Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Fixed-maturities available for sale, amortized cost	$ 5,683,372	$ 5,587,261
Trading securities amortized cost	110,676	122,472
Equity securities, cost	113,248	162,899
Reinvested cash collateral held under securities lending agreements	119,197	99,735
Reinsurance recoverables, paid losses	$ 68	$ 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)	175,636	176,509
Common stock, shares, outstanding (in shares)	155,582	157,056
Treasury stock (in shares)	20,054	19,453