Contracts Accounted for as Credit Derivatives - Credit Derivatives Net Par Outstanding by Sector (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	$ 3,203	$ 4,040
Net Fair Value Asset (Liability)	(162)	(154)
Expected Loss to be recovered	3	5
Public finance | U.S.
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,175	1,705
Net Fair Value Asset (Liability)	(79)	(72)
Public finance | Non U.S.
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,565	1,800
Net Fair Value Asset (Liability)	(58)	(48)
Structured finance | U.S.
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	342	400
Net Fair Value Asset (Liability)	(22)	(32)
Structured finance | Non U.S.
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	121	135
Net Fair Value Asset (Liability)	$ (3)	$ (2)