Note 8 - Operating Income (Loss) by Operating Segment (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
North Sea [Member]
Quarter Ended June 30, 2015
Revenue	$ 36,578,000	$ 58,254,000	$ 76,778,000	$ 110,877,000
Direct operating expenses	22,845,000	29,214,000	47,010,000	55,943,000
Drydock expense	32,000	1,381,000	2,965,000	4,049,000
General and administrative expenses	2,579,000	5,762,000	4,641,000	9,254,000
Depreciation and amortization expense	7,335,000	8,434,000	14,557,000	16,257,000
Operating income (loss)	3,787,000	6,448,000	7,605,000	18,359,000
Impairment charge		7,015,000		7,015,000
South East Asia [Member]
Quarter Ended June 30, 2015
Revenue	10,989,000	17,431,000	24,318,000	35,735,000
Direct operating expenses	4,947,000	5,395,000	9,130,000	10,879,000
Drydock expense	906,000	1,940,000	1,565,000	3,493,000
General and administrative expenses	1,265,000	1,404,000	2,388,000	2,766,000
Depreciation and amortization expense	2,605,000	2,899,000	5,199,000	5,795,000
Operating income (loss)	1,266,000	5,349,000	6,036,000	12,358,000
Impairment charge		444,000		444,000
Americas [Member]
Quarter Ended June 30, 2015
Revenue	26,894,000	55,680,000	62,457,000	104,353,000
Direct operating expenses	18,154,000	25,115,000	41,031,000	49,201,000
Drydock expense	1,498,000	1,364,000	6,879,000	4,354,000
General and administrative expenses	2,359,000	3,223,000	5,115,000	6,340,000
Depreciation and amortization expense	7,941,000	7,206,000	15,787,000	14,012,000
Operating income (loss)	$ (3,058,000)	$ 18,772,000	$ (6,355,000)	$ 30,446,000
Impairment charge
Other [Member]
Quarter Ended June 30, 2015
Revenue
Direct operating expenses
Drydock expense
General and administrative expenses	$ 5,318,000	$ 7,014,000	$ 10,341,000	$ 13,532,000
Depreciation and amortization expense	884,000	665,000	1,710,000	1,497,000
Operating income (loss)	(6,202,000)	$ (7,679,000)	(12,051,000)	$ (15,029,000)
Impairment charge
Revenue	74,461,000	$ 131,365,000	163,553,000	$ 250,965,000
Direct operating expenses	45,946,000	59,724,000	97,171,000	116,023,000
Drydock expense	2,436,000	4,685,000	11,409,000	11,896,000
General and administrative expenses	11,521,000	17,403,000	22,485,000	31,892,000
Depreciation and amortization expense	18,765,000	19,204,000	37,253,000	37,561,000
Operating income (loss)	$ (4,207,000)	22,890,000	(4,765,000)	46,134,000
Impairment charge		$ 7,459,000	$ 0	$ 7,459,000