|
Summary of Significant Accounting Policies Investment in Other Entities (Details) (Pantech [Member], USD $)
In Millions, unless otherwise specified |
12 Months Ended | |
|---|---|---|
|
Dec. 31, 2013
|
Sep. 30, 2009
|
|
|
Pantech [Member]
|
||
| Schedule of Cost and Equity method Investments [Line Items] | ||
| Cost Method Investments | $ 0us-gaap_CostMethodInvestments / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = idcc_PantechMember |
$ 21.7us-gaap_CostMethodInvestments / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = idcc_PantechMember |
| Cost-method Investments, Other than Temporary Impairment | $ (21.7)us-gaap_CostmethodInvestmentsOtherThanTemporaryImpairment / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = idcc_PantechMember |
| X | ||||||||||
|
- Definition
Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the cost method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|