Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Statement of Financial Position [Abstract]
Held-to-maturity securities, at fair value	$ 203,936	$ 226,576	$ 233,501
Preferred Stock, par value (in dollars per share)	$ 1	$ 1	$ 1
Preferred Stock, shares authorized (in shares)	1,000,000	1,000,000	1,000,000
Common Stock, par value (in dollars per share)	$ 1	$ 1	$ 1
Common Stock, shares authorized (in shares)	30,000,000	30,000,000	30,000,000
Common Stock, shares issued (in shares)	20,800,144	20,194,474	20,194,474
Treasury Stock (in shares)	4,780,496	4,678,736	4,705,102