Asset Quality (Commercial Lending Asset Quality Indicators) (Details) - USD ($) $ in Millions	Mar. 31, 2016		Dec. 31, 2015		Mar. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	$ 3,380		$ 3,522		$ 4,675
Total Loans	207,485	[1]	206,696	[1]	204,722
Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	149		169		276
Total Loans	135,130		133,544		$ 129,675
Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	99,287		98,572
Purchased impaired loans	29		36
Total Loans	99,316		98,608
Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	28,110		27,335
Purchased impaired loans	120		133
Total Loans	28,230		27,468
Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7,584		7,468
Total Loans	7,584		7,468
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	23
Pass [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	128,456		127,323
Pass [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	93,617		93,364
Pass [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	27,571		26,729
Pass [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7,245		7,230
Special Mention [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	2		6
Total Loans	2,030		2,242
Special Mention [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	1,837		2,029
Special Mention [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	91		120
Special Mention [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	100		87
Substandard [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	100		157
Total Loans	4,452		3,877
Substandard [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	3,680		3,089
Substandard [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	441		481
Substandard [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	231		150
Doubtful [Member] | Total commercial lending [Member]
Financing Receivable, Recorded Investment [Line Items]
Purchased impaired loans	24		6
Total Loans	192		102
Doubtful [Member] | Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	153		90
Doubtful [Member] | Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	7		5
Doubtful [Member] | Total commercial lending [Member] | Equipment Lease Financing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	$ 8		$ 1

[1] Our consolidated assets at March 31, 2016 included the following for which we have elected the fair value option: Federal funds sold and resale agreements of $138 million, Loans held for sale of $1.4 billion, Loans of $.9 billion, and Other assets of $375 million. 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.