Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Fixed-maturities available for sale, amortized cost	$ 5,685,122	$ 5,587,261
Trading securities amortized cost	111,226	122,472
Equity securities, cost	141,929	162,899
Reinvested cash collateral held under securities lending agreements	72,023	99,735
Reinsurance recoverables, paid losses	$ 18	$ 18
Common stock, par or stated value per share (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	485,000	485,000
Common stock, shares, issued (in shares)	177,386	176,509
Common stock, shares, outstanding (in shares)	157,350	157,056
Treasury stock (in shares)	20,036	19,453