FIXED ASSETS - Schedule of Fixed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 204,511	$ 186,195
Less – accumulated depreciation	(152,000)	(124,802)
Fixed assets, net	52,511	61,393
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 6,596	6,436
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	$ 147,237	135,100
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	$ 31,338	28,036
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	$ 19,340	$ 16,623
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	12 years