Investments - Fixed Maturities and Equity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Available-for-sale Securities Including Securities Pledged [Line Items]
Securities pledged, Amortized Cost	$ 855	$ 894
Fixed maturities, allowance for credit losses	14	7
U.S. Treasuries
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	297	404
Gross Unrealized Capital Gains	3	4
Gross Unrealized Capital Losses	25	31
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	275	377
Fixed maturities, allowance for credit losses	0	0
U.S. Government agencies and authorities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	32	33
Gross Unrealized Capital Gains	0	0
Gross Unrealized Capital Losses	2	3
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	30	30
Fixed maturities, allowance for credit losses	0	0
State, municipalities and political subdivisions
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	623	691
Gross Unrealized Capital Gains	1	1
Gross Unrealized Capital Losses	70	92
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	554	600
Fixed maturities, allowance for credit losses	0	0
U.S. corporate public securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	6,291	6,938
Gross Unrealized Capital Gains	73	32
Gross Unrealized Capital Losses	759	1,032
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	5,605	5,938
Fixed maturities, allowance for credit losses	0	0
U.S. corporate private securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	3,861	3,885
Gross Unrealized Capital Gains	31	11
Gross Unrealized Capital Losses	256	328
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	3,636	3,568
Fixed maturities, allowance for credit losses	0	0
Foreign corporate public securities and foreign governments
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	2,214	2,380
Gross Unrealized Capital Gains	27	9
Gross Unrealized Capital Losses	216	317
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	2,022	2,066
Fixed maturities, allowance for credit losses	3	6
Foreign corporate private securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	2,385	2,617
Gross Unrealized Capital Gains	20	6
Gross Unrealized Capital Losses	105	184
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	2,299	2,438
Fixed maturities, allowance for credit losses	1	1
Residential mortgage-backed securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	2,631	3,023
Gross Unrealized Capital Gains	24	21
Gross Unrealized Capital Losses	124	153
Embedded Derivatives	1	2
Fixed maturities including securities pledged, Fair Value	2,532	2,893
Fixed maturities, allowance for credit losses	0	0
Commercial mortgage-backed securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	2,781	2,978
Gross Unrealized Capital Gains	1	0
Gross Unrealized Capital Losses	415	379
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	2,358	2,599
Fixed maturities, allowance for credit losses	9	0
Other asset-backed securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	1,564	1,418
Gross Unrealized Capital Gains	8	1
Gross Unrealized Capital Losses	43	109
Embedded Derivatives	0	0
Fixed maturities including securities pledged, Fair Value	1,528	1,310
Fixed maturities, allowance for credit losses	1	0
Fixed maturities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-Sale, Amortized Cost	22,679	24,367
Total fixed maturities, less securities pledged, Amortized Cost	21,824	23,473
Gross Unrealized Capital Gains	188	85
Total fixed maturities, less securities pledged, Gross Unrealized Capital Gains	188	82
Gross Unrealized Capital Losses	2,015	2,628
Total fixed maturities, less securities pledged, Gross Unrealized Capital Losses	1,958	2,523
Embedded Derivatives	1	2
Fixed maturities including securities pledged, Fair Value	20,839	21,819
Total fixed maturities, less securities pledged, Fair Value	20,041	21,027
Fixed maturities, allowance for credit losses	14	7
OTTI	14	7
Collateral Pledged
Available-for-sale Securities Including Securities Pledged [Line Items]
Securities pledged, Gross Unrealized Capital Losses	798	792
Collateral Pledged | Fixed maturities
Available-for-sale Securities Including Securities Pledged [Line Items]
Securities pledged, Amortized Cost	855	894
Securities pledged, Gross Unrealized Capital Gains	0	3
Securities pledged, Gross Unrealized Capital Losses	57	105
Embedded Derivatives	0	0
Securities pledged, Gross Unrealized Capital Losses	798	792
Fixed maturities, allowance for credit losses	$ 0	$ 0