Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 1,531	$ 1,545
Accumulated depreciation	26,159	25,938
Accumulated amortization	$ 1,993	$ 1,939
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	24,821,446	24,777,001
Common stock outstanding (in shares)	24,167,679	24,132,910