Consolidated Variable Interest Entities - Consolidated FG VIE's By Type of Collateral (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	$ 626	$ 725
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	689	807
Financial guaranty variable interest entities' assets without recourse, at fair value	131	151
Financial guaranty variable interest entities’ liabilities without recourse, at fair value	131	151
Financial guaranty variable interest entities’ assets, at fair value	757	876
Financial guaranty variable interest entities’ liabilities, at fair value	820	958
Manufactured Housing Loans [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	71	74
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	72	75
United States [Member] | First Lien [Member] | RMBS [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	395	473
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	418	509
United States [Member] | Second Lien [Member] | RMBS [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	160	178
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	$ 199	$ 223