Note 2 - Vessel Acquisitions and Dispositions (Details) - Vessels Under Construction as of October 22, 2013 (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 ft T hp
Significant Acquisitions and Disposals [Line Items]
Expected Delivery	Q2 2014
Length (feet)	271
BHP (in Horsepower)	9,990
DWT (in US Ton)	3,600
Expected Cost (in Dollars)	$ 36.0
Rosetti Marino [Member] | North Sea [Member] | Large Platform Supply Vessel Five [Member]
Significant Acquisitions and Disposals [Line Items]
Expected Delivery	Q1 2014
Length (feet)	246
BHP (in Horsepower)	8,457	[1]
DWT (in US Ton)	3,000	[2]
Expected Cost (in Dollars)	31.0
Simek [Member] | North Sea [Member] | Large Platform Supply Vessel Seven [Member]
Significant Acquisitions and Disposals [Line Items]
Expected Delivery	Q1 2014
Length (feet)	304
BHP (in Horsepower)	11,935	[1]
DWT (in US Ton)	4,700	[2]
Expected Cost (in Dollars)	60.0
Thoma Sea [Member] | Americas [Member] | Large Platform Supply Vessel Eight [Member]
Significant Acquisitions and Disposals [Line Items]
Expected Delivery	Q1 2014
Length (feet)	271
BHP (in Horsepower)	9,990	[1]
DWT (in US Ton)	3,600	[2]
Expected Cost (in Dollars)	36.0
Bae Systems [Member] | Americas [Member] | Large Platform Supply Vessel Ten [Member]
Significant Acquisitions and Disposals [Line Items]
Expected Delivery	Q4 2014
Length (feet)	286
BHP (in Horsepower)	10,960	[1]
DWT (in US Ton)	5,300	[2]
Expected Cost (in Dollars)	48.0
Bae Systems [Member] | Americas [Member] | Large Platform Supply Vessel Eleven [Member]
Significant Acquisitions and Disposals [Line Items]
Expected Delivery	Q2 2015
Length (feet)	286
BHP (in Horsepower)	10,960	[1]
DWT (in US Ton)	5,300	[2]
Expected Cost (in Dollars)	$ 48.0

[1] BHP - Brake Horsepower

[2] DWT - Deadweight Tons