Note 9 - Commitments and Contingencies (Details Textual) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2020
Loss Contingency Accrual, Provision	$ 1,150
Accounts Receivable, Credit Loss Expense (Reversal)	$ 499	$ (619)	$ (1,026)
Standard Product Warranty Accrual, Period Increase (Decrease), Total		0	0
Standard Product Warranty Accrual, Ending Balance		159	159
Performance Guarantees [Member]
Debt Instrument, Face Amount		0
Standby Letters of Credit [Member] | Cash Collateral Security Agreement [Member]
Letters of Credit Outstanding, Amount		1,104
Receivables [Member]
Loss Contingency, Receivable, Ending Balance				$ 2,589
Failure of Equipment to Be Remedied Under Warranty Provision [Member] | Other Accrued Liabilities [Member]
Loss Contingency Accrual, Ending Balance		$ 0	$ 176