Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal, current	$ 608	$ 773	$ 454
State, current	151	176	51
Total current	759	949	505
Federal, deferred	299	123	(474)
State, deferred	4	10	71
Total deferred	303	133	(403)
Income Tax Expense (Benefit), Total	$ 1,062	$ 1,082	$ 102