Note 3 - Revenue Recognition (Details Textual) - Vessel [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Contract with Customer, Liability, Revenue Recognized	$ 3.8
Other Current Assets [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Current	1.1
Other Assets [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Current	0.6	$ 2.9
Other Current Liabilities [Member]
Contract with Customer, Liability, Current	9.4
Other Liabilities [Member]
Contract with Customer, Liability, Current	$ 2.1	1.8
Prepaid Expenses and Other Current Assets [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Current		5.4
Accounts Payable and Accrued Liabilities [Member]
Contract with Customer, Liability, Current		$ 5.0