Note 2 - Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue	$ 328,220	$ 279,310	$ 250,344	$ 226,258	$ 233,609	$ 218,977	$ 226,681	$ 203,461	$ 1,084,132	$ 882,728	$ 812,465
Sales Channel, Directly to Consumer [Member]
Revenue									551,883	473,649	373,363
Sales Channel, Through Intermediary [Member]
Revenue									532,249	409,079	439,102
Local Advertising [Member]
Revenue									442,728	451,261	403,336
National Advertising [Member]
Revenue									114,192	118,817	98,351
Political Advertising [Member]
Revenue									155,074	16,498	90,095
Advertising [Member]
Revenue									711,994	586,576	591,782
Retransmission Consent [Member]
Revenue									355,423	276,603	200,879
Service, Other [Member]
Revenue									$ 16,715	$ 19,549	$ 19,804