Income Taxes - Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current [Abstract]
Federal	$ 16,959	$ 10,355	$ 18,448
State	5,687	2,698	2,166
Deferred [Abstract]
Federal	7,280	15,647	12,865
State	1,820	2,353	1,935
Income tax provision excluding deferred tax asset revaluation and reversal of valuation allowance	31,746	31,053	35,414
Deferred tax expense (benefit) - re-measurement of deferred tax assets	25,619
Deferred tax expense (benefit) - reversal of valuation allowance	(8,650)
Income tax provision	$ 48,715	$ 31,053	$ 35,414