Fair Value Measurement Fair Value Measurement - Schedule of Level 3 Inputs Reconciliation for Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Available-for-sale Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 1,205	$ 3,330
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	7	22
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	12	42
Purchases	0	920
Sales	(88)	(112)
Issuances	0	0
Settlements	(42)	(67)
Transfers Into Level 3	85	202
Transfers Out of Level 3	(253)	(1,120)
Ending balance	926	3,217
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	9	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	333	927
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	(2)	0
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	5	10
Purchases	0	0
Sales	(68)	(112)
Issuances	0	0
Settlements	(8)	(21)
Transfers Into Level 3	0	64
Transfers Out of Level 3	(88)	(116)
Ending balance	172	752
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	0	0
RMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	561	1,304
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	8	20
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	8	28
Purchases	0	886
Sales	0	0
Issuances	0	0
Settlements	(13)	(34)
Transfers Into Level 3	85	57
Transfers Out of Level 3	(94)	(534)
Ending balance	555	1,727
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	9	20
CMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	228	739
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	0	0
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	1	2
Purchases	0	34
Sales	0	0
Issuances	0	0
Settlements	(21)	(11)
Transfers Into Level 3	0	38
Transfers Out of Level 3	(34)	(307)
Ending balance	174	495
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	0	0
Other ABS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	65	343
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	1	2
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	(2)	2
Purchases	0	0
Sales	(20)	0
Issuances	0	0
Settlements	0	(1)
Transfers Into Level 3	0	43
Transfers Out of Level 3	(37)	(163)
Ending balance	7	226
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	0	2
Other securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	18	17
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	0	0
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	0	0
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers Into Level 3	0	0
Transfers Out of Level 3	0	0
Ending balance	18	17
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	0	0
Consumer MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	53	69
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	(3)	(11)
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	0	0
Purchases	0	0
Sales	0	0
Issuances	4	4
Settlements	(1)	(1)
Transfers Into Level 3	0	0
Transfers Out of Level 3	0	0
Ending balance	53	61
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	(3)	(11)
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	66	50
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	11	0
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	0	0
Purchases	0	0
Sales	0	0
Issuances	9	2
Settlements	(12)	(3)
Transfers Into Level 3	0	0
Transfers Out of Level 3	(1)	(1)
Ending balance	73	48
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	11	0
Retained interest in securitizations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	221	199
Total Gains or (Losses) (Realized/Unrealized), Included in Net Income	2	(2)
Total Gains or (Losses) (Realized/Unrealized), Included in OCI	0	0
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers Into Level 3	0	0
Transfers Out of Level 3	0	0
Ending balance	223	197
Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held	$ 2	$ (2)

Amount of unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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