Consolidated Statements of Financial Condition (Unaudited) (Parenthetical) $ in Thousands	Sep. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares
ASSETS:
Held to maturity securities, fair value | $	$ 11,646	$ 14,988
SHAREHOLDERS' EQUITY:
Capital stock, par value (in dollars per share) | $ / shares	$ 1	$ 1
Capital stock, shares authorized (in shares)	30,000,000	30,000,000
Capital stock, shares issued (in shares)	20,041,796	20,040,966
Capital stock, shares outstanding (in shares)	19,216,101	19,286,531
Treasury stock, at cost (in shares)	825,695	754,435