BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Cash and Cash Equivalents [Line Items]
Value added tax expense	$ 4,858,000	$ 2,703,000	$ 14,692,000	$ 13,801,000
Cash and cash equivalents	209,160,000	209,490,000	209,160,000	209,490,000	$ 264,660,000	$ 473,110,000
Cash held on deposit	1,220,000	2,006,000	1,220,000	2,006,000	1,261,000
Cash restricted for capital investment	0	0	0	0	1,487,000
Purchases of property, plant and equipment			1,501,000	279,000
Sales of property, plant and equipment			1,473,000	0
Interest costs capitalized during period	1,578,000	381,000	1,197,000	0
Collections on beneficial interests on securitized trade receivables			171,565,000	183,610,000
Interest expense	33,947,000	33,564,000	102,182,000	101,105,000
Retained deficit	(213,905,000)	(151,848,000)	(213,905,000)	(151,848,000)	(156,348,000)
Accounting Standards Update 2016-15
Cash and Cash Equivalents [Line Items]
Cash collections from beneficial interests		183,610,000		183,610,000
Collections on beneficial interests on securitized trade receivables				177,259,000
Accounting Standards Update 2016-18
Cash and Cash Equivalents [Line Items]
Restricted cash		$ 2,749,000		2,749,000	$ 3,373,000
Change in restricted cash				$ 440,000
Interest expense	342,000		1,026,000
Accounting Standards Update 2018-02
Cash and Cash Equivalents [Line Items]
Retained deficit	2,931,000		2,931,000
Zimbabwe | Cash Held in Real Time Gross Settlement System
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 2,644,000		$ 2,644,000