Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal									$ 57,354	$ 60,764	$ 76,966
State									(1,344)	8,732	8,589
Current Income Tax Expense (Benefit), Total									56,010	69,496	85,555
Deferred:
Federal									2,804	(10,708)	(6,189)
State									(487)	(799)	843
Deferred Income Tax Expense (Benefit)									2,317	(11,507)	(5,346)
Income Tax Expense (Benefit), Total	$ 17,575	$ 15,171	$ 14,125	$ 11,456	$ 18,263	$ 8,720	$ 13,960	$ 17,046	$ 58,327	$ 57,989	$ 80,209