Description of Business, Interim Financial Data and Basis of Presentation (Nature of Business) (Details)	3 Months Ended
	Mar. 31, 2018 audience market station
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Weekly Audience Reach, Number of People | audience	245,000,000
Number of Owned and Operated Stations	445
Number Of Markets | market	90
Number Of Radio Stations	8,000