SEGMENT INFORMATION Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 358,442	$ 360,735	$ 373,676	$ 352,109	$ 336,194	$ 337,443	$ 357,467	$ 369,398	$ 1,444,962	$ 1,400,502	$ 1,715,513
External customer
Segment Reporting Information [Line Items]
Revenues									1,444,962	1,400,502	1,715,513
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues									14,677	11,520	15,755
Europe Caspian
Segment Reporting Information [Line Items]
Revenues									799,285	741,066	863,852
Europe Caspian | External customer
Segment Reporting Information [Line Items]
Revenues									793,630	734,344	858,144
Europe Caspian | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues									5,655	6,722	5,708
Africa
Segment Reporting Information [Line Items]
Revenues									195,681	204,522	255,256
Africa | External customer
Segment Reporting Information [Line Items]
Revenues									195,681	204,522	255,254
Africa | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues									0	0	2
Americas
Segment Reporting Information [Line Items]
Revenues									237,653	221,965	291,399
Americas | External customer
Segment Reporting Information [Line Items]
Revenues									228,658	217,500	283,565
Americas | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues									8,995	4,465	7,834
Asia Pacific
Segment Reporting Information [Line Items]
Revenues									222,500	233,903	296,842
Asia Pacific | External customer
Segment Reporting Information [Line Items]
Revenues									222,500	233,902	296,840
Asia Pacific | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues									0	1	2
Corporate and other
Segment Reporting Information [Line Items]
Revenues									4,520	10,566	23,919
Corporate and other | External customer
Segment Reporting Information [Line Items]
Revenues									4,493	10,234	21,710
Corporate and other | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues									$ 27	$ 332	$ 2,209