Variable Interest Entities - Consolidated FG VIE's By Type of Collateral (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	$ 340	$ 467
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	367	517
Financial guaranty variable interest entities' assets without recourse, at fair value	102	102
Financial guaranty variable interest entities’ liabilities without recourse, at fair value	102	102
Financial guaranty variable interest entities’ assets, at fair value	442	569
Financial guaranty variable interest entities’ liabilities, at fair value	469	619
Manufactured Housing Loans [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	0	53
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	0	54
United States [Member] | First Lien [Member] | Residential Mortgage-Backed Securities (RMBS) [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	270	299
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	297	326
United States [Member] | Second Lien [Member] | Residential Mortgage-Backed Securities (RMBS) [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	70	115
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	$ 70	$ 137