Fair Value Measurement - Fair Value Level 3 Rollforward Recurring Basis (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
Satisfaction of Forward Purchase Contract Obligation [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Purchases								$ 17
FG VIEs' liabilities with recourse, at fair value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at beginning of period		$ (1,278)		$ (1,346)		$ (1,277)		(1,790)
Radian Asset Acquisition		(114)				(114)
Net income (loss)	[1],[2]	(5)		(25)		88		(97)
Other comprehensive income (loss)	[2]	0		0		0		0
Purchases		0		0		0		0
Settlements		36		30		73		299
FG VIE consolidations		0		(25)		(131)		(25)
FG VIE deconsolidations		0		0		0		247
Fair value at end of period		(1,361)		(1,366)		(1,361)		(1,366)
Change in unrealized gains/(losses) related to financial instruments held		(6)		(24)		(12)		(53)
FG VIEs' liabilities without recourse, at fair value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at beginning of period		(145)		(101)		(142)		(1,081)
Radian Asset Acquisition		(4)				(4)
Net income (loss)	[1],[2]	(25)		(27)		(30)		(36)
Other comprehensive income (loss)	[2]	0		0		0		0
Purchases		0		0		0		0
Settlements		3		0		5		12
FG VIE consolidations		0		(21)		0		(21)
FG VIE deconsolidations		0		25		0		1,002
Fair value at end of period		(171)		(124)		(171)		(124)
Change in unrealized gains/(losses) related to financial instruments held		(14)		4		(19)		(5)
Credit Risk Contract [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value at beginning of period	[3]	(782)		(1,923)		(895)		(1,693)
Radian Asset Acquisition	[3]	(215)				(215)
Net income (loss)	[2],[3],[4]	90		103		214		(108)
Other comprehensive income (loss)	[2],[3]	0		0		0		0
Purchases	[3]	0		0		0		0
Settlements	[3]	(19)		(17)		(30)		(36)
FG VIE consolidations	[3]	0		0		0		0
FG VIE deconsolidations	[3]	0		0		0		0
Fair value at end of period	[3]	(926)		(1,837)		(926)		(1,837)
Change in unrealized gains/(losses) related to financial instruments held	[3]	82		88		186		(144)
Obligations of state and political subdivisions [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period		8		38		38		36
Radian Asset Acquisition		0				0
Net Income (loss)	[2],[5]	0		1		3		2
Other comprehensive income (loss)	[2]	(1)		0		(3)		1
Purchases		0		0		0		0
Settlements		0		(1)		(31)	[6]	(1)
FG VIE Consolidations		0		0		0		0
FG VIE deconsolidations		0		0		0		0
Fair value at end of period		7		38		7		38
Change in unrealized gains/(losses) related to financial instruments held		0		0		0		1
Corporate securities [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period		79		138		79		136
Radian Asset Acquisition		0				0
Net Income (loss)	[2],[5]	(3)		(7)		(1)		(4)
Other comprehensive income (loss)	[2]	1		(25)		(1)		(21)
Purchases		0		0		0		0
Settlements		0		0		0		(5)
FG VIE Consolidations		0		0		0		0
FG VIE deconsolidations		0		0		0		0
Fair value at end of period		77		106		77		106
Change in unrealized gains/(losses) related to financial instruments held		1		(25)		(1)		(21)
RMBS [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period		383		359		425		290
Radian Asset Acquisition		4				4
Net Income (loss)	[2],[5]	8		6		17		10
Other comprehensive income (loss)	[2]	(9)		0		(4)		14
Purchases		1		0		10		53
Settlements		(51)		(15)		(116)		(30)
FG VIE Consolidations		(1)		0		(1)		0
FG VIE deconsolidations		0		0		0		13
Fair value at end of period		335		350		335		350
Change in unrealized gains/(losses) related to financial instruments held		(7)		0		(1)		15
Asset-backed Securities [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period		226		252		228		268
Radian Asset Acquisition		0				0
Net Income (loss)	[2],[5]	3		3		1		10
Other comprehensive income (loss)	[2]	8		0		9		8
Purchases		0		0		0		0
Settlements		(1)		(1)		(2)		(32)
FG VIE Consolidations		0		0		0		0
FG VIE deconsolidations		0		0		0		0
Fair value at end of period		236		254		236		254
Change in unrealized gains/(losses) related to financial instruments held		8		0		9		7
Other invested assets [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period		76		48		78		2
Radian Asset Acquisition		2				2
Net Income (loss)	[2]	0	[5]	0	[5]	(4)	[5]	0
Other comprehensive income (loss)	[2]	0		1		2		2
Purchases		0		0		0		45	[6]
Settlements		0		0		0		0
FG VIE Consolidations		0		0		0		0
FG VIE deconsolidations		0		0		0		0
Fair value at end of period		78		49		78		49
Change in unrealized gains/(losses) related to financial instruments held		0		1		2		2
FG VIEs' assets, at fair value [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period		1,495		1,257		1,398		2,565
Radian Asset Acquisition		122				122
Net Income (loss)	[1],[2]	19		35		42		117
Other comprehensive income (loss)	[2]	0		0		0		0
Purchases		0		0		0		0
Settlements		(40)		(29)		(70)		(315)
FG VIE Consolidations		0		46		104		46
FG VIE deconsolidations		0		(25)		0		(1,129)
Fair value at end of period		1,596		1,284		1,596		1,284
Change in unrealized gains/(losses) related to financial instruments held		31		40		65		65
Other assets [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period		37		37		35		46
Radian Asset Acquisition		0				0
Net Income (loss)	[2],[7]	23		(6)		25		(15)
Other comprehensive income (loss)	[2]	0		0		0		0
Purchases		0		0		0		0
Settlements		0		0		0		0
FG VIE Consolidations		0		0		0		0
FG VIE deconsolidations		0		0		0		0
Fair value at end of period		60		31		60		31
Change in unrealized gains/(losses) related to financial instruments held		$ 23		$ (6)		$ 25		$ (15)

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

[2] 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.

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

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

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

[6] Includes a non-cash transaction.

[7] Recorded in fair value gains (losses) on CCS.