Fair Value Measurements (Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - Interest rate contracts - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Balance at beginning of period		$ 24	$ 43	$ 39	$ 22
Realized gains (losses) recorded in earnings	[1]	0	0	0	0
Unrealized gains (losses) recorded in earnings	[1]	5	1	(10)	22
Sales		0	0	0	0
Balance at end of period		$ 29	$ 44	$ 29	$ 44

[1] Realized and unrealized gains and losses due to changes in fair value are recorded in other noninterest income on the Consolidated Statements of Comprehensive Income.