SEGMENT INFORMATION - Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenue	$ 350,657	$ 373,676	$ 718,551	$ 725,785
Europe Caspian
Segment Reporting Information [Line Items]
Revenue	203,801	205,406	423,981	397,841
Africa
Segment Reporting Information [Line Items]
Revenue	39,392	49,787	75,808	100,577
Americas
Segment Reporting Information [Line Items]
Revenue	58,393	61,151	112,623	119,207
Asia Pacific
Segment Reporting Information [Line Items]
Revenue	51,628	59,284	111,824	111,730
Corporate and other
Segment Reporting Information [Line Items]
Revenue	708	1,481	898	3,215
External Customer
Segment Reporting Information [Line Items]
Revenue	350,657	373,676	718,551	725,785
External Customer | Europe Caspian
Segment Reporting Information [Line Items]
Revenue	201,547	203,923	420,047	395,322
External Customer | Africa
Segment Reporting Information [Line Items]
Revenue	39,392	49,787	75,808	100,577
External Customer | Americas
Segment Reporting Information [Line Items]
Revenue	57,382	59,201	109,975	114,963
External Customer | Asia Pacific
Segment Reporting Information [Line Items]
Revenue	51,628	59,284	111,824	111,730
External Customer | Corporate and other
Segment Reporting Information [Line Items]
Revenue	708	1,481	897	3,193
Intersegment elimination
Segment Reporting Information [Line Items]
Revenue	3,265	3,433	6,583	6,785
Intersegment elimination | Europe Caspian
Segment Reporting Information [Line Items]
Revenue	2,254	1,483	3,934	2,519
Intersegment elimination | Africa
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Intersegment elimination | Americas
Segment Reporting Information [Line Items]
Revenue	1,011	1,950	2,648	4,244
Intersegment elimination | Asia Pacific
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Intersegment elimination | Corporate and other
Segment Reporting Information [Line Items]
Revenue	0	$ 0	1	$ 22
Revenue Not from Contract with Customer [Member]
Segment Reporting Information [Line Items]
Revenue	12,200		32,000
Revenue Not from Contract with Customer [Member] | Europe Caspian
Segment Reporting Information [Line Items]
Revenue	4,100		17,100
Revenue Not from Contract with Customer [Member] | Americas
Segment Reporting Information [Line Items]
Revenue	$ 8,100		14,800
Revenue Not from Contract with Customer [Member] | Asia Pacific
Segment Reporting Information [Line Items]
Revenue			$ 100