Note 13 - Segment Reporting - Summary of Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Balance at beginning of period	$ 132	$ 168
Charged to (recovered) costs and expenses	(1)	(36)
Balance at end of period	$ 131	$ 132