Note 2 - Vessel Acquisitions and Dispositions (Details Textual) $ in Thousands, kr in Millions	1 Months Ended	3 Months Ended				6 Months Ended
	Mar. 31, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 NOK (kr)	Mar. 31, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)
Interest Costs Capitalized							$ 100
Number of Vessels Under Construction		0				0
Number of Vessel Sold						0
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property		$ 228				$ 203
Number Of Vessels Delivered1						0
Predecessor [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property			$ 32				(5,241)
North Sea [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property		$ 243				$ 243
North Sea [Member] | Predecessor [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property
Platform Supply Vessel[ Member] | North Sea [Member]
Payments for Installment on Vessel Contracts				kr 195	$ 23,100
Fast Supply Vessels [Member] | Predecessor [Member]
Number of Vessel Sold	2
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property	$ (5,300)