Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Statement of Financial Position [Abstract]
Fixed maturity securities, amortized cost	$ 24,050,085	$ 23,010,899
Fixed maturity securities, allowance for credit loss	353	671
Cumulative effect adjustment resulting from changes in accounting principles	788	1,114
Cumulative effect adjustment resulting from changes in accounting principles	38,861	39,884
Reinsurance recoverable, allowance for credit loss	$ 7,084	$ 8,350
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)	379,312,871	380,066,070
Common shares outstanding (in shares)	379,312,871	380,066,070
Treasury stock issued at cost (in shares)	414,208,938	413,455,739