Asset Quality (Commercial Lending Asset Quality Indicators) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	$ 4,858,000,000		$ 6,106,000,000		$ 7,406,000,000
Total Loans	204,817,000,000	[1],[2]	195,613,000,000	[1],[2]	185,856,000,000
Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	310,000,000		673,000,000		1,249,000,000
Total Loans	128,368,000,000		117,145,000,000		108,942,000,000
Commercial [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	97,347,000,000		88,221,000,000
Purchased impaired loans	74,000,000		157,000,000
Total Loans	97,420,000,000		88,378,000,000
Commercial Real Estate [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	23,025,000,000		20,675,000,000
Purchased impaired loans	236,000,000		516,000,000
Total Loans	23,262,000,000		21,191,000,000
Equipment Lease Financing [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7,686,000,000		7,576,000,000
Total Loans	7,686,000,000		7,576,000,000
Pass [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans			10,000,000
Total Loans	122,468,000,000		110,491,000,000
Pass [Member] | Commercial [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	92,884,000,000		83,903,000,000
Pass [Member] | Commercial Real Estate [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	22,066,000,000		19,175,000,000
Pass [Member] | Equipment Lease Financing [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7,518,000,000		7,403,000,000
Special Mention [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	4,000,000		31,000,000
Total Loans	2,346,000,000		2,303,000,000
Special Mention [Member] | Commercial [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	1,984,000,000		1,894,000,000
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	285,000,000		301,000,000
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	73,000,000		77,000,000
Substandard [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	280,000,000		469,000,000
Total Loans	3,436,000,000		4,027,000,000
Substandard [Member] | Commercial [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	2,424,000,000		2,352,000,000
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	639,000,000		1,113,000,000
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	93,000,000		93,000,000
Doubtful [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	26,000,000		163,000,000
Total Loans	118,000,000		324,000,000
Doubtful [Member] | Commercial [Member] | Criticized Commercial Loans [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	55,000,000		72,000,000
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	35,000,000		86,000,000
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	$ 2,000,000		$ 3,000,000

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

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