Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Trade accounts receivable, allowance	$ 167	$ 135
Inventory allowance	2,495	946
Accumulated depreciation	4,234	4,155
Accumulated amortization	$ 13,190	$ 11,900
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	325,000,000	325,000,000
Common stock, issued (in shares)	28,552,886	28,406,856
Common stock, outstanding (in shares)	28,552,886	28,406,856