Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Equity securities, cost	$ 2,352,925	$ 2,552,722
Debt securities, amortized cost	15,694,482	15,727,143
Allowance for credit losses	$ 8,679	$ 502
Common stock, Shares authorized	22,000,000	22,000,000
Common stock, Shares issued	17,459,961	17,459,961
Treasury stock, shares	4,004,507	3,861,426