Note 15 - Asset Dispositions, Assets Held for Sale and Asset Impairments (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2021
Number of Vessels, Held for Sale, Addition			1
Number Of Vessels Sold Or Scrapped			9
Number of Vessels, Held for Sale, Reactivation			1
Number of Vessels, Held for Sale			9		18
Asset Held For Sale, Net Book Value			$ 6,900
Number of Active Vessels Sold			0	5
Number of Vessels, Held for Sale, Sold				8
Proceeds from Sale of Vessels			$ 8,200	$ 29,400
Gain (Loss) on Sale of Assets and Asset Impairment Charges			(1,100)	(2,900)
Proceeds from Sale of Productive Assets, Total			8,163	29,560
Impairment Charge Recaptured	$ 500
Impairment of Long-Lived Assets to be Disposed of			$ 0	$ 0
Third-party Operator, Family Member of Director [Member]
Gain (Loss) on Sale of Assets and Asset Impairment Charges		$ 4,300
Proceeds from Sale of Productive Assets, Total		$ 11,400