Summary of Significant Accounting Policies (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended		1 Months Ended	3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Oct. 17, 2012 Private Forward Repurchase Transaction [Member]	Sep. 30, 2012 Private Forward Repurchase Transaction [Member]	Sep. 30, 2012 Private Forward Repurchase Transaction [Member] Additional paid-in capital [Member]	Sep. 30, 2012 Private Forward Repurchase Transaction [Member] Treasury stock [Member]
Supplemental cash flow information - Noncash activities
Transfers from loans to securities available for sale	$ 921	$ 0
Trading assets retained from securitization of MHFS	68,905	23,205
Capitalization of MSRs from sale of MHFS	3,860	2,852
Transfers from MHFS to foreclosed assets	172	169
Transfers from loans to MHFS	5,523	5,490
Transfers from loans to LHFS	118	170
Transfers from loans to foreclosed assets	6,938	7,057
Changes in consolidations (deconsolidations) of variable interest entities
Securities available for sale	(40)	6
Loans	(295)	(693)
Long-term debt	(338)	(674)
Summary Of Significant Accounting Policies Textuals [Abstract]
Forward Contract Indexed to Issuer's Equity, Contract Amount					$ 300	$ 350
Common stock repurchased, shares			9,000,000	11,000,000