Income Taxes (Schedule Of Income Tax Expense/(Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	$ 1,276	$ 1,193	$ 2,102
Non-U.S.	149	133	122
U.S. state	23	15	21
Total Current Income Tax Expense (Benefit)	1,448	1,341	2,245
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	405	(618)	(297)
Non-U.S.	(1)	(4)	4
U.S. state	(2)	(46)	27
Total deferred	402	(668)	(266)
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Total income tax expense	$ 1,850	$ 673	$ 1,979