Note 9 - Non-recourse Long-term Debt, Net - Summary of Royalty-backed Loan (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Current portion of debt, net	$ 4,766		$ 4,766		$ 2,445
Long-term debt, net	42,878		42,878		47,242
Royalty-backed Loan [Member]
Outstanding principal balance, current portion	5,044		5,044		2,686
Unamortized debt discount, current portion	(278)		(278)		(241)
Current portion of debt, net	4,766		4,766		2,445
Outstanding principal balance, long-term portion	43,528		43,528		48,066
Unamortized debt discount, long-term portion	(650)		(650)		(824)
Long-term debt, net	42,878		42,878		$ 47,242
Interest expense	1,176	$ 1,205	2,381	$ 2,398
Non-cash interest expense	74	61	137	122
Total interest expense included in interest (expense) income, net	$ 1,250	$ 1,266	$ 2,518	$ 2,520