Note 2 - Summary of Significant Accounting Policies - Valuation Assumptions (Details)		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019
Dividend yield	[1]	0.00%	0.00%
Expected volatility	[2]	28.61%	28.81%
Expected life (Year)	[3]	6 years 3 months	6 years 3 months
Assumed forfeiture rate	[4]	5.00%	4.00%
Minimum [Member]
Risk-free interest rate	[5]	0.36%	1.42%
Maximum [Member]
Risk-free interest rate	[5]	1.22%	2.78%

[1] A dividend yield of 0.0% is utilized because cash dividends have never been paid.

[2] The expected volatility was based on the historical volatility of the Company’s common stock price as adjusted for certain historical periods of extraordinary volatility in order to estimate expected volatility.

[3] The expected life reflects an 8 month to 4 year vesting period, the maximum ten year term and review of historical behavior.

[4] Forfeiture rate is determined through forfeited and expired options as a percentage of options granted over the current three year period.

[5] The risk-free interest rate is based on the five to seven year Treasury bond.