Description of Business, Interim Financial Data and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Cumulus Media Inc. (and its consolidated subsidiaries, except as the context may otherwise require, “Cumulus,” “Cumulus Media,” “we,” “us,” “our,” or the “Company”) is a Delaware corporation, organized in 2002, and successor by merger to an Illinois corporation with the same name that had been organized in 1997.
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Interim Financial Data	Interim Financial Data In the opinion of management, all adjustments (consisting only of normal, recurring adjustments) necessary for a fair statement of the Company's results of operations for, and financial condition as of the end of, the interim periods have been made. The results of operations and cash flows for the three months ended March 31, 2018, and the Company’s financial condition as of March 31, 2018, are not necessarily indicative of the results of operations or cash flows that can be expected for, or the Company’s financial condition that can be expected as of the end of, any other interim period or for the fiscal year ending December 31, 2018.
Adoption of New Accounting Standards and Recent Accounting Standards Updates	Adoption of New Accounting Standards ASU 2014-09 and related updates - Revenue from Contracts with Customers ("ASU 2014-09") or ("ASC 606"). On January 1, 2018, the Company adopted ASC 606, which is a comprehensive new revenue recognition model that requires revenue to be recognized in a manner to depict the transfer of goods or services and satisfaction of performance obligations to a customer at an amount that reflects the consideration expected to be received in exchange for those goods or services. The Company applied the modified retrospective method to contracts that were not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018, are presented under ASC 606, while prior period amounts have not been adjusted and continue to be reported under the previous accounting standards. There was not a material impact to revenues as a result of the recognition of revenue in accordance with ASC 606 for the three months ended March 31, 2018, and there have not been significant changes to the Company's business processes, systems, or internal controls as a result of implementing the standard. See Note 2, "Revenues" for further details. ASU 2016-01 - Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"). In January 2016, the FASB issued ASU 2016-01 which enhances the reporting model for financial instruments including aspects of recognition, measurement, presentation and disclosure. This ASU revises the accounting requirements related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. This ASU also changes certain disclosure requirements associated with the fair value of financial instruments. These changes require an entity to measure, at fair value, investments in equity securities and other ownership interests in an entity - including investments in partnerships, unincorporated joint ventures and limited liability companies that do not result in consolidation and are not accounted for under the equity method - and recognize the changes in fair value within net income. ASU 2016-01 is effective for fiscal years beginning after December 15, 2017, and interim periods thereafter. In February 2018, the FASB issued ASU 2018-03 - Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2018-03") which provides an option for a company to "un-elect" the measurement alternative and elect to account for the investment at fair value through current earnings for certain equity investments that do not have readily determinable fair values. However, once a company makes this election for a particular investment, it must apply the fair value through current earnings model to all identical investments and/or similar investments from the same issuer. Further, a company cannot elect the measurement alternative for future purchases of identical or similar investments of the same issuer. The Company adopted ASU 2016-01 as of January 1, 2018 on a prospective basis. The Company un-elected the measurement alternative and will continue to value joint venture investments at fair value through current earnings. As such, there was no impact to the Condensed Consolidated Financial Statements. ASU 2016-15 - Classification of Certain Cash Receipts and Cash Payments ("ASU 2016-15"). In August 2016, the FASB issued ASU 2016-15 which provides guidance for several new and/or revised disclosures pertaining to the classification of certain cash receipts and cash payments on the statement of cash flows, including contingent consideration payments made after a business acquisition. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, and interim periods thereafter. The Company adopted ASU 2016-15 as of January 1, 2018 and there was no impact to the Condensed Consolidated Financial Statements. ASU 2016-18 - Restricted Cash ("ASU 2016-18"). In November 2016, the FASB issued ASU 2016-18 which provides guidance for the accounting for the disclosure of restricted cash on the statement of cash flows. ASU 2016-18 is effective for fiscal years beginning after December 15, 2017, and interim periods thereafter. The Company adopted ASU 2016-18 as of January 1, 2018. As of March 31, 2018 and December 31, 2017, the Company had approximately $9.0 million in restricted cash on the Condensed Consolidated Balance Sheets. Upon adoption of ASU 2016-18 on January 1, 2018, restricted cash balances were included along with cash and cash equivalents as of the end of the period and beginning of the period, respectively, in the Company's Condensed Consolidated Cash Flows for all periods presented. Additionally, separate line items showing changes in restricted cash balances have been eliminated from the Condensed Consolidated Statement of Cash Flows. ASU 2017-01 - Clarifying the Definition of a Business ("ASU 2017-01"). In January 2017, the FASB issued guidance that clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill, and consolidation. The new standard is effective for fiscal years, and interim periods within fiscal years, beginning after December 15, 2017. The Company adopted ASU 2017-01 as of January 1, 2018 on a prospective basis and there was no material impact to the Condensed Consolidated Financial Statements. ASU 2017-09 - Scope of Modification Accounting ("ASU 2017-09"). In May 2017, the FASB issued an update to guidance on Topic 718, Compensation—Stock Compensation that clarifies when changes to the terms or conditions of a share-based award must be accounted for as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award, as equity or liability, changes as a result of the change in terms or conditions. ASU 2017-09 is effective for annual periods, and interim periods within annual periods, beginning after December 15, 2017. The Company adopted ASU 2017-09 as of January 1, 2018 on a prospective basis and there was no material impact to the consolidated financial statements. Recent Accounting Standards Updates ASU 2016-02 - Leases ("ASU 2016-02"). In February 2016, the FASB issued ASU 2016-02 which provides updated guidance for the accounting for leases. This update requires lessees to recognize assets and liabilities for the rights and obligations created by leases with a term longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. ASU 2016-02 will be effective for fiscal years beginning after December 15, 2018, and interim periods thereafter. Early adoption is permitted. The Company is currently assessing the impact that ASU 2016-02 will have on its consolidated financial statements and plans to adopt the new standard effective January 1, 2019.
Fair Value Measurement	s