Contracts Accounted for as Credit Derivatives - Credit Derivatives Subordination and Ratings (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Credit Derivatives
Estimated remaining weighted average life of credit derivatives (in years)	12 years 7 months 6 days	12 years 9 months 18 days
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	$ 3,205	$ 3,203
Net Fair Value Asset (Liability)	(57)	(162)
Expected loss to be recovered	3	3
Public finance | United States
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,131	1,175
Net Fair Value Asset (Liability)	(17)	(79)
Public finance | Non United States
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,611	1,565
Net Fair Value Asset (Liability)	(22)	(58)
Structured finance | United States
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	336	342
Net Fair Value Asset (Liability)	(16)	(22)
Structured finance | Non United States
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	127	121
Net Fair Value Asset (Liability)	$ (2)	$ (3)