Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale, Amortized Cost	$ 2,100	$ 2,041
Debt Securities, Available-for-sale, Allowance for Credit Loss	2	0
Premium Receivable, Allowance for Credit Loss	$ 4	$ 5
Preferred stock, par value	$ 0.01
Preferred stock, shares authorized	20,000,000
Preferred Stock, Shares Issued	0	0
Common stock, par value	$ 0.01
Common stock, shares authorized	130,000,000
Common stock, shares issued	46,659,144	46,658,990
Common stock, shares outstanding	45,187,327
Equity investments in pooled funds [Member]
Other Investment Not Readily Marketable, Fair Value	$ 449	$ 556
Variable Interest Entity, Primary Beneficiary [Member]
Long-term debt	$ 2,535	$ 2,788