Note 2 - Vessel Acquisitions and Dispositions (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended			3 Months Ended		1 Months Ended		3 Months Ended	9 Months Ended
	Jan. 31, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 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]	Mar. 31, 2013 US Gulf of Mexico [Member]	Sep. 30, 2012 Thoma Sea [Member]
Note 2 - Vessel Acquisitions and Dispositions (Details) [Line Items]
Proceeds from Sale of Property Held-for-sale	$ 700,000
Interest Costs Capitalized		3,700,000	1,000,000	6,400,000	1,800,000
Number Of Shipyards Use In Agreements							3
Number Of Vessels Expected To Operate							6				4
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
Increase (Decrease) in Restricted Cash												52,400,000
Escrow Deposit		$ 32,258,000		$ 32,258,000		$ 47,028,000