Note 15 - Asset Dispositions, Asset Held for Sale and Asset Impairments - Activity in Assets Held for Sale (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Beginning balance			23	46	46
Additions			2		32
Sales			(9)		(53)
Transfers	(1)	0	(2)	0
Transfers	$ (250)	$ 0	$ (3,250)	$ 0
Ending balance	14		14		23
Vessels Held for Sale [Member]
Beginning balance	14	46	23	46	46
Beginning balance	$ 17,214	$ 29,064	$ 34,396	$ 39,287	$ 39,287
Additions	2	0	2	22
Additions	$ 4,089	$ 0	$ 4,089	$ 65,812
Sales	(1)	(22)	(9)	(44)
Sales	$ (1,250)	$ (9,901)	$ (15,432)	$ (20,247)
Impairment	$ (1,912)	$ 0	$ (1,912)	$ (65,689)
Ending balance	14	24	14	24	23
Ending balance	$ 17,891	$ 19,163	$ 17,891	$ 19,163	$ 34,396