Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Available-for-sale, amortized cost	$ 385,736	$ 396,168
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)	3,612,677	3,576,270
Common stock, shares outstanding (in shares)	3,448,108	3,411,701
Treasury stock, shares (in shares)	164,569	164,569