Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ / shares in Thousands, $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Available for sale debt securities, amortized cost	$ 675,478	$ 574,722
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	22,781,000	22,692,000
Common stock, shares outstanding (in shares)	22,781,000	22,692,000