Investment Securities (Summary Of Investment Securities Available-For-Sale In Unrealized Loss Positions) (Details) - USD ($) $ in Millions		Dec. 31, 2015		Dec. 31, 2014
Temporarily Impaired Less than 12 Months, Fair Value		$ 4,944		$ 924
Temporarily Impaired, Less than 12 Months, Unrealized Losses		28		3
Temporarily Impaired 12 Months or more, Fair Value		1,986		3,247
Temporarily Impaired, 12 Months or more, Unrealized Losses		51		73
Temporarily Impaired Total, Fair Value		6,930		4,171
Temporarily Impaired Total, Unrealized Losses		79		76
U.S. Treasury and other U.S. government agency securities
Temporarily Impaired Less than 12 Months, Fair Value		2,265		298
Temporarily Impaired, Less than 12 Months, Unrealized Losses		7		0	[1]
Temporarily Impaired 12 Months or more, Fair Value		0		0
Temporarily Impaired, 12 Months or more, Unrealized Losses		0		0
Temporarily Impaired Total, Fair Value		2,265		298
Temporarily Impaired Total, Unrealized Losses		7		0	[1]
Residential mortgage-backed securities
Temporarily Impaired Less than 12 Months, Fair Value	[2]	2,665		626
Temporarily Impaired, Less than 12 Months, Unrealized Losses	[2]	21		3
Temporarily Impaired 12 Months or more, Fair Value	[2]	1,976		3,112
Temporarily Impaired, 12 Months or more, Unrealized Losses	[2]	51		71
Temporarily Impaired Total, Fair Value	[2]	4,641		3,738
Temporarily Impaired Total, Unrealized Losses	[2]	72		74
State and municipal securities
Temporarily Impaired Less than 12 Months, Fair Value	[3]	0		0
Temporarily Impaired, Less than 12 Months, Unrealized Losses	[3]	0		0
Temporarily Impaired 12 Months or more, Fair Value	[3]	9		22
Temporarily Impaired, 12 Months or more, Unrealized Losses	[3]	0	[1]	1
Temporarily Impaired Total, Fair Value	[3]	9		22
Temporarily Impaired Total, Unrealized Losses	[3]	0	[1]	1
Corporate debt securities
Temporarily Impaired Less than 12 Months, Fair Value	[3]	0		0
Temporarily Impaired, Less than 12 Months, Unrealized Losses	[3]	0		0
Temporarily Impaired 12 Months or more, Fair Value	[3]	1		1
Temporarily Impaired, 12 Months or more, Unrealized Losses	[1],[3]	0		0
Temporarily Impaired Total, Fair Value	[3]	1		1
Temporarily Impaired Total, Unrealized Losses	[1],[3]	0		0
Equity and other non-debt securities
Temporarily Impaired Less than 12 Months, Fair Value	[3]	14		0
Temporarily Impaired, Less than 12 Months, Unrealized Losses	[3]	0	[1]	0
Temporarily Impaired 12 Months or more, Fair Value	[3]	0		112
Temporarily Impaired, 12 Months or more, Unrealized Losses	[3]	0		1
Temporarily Impaired Total, Fair Value	[3]	14		112
Temporarily Impaired Total, Unrealized Losses	[3]	$ 0	[1]	$ 1

[1] Unrealized losses less than $0.5 million.

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

[3] Primarily auction-rate securities.