CONDENSED CONSOLIDATED STATEMENTS OF CONDITION (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Available-for-sale securities, at amortized cost	$ 1,301,271	$ 1,293,239
Equity securities, at amortized cost	$ 934	$ 915
Common stock, par value (in dollars per share)	$ 0.10
Common stock, authorized (in shares)	25,000,000
Common stock, issued (in shares)	14,950,368	15,014,499
Treasury stock, shares (in shares)	119,092	123,956