Note 16 - Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020
Expected life	10 years
Minimum
Vesting period	3 years
Maximum
Vesting period	7 years
2010 Equity Incentive Plan [Member]
Shares of common stock authorized	350,000
The 2013 Equity Incentive Plan [Member]
Shares of common stock authorized	350,000
The 2016 Equity Incentive Plan [Member]
Shares of common stock authorized	400,000
Remaining shares of common stock available for grant	170,833
Employee Stock Purchase Plan
Remaining shares of common stock available for grant				89,582
Maximum amount any one participant can elect in an offering period	$ 10
Maximum amount any one participant can contribute (as a percent)	15.00%	15.00%	10.00%