SEGMENT INFORMATION - Operating Performance and Total Assets by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 2,860,804		$ 2,860,804		$ 3,165,002
Total earnings from unconsolidated affiliates, net of losses - equity method investments	(96)	$ 2,063	(3,113)	$ 1,398
Loss on disposal of assets	(1,293)	(8,526)	(2,971)	(7,827)
Operating loss	(129,691)	(12,946)	(133,489)	(37,564)
Depreciation and amortization	30,489	31,381	61,430	62,437
Total investments in unconsolidated affiliates - equity method	104,351		104,351		119,884
Construction in progress within property and equipment	64,300		64,300		67,700
OEM Cost recoveries | Rent Expense
Segment Reporting Information [Line Items]
Offset Amount, Expense	2,400		5,900		16,600
Europe Caspian
Segment Reporting Information [Line Items]
Assets	916,960		916,960		1,087,437
Total earnings from unconsolidated affiliates, net of losses - equity method investments	(6)	61	19	91
Total business unit operating income	(11,414)	9,854	10,514	14,225
Depreciation and amortization	12,189	12,196	24,944	24,018
Total investments in unconsolidated affiliates - equity method	234		234		270
Europe Caspian | OEM Cost recoveries | Rent Expense
Segment Reporting Information [Line Items]
Offset Amount, Expense	1,700		4,400
Africa
Segment Reporting Information [Line Items]
Assets	392,865		392,865		374,121
Total business unit operating income	1,465	7,835	2,606	17,883
Depreciation and amortization	3,665	3,590	7,079	6,666
Americas
Segment Reporting Information [Line Items]
Assets	744,494		744,494		788,879
Total earnings from unconsolidated affiliates, net of losses - equity method investments	16	2,150	(2,891)	1,615
Total business unit operating income	1,813	7,483	(5,774)	6,227
Depreciation and amortization	7,310	6,998	14,191	13,997
Total investments in unconsolidated affiliates - equity method	101,239		101,239		116,276
Asia Pacific
Segment Reporting Information [Line Items]
Assets	289,379		289,379		342,166
Total business unit operating income	(6,988)	(5,903)	(7,959)	(18,433)
Depreciation and amortization	4,054	5,058	8,409	10,868
Asia Pacific | OEM Cost recoveries | Rent Expense
Segment Reporting Information [Line Items]
Offset Amount, Expense	700		1,500
Corporate and other
Segment Reporting Information [Line Items]
Assets	517,106		517,106		572,399
Total earnings from unconsolidated affiliates, net of losses - equity method investments	(106)	(148)	(241)	(308)
Total business unit operating income	(113,274)	(23,689)	(129,905)	(49,639)
Depreciation and amortization	3,271	$ 3,539	6,807	$ 6,888
Total investments in unconsolidated affiliates - equity method	$ 2,878		$ 2,878		$ 3,338