Asset Quality (Commercial Lending Asset Quality Indicators) (Details) - USD ($)	Sep. 30, 2015		Dec. 31, 2014		Sep. 30, 2014
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	$ 4,167,000,000		$ 4,858,000,000		$ 5,167,000,000
Total Loans	204,983,000,000	[1],[2]	204,817,000,000	[1],[2]	200,872,000,000
Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	204,000,000		310,000,000		405,000,000
Total Loans	131,164,000,000		128,368,000,000		$ 124,063,000,000
Commercial [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	97,384,000,000		97,347,000,000
Purchased impaired loans	43,000,000		74,000,000
Total Loans	97,427,000,000		97,420,000,000
Commercial Real Estate [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	25,932,000,000		23,025,000,000
Purchased impaired loans	161,000,000		236,000,000
Total Loans	26,093,000,000		23,262,000,000
Equipment Lease Financing [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7,644,000,000		7,686,000,000
Total Loans	7,644,000,000		7,686,000,000
Pass [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	124,933,000,000		122,468,000,000
Pass [Member] | Commercial [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	92,334,000,000		92,884,000,000
Pass [Member] | Commercial Real Estate [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	25,224,000,000		22,066,000,000
Pass [Member] | Equipment Lease Financing [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7,375,000,000		7,518,000,000
Special Mention [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	7,000,000		4,000,000
Total Loans	2,256,000,000		2,346,000,000
Special Mention [Member] | Commercial [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	1,971,000,000		1,984,000,000
Special Mention [Member] | Commercial Real Estate [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	203,000,000		285,000,000
Special Mention [Member] | Equipment Lease Financing [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	75,000,000		73,000,000
Substandard [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	164,000,000		280,000,000
Total Loans	3,793,000,000		3,436,000,000
Substandard [Member] | Commercial [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	2,962,000,000		2,424,000,000
Substandard [Member] | Commercial Real Estate [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	478,000,000		639,000,000
Substandard [Member] | Equipment Lease Financing [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	189,000,000		93,000,000
Doubtful [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	33,000,000		26,000,000
Total Loans	182,000,000		118,000,000
Doubtful [Member] | Commercial [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	117,000,000		55,000,000
Doubtful [Member] | Commercial Real Estate [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	27,000,000		35,000,000
Doubtful [Member] | Equipment Lease Financing [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	$ 5,000,000		$ 2,000,000

[1] Amounts represent items for which we have elected the fair value option.

[2] Amounts represent the assets or liabilities of consolidated variable interest entities (VIEs).