Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Fixed income securities, amortized cost	$ 2,041
Short-term investments, amortized cost	507	$ 415
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Uncollectable premium receivables	5	9
Reinsurance Recoverable, Allowance for Credit Loss	$ 0	$ 0
Preferred stock, par value	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred Stock, Shares Outstanding	0	0
Common stock, shares authorized	130,000,000	130,000,000
Common stock, shares issued	46,658,990	46,477,068
Common Stock, Shares, Outstanding	44,973,757
Treasury stock, shares	1,685,233	172,929
Fixed Income Securities [Member]
Fixed income securities, amortized cost	$ 1,469	$ 1,605
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Equity investments in pooled funds [Member]
Other Investment Not Readily Marketable, Fair Value	556	683
Collateral Pledged [Member]
Short-term investments, amortized cost	64	105
Collateral Pledged [Member] | Fixed Income Securities [Member]
Fixed income securities, amortized cost	0	15
Short-term Investments [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Short-term Investments [Member] | Collateral Pledged [Member] | Fixed Income Securities [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Variable Interest Entity, Primary Beneficiary [Member]
Long-term Debt	2,788	4,056
Parent Company [Member]
Fixed income securities, amortized cost	13	130
Short-term investments, amortized cost	175	124
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	3
Parent Company [Member] | Short-term Investments [Member]
Fixed income securities, amortized cost	$ 175	$ 124