FIXED ASSETS - Schedule of Fixed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 232,760	$ 204,511
Less – accumulated depreciation	(173,809)	(152,000)
Fixed assets, net	58,951	52,511
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 9,373	6,596
Furniture and fixtures | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Furniture and fixtures | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Computer equipment and internal use software
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Fixed assets, gross	$ 158,797	147,237
Computer equipment and internal use software | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer equipment and internal use software | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Demonstration and spare part units
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 17,928	31,338
Demonstration and spare part units | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	2 years
Demonstration and spare part units | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 46,662	$ 19,340
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	12 years