Asset Quality (Commercial Lending Asset Quality Indicators) (Details) - USD ($)	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	$ 3,522,000,000		$ 4,858,000,000		$ 6,106,000,000
Total Loans	206,696,000,000	[1]	204,817,000,000	[1]	195,613,000,000
Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	169,000,000		310,000,000		673,000,000
Total Loans	133,544,000,000		128,368,000,000		$ 117,145,000,000
Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	98,572,000,000		97,347,000,000
Purchased impaired loans	36,000,000		74,000,000
Total Loans	98,608,000,000		97,420,000,000
Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	27,335,000,000		23,025,000,000
Purchased impaired loans	133,000,000		236,000,000
Total Loans	27,468,000,000		23,262,000,000
Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7,468,000,000		7,686,000,000
Total Loans	7,468,000,000		7,686,000,000
Pass [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	127,323,000,000		122,468,000,000
Pass [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	93,364,000,000		92,884,000,000
Pass [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	26,729,000,000		22,066,000,000
Pass [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7,230,000,000		7,518,000,000
Special Mention [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	6,000,000		4,000,000
Total Loans	2,242,000,000		2,346,000,000
Special Mention [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	2,029,000,000		1,984,000,000
Special Mention [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	120,000,000		285,000,000
Special Mention [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	87,000,000		73,000,000
Substandard [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	157,000,000		280,000,000
Total Loans	3,877,000,000		3,436,000,000
Substandard [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	3,089,000,000		2,424,000,000
Substandard [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	481,000,000		639,000,000
Substandard [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	150,000,000		93,000,000
Doubtful [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	6,000,000		26,000,000
Total Loans	102,000,000		118,000,000
Doubtful [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	90,000,000		55,000,000
Doubtful [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	5,000,000		35,000,000
Doubtful [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	$ 1,000,000		$ 2,000,000

[1] Our consolidated assets at December 31, 2015 included the following for which we have elected the fair value option: Federal funds sold and resale agreements of $137 million, Loans held for sale of $1.5 billion, Loans of $.9 billion, and Other assets of $521 million. Our consolidated assets at December 31, 2014 included the following for which we have elected the fair value option: Federal funds sold and resale agreements of $155 million, Loans held for sale of $2.2 billion, Loans of $1.0 billion, and Other assets of $412 million.