CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Available for sale debt securities, amortized cost	$ 1,049,044	$ 881,570
Available for sale debt securities, allowance for credit losses	$ 0	$ 0
Common stock, par value	$ 0.0625	$ 0.0625
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	17,363,457	17,363,457
Common stock, shares outstanding	17,320,449	17,265,337
Treasury stock, shares	43,008	98,120