Note 3 - Revenue (Details Textual) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Other Current Liabilities [Member] | Maintenance [Member]
Contract with Customer, Liability, Current	$ 8.4	$ 7.7
Other Liabilities [Member] | Maintenance [Member]
Contract with Customer, Liability, Noncurrent	$ 3.3	$ 3.5
Short-Term Contract with Customer [Member]
Standard Prepaid Maintenance Contract Time Period (Month)	12 months
Long-Term Contract with Customer [Member]
Standard Prepaid Maintenance Contract Time Period (Month)	60 months