CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Amortized cost	$ 13,009,189	$ 12,634,254
Fixed maturities, available for sale, allowance for credit loss	4,631	10,759
Fixed maturities, held to maturity, fair value	629,323	675,851
Fixed maturities, held to maturity, allowance for credit loss	0	0
Equity securities, cost	547,443	543,833
Mortgage loans, held for investment, allowance for credit loss	20,681	6,220
Allowance for expected credit losses on insurance and reinsurance premium balances receivable	14,864	11,997
Allowance for expected credit losses on reinsurance recoverable for unpaid losses and loss expenses	$ 43,043	$ 36,611
Common shares, shares issued (in shares)	176,580	176,580
Common shares, shares outstanding (in shares)	84,179	85,286
Treasury shares, shares (in shares)	92,401	91,294