Asset Quality (Home Equity and Residential Real Estate Balances) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011
Financing Receivable, Recorded Investment [Line Items]
Purchased Impaired Loans - Outstanding Balance	$ 6,976		$ 6,533
Government insured or guaranteed residential real estate mortgages	2,294		2,884
Total loans	181,864	[1],[2],[3],[4]	159,014	[1],[2],[3],[4]	154,543
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Outstanding - Excluding Purchased Impaired Loans	10,487		10,021
Purchased Impaired Loans - Outstanding Balance	3,833		3,128
Total consumer real estate secured loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Outstanding - Excluding Purchased Impaired Loans	44,767		41,014
Purchased Impaired Loans - Outstanding Balance	6,976		6,533
Government insured or guaranteed residential real estate mortgages	2,294		2,884
Purchase accounting, deferred fees and other accounting adjustments	(2,776)		(2,873)
Total loans	$ 51,261		$ 47,558

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

[2] Amounts represent items for which the Corporation has elected the fair value option.

[3] Net of unearned income, net deferred loan fees, unamortized discounts and premiums, and purchase discounts and premiums totaling $2.9 billion and $2.3 billion atSeptember 30, 2012 and December 31, 2011, respectively.

[4] Future accretable yield related to purchased impaired loans is not included in loans outstanding.