Fair Value of Financial Instruments Fair Value of Financial Instruments - Schedule of Level 3 Inputs Reconciliation for Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Available-for-sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 2,219	$ 2,953	$ 3,330	$ 2,689
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	11	(6)	51	(17)
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	7	65	73	73
Purchases	200	401	1,214	1,391
Sales	(91)	0	(203)	(51)
Issuances	0	0	0	0
Settlements	(81)	(101)	(284)	(303)
Transfers Into Level 3	88	331	384	1,073
Transfers Out of Level 3	(887)	(741)	(3,099)	(1,953)
Ending balance	1,466	2,902	1,466	2,902
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	15	(5)	55	(22)
Corporate debt securities guaranteed by U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	739	832	927	650
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	(5)	0	(5)	0
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	3	4	18	(31)
Purchases	0	61	0	272
Sales	(91)	0	(203)	0
Issuances	0	0	0	0
Settlements	(16)	(19)	(55)	(47)
Transfers Into Level 3	0	47	64	125
Transfers Out of Level 3	(246)	1	(362)	(43)
Ending balance	384	926	384	926
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	(1)	0	(1)	0
RMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	836	1,535	1,304	1,335
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	16	(6)	53	(16)
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	3	57	39	141
Purchases	42	85	1,022	277
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(24)	(72)	(156)	(217)
Transfers Into Level 3	79	152	199	681
Transfers Out of Level 3	(295)	(430)	(1,804)	(880)
Ending balance	657	1,321	657	1,321
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	16	(5)	53	(21)
CMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	449	461	739	587
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	0	0	0	0
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	(2)	(2)	3	(49)
Purchases	158	96	192	643
Sales	0	0	0	(10)
Issuances	0	0	0	0
Settlements	(34)	(4)	(64)	(31)
Transfers Into Level 3	0	48	66	168
Transfers Out of Level 3	(268)	(295)	(633)	(1,004)
Ending balance	303	304	303	304
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	0	0	0	0
Other ABS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	175	109	343	102
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	1	0	4	(1)
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	3	6	13	12
Purchases	0	129	0	169
Sales	0	0	0	(41)
Issuances	0	0	0	0
Settlements	0	0	(2)	(2)
Transfers Into Level 3	9	84	52	98
Transfers Out of Level 3	(78)	(15)	(300)	(24)
Ending balance	110	313	110	313
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	1	0	4	(1)
Other securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	20	16	17	15
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	(1)	0	(1)	0
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	0	0	0	0
Purchases	0	30	0	30
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(7)	(6)	(7)	(6)
Transfers Into Level 3	0	0	3	1
Transfers Out of Level 3	0	(2)	0	(2)
Ending balance	12	38	12	38
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	(1)	0	(1)	0
Consumer MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	57	61	69	55
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	(2)	(5)	(19)	25
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	4	4	11	9
Settlements	(1)	(2)	(3)	(5)
Transfers Into Level 3	0	0	0	0
Transfers Out of Level 3	0	0	0	(26)
Ending balance	58	58	58	58
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	(2)	(5)	(19)	25
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	50	72	50	90
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	2	(13)	5	(20)
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	6	4	13	8
Settlements	(8)	(3)	(14)	(15)
Transfers Into Level 3	0	0	0	0
Transfers Out of Level 3	1	(6)	(3)	(9)
Ending balance	51	54	51	54
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	2	(13)	5	(20)
Retained interest in securitizations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	195	198	199	204
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	8	3	4	(3)
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers Into Level 3	0	0	0	0
Transfers Out of Level 3	0	0	0	0
Ending balance	203	201	203	201
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	$ 8	$ 3	$ 4	$ (3)