Note 4 - Vessel Acquisitions and Dispositions - Vessel Additions (Details) - North Sea [Member] - Vessel [Member] - North Barent [Member]	6 Months Ended
	Jun. 30, 2017 Boe T
Vessels Additions, Year Built	2017
Vessels Additions, Length	304
Vessels Additions, Brake Horsepower (Barrel of Oil Equivalent) | Boe	11,935	[1]
Vessels Additions, Deadweight Tons (US Ton) | T	4,700	[2]
Vessels Additions, Month Delivered	Jan-17

[1] BHP - Brake Horsepower

[2] DWT - Deadweight Tons