Unaudited Quarterly Data - Unaudited Quarterly Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net revenue	$ 653,664	$ 611,870	$ 626,115	$ 540,317	$ 309,879	$ 275,659	$ 261,994	$ 255,658	$ 2,431,966	$ 1,103,190	$ 896,377
Income from operations	140,837	129,072	138,685	110,151	92,475	72,897	64,007	57,929	518,745	287,308	206,107
(Loss) income before income taxes	87,519	74,085	80,777	(997)	47,101	43,149	43,283	37,139	241,384	170,672	125,070
Net income attributable to Nexstar	$ 378,481	$ 46,475	$ 43,992	$ 6,049	$ 20,482	$ 24,799	$ 24,529	$ 21,727	$ 474,997	$ 91,537	$ 77,684
Basic net income per common share	$ 8.27	$ 1.01	$ 0.94	$ 0.14	$ 0.67	$ 0.81	$ 0.80	$ 0.71	$ 10.38	$ 2.98	$ 2.50
Basic weighted average shares outstanding	45,754	46,107	46,931	44,200	30,713	30,695	30,680	30,658	45,754	30,687	31,100
Diluted net income per common share	$ 8.03	$ 0.98	$ 0.91	$ 0.13	$ 0.64	$ 0.78	$ 0.78	$ 0.69	$ 10.07	$ 2.89	$ 2.42
Diluted weighted average shares outstanding	47,149	47,452	48,195	45,419	31,798	31,698	31,620	31,538	47,149	31,664	32,091