Consolidated Variable Interest Entities - Consolidated FG VIE's By Type of Collateral (Details) - USD ($) $ in Millions	Jun. 30, 2015		Dec. 31, 2014
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	$ 1,421	[1]	$ 1,239
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	1,361	[1]	1,277
Financial guaranty variable interest entities' assets without recourse, at fair value	180	[1]	163
Financial guaranty variable interest entities’ liabilities without recourse, at fair value	171	[1]	142
Financial guaranty variable interest entities’ assets, at fair value	1,601	[1]	1,402
Financial guaranty variable interest entities’ liabilities, at fair value	1,532	[1]	1,419
Other Insurance Product Line [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	455	[1]	369
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	455	[1]	369
United States [Member] | First Lien [Member] | RMBS [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	743	[1]	632
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	594	[1]	581
United States [Member] | Second Lien [Member] | RMBS [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	223	[1]	238
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	312	[1]	$ 327
Radian [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities’ assets, at fair value	119
Financial guaranty variable interest entities’ liabilities, at fair value	$ 115

[1] nclude $119 million of FG VIE assets and $115 million of FG VIE liabilities acquired from Radian Asset.