Note 4 - Long-term Debt - Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Senior Note Due 2022 [Member]
Long-term Debt, Gross	$ 429,640	$ 499,000
Multicurrency Credit Facility [Member]
Long-term Debt, Gross	28,000
Norwegian Facility [Member]
Long-term Debt, Gross	11,194
Long-term Debt, Gross	468,834	499,000
Debt Premium Associated with the Senior Notes	480	607
Debt Issuance Costs Associated with the Senior Notes	(7,400)	(9,018)
Total	$ 461,914	$ 490,589