Note 3 - Summary of Significant Accounting Policies (Details Textual)	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) shares	Jun. 30, 2021 shares	Jun. 30, 2022 USD ($) shares	Jun. 30, 2021 shares	Dec. 31, 2021 USD ($)
Number of Operating Segments			2
Short-Term Investments, Total	$ 10.7		$ 10.7		$ 13,900,000
Accounts Receivable, Allowance for Credit Loss, Ending Balance	10,000		10,000		10,000
Unrecognized Tax Benefits, Ending Balance	$ 0		0		$ 0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total			$ 0
Open Tax Year			2018 2019 2020 2021
Weighted Average Number of Shares Outstanding, Basic, Total (in shares) | shares	70,356,796	69,220,795	70,585,590	68,286,033
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares	8,166,380			8,015,193