Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Statement of Financial Position [Abstract]
Held-to-maturity securities, at fair value	$ 242,804	$ 249,618	$ 280,414
Preferred Stock, par value (in dollars per share)	$ 1	$ 1	$ 5
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	20,000,000
Common Stock, shares issued (in shares)	19,606,449	19,606,449	19,035,565
Unallocated ESOP Shares (in shares)	0	0	5,501
Treasury Stock (in shares)	4,624,348	4,608,258	4,556,083