Note 4 - Revenue Recognition (Details Textual) - Vessel [Member] - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2025	Dec. 31, 2024
Contract with Customer, Liability, Revenue Recognized	$ 7.8
Prepaid Expenses and Other Current Assets [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Current	0.4	$ 1.1
Other Assets [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Current	1.0	0.6
Accounts Payable and Accrued Liabilities [Member]
Contract with Customer, Liability, Current	6.1	9.4
Other Liabilities [Member]
Contract with Customer, Liability, Current	$ 4.0	$ 2.1

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-11

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479837/606-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479837/606-10-45-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-8

Name:	us-gaap_ContractWithCustomerAssetNetCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant