Securitizations and Variable Interest Entities, Cash Flow Securitizations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Securitizations and Variable Interest Entities Textual [Abstract]
Amount paid to third party investors to settle repurchase liabilities	$ 0	$ 0	$ 0	$ 78
Amount paid to repurchase loans from securitization vehicles	2,200	3,200	8,200	10,100
Net gains from sale of assets securitizations	88	55	404	152
Residential Mortgage [Member]
Securitizations and Variable Interest Entities Textual [Abstract]
Amount of mortgages transferred in securitization and whole loan sale transactions	50,200	40,900	143,100	111,400
Mortgage loans [Member]
Cash Flow Securitizations [Abstract]
Proceeds from securitizations and whole loan sales	52,733	45,466	153,626	122,910
Fees from servicing rights retained	902	980	2,760	2,987
Cash flows from other interests held	328	470	942	1,132
Servicing advances, net of repayments	(88)	(21)	(342)	(156)
Other financial assets [Member]
Cash Flow Securitizations [Abstract]
Proceeds from securitizations and whole loan sales	192	0	373	0
Fees from servicing rights retained	1	2	5	6
Cash flows from other interests held	10	19	33	58
Servicing advances, net of repayments	0	0	0	0
Commercial Mortgage [Member]
Securitizations and Variable Interest Entities Textual [Abstract]
Net gains from sale of assets securitizations	63	30	263	71
Amount of mortgages transferred in securitization and whole loan sale transactions	3,000	2,200	12,500	4,500
Non-Agency Securitizations And Whole Loan Transactions [Member] | Mortgage loans [Member]
Cash Flow Securitizations [Abstract]
Repurchases of assets/loss reimbursements	3	2	10	5
Non-Agency Securitizations And Whole Loan Transactions [Member] | Other financial assets [Member]
Cash Flow Securitizations [Abstract]
Repurchases of assets/loss reimbursements	0	0	0	0
Agency securitizations | Mortgage loans [Member]
Cash Flow Securitizations [Abstract]
Repurchases of assets/loss reimbursements	72	87	210	256
Agency securitizations | Other financial assets [Member]
Cash Flow Securitizations [Abstract]
Repurchases of assets/loss reimbursements	$ 0	$ 0	0	0
Fair Value, Inputs, Level 3 [Member] | Residential Mortgage [Member]
Securitizations and Variable Interest Entities Textual [Abstract]
Amount of servicing asset at fair value			1,184	900
Amount of liability for repurchase reserves at fair value			34	34
Fair Value, Inputs, Level 3 [Member] | Commercial Mortgage [Member]
Securitizations and Variable Interest Entities Textual [Abstract]
Amount of servicing asset at fair value			131	12
Fair Value, Inputs, Level 2 [Member] | Residential Mortgage [Member]
Securitizations and Variable Interest Entities Textual [Abstract]
Securities, at fair value			787
Fair Value, Inputs, Level 2 [Member] | Commercial Mortgage [Member]
Securitizations and Variable Interest Entities Textual [Abstract]
Securities, at fair value			$ 209	$ 100