Consolidated Variable Interest Entities - Consolidated FG VIE's By Type of Collateral (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	$ 1,332	$ 1,239
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	1,278	1,277
Financial guaranty variable interest entities' assets without recourse, at fair value	167	163
Financial guaranty variable interest entities’ liabilities without recourse, at fair value	145	142
Financial guaranty variable interest entities’ assets, at fair value	1,499	1,402
Financial guaranty variable interest entities’ liabilities, at fair value	1,423	1,419
Other Insurance Product Line [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	365	369
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	365	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	739	632
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	591	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	228	238
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	$ 322	$ 327