Note 2 - Vessel Acquisitions and Dispositions (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended			3 Months Ended		1 Months Ended		9 Months Ended	1 Months Ended
	Jan. 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2011 North Sea [Member]	Sep. 30, 2011 Simek [Member]	Jul. 31, 2012 US Gulf of Mexico [Member]	Jun. 30, 2012 US Gulf of Mexico [Member]	Sep. 30, 2012 Thoma Sea [Member]	Aug. 31, 2013 North Sea [Member]	Sep. 30, 2013 Americas [Member]
Note 2 - Vessel Acquisitions and Dispositions (Details) [Line Items]
Proceeds from Sale of Property Held-for-sale	$ 700,000
Number of Vessels Sold		3										2	1
Proceeds from Sale of Property, Plant, and Equipment				13,500,000	40,565,000							10,800,000	2,100,000
Gain (Loss) on Disposition of Assets		6,000,000
Interest Costs Capitalized		4,200,000	1,600,000	10,700,000	3,400,000
Number Of Shipyards Use In Agreements							3
Number Of Vessels Expected To Operate							6			2
Estimated Cost Of Building Vessels							228,000,000			72,000,000
Estimated Cost Of Additional Vessel								60,000,000	96,000,000
Number Of Vessels Under Construction									2		2
Increase (Decrease) in Restricted Cash											52,400,000
Escrow Deposit		$ 19,624,000		$ 19,624,000		$ 47,028,000