Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Fixed maturity securities, amortized cost	$ 18,467,661	$ 16,471,304
Fixed maturity securities, allowance for credit loss	34,716	22,625
Cumulative effect adjustment resulting from changes in accounting principles	1,992	1,718
Cumulative effect adjustment resulting from changes in accounting principles	30,578	25,218
Reinsurance recoverable, allowance for credit loss	$ 7,999	$ 7,713
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	750,000,000
Common shares issued (in shares)	265,801,717	265,170,882
Common shares outstanding (in shares)	265,801,717	265,170,882
Treasury stock issued at cost (in shares)	263,212,911	263,843,868