Fair Value Measurement - Financial Instruments Carried at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets:
Estimated Fair Value	$ 6,267	$ 7,119
Fixed-maturity securities, trading	350	303
Short-term investments, at fair value	1,426	810
Other invested assets	765	133
FG VIEs’ assets	326	413
Other assets	112	148
Liabilities:
Credit derivative liabilities	50	163
FG VIEs' liabilities	542	715
Obligations of state and political subdivisions
Assets:
Estimated Fair Value	2,766	3,394
U.S. government and agencies
Assets:
Estimated Fair Value	58	111
Corporate securities
Assets:
Estimated Fair Value	2,009	2,084
RMBS
Assets:
Estimated Fair Value	330	340
CMBS
Assets:
Estimated Fair Value	188	271
Non-U.S. government securities
Assets:
Estimated Fair Value	93	98
Fair Value Measured at Net Asset Value Per Share | Fund investments: | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		5
Recurring
Assets:
Short-term investments, at fair value	1,426	810
Other invested assets	3	7
Other assets	112	148
Total assets carried at fair value	8,802	14,031
Liabilities:
Credit derivative liabilities	50	163
Other liabilities		7
Total liabilities carried at fair value	592	5,316
Recurring | Financial Guaranty Variable Interest Entities
Liabilities:
FG VIEs' liabilities	542	715
Recurring | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		4,431
Recurring | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	326	413
Recurring | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	318	5,231
Recurring | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		313
Recurring | Securitized borrowing | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		28
Recurring | CLO obligations of CFEs | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		4,090
Recurring | Fixed-maturity securities, available-for-sale
Assets:
Estimated Fair Value	6,267	7,119
Fixed-maturity securities, trading	350	303
Recurring | Fixed-maturity securities, available-for-sale | Obligations of state and political subdivisions
Assets:
Estimated Fair Value	2,766	3,394
Recurring | Fixed-maturity securities, available-for-sale | U.S. government and agencies
Assets:
Estimated Fair Value	58	111
Recurring | Fixed-maturity securities, available-for-sale | Corporate securities
Assets:
Estimated Fair Value	2,009	2,084
Recurring | Fixed-maturity securities, available-for-sale | RMBS
Assets:
Estimated Fair Value	330	340
Recurring | Fixed-maturity securities, available-for-sale | CMBS
Assets:
Estimated Fair Value	188	271
Recurring | Fixed-maturity securities, available-for-sale | Asset-backed securities
Assets:
Estimated Fair Value	823	821
Recurring | Fixed-maturity securities, available-for-sale | Non-U.S. government securities
Assets:
Estimated Fair Value	93	98
Recurring | Fund investments: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		96
Recurring | Fund investments: | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	79	302
Recurring | Fund investments: | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	239	128
Recurring | CLOs and CLO warehouse assets: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		4,570
Recurring | CLOs and CLO warehouse assets: | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		135
Recurring | Level 1
Assets:
Short-term investments, at fair value	1,418	771
Other invested assets	0	2
Other assets	51	54
Total assets carried at fair value	1,469	962
Liabilities:
Credit derivative liabilities	0	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
Recurring | Level 1 | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	0	0
Recurring | Level 1 | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	135
Recurring | Level 1 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		0
Recurring | Level 1 | Securitized borrowing | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		0
Recurring | Level 1 | CLO obligations of CFEs | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		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
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
Recurring | Level 1 | CLOs and CLO warehouse assets: | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		135
Recurring | Level 2
Assets:
Short-term investments, at fair value	8	39
Other invested assets	0	0
Other assets	48	46
Total assets carried at fair value	5,938	11,353
Liabilities:
Credit derivative liabilities	0	0
Other liabilities		7
Total liabilities carried at fair value	0	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		277
Recurring | Level 2 | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	146	209
Recurring | Level 2 | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	70	4,657
Recurring | Level 2 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		277
Recurring | Level 2 | Securitized borrowing | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		0
Recurring | Level 2 | CLO obligations of CFEs | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		0
Recurring | Level 2 | Fixed-maturity securities, available-for-sale
Assets:
Estimated Fair Value	5,316	6,099
Fixed-maturity securities, trading	350	303
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | Obligations of state and political subdivisions
Assets:
Estimated Fair Value	2,764	3,347
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | U.S. government and agencies
Assets:
Estimated Fair Value	58	111
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | Corporate securities
Assets:
Estimated Fair Value	2,009	2,084
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | RMBS
Assets:
Estimated Fair Value	177	161
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | CMBS
Assets:
Estimated Fair Value	188	271
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | Asset-backed securities
Assets:
Estimated Fair Value	27	27
Recurring | Level 2 | Fixed-maturity securities, available-for-sale | Non-U.S. government securities
Assets:
Estimated Fair Value	93	98
Recurring | Level 2 | Fund investments: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		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	66	82
Recurring | Level 2 | CLOs and CLO warehouse assets: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		4,570
Recurring | Level 2 | CLOs and CLO warehouse assets: | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		0
Recurring | Level 3
Assets:
Short-term investments, at fair value	0	0
Other invested assets	3	5
Other assets	13	48
Total assets carried at fair value	1,395	1,716
Liabilities:
Credit derivative liabilities	50	163
Other liabilities		0
Total liabilities carried at fair value	592	5,032
Recurring | Level 3 | Financial Guaranty Variable Interest Entities
Liabilities:
FG VIEs' liabilities	542	715
Recurring | Level 3 | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		4,154
Recurring | Level 3 | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	180	204
Recurring | Level 3 | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	248	439
Recurring | Level 3 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		36
Recurring | Level 3 | Securitized borrowing | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		28
Recurring | Level 3 | CLO obligations of CFEs | Consolidated Investment Vehicles
Liabilities:
FG VIEs' liabilities		4,090
Recurring | Level 3 | Fixed-maturity securities, available-for-sale
Assets:
Estimated Fair Value	951	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	2	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	153	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	796	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		96
Recurring | Level 3 | Fund investments: | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	75	297
Recurring | Level 3 | Fund investments: | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	$ 173	46
Recurring | Level 3 | CLOs and CLO warehouse assets: | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		0
Recurring | Level 3 | CLOs and CLO warehouse assets: | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		$ 0