Income Taxes - Schedule of Provision for Income Tax Expense (Details) - USD ($) $ 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
Current:
Federal									$ 65,196	$ 111,302	$ 140,778
State									1,246	3,019	4,530
Foreign									(35)	(13)	23
Total current provision									66,407	114,308	145,331
Deferred:
Federal									(8,270)	25,423	3,572
State									6,618	1,976	3,875
Foreign									108	(394)	(398)
Total deferred provision									(1,544)	27,005	7,049
Provision for income tax expense	$ (5,486)	$ 25,562	$ 16,032	$ 28,755	$ 54,128	$ 47,715	$ 15,036	$ 24,433	$ 64,863	$ 141,313	$ 152,380