Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended																12 Months Ended
	Feb. 04, 2015	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Revenues
Net earned premiums		$ 192		$ 213		$ 219		$ 142		$ 158		$ 144		$ 136		$ 132		$ 766	[1]	$ 570	[1]	$ 752	[1]
Net investment income		112		112		98		101		102		102		96		103		423		403		393
Net realized investment gains (losses)		(6)		(27)		(9)		16		(35)		(19)		(8)		2		(26)		(60)		52
Net change in fair value of credit derivatives		428		86		90		124		676		255		103		(211)		728		823		65
Fair value gains (losses) on CCS		17		(15)		23		2		0		4		(6)		(9)		27		(11)		10
Fair value gains (losses) on FG VIEs		38		2		5		(7)		23		50		25		157		38		255
Bargain purchase gain and settlement of pre-existing relationships		0		0		214		0		0		0		0		0		214		0		0
Other income (loss)		(6)		(3)		55		(9)		(3)		(11)		7		21		37		14		(10)
Expenses
Loss and LAE		106		112		188		18		72		(44)		57		41		424		126		154
Amortization of DAC		5		5		6		4		13		4		3		5		20		25		12
Interest expense		25		25		26		25		25		27		20		20		101		92		82
Other operating expenses		55		54		66		56		55		50		55		60		231		220		218
Income (loss) before provision for income taxes		584		172		409		266		756		488		218		69		1,431		1,531		1,142
Provision (benefit) for income taxes		155		43		112		65		224		133		59		27		375		443		334
Net income (loss)		$ 429		$ 129		$ 297		$ 201		$ 532		$ 355		$ 159		$ 42		$ 1,056		$ 1,088		$ 808
Earnings per share:
Basic (in dollars per share)		$ 3.05	[2]	$ 0.88	[2]	$ 1.97	[2]	$ 1.29	[2]	$ 3.30	[2]	$ 2.10	[2]	$ 0.89	[2]	$ 0.23	[2]	$ 7.12	[2]	$ 6.30	[2]	$ 4.32
Diluted (in dollars per share)		3.03	[2]	0.88	[2]	1.96	[2]	1.28	[2]	3.28	[2]	2.09	[2]	0.89	[2]	0.23	[2]	7.08	[2]	6.26	[2]	4.30
Dividends (in dollars per share)	$ 0.12	$ 0.12	[2]	$ 0.12	[2]	$ 0.12	[2]	$ 0.12	[2]	$ 0.11	[2]	$ 0.11	[2]	$ 0.11	[2]	$ 0.11	[2]	$ 0.48	[2]	$ 0.44	[2]	$ 0.40

[1] Excludes $21 million, $32 million and $60 million for the year ended December 31, 2015, 2014 and 2013, respectively, related to consolidated FG VIEs.

[2] Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.