Note 13 - Stockholders' Equity - Weighted Average Fair Value Assumptions (Details)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Volatility		32.29%	45.91%	37.47%
Risk-free interest rate		2.16%	2.55%	2.23%
Dividend yield		0.00%	0.00%	0.00%
Pre-vest cancellation rate	[1]	4.63%	2.68%	4.06%
Post-vest cancellation rate	[2]	2.28%	3.34%	3.45%
Suboptimal exercise factor	[3]	1.229%	1.49%	1.31%
Expected life (Year)		4 years 335 days	5 years 335 days	4 years 80 days

[1] The pre-vest cancellation rate was calculated on an annual basis and is presented here on an annual basis.

[2] The post-vest cancellation rate was calculated on a monthly basis and is presented here on an annual basis.

[3] The ratio of the stock price to strike price at the time of exercise of the option.