Programs and Program Licenses - Summary of Programs and Program Licenses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Programs And Program Licenses [Abstract]
Cost of programs available for broadcast	$ 2,758,730	$ 2,610,364
Accumulated amortization	(1,971,839)	(1,823,985)
Cost of programs available for broadcast, net	786,891	786,379
Progress payments on programs not yet available for broadcast	322,411	305,021
Total programs and program licenses	$ 1,109,302	$ 1,091,400