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
		Mar. 31, 2018		Mar. 31, 2017
Change in classification		$ (81)		$ 0
Interest rate contracts
Balance at beginning of period		14		11
Change in classification	[1]	0		0
Realized gains (losses) recorded in earnings		0		0
Unrealized gains (losses) recorded in earnings		(7)	[2]	0
Redemptions		0		0
Balance at end of period		7		11
Warrants
Balance at beginning of period		2		3
Change in classification	[1]	0		0
Realized gains (losses) recorded in earnings		0		1	[2]
Unrealized gains (losses) recorded in earnings		0		(1)	[2]
Redemptions		0		(1)
Balance at end of period		2		2
Investment Securities Available-For-Sale
Balance at beginning of period		49		54
Change in classification	[1]	(44)		0
Realized gains (losses) recorded in earnings		0		0
Unrealized gains (losses) recorded in earnings		0		0
Redemptions		(5)		(3)
Balance at end of period		0		51
Equity and other non-debt securities | Equity and other non-debt securities
Balance at beginning of period	[2]	0
Change in classification	[1]	(44)
Realized gains (losses) recorded in earnings	[2]	0
Unrealized gains (losses) recorded in earnings	[2]	0
Redemptions	[2]	(44)
Balance at end of period	[2]	0
Equity and other non-debt securities | Investment Securities Available-For-Sale
Balance at beginning of period	[3]	44		47
Change in classification	[1],[3]	(44)		0
Realized gains (losses) recorded in earnings	[3]	0		0
Unrealized gains (losses) recorded in earnings	[3]	0		0
Redemptions	[3]	0		(1)
Balance at end of period	[3]	0		46	[2]
State and municipal securities | Investment Securities Available-For-Sale
Balance at beginning of period	[3]	5		7
Change in classification	[1],[3]	0		0
Realized gains (losses) recorded in earnings	[3]	0		0
Unrealized gains (losses) recorded in earnings	[3]	0		0
Redemptions	[3]	(5)		(2)
Balance at end of period	[3]	$ 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.