Fair Value Measurement - Financial Instruments Carried at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	$ 6,307	$ 7,119
Fixed-maturity securities, trading, at fair value	318	303
Short-term investments, at fair value	1,661	810
Other invested assets	829	133
FG VIEs’ assets	174	413
Other assets	123	148
Liabilities:
Credit derivative liabilities	53	163
Liabilities of CIVs	554	715
Obligations of state and political subdivisions
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	2,661	3,394
U.S. government and agencies
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	60	111
Corporate securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	2,141	2,084
RMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	342	340
CMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	151	271
Non-U.S. government securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	100	98
Recurring
Assets:
Short-term investments, at fair value	1,661
Other invested assets	3	7
Other assets	123	148
Total assets carried at fair value	8,917	14,031
Liabilities:
Credit derivative liabilities	53	163
Liabilities of CIVs		715
Other liabilities		7
Total liabilities carried at fair value	607	5,316
Recurring | Financial Guaranty Variable Interest Entities
Liabilities:
Liabilities of CIVs	554
Recurring | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		4,431
Recurring | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	174	413
Recurring | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	331	5,231
Recurring | CLO obligations, FVO | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		4,090
Recurring | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		313
Recurring | Borrowings | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		28
Recurring | Level 1
Assets:
Short-term investments, at fair value	1,657
Other invested assets	0	2
Other assets	55	54
Total assets carried at fair value	1,712	962
Liabilities:
Credit derivative liabilities	0	0
Liabilities of CIVs		0
Other liabilities		0
Total liabilities carried at fair value	0	0
Recurring | Level 1 | Financial Guaranty Variable Interest Entities
Liabilities:
Liabilities of CIVs	0
Recurring | Level 1 | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		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 | CLO obligations, FVO | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		0
Recurring | Level 1 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		0
Recurring | Level 1 | Borrowings | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		0
Recurring | Level 2
Assets:
Short-term investments, at fair value	4
Other invested assets	0	0
Other assets	52	46
Total assets carried at fair value	5,780	11,353
Liabilities:
Credit derivative liabilities	0	0
Liabilities of CIVs		0
Other liabilities		7
Total liabilities carried at fair value	0	284
Recurring | Level 2 | Financial Guaranty Variable Interest Entities
Liabilities:
Liabilities of CIVs	0
Recurring | Level 2 | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		277
Recurring | Level 2 | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	0	209
Recurring | Level 2 | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	62	4,657
Recurring | Level 2 | CLO obligations, FVO | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		0
Recurring | Level 2 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		277
Recurring | Level 2 | Borrowings | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		0
Recurring | Level 3
Assets:
Short-term investments, at fair value	0
Other invested assets	3	5
Other assets	16	48
Total assets carried at fair value	1,425	1,716
Liabilities:
Credit derivative liabilities	53	163
Liabilities of CIVs		715
Other liabilities		0
Total liabilities carried at fair value	607	5,032
Recurring | Level 3 | Financial Guaranty Variable Interest Entities
Liabilities:
Liabilities of CIVs	554
Recurring | Level 3 | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		4,154
Recurring | Level 3 | Financial Guaranty Variable Interest Entities
Assets:
FG VIEs’ assets	174	204
Recurring | Level 3 | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	269	439
Recurring | Level 3 | CLO obligations, FVO | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		4,090
Recurring | Level 3 | Warehouse financing debt | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		36
Recurring | Level 3 | Borrowings | Consolidated Investment Vehicles
Liabilities:
Liabilities of CIVs		28
Fixed-maturity securities | Recurring
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	6,307	7,119
Fixed-maturity securities, trading, at fair value	318	303
Fixed-maturity securities | Recurring | Obligations of state and political subdivisions
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	2,661	3,394
Fixed-maturity securities | Recurring | U.S. government and agencies
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	60	111
Fixed-maturity securities | Recurring | Corporate securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	2,141	2,084
Fixed-maturity securities | Recurring | RMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	342	340
Fixed-maturity securities | Recurring | CMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	151	271
Fixed-maturity securities | Recurring | Asset-backed securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	852	821
Fixed-maturity securities | Recurring | Non-U.S. government securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	100	98
Fixed-maturity securities | Recurring | Level 1
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities, trading, at fair value	0	0
Fixed-maturity securities | Recurring | Level 1 | Obligations of state and political subdivisions
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 1 | U.S. government and agencies
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 1 | Corporate securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 1 | RMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 1 | CMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 1 | Asset-backed securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 1 | Non-U.S. government securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 2
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	5,344	6,099
Fixed-maturity securities, trading, at fair value	318	303
Fixed-maturity securities | Recurring | Level 2 | Obligations of state and political subdivisions
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	2,655	3,347
Fixed-maturity securities | Recurring | Level 2 | U.S. government and agencies
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	60	111
Fixed-maturity securities | Recurring | Level 2 | Corporate securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	2,141	2,084
Fixed-maturity securities | Recurring | Level 2 | RMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	188	161
Fixed-maturity securities | Recurring | Level 2 | CMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	151	271
Fixed-maturity securities | Recurring | Level 2 | Asset-backed securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	49	27
Fixed-maturity securities | Recurring | Level 2 | Non-U.S. government securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	100	98
Fixed-maturity securities | Recurring | Level 3
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	963	1,020
Fixed-maturity securities, trading, at fair value	0	0
Fixed-maturity securities | Recurring | Level 3 | Obligations of state and political subdivisions
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	6	47
Fixed-maturity securities | Recurring | Level 3 | U.S. government and agencies
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 3 | Corporate securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 3 | RMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	154	179
Fixed-maturity securities | Recurring | Level 3 | CMBS
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Fixed-maturity securities | Recurring | Level 3 | Asset-backed securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	803	794
Fixed-maturity securities | Recurring | Level 3 | Non-U.S. government securities
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss	0	0
Short-term investments | Recurring
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss		810
Short-term investments | Recurring | Level 1
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss		771
Short-term investments | Recurring | Level 2
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss		39
Short-term investments | Recurring | Level 3
Assets:
Fixed-maturity securities, available-for-sale, at fair value, net of allowance for credit loss		0
Fund Investments | Fair Value Measured at Net Asset Value | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		5
Fund Investments | Recurring | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		96
Fund Investments | Recurring | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	83	302
Fund Investments | Recurring | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	248	128
Fund Investments | Recurring | Level 1 | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		0
Fund Investments | Recurring | Level 1 | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Fund Investments | Recurring | Level 1 | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	0	0
Fund Investments | Recurring | Level 2 | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		0
Fund Investments | Recurring | Level 2 | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	3	5
Fund Investments | Recurring | Level 2 | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	59	82
Fund Investments | Recurring | Level 3 | Corporate securities | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		96
Fund Investments | Recurring | Level 3 | Equity securities and warrants | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	80	297
Fund Investments | Recurring | Level 3 | Structured products | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets	$ 189	46
CLOs | Recurring | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		135
CLOs | Recurring | Loans | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		4,570
CLOs | Recurring | Level 1 | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		135
CLOs | Recurring | Level 1 | Loans | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		0
CLOs | Recurring | Level 2 | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		0
CLOs | Recurring | Level 2 | Loans | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		4,570
CLOs | Recurring | Level 3 | Short-term investments | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		0
CLOs | Recurring | Level 3 | Loans | Consolidated Investment Vehicles
Assets:
FG VIEs’ assets		$ 0