Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	$ 1,007,834	$ 1,187,499
Preferred Stock, Shares Authorized	200,000	200,000
Preferred Stock, Shares Issued	0	0
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	20,000,000	20,000,000
Common Stock, Shares, Issued	17,623,163	17,623,199
Treasury Stock, Shares	1,308,966	1,276,757