Variable Interest Entities - Loans Sold to Third-Party Sponsored Securitization Entities (Details 5) (Variable Interest Entity, Not Primary Beneficiary [Member], USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Variable Interest Entity, Not Primary Beneficiary [Member]
Summary of loan sale activities [Abstract]
Carrying value of loans sold	$ 180,097,000,000	$ 150,632,000,000	$ 156,615,000,000
Proceeds from Sale of Mortgage Loans Held-for-sale	1,270,000,000	2,864,000,000	3,887,000,000
Proceeds received from loan sales as securities	176,592,000,000	145,340,000,000	149,786,000,000
Total proceeds received from loan sales	177,862,000,000	148,204,000,000	153,673,000,000
Gains on loan sales	141,000,000	133,000,000	212,000,000
Loans Repurchased Or Loans With The Option To Repurchase	15,600,000,000	15,700,000,000
Real Estate Acquired Through Foreclosure	$ 1,600,000,000	$ 1,000,000,000