Note 7 - Assets Held for Sale, Asset Sales and Asset Impairments - Summary of Vessel Sales and Gains on Sales of Vessels (Details) $ in Thousands	12 Months Ended
Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Vessels sold from active fleet	10	3
Gain on sale of vessels	$ (2,901)	$ 7,591	$ 2,263
Vessels sold from assets held for sale		53
Total vessels sold	9
Vessels Held for Sale [Member]
Gain on sale of vessels	$ (6,209)	$ 6,384	$ 0
Vessels sold from assets held for sale	9	53	(0)
Vessels, Active Fleet [Member]
Vessels sold from active fleet	10	3	40
Gain on sale of vessels	$ 3,499	$ 1,217	$ 2,434
Vessel [Member]
Gain on sale of vessels	$ (2,710)	$ 7,601	$ 2,434
Total vessels sold	19	56	40

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123351718&loc=d3e2443-110228

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2941-110230

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