Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Fixed maturity securities, amortized cost	$ 23,003,148	$ 20,915,245
Fixed maturity securities, allowance for credit loss	6,983	36,751
Cumulative effect adjustment resulting from changes in accounting principles	1,425	3,004
Cumulative effect adjustment resulting from changes in accounting principles	38,071	35,110
Reinsurance recoverable, allowance for credit loss	$ 8,332	$ 8,404
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)	381,189,906	384,817,136
Common shares outstanding (in shares)	381,189,906	384,817,136
Treasury stock issued at cost (in shares)	412,331,903	408,704,807