SEGMENT INFORMATION (Details) (USD $)	3 Months Ended								12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013 number	Mar. 31, 2012	Mar. 31, 2011
Segment Reporting Information [Line Items]
Total intrasegment gross revenue									$ 2,337,000	$ 1,740,000	$ 4,243,000
Total consolidated gross revenue	391,642,000	388,469,000	365,754,000	362,608,000	358,371,000	331,335,000	330,992,000	321,105,000	1,508,473,000	1,341,803,000	1,232,808,000
Income (Loss) from Equity Method Investments									25,042,000	8,282,000	17,452,000
Total consolidated operating income	62,703,000	74,120,000	47,328,000	39,993,000	26,213,000	43,553,000	9,595,000	36,405,000	224,144,000	115,766,000	189,724,000
Capital expenditures									571,425,000	326,420,000	145,518,000
Total depreciation and amortization									96,284,000	96,144,000	89,377,000
Total identifiable assets	2,950,692,000				2,740,363,000				2,950,692,000	2,740,363,000
Total investments in unconsolidated affiliates - equity method	265,837,000				198,814,000				265,837,000	198,814,000
Revenue	391,642,000	388,469,000	365,754,000	362,608,000	358,371,000	331,335,000	330,992,000	321,105,000	1,508,473,000	1,341,803,000	1,232,808,000
Construction in progress payments not allocated									140,100,000	111,900,000	64,900,000
Construction in progress within property and equipment	222,800,000				126,600,000				222,800,000	126,600,000
Total property and equipment, net	1,921,072,000				1,722,775,000				1,921,072,000	1,722,775,000
Countries operated in									20
Top ten clients percentage									60.70%
One [Member]
Segment Reporting Information [Line Items]
Percentage to client over ten percent									13.00%	12.00%	11.00%
Gain Loss On Disposition Of Other Assets [Member]
Segment Reporting Information [Line Items]
Total consolidated operating income									8,068,000	(31,670,000)	8,678,000
Europe Business Unit [Member]
Segment Reporting Information [Line Items]
Total segment gross revenue									619,480,000	559,306,000	475,726,000
Total intrasegment gross revenue									65,000	391,000	729,000
Total consolidated gross revenue									619,545,000	559,697,000	476,455,000
Income (Loss) from Equity Method Investments									10,517,000	11,014,000	9,685,000
Total consolidated operating income									111,785,000	94,277,000	89,320,000
Capital expenditures									175,270,000	66,016,000	17,185,000
Total depreciation and amortization									33,101,000	34,345,000	27,361,000
Total identifiable assets	808,568,000				779,160,000				808,568,000	779,160,000
Total investments in unconsolidated affiliates - equity method	8,569,000				11,410,000				8,569,000	11,410,000
Revenue									619,545,000	559,697,000	476,455,000
West Africa Business Unit [Member]
Segment Reporting Information [Line Items]
Total segment gross revenue									296,933,000	258,258,000	226,175,000
Total intrasegment gross revenue									0	0	0
Total consolidated gross revenue									296,933,000	258,258,000	226,175,000
Total consolidated operating income									70,315,000	63,768,000	62,051,000
Capital expenditures									11,501,000	13,375,000	1,541,000
Total depreciation and amortization									13,077,000	12,805,000	11,155,000
Total identifiable assets	390,402,000				376,903,000				390,402,000	376,903,000
Revenue									296,933,000	258,258,000	226,175,000
North America Business Unit [Member]
Segment Reporting Information [Line Items]
Total segment gross revenue									226,114,000	176,797,000	193,370,000
Total intrasegment gross revenue									283,000	1,020,000	475,000
Total consolidated gross revenue									226,397,000	177,817,000	193,845,000
Income (Loss) from Equity Method Investments									(736,000)	0	0
Total consolidated operating income									27,538,000	8,378,000	14,527,000
Capital expenditures									201,439,000	53,367,000	19,755,000
Total depreciation and amortization									20,193,000	16,243,000	16,803,000
Total identifiable assets	527,710,000				276,074,000				527,710,000	276,074,000
Total investments in unconsolidated affiliates - equity method	60,517,000				2,378,000				60,517,000	2,378,000
Revenue									226,397,000	177,817,000	193,845,000
Australia Business Unit [Member]
Segment Reporting Information [Line Items]
Total segment gross revenue									186,752,000	162,727,000	158,845,000
Total intrasegment gross revenue									0	462,000	275,000
Total consolidated gross revenue									186,752,000	163,189,000	159,120,000
Total consolidated operating income									25,283,000	19,840,000	30,497,000
