Nature of Business, Interim Financial Data and Basis of Presentation (Nature of Business) (Details)	9 Months Ended
	Sep. 30, 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	440
Number of markets | market	90
Number of radio stations	8,000