Note 12 - Properties and Equipment, Accrued Expenses, Other Current Liabilities and Other Liabilities - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Vessels and related equipment	$ 911,242		$ 940,175
Other properties and equipment	16,868		16,861
Property, Plant and Equipment, Gross, Ending Balance	928,110		957,036
Less accumulated depreciation and amortization	218,786		176,718
Properties and equipment, net	$ 709,324	$ 780,318	$ 780,318

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment.

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