Note 13 - Equity-based Compensation - Summary of Stock-based Compensation Expense Included in Results of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-based compensation expense	$ 486	$ 671	$ 2,542
Research and Development Expense [Member]
Stock-based compensation expense	42	32	113
Selling and Marketing Expense [Member]
Stock-based compensation expense	93	141	152
General and Administrative Expense [Member]
Stock-based compensation expense	$ 351	$ 498	$ 2,277