BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 264,406	$ 158,211	$ 473,110
Value added tax expense	3,854	$ 6,185
ZIMBABWE | Cash Held in Real Time Gross Settlement System
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 13,576