Summary of Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Supplemental cash flow information - Noncash activities
Transfers from (to) loans to (from) securities available for sale	$ 297	$ 921
Trading assets retained from securitizations of MHFS	39,963	68,905
Capitalization of MSRs from sale of MHFS	3,068	3,860
Transfers from MHFS to foreclosed assets	160	172
Transfers from loans to MHFS	6,199	5,523
Transfers from loans to LHFS	207	118
Transfers from loans to foreclosed assets	5,835	6,938
Changes in consolidations (deconsolidations) of variable interest entities:
Trading assets	1,950	0
Securities available for sale	0	(40)
Loans	(2,268)	(295)
Long-term debt	(342)	(338)
Government insured/guaranteed [Member]
Supplemental cash flow information - Noncash activities
Transfers from loans to foreclosed assets	4,500	4,800
Private Forward Repurchase Transaction [Member]
Summary Of Significant Accounting Policies Textuals [Abstract]
Forward Contract Indexed to Issuer's Equity, Contract Amount	$ 400