Note 1 - Nature of Operations and Summary of Significant Accounting Policies (Details Textual) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2025 USD ($)	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation			$ 16,870	$ (8,623)	$ 511
Highly Liquid Investments Maturity Period (Year)			3 years
Inspection Interval (Year)			5 years
Increase Of Amortization Period (Month)			30 months
Number of Vessels			208	211
Number of Vessels Under Finance Leases			2
Finance Lease, Right-of-Use Asset, after Accumulated Amortization			$ 24,147	$ 0
Wage and Sick Cost Refund, Amount			$ 12,900	$ 11,800	6,100
Marine Equipment [Member]
Property, Plant and Equipment, Salvage Value, Percentage			7.50%
Marine Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)			10 years
Marine Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)			20 years
Property, Plant and Equipment, Other Types [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)			3 years
Property, Plant and Equipment, Other Types [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)			10 years
Actively Employed Vessels [Member]
Number of Vessels			200	210
Stacked Vessels [Member]
Number of Vessels			8
Bareboat Charter Agreement [Member]
Number of Vessels				1
Number of Vessels Under Finance Leases			2
Finance Lease, Right-of-Use Asset, after Accumulated Amortization			$ 23,700
Vessel [Member]
Payments to Acquire Productive Assets			$ 4,900
Revision of Prior Period, Adjustment [Member]
Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation	$ 5,600	$ 17,300		$ 8,600	$ 500