Asset Quality (Home Equity and Residential Real Estate Balances) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2012
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 189,775	[1],[2]	$ 185,856	[1],[2]	$ 180,425
Total home equity and residential real estate loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Outstanding - Excluding Purchased Impaired Loans	43,372		42,725
Purchased Impaired Loans - Outstanding Balance	6,094		6,638
Government insured or guaranteed residential real estate mortgages	2,012		2,279
Purchase accounting adjustments - purchased impaired loans	(285)		(482)
Total loans	$ 51,193		$ 51,160

[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.