Fair Value Measurement - Financial Instruments Carried at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Assets:
Estimated Fair Value	$ 6,488	$ 7,119
Fixed-maturity securities, trading	340	303
Short-term investments, at fair value	1,650	810
Other invested assets	146	133
FG VIEs’ assets	411	413
Assets held for sale	221	0
Other assets	141	148
Liabilities:
Credit derivative liabilities	58	163
FG VIEs' liabilities	699	715
Liabilities held for sale	50	0
Obligations of state and political subdivisions
Assets:
Estimated Fair Value	2,876	3,394
U.S. government and agencies
Assets:
Estimated Fair Value	64	111
Corporate securities
Assets:
Estimated Fair Value	2,066	2,084
RMBS
Assets:
Estimated Fair Value	352	340
CMBS
Assets:
Estimated Fair Value	204	271
Non-U.S. government securities
Assets:
Estimated Fair Value	98	98
Fair Value Measured at Net Asset Value Per Share
Assets:
Other invested assets	23	23
Fair Value Measured at Net Asset Value Per Share | Fund investments: | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	5	5
Fair Value Measured at Net Asset Value Per Share | Municipal Relative Fund Member | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		127
Recurring
Assets:
Short-term investments, at fair value	1,650	810
Other invested assets	3	7
Assets held for sale	1
Other assets	141	148
Total assets carried at fair value	14,007	14,031
Liabilities:
Credit derivative liabilities	58	163
Liabilities held for sale	7
Other liabilities		7
Total liabilities carried at fair value	5,090	5,316
Recurring | Financial Guaranty Variable Interest Entities
Liabilities:
FG VIEs' liabilities	699	715
Recurring | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	4,326	4,431
Recurring | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	411	413
Recurring | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	4,973	5,231
Recurring | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	157	313
Recurring | Securitized borrowing | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	31	28
Recurring | CLO obligations of CFEs | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	4,138	4,090
Recurring | Fixed-maturity securities, available-for-sale
Assets:
Estimated Fair Value	6,488	7,119
Fixed-maturity securities, trading	340	303
Recurring | Fixed-maturity securities, available-for-sale | Obligations of state and political subdivisions
Assets:
Estimated Fair Value	2,876	3,394
Recurring | Fixed-maturity securities, available-for-sale | U.S. government and agencies
Assets:
Estimated Fair Value	64	111
Recurring | Fixed-maturity securities, available-for-sale | Corporate securities
Assets:
Estimated Fair Value	2,066	2,084
Recurring | Fixed-maturity securities, available-for-sale | RMBS
Assets:
Estimated Fair Value	352	340
Recurring | Fixed-maturity securities, available-for-sale | CMBS
Assets:
Estimated Fair Value	204	271
Recurring | Fixed-maturity securities, available-for-sale | Asset-backed securities
Assets:
Estimated Fair Value	828	821
Recurring | Fixed-maturity securities, available-for-sale | Non-U.S. government securities
Assets:
Estimated Fair Value	98	98
Recurring | Fund investments: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	84	96
Recurring | Fund investments: | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	294	302
Recurring | Fund investments: | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	74	128
Recurring | CLOs and CLO warehouse assets: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	4,452	4,570
Recurring | CLOs and CLO warehouse assets: | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	69	135
Recurring | Level 1
Assets:
Short-term investments, at fair value	1,629	771
Other invested assets	0	2
Assets held for sale	1
Other assets	59	54
Total assets carried at fair value	1,758	962
Liabilities:
Credit derivative liabilities	0	0
Liabilities held for sale	0
Other liabilities		0
Total liabilities carried at fair value	0	0
Recurring | Level 1 | Financial Guaranty Variable Interest Entities
Liabilities:
FG VIEs' liabilities	0	0
Recurring | Level 1 | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	0	0
Recurring | Level 1 | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	0	0
Recurring | Level 1 | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	69	135
Recurring | Level 1 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	0	0
Recurring | Level 1 | Securitized borrowing | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	0	0
Recurring | Level 1 | CLO obligations of CFEs | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	0	0
Recurring | Level 1 | Fixed-maturity securities, available-for-sale
Assets:
Estimated Fair Value	0	0
Fixed-maturity securities, trading	0	0
Recurring | Level 1 | Fixed-maturity securities, available-for-sale | Obligations of state and political subdivisions
Assets:
Estimated Fair Value	0	0
Recurring | Level 1 | Fixed-maturity securities, available-for-sale | U.S. government and agencies
Assets:
Estimated Fair Value	0	0
Recurring | Level 1 | Fixed-maturity securities, available-for-sale | Corporate securities
Assets:
Estimated Fair Value	0	0
Recurring | Level 1 | Fixed-maturity securities, available-for-sale | RMBS
Assets:
Estimated Fair Value	0	0
Recurring | Level 1 | Fixed-maturity securities, available-for-sale | CMBS
Assets:
Estimated Fair Value	0	0
Recurring | Level 1 | Fixed-maturity securities, available-for-sale | Asset-backed securities
Assets:
Estimated Fair Value	0	0
Recurring | Level 1 | Fixed-maturity securities, available-for-sale | Non-U.S. government securities
Assets:
