Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Fixed maturity securities, amortized cost	$ 18,988,459	$ 18,715,483
Fixed maturity securities, allowance for credit loss	37,249	37,466
Cumulative effect adjustment resulting from changes in accounting principles	1,609	1,791
Cumulative effect adjustment resulting from changes in accounting principles	32,353	30,660
Reinsurance recoverable, allowance for credit loss	$ 8,703	$ 8,064
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock issued (in shares)	5,000,000	5,000,000
Preferred stock outstanding (in shares)	0	0
Common stock, par value (in dollar per share)	$ 0.20	$ 0.20
Common shares authorized (in shares)		1,250,000,000
Common shares issued (in shares)	262,536,530	264,546,100
Common shares outstanding (in shares)	262,536,530	264,546,100
Treasury stock issued at cost (in shares)	266,478,098	264,468,528