Note 10 - Non-recourse Long-term Debt, Net - Summary of Royalty-backed Loan (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Current portion of debt, net	$ 6,064		$ 5,419
Long-term debt, net	37,568		39,180
Royalty-backed Loan [Member]
Outstanding principal balance, current portion	6,326		5,688
Unamortized debt discount, current portion	(262)		(269)
Current portion of debt, net	6,064		5,419
Outstanding principal balance, long-term portion	37,999		39,674
Unamortized debt discount, long-term portion	(431)		(494)
Long-term debt, net	37,568		$ 39,180
Interest expense	1,077	$ 1,205
Non-cash interest expense	71	63
Total interest expense included in interest (expense) income, net	$ 1,148	$ 1,268