Estimated Fair Value	0	0
Recurring | Level 1 | Fund investments: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Recurring | Level 1 | Fund investments: | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Recurring | Level 1 | Fund investments: | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Recurring | Level 1 | CLOs and CLO warehouse assets: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Recurring | Level 1 | CLOs and CLO warehouse assets: | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	69	135
Recurring | Level 2
Assets:
Short-term investments, at fair value	21	39
Other invested assets	0	0
Assets held for sale	0
Other assets	49	46
Total assets carried at fair value	10,643	11,353
Liabilities:
Credit derivative liabilities	0	0
Liabilities held for sale	7
Other liabilities		7
Total liabilities carried at fair value	134	284
Recurring | Level 2 | Financial Guaranty Variable Interest Entities
Liabilities:
FG VIEs' liabilities	0	0
Recurring | Level 2 | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	127	277
Recurring | Level 2 | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	223	209
Recurring | Level 2 | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	4,530	4,657
Recurring | Level 2 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	127	277
Recurring | Level 2 | Securitized borrowing | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	0	0
Recurring | Level 2 | CLO obligations of CFEs | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	0	0
Recurring | Level 2 | Fixed-maturity securities, available-for-sale
Assets:
Estimated Fair Value	5,480	6,099
Fixed-maturity securities, trading	340	303
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | Obligations of state and political subdivisions
Assets:
Estimated Fair Value	2,830	3,347
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | U.S. government and agencies
Assets:
Estimated Fair Value	64	111
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | Corporate securities
Assets:
Estimated Fair Value	2,066	2,084
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | RMBS
Assets:
Estimated Fair Value	190	161
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | CMBS
Assets:
Estimated Fair Value	204	271
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | Asset-backed securities
Assets:
Estimated Fair Value	28	27
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | Non-U.S. government securities
Assets:
Estimated Fair Value	98	98
Recurring | Level 2 | Fund investments: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Recurring | Level 2 | Fund investments: | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	4	5
Recurring | Level 2 | Fund investments: | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	74	82
Recurring | Level 2 | CLOs and CLO warehouse assets: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	4,452	4,570
Recurring | Level 2 | CLOs and CLO warehouse assets: | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Recurring | Level 3
Assets:
Short-term investments, at fair value	0	0
Other invested assets	3	5
Assets held for sale	0
Other assets	33	48
Total assets carried at fair value	1,606	1,716
Liabilities:
Credit derivative liabilities	58	163
Liabilities held for sale	0
Other liabilities		0
Total liabilities carried at fair value	4,956	5,032
Recurring | Level 3 | Financial Guaranty Variable Interest Entities
Liabilities:
FG VIEs' liabilities	699	715
Recurring | Level 3 | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	4,199	4,154
Recurring | Level 3 | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	188	204
Recurring | Level 3 | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	374	439
Recurring | Level 3 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	30	36
Recurring | Level 3 | Securitized borrowing | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	31	28
Recurring | Level 3 | CLO obligations of CFEs | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities	4,138	4,090
Recurring | Level 3 | Fixed-maturity securities, available-for-sale
Assets:
Estimated Fair Value	1,008	1,020
Fixed-maturity securities, trading	0	0
Recurring | Level 3 | Fixed-maturity securities, available-for-sale | Obligations of state and political subdivisions
Assets:
Estimated Fair Value	46	47
Recurring | Level 3 | Fixed-maturity securities, available-for-sale | U.S. government and agencies
Assets:
Estimated Fair Value	0	0
Recurring | Level 3 | Fixed-maturity securities, available-for-sale | Corporate securities
Assets:
Estimated Fair Value	0	0
Recurring | Level 3 | Fixed-maturity securities, available-for-sale | RMBS
Assets:
Estimated Fair Value	162	179
Recurring | Level 3 | Fixed-maturity securities, available-for-sale | CMBS
Assets:
Estimated Fair Value	0	0
Recurring | Level 3 | Fixed-maturity securities, available-for-sale | Asset-backed securities
Assets:
Estimated Fair Value	800	794
Recurring | Level 3 | Fixed-maturity securities, available-for-sale | Non-U.S. government securities
Assets:
Estimated Fair Value	0	0
Recurring | Level 3 | Fund investments: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	84	96
Recurring | Level 3 | Fund investments: | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	290	297
Recurring | Level 3 | Fund investments: | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	46
Recurring | Level 3 | CLOs and CLO warehouse assets: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Recurring | Level 3 | CLOs and CLO warehouse assets: | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	$ 0	$ 0