Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale, Amortized Cost	$ 2,005
Debt Securities, Available-for-sale, Allowance for Credit Loss	1	$ 0
Premium Receivable, Allowance for Credit Loss	$ 8	$ 9
Preferred stock, par value	$ 0.01
Preferred stock, shares authorized	20,000,000
Preferred Stock, Shares Issued	0
Common stock, par value	$ 0.01
Common stock, shares authorized	130,000,000
Common stock, shares issued	46,658,990	46,477,068
Common stock, shares outstanding	46,545,232
Treasury stock, shares	113,758	172,929
Equity investments in pooled funds [Member]
Other Investment Not Readily Marketable, Fair Value	$ 652	$ 683
Variable Interest Entity, Primary Beneficiary [Member]
Long-term debt	$ 3,701	$ 4,056