Note 5 - Debt - Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Long-term debt	$ 134,156		$ 489,797
Debt Premium			423
Debt Issuance Costs Associated with the Senior Notes			(6,894)
Total	134,156		483,326
Multicurrency Credit Facility [Member]
Long-term debt	72,000		49,000
Norwegian Facility [Member]
Long-term debt	45,156		11,157
Senior Note Due 2022 [Member]
Long-term debt			429,640	$ 479,000	$ 499,000
Debt Premium		$ 400
Debt Issuance Costs Associated with the Senior Notes		$ (6,700)
Debtor-in-Possession, Norwegian Facility Agreement [Member]
Long-term debt	$ 17,000