Consolidated Balance Sheets (Parentheticals) - USD ($) $ / shares in Thousands, $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Securities available for sale, amortized cost	$ 577,406	$ 571,936
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, authorized (in shares)	1,000,000	1,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, authorized (in shares)	40,000,000	40,000,000
Common stock, issued (in shares)	22,679,362	22,617,098
Common stock, outstanding (in shares)	22,679,362	22,617,098