SEGMENT INFORMATION - Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Revenue	$ 367,894	$ 352,109
Europe Caspian
Segment Reporting Information [Line Items]
Revenue	220,180	192,435
Africa
Segment Reporting Information [Line Items]
Revenue	36,416	50,790
Americas
Segment Reporting Information [Line Items]
Revenue	54,230	58,056
Asia Pacific
Segment Reporting Information [Line Items]
Revenue	60,196	52,446
Corporate and other
Segment Reporting Information [Line Items]
Revenue	190	1,734
External Customer
Segment Reporting Information [Line Items]
Revenue	367,894	352,109
External Customer | Europe Caspian
Segment Reporting Information [Line Items]
Revenue	218,500	191,399
External Customer | Africa
Segment Reporting Information [Line Items]
Revenue	36,416	50,790
External Customer | Americas
Segment Reporting Information [Line Items]
Revenue	52,593	55,762
External Customer | Asia Pacific
Segment Reporting Information [Line Items]
Revenue	60,196	52,446
External Customer | Corporate and other
Segment Reporting Information [Line Items]
Revenue	189	1,712
Intersegment elimination
Segment Reporting Information [Line Items]
Revenue	3,318	3,352
Intersegment elimination | Europe Caspian
Segment Reporting Information [Line Items]
Revenue	1,680	1,036
Intersegment elimination | Africa
Segment Reporting Information [Line Items]
Revenue	0	0
Intersegment elimination | Americas
Segment Reporting Information [Line Items]
Revenue	1,637	2,294
Intersegment elimination | Asia Pacific
Segment Reporting Information [Line Items]
Revenue	0	0
Intersegment elimination | Corporate and other
Segment Reporting Information [Line Items]
Revenue	1	$ 22
Revenue Not from Contract with Customer [Member]
Segment Reporting Information [Line Items]
Revenue	19,800
Revenue Not from Contract with Customer [Member] | Europe Caspian
Segment Reporting Information [Line Items]
Revenue	13,000
Revenue Not from Contract with Customer [Member] | Americas
Segment Reporting Information [Line Items]
Revenue	6,700
Revenue Not from Contract with Customer [Member] | Asia Pacific
Segment Reporting Information [Line Items]
Revenue	$ 100