Fair Value Measurement (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Obligations of state and political subdivisions
Fair Value Level 3 Rollforward
Balance at the beginning of the period	$ 10				$ 10
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	0	[1],[2]			0	[1],[2]
Other comprehensive income (loss)	0	[1]			1	[1]
Purchases	1				1
Settlements	0				(1)
FG VIE Consolidations	0				0
Balance at the end of the period	11				11
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	0				1
RMBS
Fair Value Level 3 Rollforward
Balance at the beginning of the period	167		88		134		100
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	4	[1],[2]	6	[1],[2]	9	[1],[2]	(25)	[1],[2]
Other comprehensive income (loss)	13	[1]	(37)	[1]	6	[1]	(85)	[1]
Purchases	42		43		97		195
Sales			(8)				(29)
Settlements	(17)		0		(37)		0
FG VIE Consolidations	0		0		0		(64)
Balance at the end of the period	209		92		209		92
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	10		(37)		2		(85)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0				0
Asset-backed securities
Fair Value Level 3 Rollforward
Balance at the beginning of the period	274		274		235		210
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	6	[1],[2]	(8)	[1],[2]	20	[1],[2]	(4)	[1],[2]
Other comprehensive income (loss)	20	[1]	(15)	[1]	8	[1]	(2)	[1]
Purchases	1		0		41		47
Sales			(1)				(1)
Settlements	(2)		0		(5)		0
FG VIE Consolidations	0		0		0		0
Balance at the end of the period	299		250		299		250
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	20		(15)		8		(2)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0				0
Other invested assets
Fair Value Level 3 Rollforward
Balance at the beginning of the period	1		2		2		2
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	0	[1]	0	[1]	0	[1]	0	[1]
Other comprehensive income (loss)	0	[1]	0	[1]	(1)	[1]	0	[1]
Purchases	0		0		0		0
Sales			0				0
Settlements	0		0		0		0
FG VIE Consolidations	0		0		0		0
Balance at the end of the period	1		2		1		2
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	0		0		(1)		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0				0
FG VIEs' assets, at fair value
Fair Value Level 3 Rollforward
Balance at the beginning of the period	2,726		3,492		2,819		3,657
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	91	[1],[3]	(313)	[1],[3]	269	[1],[3]	(290)	[1],[3]
Other comprehensive income (loss)	0	[1]	0	[1]	0	[1]	0	[1]
Purchases	0		0		0		0
Sales			0				0
Settlements	(124)		(174)		(410)		(644)
FG VIE Consolidations	0		0		15		282
Balance at the end of the period	2,693		3,005		2,693		3,005
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	165		(181)		468		(158)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0				0
Other assets
Fair Value Level 3 Rollforward
Balance at the beginning of the period	44		0		54		0
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	(2)	[1],[4]	2	[1],[4]	(12)	[1],[4]	2	[1],[4]
Other comprehensive income (loss)	0	[1]	0	[1]	0	[1]	0	[1]
Purchases	0		0		0		0
Sales			0				0
Settlements	0		0		0		0
FG VIE Consolidations	0		0		0		0
Balance at the end of the period	42		22		42		22
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	(2)		2		(12)		2
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			20				20
Credit Derivative, Asset, Liability Net [Member]
Fair Value Level 3 Rollforward
Balance at the beginning of the period	(1,666)	[5]	(2,188)	[5]	(1,304)	[5]	(1,870)
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	(36)	[1],[5],[6]	1,156	[1],[5],[6]	(466)	[1],[5],[6]	855	[1],[5],[6]
Other comprehensive income (loss)	0	[1],[5]	0	[1]	0	[1],[5]	0	[1],[5]
Purchases	0	[5]	0		0	[5]	0
Sales			0				0	[5]
Settlements	1	[5]	4	[5]	69	[5]	(13)	[5]
FG VIE Consolidations	0	[5]	0		0	[5]	0
Balance at the end of the period	(1,701)	[5]	(1,028)	[5]	(1,701)	[5]	(1,028)	[5]
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	(39)	[5]	1,159	[5]	(391)	[5]	848	[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0				0
Financial Guaranty Variable Interest Liabilities with Recourse [Member]
Fair Value Level 3 Rollforward
Balance at the beginning of the period	(2,239)		(2,849)		(2,397)		(3,031)
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	(76)	[1],[3]	97	[1],[3]	(212)	[1],[3]	101	[1],[3]
Other comprehensive income (loss)	0	[1]	0	[1]	0	[1]	0
Purchases	0		0		0		0
Sales			0				0
Settlements	146		176		461		626
FG VIE Consolidations	0		0		(21)		(272)
Balance at the end of the period	(2,169)		(2,576)		(2,169)		(2,576)
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	(55)		98		(180)		101
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0				0
FG VIEs' liabilities without recourse, at fair value
Fair Value Level 3 Rollforward
Balance at the beginning of the period	(1,042)		(1,283)		(1,061)		(1,337)
Total pretax realized and unrealized gains/(losses) recorded in
Net Income (loss)	(19)	[1],[3]	89		(112)	[1],[3]	40	[1],[3]
Other comprehensive income (loss)	0	[1]	0	[1]	0	[1]	0	[1]
Purchases	0		0		0		0
Sales			0				0
Settlements	43		61		155		227
FG VIE Consolidations	0		0		0		(63)
Balance at the end of the period	(1,018)		(1,133)		(1,018)		(1,133)
Total pre-tax realized/unrealized gains/(losses) recorded in
Change in unrealized gains/(losses) related to financial instruments held at the reporting date	(58)		60		(213)		11
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			$ 0				$ 0

[1] Realized and unrealized gains (losses) from changes in values of Level 3 financial instruments represent gains (losses) from changes in values of those financial instruments only for the periods in which the instruments were classified as Level 3.

[2] Included in net realized investment gains (losses) and net investment income.

[3] Included in fair value gains (losses) on FG VIEs.

[4] Recorded in fair value gain (loss) on committed capital securities.

[5] Represents net position of credit derivatives. The consolidated balance sheet presents gross assets and liabilities based on net counterparty exposure.

[6] Reported in net change in fair value of credit derivatives.