Income Taxes (Schedule Of Income Tax Expense/(Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	$ (3,968)	$ (308)	$ 1,873
Non-U.S.	148	169	169
U.S. state	21	(161)	97
Total Current Income Tax Expense (Benefit)	(3,799)	(300)	2,139
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.S. federal	652	(953)	(996)
Non-U.S.		(3)	(4)
U.S. state	612	(367)	5
Total deferred	1,264	(1,323)	(995)
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Total income tax (benefit)/expense	$ (2,535)	$ (1,623)	$ 1,144