Note 2 - Revenue Recognition (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue from Contract with Customer, Excluding Assessed Tax	$ 9,732,000	$ 9,972,000
Contract with Customer, Asset, Credit Loss Expense (Reversal)	0	0
Capitalized Contract Cost, Amortization	4,000	22,000
Capitalized Contract Cost, Impairment Loss	0	0
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	9,300,000	8,800,000
Transferred over Time [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 400,000	$ 1,200,000