Significant Accounting Policies (Notes)	6 Months Ended
Jun. 30, 2015
Basis of Presentation [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	BASIS OF PRESENTATION: In the opinion of management, the accompanying unaudited, condensed consolidated financial statements contain all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the financial position of InterDigital, Inc. (individually and/or collectively with its subsidiaries referred to as “InterDigital,” the “Company,” “we,” “us” or “our,” unless otherwise indicated) as of June 30, 2015, and the results of our operations for the three and six months ended June 30, 2015 and 2014 and our cash flows for the six months June 30, 2015 and 2014. The accompanying unaudited, condensed consolidated financial statements have been prepared in accordance with the instructions for Form 10-Q and, accordingly, do not include all of the detailed schedules, information and notes necessary to state fairly the financial condition, results of operations and cash flows in conformity with generally accepted accounting principles (“GAAP”). The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP for year-end financial statements. Therefore, these financial statements should be read in conjunction with the financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2014 (our “2014 Form 10-K”) as filed with the Securities and Exchange Commission (“SEC”) on February 19, 2015. The results of operations for interim periods are not necessarily indicative of the results to be expected for the entire year. We have one reportable segment. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities as of the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. Change in Accounting Policies There have been no material changes or updates in our existing accounting policies from the disclosures included in our 2014 Form 10-K except as stated below in "New Accounting Guidance." Reclassifications Certain reclassifications have been made to prior year amounts to conform to the current year presentation. New Accounting Guidance Accounting Standards Update: Debt issuance costs In March 2015, as part of their simplification initiative, the Financial Accounting Standards Board ("FASB") issued amendments to guidance for reporting debt issuance costs. According to the revised standard, an entity will recognize debt issuance costs as a direct deduction from the debt liability as opposed to an asset. The costs will continue to be amortized and included within interest expense in the entity's financial statements. The guidance is effective for interim and annual periods beginning on or after December 15, 2015 but early adoption is permitted. The Company has elected to early adopt this guidance effective first quarter 2015 and we have retrospectively applied the change within our Consolidated Balance Sheets included in this Quarterly Report on Form 10-Q. The impact of this change to our December 31, 2014 balance sheet was reductions of $1.3 million and $0.3 million to Prepaid and other current assets and Other non-current assets, respectively, and $1.6 million to Long-term debt. See Note 8, “Long-Term Debt” for further information on our debt issuance costs. Accounting Standards Update: Consolidation In February 2015, the FASB issued ASU No. 2015-2, “Consolidation (Topic 820): Amendments to the Consolidation Analysis.” ASU 2015-2 provides a revised consolidation model for all reporting entities to use in evaluating whether they should consolidate certain legal entities. All legal entities will be subject to reevaluation under this revised consolidation model. The revised consolidation model, among other things, (i) modifies the evaluation of whether limited partnerships and similar legal entities are voting interest entities, or VIEs, (ii) eliminates the presumption that a general partner should consolidate a limited partnership and (iii) modifies the consolidation analysis of reporting entities that are involved with VIEs through fee arrangements and related party relationships. ASU 2015-2 is effective for fiscal years, and interim reporting periods within those fiscal years, beginning after December 15, 2015. We are still evaluating what impact, if any, this ASU will have on the Company’s consolidated financial position, results of operations or cash flows. Accounting Standards Update: Revenue Recognition In May 2014, the FASB issued guidance on revenue from contracts with customers that will supersede most current revenue recognition guidance, including industry-specific guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance provides a five-step analysis of transactions to determine when and how revenue is recognized. Other major provisions include capitalization of certain contract costs, consideration of time value of money in the transaction price, and allowing estimates of variable consideration to be recognized before contingencies are resolved in certain circumstances. The guidance also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from an entity’s contracts with customers. The guidance is effective for the interim and annual periods beginning on or after December 15, 2017 (early adoption is permitted as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within those annual periods). The guidance permits the use of either a retrospective or cumulative effect transition method. We have not yet selected a transition method. We are currently evaluating the effect that adopting this guidance will have on the Company's financial position, results of operations or cash flows.

