Note 6 - Note Payable - Summary of Note Payable (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	[1]
2017 (remaining 3 months)	$ 441
2018	1,793
2019	1,867
2020	1,949
2021	11,204
Thereafter	17,154
Total payments	34,408
Less: Amount representing interest	(14,123)
Present value of obligations	20,285
Less: Unamortized debt discount	(1,620)
Note payable, noncurrent portion	$ 18,665	$ 7,762

[1] The condensed consolidated balance sheet as of December 31, 2016 has been derived from the audited consolidated financial statements as of that date.