Income Taxes - Components of Provision (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current									$ 4,326	$ 13,812	$ 16,492
Deferred									9,839	20,418	1,676
Total income tax expense	$ 1,746	$ 4,066	$ 3,723	$ 4,630	$ 19,924	$ 4,766	$ 4,905	$ 4,635	$ 14,165	$ 34,230	$ 18,168