STOCK PLANS AND STOCK-BASED COMPENSATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 41,934	$ 33,959	$ 33,539
Income tax benefit	(9,891)	(7,880)	(10,768)
Total stock-based compensation expense, net of tax	32,043	26,079	22,771
Cost of revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,176	3,622	3,244
Research, development and engineering
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	11,699	8,071	8,616
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	26,059	22,266	21,679
Stock-based compensation expense included in operating expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 37,758	$ 30,337	$ 30,295