Financial Guaranty Insurance Premiums - Net Earned Premiums (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Financial Guarantee Insurance Premiums [Line Items]
Net earned premiums		$ 219	$ 136	$ 361	$ 268
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Financial Guarantee Insurance Premiums [Line Items]
Scheduled net earned premiums		118	106	214	213
Acceleration of net earned premiums		96	24	137	43
Accretion of discount on net premiums receivable		5	5	9	11
Financial guaranty insurance net earned premiums		219	135	360	267
Other		0	1	1	1
Net earned premiums	[1]	219	136	361	268
Variable Interest Entity, Primary Beneficiary [Member]
Financial Guarantee Insurance Premiums [Line Items]
Net earned premiums		$ 5	$ 5	$ 10	$ 22

[1] Excludes $5 million and $5 million for Second Quarter 2015 and 2014, respectively, and $10 million and $22 million for Six Months 2015 and 2014, respectively, related to consolidated financial guaranty ("FG") VIEs.