Income Taxes (Schedule of Components of the Provision for Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Provision for income taxes
Federal income tax expense, current	$ 401,331	$ 315,061	$ 289,953
State income tax expense, current	97,085	62,795	59,487
International income tax expense, current	3,306	273	0
Current income tax expense	501,722	378,129	349,440
Federal income tax expense, deferred	16,749	19,367	16,309
State income tax (benefit) expense, deferred	(2,865)	2,027	3,851
International income tax benefit. deferred	(1,503)	(236)	0
Total deferred	12,381	21,158	20,160
Provision for income taxes	$ 514,103	$ 399,287	$ 369,600