SEGMENT INFORMATION - Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 373,676	$ 357,467	$ 725,785	$ 726,865
Europe Caspian
Segment Reporting Information [Line Items]
Revenue	205,406	193,725	397,841	390,688
Africa
Segment Reporting Information [Line Items]
Revenue	49,787	51,644	100,577	105,906
Americas
Segment Reporting Information [Line Items]
Revenue	61,151	57,207	119,207	116,251
Asia Pacific
Segment Reporting Information [Line Items]
Revenue	59,284	55,256	111,730	114,400
Corporate and other
Segment Reporting Information [Line Items]
Revenue	1,481	2,676	3,215	5,892
External Customer
Segment Reporting Information [Line Items]
Revenue	373,676	357,467	725,785	726,865
External Customer | Europe Caspian
Segment Reporting Information [Line Items]
Revenue	203,923	191,834	395,322	386,658
External Customer | Africa
Segment Reporting Information [Line Items]
Revenue	49,787	51,644	100,577	105,906
External Customer | Americas
Segment Reporting Information [Line Items]
Revenue	59,201	56,092	114,963	114,289
External Customer | Asia Pacific
Segment Reporting Information [Line Items]
Revenue	59,284	55,255	111,730	114,399
External Customer | Corporate and other
Segment Reporting Information [Line Items]
Revenue	1,481	2,642	3,193	5,613
Intersegment elimination
Segment Reporting Information [Line Items]
Revenue	3,433	3,041	6,785	6,272
Intersegment elimination | Europe Caspian
Segment Reporting Information [Line Items]
Revenue	1,483	1,891	2,519	4,030
Intersegment elimination | Africa
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Intersegment elimination | Americas
Segment Reporting Information [Line Items]
Revenue	1,950	1,115	4,244	1,962
Intersegment elimination | Asia Pacific
Segment Reporting Information [Line Items]
Revenue	0	1	0	1
Intersegment elimination | Corporate and other
Segment Reporting Information [Line Items]
Revenue	$ 0	$ 34	$ 22	$ 279