Asset Quality (Home Equity and Residential Real Estate Balances) (Details) - USD ($) $ in Millions	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Purchased Impaired Loans - Outstanding Balance	$ 3,933		$ 5,007
Total loans	206,696	[1]	204,817	[1]	$ 195,613
Total home equity and residential real estate loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding Purchased Impaired Loans	42,268		43,348
Purchased Impaired Loans - Outstanding Balance	3,684		4,541
Government insured or guaranteed residential real estate mortgages	923		1,188
Difference between outstanding balance and recorded investment - purchased impaired loans	(331)		7
Total loans	$ 46,544		$ 49,084

[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.