Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accounts receivable, allowance for doubtful accounts	$ 24	$ 10
Inventory, allowance for excess and obsolete inventory and lower of cost or estimated net realizable value adjustments	$ 110	$ 104
Preferred stock, shares authorized (in shares)	5,000	5,000
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	50,000	240,000
Common stock, shares issued (in shares)	17,095	17,089
Common stock, shares outstanding (in shares)	17,095	17,089