Note 2 - Summary of Significant Accounting Policies - Cumulative Effect of Adjustments for New Accounting Pronouncements on Consolidated Balance Sheet (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Other assets		$ 195	$ 526	$ 800	$ 171
Total assets		16,630	26,977	47,463	46,834
Total accrued liabilities		2,416	4,698	6,996	6,766
Total current liabilities		4,215	6,306	10,990	10,760
Other noncurrent liabilities		498	167	1,033	634
Total liabilities		9,656	10,456	42,551	41,922
Total liabilities and stockholders' equity		$ 16,630	$ 26,977	47,463	$ 46,834
Accounting Standards Update 2016-02 [Member]
Other assets	[1]			629
Total assets	[1]			629
Total accrued liabilities	[2]			230
Total current liabilities	[2]			230
Other noncurrent liabilities	[2]			399
Total liabilities	[2]			629
Total liabilities and stockholders' equity	[2]			$ 629

[1] Represents capitalization of operating lease right-of-use assets and reclassification of deferred rent.

[2] Represents recognition of operating lease liabilities.