Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018 Segment Station	Mar. 31, 2017
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	3
Percentage of revenue generated from outside the United States	19.00%	0.00%
Television
Segment Reporting Information [Line Items]
Number of stations owned	55
Radio
Segment Reporting Information [Line Items]
Number of stations owned	49
Advertisements and Syndicates Radio Programming | Minimum
Segment Reporting Information [Line Items]
Number of stations owned	300