Significant Accounting Policies (Notes)	9 Months Ended
Sep. 30, 2014
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 September 30, 2014, and the results of our operations for the three and nine months ended September 30, 2014 and 2013 and our cash flows for the nine months ended September 30, 2014 and 2013. 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, 2013 (our “2013 Form 10-K”) as filed with the Securities and Exchange Commission (“SEC”) on February 24, 2014. 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 2013 Form 10-K. New Accounting Guidance Accounting Standards Update: Discontinued Operations In April 2014, the Financial Accounting Standards Board ("FASB") issued amendments to guidance for reporting discontinued operations and disposals of components of an entity. The amended guidance requires that a disposal representing a strategic shift that has (or will have) a major effect on an entity’s financial results or a business activity classified as held for sale should be reported as discontinued operations. The amendments also expand the disclosure requirements for discontinued operations and add new disclosures for individually significant dispositions that do not qualify as discontinued operations. The amendments are effective prospectively for fiscal years, and interim reporting periods within those years, beginning after December 15, 2014 (early adoption is permitted only for disposals that have not been previously reported). The implementation of the amended guidance is not expected to have a material impact on our consolidated financial position or results of operations. 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, 2016 (early adoption is not permitted). The guidance permits the use of either a retrospective or cumulative effect transition method. We have not yet selected a transition method and are currently evaluating the impact of the amended guidance on our consolidated financial position, results of operations and related disclosures.

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 September 30, 2014, and the results of our operations for the three and nine months ended September 30, 2014 and 2013 and our cash flows for the nine months ended September 30, 2014 and 2013. 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, 2013 (our “2013 Form 10-K”) as filed with the Securities and Exchange Commission (“SEC”) on February 24, 2014. 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 2013 Form 10-K.

New Accounting Guidance

Accounting Standards Update: Discontinued Operations

In April 2014, the Financial Accounting Standards Board ("FASB") issued amendments to guidance for reporting discontinued operations and disposals of components of an entity. The amended guidance requires that a disposal representing a strategic shift that has (or will have) a major effect on an entity’s financial results or a business activity classified as held for sale should be reported as discontinued operations. The amendments also expand the disclosure requirements for discontinued operations and add new disclosures for individually significant dispositions that do not qualify as discontinued operations. The amendments are effective prospectively for fiscal years, and interim reporting periods within those years, beginning after December 15, 2014 (early adoption is permitted only for disposals that have not been previously reported). The implementation of the amended guidance is not expected to have a material impact on our consolidated financial position or results of operations.

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, 2016 (early adoption is not permitted). The guidance permits the use of either a retrospective or cumulative effect transition method. We have not yet selected a transition method and are currently evaluating the impact of the amended guidance on our consolidated financial position, results of operations and related disclosures.