Financial Guaranty Insurance Losses - BIG Transaction Loss Summary (Details) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2015 USD ($) risk	Dec. 31, 2014 USD ($) risk
Discount
Total		$ (406)
Reserves (salvage)
Total		$ 782	$ 567
BIG [Member]
Number of risks
Total (in contracts) | risk	[1]	451	358
Remaining weighted average contract period
Total (in years)		10 years 2 months	10 years 3 months 18 days
Principal
Total		$ 15,582	$ 15,222
Interest
Total		8,043	7,651
Total net outstanding exposure
Total	[2]	23,625	22,873
Expected cash outflows (inflows)
Total		3,311	3,118
Potential recoveries
Total, Undiscounted R&W		(88)	(239)
Total, Other	[3]	(1,672)	(1,477)
Total		(1,760)	(1,716)
Subtotal
Total		1,551	1,402
Discount
Total		(406)	(413)
Present value of expected cash flows
Net expected loss to be paid		1,145	989
Deferred premium revenue
Total		807	584
Reserves (salvage)
Total		$ 764	$ 571
BIG [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Number of risks
Total (in contracts) | risk	[1],[4],[5]	451	358
Remaining weighted average contract period
Total (in years)		10 years 2 months	10 years 3 months 18 days
Principal
Total	[5]	$ 15,582	$ 15,222
Interest
Total		8,043	7,651
Total net outstanding exposure
Total	[2]	23,625	22,873
Expected cash outflows (inflows)
Total		3,644	3,463
Potential recoveries
Total, Undiscounted R&W		(96)	(247)
Total, Other	[3]	(1,845)	(1,654)
Total		(1,941)	(1,901)
Subtotal
Total		1,703	1,562
Discount
Total		(441)	(447)
Present value of expected cash flows
Net expected loss to be paid		1,262	1,115
Deferred premium revenue
Total		910	700
Reserves (salvage)
Total		$ 836	$ 650
BIG [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | BIG 1 [Member]
Number of risks
Ceded (in contracts) | risk	[1]	(50)	(59)
Total (in contracts) | risk	[1],[4],[5]	239	164
Remaining weighted average contract period
Gross (in years)		9 years 10 months 24 days	9 years 10 months 24 days
Ceded (in years)		6 years 9 months	7 years 4 months 24 days
Principal
Gross		$ 11,001	$ 12,358
Ceded		(1,449)	(2,163)
Total	[5]	9,552	10,195
Interest
Gross		5,676	6,350
Ceded		(509)	(838)
Total net outstanding exposure
Gross	[2]	16,677	18,708
Ceded	[2]	(1,958)	(3,001)
Expected cash outflows (inflows)
Gross		1,809	1,762
Ceded		(566)	(626)
Total		167	39
Potential recoveries
Gross, Undiscounted R&W		42	(39)
Ceded, Undiscounted R&W		(1)	0
Gross, Other	[3]	(1,663)	(1,687)
Ceded, Other	[3]	514	608
Ceded		513	608
Gross		(1,621)	(1,726)
Subtotal
Gross		188	36
Ceded		(53)	(18)
Discount
Gross		(21)	3
Ceded		8	0
Present value of expected cash flows
Ceded		(45)	(18)
Deferred premium revenue
Gross		510	378
Ceded		(47)	(70)
Reserves (salvage)
Gross		30	(42)
Ceded		$ (36)	$ (5)
BIG [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | BIG 2 [Member]
Number of risks
Ceded (in contracts) | risk	[1]	(13)	(15)
Total (in contracts) | risk	[1],[4],[5]	87	75
Remaining weighted average contract period
Gross (in years)		11 years	10 years 1 month 6 days
Ceded (in years)		9 years 2 months	8 years 10 months 24 days
Principal
Gross		$ 3,673	$ 2,421
Ceded		(263)	(286)
Total	[5]	3,410	2,135
Interest
Gross		2,102	1,274
Ceded		(118)	(121)
Total net outstanding exposure
Gross	[2]	5,775	3,695
Ceded	[2]	(381)	(407)
Expected cash outflows (inflows)
Gross		1,110	763
Ceded		(67)	(77)
Total		609	392
Potential recoveries
Gross, Undiscounted R&W		(49)	(48)
Ceded, Undiscounted R&W		1	2
Gross, Other	[3]	(258)	(206)
Ceded, Other	[3]	11	5
Ceded		12	7
Gross		(307)	(254)
Subtotal
Gross		803	509
Ceded		(55)	(70)
Discount
Gross		(194)	(117)
Ceded		10	11
Present value of expected cash flows
Ceded		(45)	(59)
Deferred premium revenue
Gross		144	119
Ceded		(4)	(6)
Reserves (salvage)
Gross		502	278
Ceded		$ (42)	$ (53)
BIG [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | BIG 3 [Member]
Number of risks
Ceded (in contracts) | risk	[1]	(41)	(38)
Total (in contracts) | risk	[1],[4],[5]	125	119
Remaining weighted average contract period
Gross (in years)		8 years	9 years 7 months 6 days
Ceded (in years)		6 years 2 months	6 years 10 months 24 days
Principal
Gross		$ 2,780	$ 3,067
Ceded		(160)	(175)
Total	[5]	2,620	2,892
Interest
Gross		926	1,034
Ceded		(34)	(48)
Total net outstanding exposure
Gross	[2]	3,706	4,101
Ceded	[2]	(194)	(223)
Expected cash outflows (inflows)
Gross		1,402	1,716
Ceded		(44)	(75)
Total		683	788
Potential recoveries
Gross, Undiscounted R&W		(94)	(171)
Ceded, Undiscounted R&W		5	9
Gross, Other	[3]	(467)	(404)
Ceded, Other	[3]	18	30
Ceded		23	39
Gross		(561)	(575)
Subtotal
Gross		841	1,141
Ceded		(21)	(36)
Discount
Gross		(158)	(353)
Ceded		(86)	9
Present value of expected cash flows
Ceded		(107)	(27)
Deferred premium revenue
Gross		333	312
Ceded		(26)	(33)
Reserves (salvage)
Gross		389	482
Ceded		(7)	(10)
BIG [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Expected cash outflows (inflows)
Total		(333)	(345)
Potential recoveries
Total, Undiscounted R&W		8	8
Total, Other	[3]	173	177
Total		181	185
Subtotal
Total		(152)	(160)
Discount
Total		35	34
Present value of expected cash flows
Net expected loss to be paid		(117)	(126)
Deferred premium revenue
Total		(103)	(116)
Reserves (salvage)
Total		$ (72)	$ (79)

[1] A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments. The ceded number of risks represents the number of risks for which the Company ceded a portion of its exposure

[2] Includes BIG amounts related to FG VIEs.

[3] Includes excess spread and draws on HELOCs.

[4] A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments.

[5] Includes net par outstanding for VIEs.