Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) shares in Thousands, $ / shares in Thousands, $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt securities held to maturity, allowance for credit losses	$ 1	$ 1
Debt securities held to maturity, fair value	$ 818,395	$ 873,511
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, authorized (in shares)	150,000	150,000
Common stock, issued (in shares)	26,649	26,913
Common stock, outstanding (in shares)	26,649	26,913