FujitsuandanothercustomerDomain
Fujitsu and another customer [Domain] | Past Infringement [Member]
Significant Events [Abstract]
Revenues									0us-gaap_Revenues / us-gaap_MajorCustomersAxis = idcc_FujitsuandanothercustomerDomain / idcc_RoyaltyRevenueAxis = idcc_PastInfringementMember
Fujitsu and another customer [Domain] | Recurring Revenue [Domain]
Significant Events [Abstract]
Revenues									$ 16,000us-gaap_Revenues / us-gaap_MajorCustomersAxis = idcc_FujitsuandanothercustomerDomain / idcc_RoyaltyRevenueAxis = idcc_RecurringRevenueDomain

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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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