Significant Accounting Policies (Notes)	6 Months Ended
Jun. 30, 2011
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, 2011, and the results of our operations for the three and six months ended June 30, 2011 and 2010 and our cash flows for the six months ended June 30, 2011 and 2010. 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/A for the fiscal year ended December 31, 2010 (our “2010 Form 10-K/A”) as filed with the Securities and Exchange Commission (“SEC”) on March 28, 2011. 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 in our existing accounting policies from the disclosures included in our 2010 Form 10-K/A. New Accounting Guidance Accounting Standards Updates: Revenue Arrangements with Multiple Deliverables In September 2009, the Financial Accounting Standards Board (“FASB”) finalized revenue recognition guidance for Revenue Arrangements with Multiple Deliverables. By providing another alternative for determining the selling price of deliverables, the Accounting Standard Update related to revenue arrangements with multiple deliverables will allow companies to allocate arrangement consideration in multiple deliverable arrangements in a manner that better reflects the transaction’s economics. In addition, the residual method of allocating arrangement consideration is no longer permitted under this new guidance. This guidance is effective for fiscal years beginning on or after June 15, 2010. The guidance may be applied either prospectively from the beginning of the fiscal year for new or materially modified arrangements or retrospectively. We have adopted this guidance effective January 1, 2011, and will apply this guidance on a prospective basis for all new or materially modified revenue arrangements with multiple deliverables entered into on or after January 1, 2011. As a result of this new guidance, we will recognize revenue from new or materially modified agreements with multiple elements and fixed payments earlier than we would have under our old policy. As we did not enter into any new or materially modified agreements with multiple elements and fixed payments in first half 2011 that would have been impacted by this guidance, the adoption did not have a material impact on the timing or pattern of revenue recognition. Accounting Standards Updates: Fair Value Measurements: Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRS In May 2011, the FASB issued authoritative guidance that is more closely aligned with the fair value measurement and disclosure guidance issued by the International Accounting Standards Board ("IASB"). The issuance of this standard results in global fair value measurement and disclosure guidance that minimizes the differences between U.S. GAAP and International Financial Reporting Standards. Many of the changes in the final standard represent clarifications to existing guidance, while some changes related to the valuation premise and the application of premiums and discounts and new required disclosures are more significant. This guidance is effective for interim and annual periods beginning after December 15, 2011. Based upon our preliminary assessment, we do not believe the adoption of this guidance will have a significant impact on the Company’s financial statements or related disclosures. Accounting Standards Updates: Presentation of Comprehensive Income In June 2011, the FASB issued authoritative guidance requiring most entities to present items of net income and other comprehensive income either in one continuous statement, referred to as the statement of comprehensive income, or in two separate, but consecutive, statements of net income and other comprehensive income. The option to present items of other comprehensive income in the statement of changes in equity was eliminated. This guidance is effective for interim and annual periods beginning after December 15, 2011. Based upon our assessment of the impact of this guidance, the manner in which we present other comprehensive income in our financial statements will be modified upon adoption.

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, 2011, and the results of our operations for the three and six months ended June 30, 2011 and 2010 and our cash flows for the six months ended June 30, 2011 and 2010. 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/A for the fiscal year ended December 31, 2010 (our “2010 Form 10-K/A”) as filed with the Securities and Exchange Commission (“SEC”) on March 28, 2011. 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 in our existing accounting policies from the disclosures included in our 2010 Form 10-K/A.

New Accounting Guidance

Accounting Standards Updates: Revenue Arrangements with Multiple Deliverables

In September 2009, the Financial Accounting Standards Board (“FASB”) finalized revenue recognition guidance for Revenue Arrangements with Multiple Deliverables. By providing another alternative for determining the selling price of deliverables, the Accounting Standard Update related to revenue arrangements with multiple deliverables will allow companies to allocate arrangement consideration in multiple deliverable arrangements in a manner that better reflects the transaction’s economics. In addition, the residual method of allocating arrangement consideration is no longer permitted under this new guidance. This guidance is effective for fiscal years beginning on or after June 15, 2010. The guidance may be applied either prospectively from the beginning of the fiscal year for new or materially modified arrangements or retrospectively. We have adopted this guidance effective January 1, 2011, and will apply this guidance on a prospective basis for all new or materially modified revenue arrangements with multiple deliverables entered into on or after January 1, 2011. As a result of this new guidance, we will recognize revenue from new or materially modified agreements with multiple elements and fixed payments earlier than we would have under our old policy. As we did not enter into any new or materially modified agreements with multiple elements and fixed payments in first half 2011 that would have been impacted by this guidance, the adoption did not have a material impact on the timing or pattern of revenue recognition.

Accounting Standards Updates: Fair Value Measurements: Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRS

In May 2011, the FASB issued authoritative guidance that is more closely aligned with the fair value measurement and disclosure guidance issued by the International Accounting Standards Board ("IASB"). The issuance of this standard results in global fair value measurement and disclosure guidance that minimizes the differences between U.S. GAAP and International Financial Reporting Standards. Many of the changes in the final standard represent clarifications to existing guidance, while some changes related to the valuation premise and the application of premiums and discounts and new required disclosures are more significant. This guidance is effective for interim and annual periods beginning after December 15, 2011. Based upon our preliminary assessment, we do not believe the adoption of this guidance will have a significant impact on the Company’s financial statements or related disclosures.

Accounting Standards Updates: Presentation of Comprehensive Income

In June 2011, the FASB issued authoritative guidance requiring most entities to present items of net income and other comprehensive income either in one continuous statement, referred to as the statement of comprehensive income, or in two separate, but consecutive, statements of net income and other comprehensive income. The option to present items of other comprehensive income in the statement of changes in equity was eliminated. This guidance is effective for interim and annual periods beginning after December 15, 2011. Based upon our assessment of the impact of this guidance, the manner in which we present other comprehensive income in our financial statements will be modified upon adoption.