Note 8 - Assets Held for Sale, Asset Sales and Asset Impairments (Details Textual) $ in Thousands	3 Months Ended		12 Months Ended
	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019
Number of Vessels, Held for Sale, Addition			3	7	32	46
Number of Vessels, Held for Sale, Sold					53
Number of Vessels, Transfer from Held for Sale to Active Fleet			1	3	2
Number of Vessels, Held for Sale		23	8	18	23
Number of Active Vessels Sold				10	3
Number of Vessels Sold			12	9
Proceeds from Sale of Productive Assets, Total			$ 13,568	$ 34,010	$ 38,296
Proceeds from Sale of Vessels and Other Assets			13,600	34,000	38,300
Impairment of Long-Lived Assets to be Disposed of				13,700	75,200
Impairment Charge Recaptured			500	1,700	1,000
Asset Impairment Charges, Total			714	15,643	74,109
Expense Recovered on contract to Shipyard		$ 4,000
Vessel, Obsolete Inventory [Member]
Asset Impairment Charges, Total			$ 1,214	$ 1,905	$ 2,959
Third-party Operator, Family Member of Director [Member]
Proceeds from Sale of Productive Assets, Total	$ 11,400
Gain (Loss) on Sale of Assets and Asset Impairment Charges	$ 4,300