Note 8 - Assets Held for Sale, Asset Sales and Asset Impairments - Activity in Assets Held for Sale (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Beginning balance	8	18
Additions		3	7	88
Impairment			$ 13,700
Ending balance	0	8	18
Vessels Held for Sale [Member]
Beginning balance	8	18	23
Beginning balance	$ 4,195	$ 14,421	$ 34,396
Additions	0	3	7
Additions	$ 0	$ 2,561	$ 18,096
Sales	(8)	(12)	(9)
Sales	$ (4,195)	$ (11,287)	$ (15,433)
Reactivation	0	(1)	(3)
Reactivation	$ 0	$ (1,500)	$ (7,250)
Impairment	$ 0	$ 0	$ (15,388)
Ending balance	0	8	18	23
Ending balance	$ 0	$ 4,195	$ 14,421	$ 34,396