Variable Interest Entities - Loans Sold to Third-Party Sponsored Securitization Entities (Details 5) (Variable Interest Entity, Not Primary Beneficiary, USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Variable Interest Entity, Not Primary Beneficiary
Summary of loan sale activities [Abstract]
Carrying value of loans sold	$ 48,045,000,000	$ 43,925,000,000	$ 102,925,000,000	$ 83,733,000,000
Proceeds received from loan sales as cash	295,000,000	23,000,000	461,000,000	41,000,000
Proceeds from loans sales as securities	47,223,000,000	43,436,000,000	101,392,000,000	82,691,000,000
Total proceeds received from loan sales	47,518,000,000	43,459,000,000	101,853,000,000	82,732,000,000
Gains on loan sales	112,000,000	56,000,000	250,000,000	91,000,000
Loans Repurchased Or Loans With The Option To Repurchase	14,600,000,000		14,600,000,000		15,600,000,000
Real Estate Acquired Through Foreclosure	$ 1,800,000,000		$ 1,800,000,000		$ 1,600,000,000