Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Available-for-sale, amortized cost	$ 546,852	$ 428,495
Equity securities, cost	$ 13,705	$ 12,784
Common stock, par value (in dollars per share)	$ 0.625	$ 0.625
Common stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, shares issued (in shares)	3,746,606	3,725,202
Common stock, shares outstanding (in shares)	3,559,546	3,556,533
Treasury stock, shares (in shares)	187,060	168,669