Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Loan Losses And Related Loan Amounts) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for loan losses	$ 2		$ 5	$ 11	$ 9	$ 9		$ 8	$ 13	$ 16	$ 27		$ 46		$ 79
PCI loans	2					5					2		5
Total loans	48,593					45,470					48,593		45,470
Allowance for PCI loans	0					0					0		0
Business loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	44,380					41,536					44,380		41,536
Retail loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	4,213					3,934					4,213		3,934
Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period					598					629	598		629		726
Loan charge-offs											(102)		(153)		(245)
Recoveries on loans previously charged-off											77		80		75
Net loan charge-offs											(25)		(73)		(170)
Provision for loan losses											22		42		73
Foreign currency translation adjustment											(1)		0		0
Balance at end of period	594					598					594		598		629
Allowance for loan losses as a percentage of total loans	1.22%					1.32%					1.22%		1.32%		1.37%
Allowance for loan losses individually evaluated for impairment	39					57					39		57		76
Allowance for loan losses collectively evaluated for impairment	555					541					555		541		553
Total allowance for loan losses	594					598					594		598		629
Loans individually evaluated for impairment	219					274					219		274		419
Loans collectively evaluated for impairment	48,372					45,191					48,372		45,191		45,602
PCI loans	2	[1]				5	[1]				2	[1]	5	[1]	36	[1]
Total loans	48,593					45,470					48,593		45,470		46,057
Financing Receivable [Member] | Business loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period					531					552	531		552		648
Loan charge-offs											(87)		(130)		(212)
Recoveries on loans previously charged-off											68		70		65
Net loan charge-offs											(19)		(60)		(147)
Provision for loan losses											23		39		51
Foreign currency translation adjustment											(1)		0		0
Balance at end of period	534					531					534		531		552
Allowance for loan losses as a percentage of total loans	1.20%					1.28%					1.20%		1.28%		1.30%
Allowance for loan losses individually evaluated for impairment	39					57					39		57		76
Allowance for loan losses collectively evaluated for impairment	495					474					495		474		476
Total allowance for loan losses	534					531					534		531		552
Loans individually evaluated for impairment	177					223					177		223		368
Loans collectively evaluated for impairment	44,203					41,311					44,203		41,311		41,979
PCI loans	0	[1]				2	[1]				0	[1]	2	[1]	30	[1]
Total loans	44,380					41,536					44,380		41,536		42,377
Financing Receivable [Member] | Retail loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period					67					77	67		77		78
Loan charge-offs											(15)		(23)		(33)
Recoveries on loans previously charged-off											9		10		10
Net loan charge-offs											(6)		(13)		(23)
Provision for loan losses											(1)		3		22
Foreign currency translation adjustment											0		0		0
Balance at end of period	60					67					60		67		77
Allowance for loan losses as a percentage of total loans	1.43%					1.70%					1.43%		1.70%		2.10%
Allowance for loan losses individually evaluated for impairment	0					0					0		0		0
Allowance for loan losses collectively evaluated for impairment	60					67					60		67		77
Total allowance for loan losses	60					67					60		67		77
Loans individually evaluated for impairment	42					51					42		51		51
Loans collectively evaluated for impairment	4,169					3,880					4,169		3,880		3,623
PCI loans	2	[1]				3	[1]				2	[1]	3	[1]	6	[1]
Total loans	$ 4,213					$ 3,934					$ 4,213		$ 3,934		$ 3,680

[1] No allowance for loan losses was required for PCI loans at December 31, 2014, 2013 and 2012.