Capital expenditures									3,736,000	2,421,000	33,253,000
Total depreciation and amortization									9,995,000	11,352,000	11,337,000
Total identifiable assets	245,757,000				295,895,000				245,757,000	295,895,000
Revenue									186,752,000	163,189,000	159,120,000
Other International Business Unit [Member]
Segment Reporting Information [Line Items]
Total segment gross revenue									132,662,000	145,593,000	148,239,000
Total intrasegment gross revenue									0	0	0
Total consolidated gross revenue									132,662,000	145,593,000	148,239,000
Income (Loss) from Equity Method Investments									15,261,000	(2,732,000)	7,767,000
Total consolidated operating income									45,201,000	36,343,000	42,038,000
Capital expenditures									33,147,000	48,498,000	5,000,000
Total depreciation and amortization									17,018,000	16,660,000	13,997,000
Total identifiable assets	589,361,000				602,174,000				589,361,000	602,174,000
Total investments in unconsolidated affiliates - equity method	196,751,000				185,026,000				196,751,000	185,026,000
Revenue									132,662,000	145,593,000	148,239,000
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total segment gross revenue									46,532,000	39,122,000	30,453,000
Total intrasegment gross revenue									1,989,000	(133,000)	2,764,000
Total consolidated gross revenue									48,521,000	38,989,000	33,217,000
Income (Loss) from Equity Method Investments									0	0	0
Total consolidated operating income									(64,046,000)	(75,170,000)	(57,387,000)
Capital expenditures									146,332,000	142,743,000	68,784,000
Total depreciation and amortization									2,900,000	4,739,000	8,724,000
Total identifiable assets	388,894,000				410,157,000				388,894,000	410,157,000
Revenue									48,521,000	38,989,000	33,217,000
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									(2,337,000)	(1,740,000)	(4,243,000)
Revenue									(2,337,000)	(1,740,000)	(4,243,000)
U.K. [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									383,398,000	345,405,000	303,893,000
Revenue									383,398,000	345,405,000	303,893,000
Long-Lived Assets	394,557,000				391,540,000				394,557,000	391,540,000
Nigeria [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									296,933,000	258,258,000	226,175,000
Revenue									296,933,000	258,258,000	226,175,000
Long-Lived Assets	242,095,000				240,323,000				242,095,000	240,323,000
United States [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									237,311,000	208,931,000	216,281,000
Revenue									237,311,000	208,931,000	216,281,000
Long-Lived Assets	183,890,000				174,355,000				183,890,000	174,355,000
Norway [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									249,023,000	200,926,000	162,006,000
Revenue									249,023,000	200,926,000	162,006,000
Long-Lived Assets	162,591,000				193,962,000				162,591,000	193,962,000
Australia [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									186,752,000	162,727,000	158,845,000
Revenue									186,752,000	162,727,000	158,845,000
Long-Lived Assets	180,914,000				235,261,000				180,914,000	235,261,000
Malaysia [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									25,284,000	26,416,000	15,273,000
Revenue									25,284,000	26,416,000	15,273,000
Long-Lived Assets	101,764,000				106,217,000				101,764,000	106,217,000
Mexico [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									6,545,000	9,071,000	34,548,000
Revenue									6,545,000	9,071,000	34,548,000
Long-Lived Assets	33,968,000				37,576,000				33,968,000	37,576,000
Trinidad [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									43,763,000	39,478,000	29,489,000
Revenue									43,763,000	39,478,000	29,489,000
Long-Lived Assets	51,004,000				53,904,000				51,004,000	53,904,000
Brazil [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	113,562,000				94,052,000				113,562,000	94,052,000
Canada [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									16,447,000	0	0
Revenue									16,447,000	0	0
Long-Lived Assets	211,316,000				0				211,316,000	0
Other countries [Member]
Segment Reporting Information [Line Items]
Total consolidated gross revenue									63,017,000	90,591,000	86,298,000
Revenue									63,017,000	90,591,000	86,298,000
Long-Lived Assets	22,594,000				69,031,000				22,594,000	69,031,000
Construction in progress attributable to aircraft [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 222,817,000				$ 126,554,000				$ 222,817,000	$ 126,554,000