Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Trade receivables, allowance for doubtful accounts	$ 341	$ 304
Common stock par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	33,927,595	33,528,915
Treasury stock, at cost (in shares)	1,583,909	1,729,727