Investment Securities (Summary Of Investment Securities Available-For-Sale In Unrealized Loss Positions) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Temporarily Impaired Less than 12 months, Fair Value		$ 609	$ 4,944
Temporarily Impaired Less than 12 Months, Unrealized Losses		2	28
Temporarily Impaired 12 months or more, Fair Value		1,261	1,986
Temporarily Impaired 12 Months or more, Unrealized Losses		16	51
Temporarily Impaired Total, Fair Value		1,870	6,930
Temporarily Impaired Total, Unrealized Losses		18	79
U.S. Treasury and other U.S. government agency securities
Temporarily Impaired Less than 12 months, Fair Value			2,265
Temporarily Impaired Less than 12 Months, Unrealized Losses			7
Temporarily Impaired 12 months or more, Fair Value			0
Temporarily Impaired 12 Months or more, Unrealized Losses			0
Temporarily Impaired Total, Fair Value			2,265
Temporarily Impaired Total, Unrealized Losses			7
Residential mortgage-backed securities
Temporarily Impaired Less than 12 months, Fair Value	[1]	573	2,665
Temporarily Impaired Less than 12 Months, Unrealized Losses	[1]	1	21
Temporarily Impaired 12 months or more, Fair Value	[1]	1,244	1,976
Temporarily Impaired 12 Months or more, Unrealized Losses	[1]	15	51
Temporarily Impaired Total, Fair Value	[1]	1,817	4,641
Temporarily Impaired Total, Unrealized Losses	[1]	16	72
State and municipal securities
Temporarily Impaired Less than 12 months, Fair Value	[2]	0	0
Temporarily Impaired Less than 12 Months, Unrealized Losses	[2]	0	0
Temporarily Impaired 12 months or more, Fair Value	[2]	7	9
Temporarily Impaired 12 Months or more, Unrealized Losses	[2],[3]	0	0
Temporarily Impaired Total, Fair Value	[2]	7	9
Temporarily Impaired Total, Unrealized Losses	[2],[3]	0	0
Corporate debt securities
Temporarily Impaired Less than 12 months, Fair Value	[2]		0
Temporarily Impaired Less than 12 Months, Unrealized Losses	[2]		0
Temporarily Impaired 12 months or more, Fair Value	[2]		1
Temporarily Impaired 12 Months or more, Unrealized Losses	[2],[3]		0
Temporarily Impaired Total, Fair Value	[2]		1
Temporarily Impaired Total, Unrealized Losses	[2],[3]		0
Equity and other non-debt securities
Temporarily Impaired Less than 12 months, Fair Value	[2]	36	14
Temporarily Impaired Less than 12 Months, Unrealized Losses	[2]	1	0	[3]
Temporarily Impaired 12 months or more, Fair Value	[2]	10	0
Temporarily Impaired 12 Months or more, Unrealized Losses	[2]	1	0
Temporarily Impaired Total, Fair Value	[2]	46	14
Temporarily Impaired Total, Unrealized Losses	[2]	$ 2	$ 0	[3]

[1] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises

[2] Primarily auction-rate securities.

[3] Unrealized losses less than $0.5 million.