Income Taxes - Summary of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 35,673	$ 33,032	$ 11,917
State	7,179	6,958	2,173
Total	42,852	39,990	14,090
Deferred:
Federal	2,924	2,163	13,646
State	(1,037)	838	4,004
Total	1,887	3,001	17,650
Tax provision	$ 44,739	$ 42,991	$ 31,740