Note 8 - Operating Segment Information - Operating Income (Loss) by Operating Segment (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
North Sea Segment [Member]
Revenue	$ 21,077,000	$ 36,578,000	$ 44,009,000	$ 76,778,000
Direct operating expenses	12,328,000	22,845,000	26,019,000	47,010,000
Drydock expense	36,000	32,000	873,000	2,965,000
General and administrative expenses	1,832,000	2,579,000	3,961,000	4,641,000
Depreciation and amortization expense	6,532,000	7,335,000	13,089,000	14,557,000
Impairment charges			1,986,000
(Gain) loss on sale of assets	5,923,000		5,923,000
Operating income (loss)	(5,574,000)	3,787,000	(7,842,000)	7,605,000
June 30, 2016	541,350,000		541,350,000		$ 589,934,000
Southeast Asia Segment [Member]
Revenue	4,382,000	10,989,000	6,869,000	24,318,000
Direct operating expenses	3,295,000	4,947,000	6,252,000	9,130,000
Drydock expense	27,000	906,000	17,000	1,565,000
General and administrative expenses	834,000	1,265,000	1,707,000	2,388,000
Depreciation and amortization expense	2,346,000	2,605,000	4,947,000	5,199,000
Impairment charges	30,268,000		50,437,000
(Gain) loss on sale of assets
Operating income (loss)	(32,388,000)	1,266,000	(56,491,000)	6,036,000
June 30, 2016	174,006,000		174,006,000		232,356,000
Americas Segment [Member]
Revenue	5,028,000	26,894,000	18,403,000	62,457,000
Direct operating expenses	5,309,000	18,154,000	12,396,000	41,031,000
Drydock expense		1,498,000		6,879,000
General and administrative expenses	1,667,000	2,359,000	3,698,000	5,115,000
Depreciation and amortization expense	5,150,000	7,941,000	11,118,000	15,787,000
Impairment charges	15,883,000		110,385,000
(Gain) loss on sale of assets	(9,000)		(5,000)
Operating income (loss)	(22,972,000)	(3,058,000)	(119,189,000)	(6,355,000)
June 30, 2016	405,802,000		405,802,000		529,654,000
Other Segments [Member]
Revenue
Direct operating expenses
Drydock expense
General and administrative expenses	4,521,000	5,318,000	9,276,000	10,341,000
Depreciation and amortization expense	883,000	884,000	1,796,000	1,710,000
Impairment charges
(Gain) loss on sale of assets
Operating income (loss)	(5,404,000)	(6,202,000)	(11,072,000)	(12,051,000)
June 30, 2016	6,141,000		6,141,000		9,308,000
Revenue	30,487,000	74,461,000	69,281,000	163,553,000
Direct operating expenses	20,932,000	45,946,000	44,667,000	97,171,000
Drydock expense	63,000	2,436,000	890,000	11,409,000
General and administrative expenses	8,854,000	11,521,000	18,642,000	22,485,000
Depreciation and amortization expense	14,911,000	18,765,000	30,950,000	37,253,000
Impairment charges	46,151,000		162,808,000
(Gain) loss on sale of assets	5,914,000		5,918,000
Operating income (loss)	(66,338,000)	$ (4,207,000)	(194,594,000)	$ (4,765,000)
June 30, 2016	$ 1,127,299,000		$ 1,127,299,000		$ 1,361,252,000