Business Segment Information (Market Segment Financial Results) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013
Net interest income (expense) (FTE)			$ 828		$ 831
Provision for credit losses	11	13	20		29
Noninterest income	220	222	428		435
Noninterest expenses	404	416	810		832
Provision (benefit) for income taxes (FTE)			136		128
Net income (loss)	151	143	290		277
Net credit-related charge-offs (recoveries)			21		41
Assets, average			64,794		63,733
Loans, average			45,905		44,756
Deposits, average			53,079		51,095
Return on average assets			0.90%	[1]	0.87%	[1]
Efficiency ratio			64.55%	[2]	65.59%	[2]
Michigan
Net interest income (expense) (FTE)			364		378
Provision for credit losses			(5)		(4)
Noninterest income			182		180
Noninterest expenses			320		329
Provision (benefit) for income taxes (FTE)			82		82
Net income (loss)			149		151
Net credit-related charge-offs (recoveries)			10		9
Assets, average			13,835		14,033
Loans, average			13,478		13,626
Deposits, average			20,668		20,206
Return on average assets			1.37%	[1]	1.42%	[1]
Efficiency ratio			58.69%	[2]	58.85%	[2]
California
Net interest income (expense) (FTE)			349		344
Provision for credit losses			25		24
Noninterest income			72		71
Noninterest expenses			197		197
Provision (benefit) for income taxes (FTE)			74		71
Net income (loss)			125		123
Net credit-related charge-offs (recoveries)			15		22
Assets, average			15,429		13,976
Loans, average			15,133		13,728
Deposits, average			15,078		14,514
Return on average assets			1.56%	[1]	1.59%	[1]
Efficiency ratio			46.75%	[2]	47.39%	[2]
Texas
Net interest income (expense) (FTE)			273		266
Provision for credit losses			29		13
Noninterest income			62		65
Noninterest expenses			178		180
Provision (benefit) for income taxes (FTE)			46		48
Net income (loss)			82		90
Net credit-related charge-offs (recoveries)			8		3
Assets, average			11,367		10,841
Loans, average			10,667		10,125
Deposits, average			10,799		10,074
Return on average assets			1.37%	[1]	1.59%	[1]
Efficiency ratio			53.22%	[2]	54.19%	[2]
Other Markets
Net interest income (expense) (FTE)			148		161
Provision for credit losses			(20)		(1)
Noninterest income			79		84
Noninterest expenses			93		96
Provision (benefit) for income taxes (FTE)			39		39
Net income (loss)			115		111
Net credit-related charge-offs (recoveries)			(12)		7
Assets, average			7,074		7,796
Loans, average			6,627		7,277
Deposits, average			5,986		5,794
Return on average assets			3.25%	[1]	2.85%	[1]
Efficiency ratio			41.11%	[2]	39.34%	[2]
Finance & Other
Net interest income (expense) (FTE)			(306)		(318)
Provision for credit losses			(9)		(3)
Noninterest income			33		35
Noninterest expenses			22		30
Provision (benefit) for income taxes (FTE)			(105)		(112)
Net income (loss)			(181)		(198)
Net credit-related charge-offs (recoveries)			0		0
Assets, average			17,089		17,087
Loans, average			0		0
Deposits, average			$ 548		$ 507

[1] Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

[2] Noninterest expenses as a percentage of the sum of net interest income (FTE) and noninterest income excluding net securities gains.