Fair Value Measurements (Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017		Mar. 31, 2018
Change in classification		$ 81	$ 0	$ 81	$ 0
Interest rate contracts
Balance at beginning of period		6	13	14	11
Change in classification	[1]	0	0	0	0
Realized gains (losses) recorded in earnings		0	0	0	0
Unrealized gains (losses) recorded in earnings	[2]	(4)	1	(12)	3
Recorded in Other Comprehensive Income			0		0
Sales and redemptions		0	0	0	0
Balance at end of period		2	14	2	14
Warrants
Balance at beginning of period		2	2	2	3
Change in classification	[1]	0	0	0	0
Realized gains (losses) recorded in earnings	[2]	2	0	3	5
Unrealized gains (losses) recorded in earnings		0	0	0	(1)	[2]
Recorded in Other Comprehensive Income			0		0
Sales and redemptions		(2)	0	(3)	(5)
Balance at end of period		2	2	2	2
Investment Securities Available-For-Sale
Balance at beginning of period			51	49	54
Change in classification	[1]		0		0		$ 44
Realized gains (losses) recorded in earnings			0	0	0
Unrealized gains (losses) recorded in earnings			0	0	0
Recorded in Other Comprehensive Income		0	(1)	0	(1)
Sales and redemptions			0	(5)	(3)
Balance at end of period		0	50	0	50
Equity and other non-debt securities | Equity and other non-debt securities
Balance at beginning of period				0
Change in classification	[1]						(44)
Realized gains (losses) recorded in earnings				0
Unrealized gains (losses) recorded in earnings				0
Recorded in Other Comprehensive Income			0		0
Sales and redemptions				(44)
Balance at end of period		0		0
Equity and other non-debt securities | Investment Securities Available-For-Sale
Balance at beginning of period	[3]		46	44	47
Change in classification	[1],[3]		0		0		(44)
Realized gains (losses) recorded in earnings	[3]		0	0	0
Unrealized gains (losses) recorded in earnings	[3]		0	0	0
Recorded in Other Comprehensive Income	[3]	0	(1)	0	(1)
Sales and redemptions	[3]		0	0	(1)
Balance at end of period	[3]	0	45	0	45
State and municipal securities | Investment Securities Available-For-Sale
Balance at beginning of period	[3]		5	5	7
Change in classification	[1],[3]		0		0		$ 0
Realized gains (losses) recorded in earnings	[3]		0	0	0
Unrealized gains (losses) recorded in earnings	[3]		0	0	0
Recorded in Other Comprehensive Income	[3]		0		0
Sales and redemptions	[3]		0	(5)	(2)
Balance at end of period	[3]	$ 0	$ 5	$ 0	$ 5

[1] Reflects the reclassification of equity securities resulting from the adoption of ASU 2016-01.

[2] Realized and unrealized gains and losses due to changes in fair value recorded in Other Noninterest Income on the Consolidated Statements of Comprehensive Income.

[3] Auction-rate securities.