Income Taxes - Components of Provision for Income Taxes (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 provision:
Federal									$ 296,400	$ 249,358	$ 263,231
State									132,357	123,264	67,046
Deferred expense (benefit):
Federal									(1,530)	(11,777)	24,654
State									(1,542)	(9,284)	532
Income tax expense	$ 94,061	$ 105,075	$ 119,114	$ 107,435	$ 105,000	$ 95,308	$ 77,287	$ 73,966	$ 425,685	$ 351,561	$ 355,463