Financial Guaranty Contracts Accounted for as Credit Derivatives - Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Sep. 12, 2014 Transaction	Oct. 10, 2013 Transaction
Credit Derivatives
Estimated remaining weighted average life of credit derivatives (in years)									4 years 7 months 30 days		4 years 1 month 15 days
Net par outstanding	$ 34,996				$ 54,482				$ 34,996		$ 54,482
Net unrealized gains (losses)									800	[1]	107	[1]	(477)	[1]
Net change in fair value of credit derivatives	676	255	103	(211)	229	354	74	(592)	823		65		(585)
Gain from narrowing of spreads	346								1,413
Collateral agreed to be posted	376				677				376		677
Market value collateralized debt obligations of corporate obligations [Member]
Credit Derivatives
Maximum average obligor size (as a percent)	1.00%								1.00%
Maximum exposure of one industry (as a percent)	10.00%								10.00%
Net par outstanding	23,621				37,321				23,621		37,321
Net unrealized gains (losses)									(18)		(32)		59
Other pooled infrastructure [Member]
Credit Derivatives
Net par outstanding	2,000								2,000
Pooled infrastructure [Member]
Credit Derivatives
Number of transactions	1								1
Remaining other CDS [Member]
Credit Derivatives
Net par outstanding	4,400								4,400
Film securitization CDS [Member]
Credit Derivatives
Net unrealized gains (losses)											127
Net change in fair value of credit derivatives											7
Collateral Debt Obligations, Collateral Requirement [Member]
Credit Derivatives
Amount of par subject to collateral for which the amount of collateral is capped	6,100								6,100
Collateral Debt Obligations, Collateral Cap Negotiated [Member]
Credit Derivatives
Amount of par subject to collateral for which the amount of collateral is capped	5,900								5,900
Collateral Debt Obligations, No Cap Negotiated [Member]
Credit Derivatives
Amount of par subject to collateral for which the amount of collateral is capped	665								665
Collateral agreed to be posted	376				677				376		677
Notional amount subject to collateral based on movements in the mark-to-market valuation of the underlying exposure	242				347				242		347
Collateral posted, based on mark-to-market valuation	25				62				25		62
Credit Risk Contract [Member]
Credit Derivatives
Realized gains (losses) and other settlements									1		21		3
Credit Risk Contract [Member] | Film securitization CDS [Member]
Credit Derivatives
Realized gains (losses) and other settlements											120
Deutsche Bank [Member]
Credit Derivatives
Number of transactions terminated	1								1						2	1
Variable Interest Entity, Primary Beneficiary [Member] | Deutsche Bank [Member] | Settled Litigation [Member]
Credit Derivatives
Net unrealized gains (losses)													85
Option Adjustable Rate Mortgage and Alt-A Mortgage [Member] | First Lien [Member] | RMBS [Member]
Credit Derivatives
Unrealized fair value gain on termination of transactions									$ 543
Alt-A [Member] | First Lien [Member] | RMBS [Member]
Credit Derivatives
Number of transactions terminated	3								3
Option Adjustable Rate Mortgage [Member] | First Lien [Member] | RMBS [Member]
Credit Derivatives
Number of transactions terminated	1								1

[1] Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.