Note 8 - Operating Segment Information - Operating Income (Loss) by Operating Segment (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
North Sea Segment [Member]
Revenue	$ 22,932,000	$ 40,200,000
Direct operating expenses	13,691,000	24,165,000
Drydock expense	837,000	2,933,000
General and administrative	2,129,000	2,062,000
Depreciation expense	6,557,000	7,222,000
Impairment charges	$ 1,986,000
Loss on sale of assets
Operating income (loss)	$ (2,268,000)	3,818,000
March 31, 2016	582,354,000		$ 589,934,000
Southeast Asia Segment [Member]
Revenue	2,487,000	13,329,000
Direct operating expenses	2,957,000	4,183,000
Drydock expense	(10,000)	659,000
General and administrative	873,000	1,123,000
Depreciation expense	2,601,000	2,594,000
Impairment charges	$ 20,169,000
Loss on sale of assets
Operating income (loss)	$ (24,103,000)	4,770,000
March 31, 2016	206,981,000		232,356,000
Americas Segment [Member]
Revenue	13,375,000	35,563,000
Direct operating expenses	$ 7,087,000	22,877,000
Drydock expense		5,381,000
General and administrative	$ 2,031,000	2,756,000
Depreciation expense	5,968,000	7,846,000
Impairment charges	94,502,000
Loss on sale of assets	4,000
Operating income (loss)	(96,217,000)	$ (3,297,000)
March 31, 2016	$ 428,104,000		529,654,000
Other Segments [Member]
Revenue
Direct operating expenses
Drydock expense
General and administrative	$ 4,755,000	$ 5,023,000
Depreciation expense	$ 913,000	826,000
Impairment charges
Loss on sale of assets
Operating income (loss)	$ (5,668,000)	(5,849,000)
March 31, 2016	6,530,000		9,308,000
Revenue	38,794,000	89,092,000
Direct operating expenses	23,735,000	51,225,000
Drydock expense	827,000	8,973,000
General and administrative	9,788,000	10,964,000
Depreciation expense	16,039,000	$ 18,488,000
Impairment charges	116,657,000
Loss on sale of assets	4,000
Operating income (loss)	(128,256,000)	$ (558,000)
March 31, 2016	$ 1,223,969,000		$ 1,361,252,000