Segment Information - Disaggregation of Revenue Generating Activities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 349,777	$ 302,726	$ 979,435	$ 840,312
Core advertising
Disaggregation of Revenue [Line Items]
Total operating revenues	214,981	165,587	598,828	511,434
Political
Disaggregation of Revenue [Line Items]
Total operating revenues	5,037	40,018	8,033	57,484
Retransmission and carriage
Disaggregation of Revenue [Line Items]
Total operating revenues	97,128	79,673	277,736	225,391
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 32,631	$ 17,448	$ 94,838	$ 46,003