Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Statement of Financial Position [Abstract]
Held-to-maturity securities, at fair value	$ 241,875	$ 249,618	$ 266,068
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)	19,606,449	19,606,449	19,035,565
Unallocated ESOP Shares (in shares)	0	0	5,001
Treasury Stock (in shares)	4,595,891	4,608,258	4,517,412