Income Taxes (Reconciliation of the Provision for Income Taxes to the Amounts Computed at the Federal Statutory Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal income taxes at statutory rate	$ 375,942	$ 355,758	$ 573,231
State income taxes, net of federal tax benefit	54,739	56,345	39,062
Excess tax benefit from share-based compensation	(25,992)	(34,703)	(48,688)
Revaluation of deferred tax liability	0	(1,262)	(53,240)
Other items, net	(5,402)	(6,538)	(6,365)
Provision for income taxes	$ 399,287	$ 369,600	$ 504,000