Note 2 - Impairment Charges (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2016	Mar. 31, 2016
U.S. Gulf of Mexico and Southeast Asia [Member]
Impairment of Long-Lived Assets Held-for-use	$ 46.2	$ 114.1
U.S Gulf of Mexico [Member] | Americas Segment [Member]
Impairment of Long-Lived Assets Held-for-use		94.5
Americas Segment [Member]
Impairment of Long-Lived Assets Held-for-use	15.9
Southeast Asia Segment [Member]
Impairment of Long-Lived Assets Held-for-use	$ 30.3
Southeast Asia Segment [Member] | Vessel Component [Member]
Impairment of Long-Lived Assets to be Disposed of		0.6
Southeast Asia Segment [Member]
Impairment of Long-Lived Assets Held-for-use		19.6
North Sea and Southeast Asia Segments [Member] | Vessel Component [Member]
Impairment of Long-Lived Assets to be Disposed of		2.6
North Sea Segment [Member] | Vessel Component [Member]
Impairment of Long-Lived Assets to be Disposed of		$ 2.0