Income Taxes - Schedule of Effective Income Tax Expense Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective income tax expense reconciliation [Abstract]
Income tax expense at 35% statutory federal rate	$ 84,476	$ 59,735	$ 43,774
State and local taxes, net of federal benefit	10,676	7,697	3,315
Nondeductible compensation	6,375	709	652
Nontaxable proceeds on station divestiture	(9,146)
Nondeductible earnout payments		1,415
Nondeductible acquisition costs	3,901	12	251
Nondeductible meals and entertainment	1,546	504	417
Nondeductible goodwill impairment	3,577	5,276
Domestic production activities deduction	(11,178)
Excess tax benefit on stock-based compensation	(8,106)
Disposition of nondeductible goodwill	3,279
Impact of federal tax rate reduction	(322,193)
Change in beginning of year valuation allowance	1,635
Other	1,215	2,224	278
Income tax (benefit) expense	$ (233,943)	$ 77,572	$ 48,687