Note 8 - Revenues From Contracts With Customers and Other Revenue (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Revenue from Contract with Customer, Including Assessed Tax	$ 533	$ 5,463	$ 24,453
Contract with Customer, Asset, after Allowance for Credit Loss, Total	$ 0	0
Accounts Receivable, Allowance for Credit Loss, Ending Balance		0
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Number of Major Customers	1
Customer Concentration Risk [Member] | Accounts Receivable [Member] | One Customer [Member[
Concentration Risk, Percentage	27.00%
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 533	5,310	24,453
Transferred at Point in Time [Member] | Variable Consideration or Multiple Performance Obligations [Member]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0
Revenue, Remaining Performance Obligation, Amount	0	0
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	0	153	0
Transferred over Time [Member] | Variable Consideration or Multiple Performance Obligations [Member]
Revenue from Contract with Customer, Including Assessed Tax	0	0	$ 0
Revenue, Remaining Performance Obligation, Amount	$ 0	$ 0