BASIS OF PRESENTATION:

In the opinion of management, the accompanying unaudited, condensed consolidated financial statements contain all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the financial position of InterDigital, Inc. (individually and/or collectively with its subsidiaries referred to as “InterDigital,” the “Company,” “we,” “us” or “our,” unless otherwise indicated) as of June 30, 2015, and the results of our operations for the three and six months ended June 30, 2015 and 2014 and our cash flows for the six months June 30, 2015 and 2014. The accompanying unaudited, condensed consolidated financial statements have been prepared in accordance with the instructions for Form 10-Q and, accordingly, do not include all of the detailed schedules, information and notes necessary to state fairly the financial condition, results of operations and cash flows in conformity with generally accepted accounting principles (“GAAP”). The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP for year-end financial statements. Therefore, these financial statements should be read in conjunction with the financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2014 (our “2014 Form 10-K”) as filed with the Securities and Exchange Commission (“SEC”) on February 19, 2015. The results of operations for interim periods are not necessarily indicative of the results to be expected for the entire year. We have one reportable segment.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities as of the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.

Change in Accounting Policies

There have been no material changes or updates in our existing accounting policies from the disclosures included in our 2014 Form 10-K except as stated below in "New Accounting Guidance."

Reclassifications

Certain reclassifications have been made to prior year amounts to conform to the current year presentation.

New Accounting Guidance

Accounting Standards Update: Debt issuance costs

In March 2015, as part of their simplification initiative, the Financial Accounting Standards Board ("FASB") issued amendments to guidance for reporting debt issuance costs. According to the revised standard, an entity will recognize debt issuance costs as a direct deduction from the debt liability as opposed to an asset. The costs will continue to be amortized and included within interest expense in the entity's financial statements. The guidance is effective for interim and annual periods beginning on or after December 15, 2015 but early adoption is permitted. The Company has elected to early adopt this guidance effective first quarter 2015 and we have retrospectively applied the change within our Consolidated Balance Sheets included in this Quarterly Report on Form 10-Q. The impact of this change to our December 31, 2014 balance sheet was reductions of $1.3 million and $0.3 million to Prepaid and other current assets and Other non-current assets, respectively, and $1.6 million to Long-term debt. See Note 8, “Long-Term Debt” for further information on our debt issuance costs.

Accounting Standards Update: Consolidation

In February 2015, the FASB issued ASU No. 2015-2, “Consolidation (Topic 820): Amendments to the Consolidation Analysis.” ASU 2015-2 provides a revised consolidation model for all reporting entities to use in evaluating whether they should consolidate certain legal entities. All legal entities will be subject to reevaluation under this revised consolidation model. The revised consolidation model, among other things, (i) modifies the evaluation of whether limited partnerships and similar legal entities are voting interest entities, or VIEs, (ii) eliminates the presumption that a general partner should consolidate a limited partnership and (iii) modifies the consolidation analysis of reporting entities that are involved with VIEs through fee arrangements and related party relationships. ASU 2015-2 is effective for fiscal years, and interim reporting periods within those fiscal years, beginning after December 15, 2015. We are still evaluating what impact, if any, this ASU will have on the Company’s consolidated financial position, results of operations or cash flows.

Accounting Standards Update: Revenue Recognition

In May 2014, the FASB issued guidance on revenue from contracts with customers that will supersede most current revenue recognition guidance, including industry-specific guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance provides a five-step analysis of transactions to determine when and how revenue is recognized. Other major provisions include capitalization of certain contract costs, consideration of time value of money in the transaction price, and allowing estimates of variable consideration to be recognized before contingencies are resolved in certain circumstances. The guidance also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from an entity’s contracts with customers. The guidance is effective for the interim and annual periods beginning on or after December 15, 2017 (early adoption is permitted as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within those annual periods). The guidance permits the use of either a retrospective or cumulative effect transition method. We have not yet selected a transition method. We are currently evaluating the effect that adopting this guidance will have on the Company's financial position, results of operations or cash flows.