Financial Guaranty Insurance Premiums - Net Earned Premiums (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Financial Guarantee Insurance Premiums [Line Items]
Net earned premiums	$ 142		$ 132
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Financial Guarantee Insurance Premiums [Line Items]
Scheduled net earned premiums	96		107
Acceleration of net earned premiums	41		19
Accretion of discount on net premiums receivable	4		6
Financial guaranty insurance net earned premiums	141		132
Other	1		0
Net earned premiums	142	[1]	132	[1]
Variable Interest Entity, Primary Beneficiary [Member]
Financial Guarantee Insurance Premiums [Line Items]
Net earned premiums	$ 5		$ 17

[1] Excludes $5 million and $17 million for First Quarter 2015 and 2014, respectively, related to consolidated FG VIEs.