STOCK PLANS AND STOCK-BASED COMPENSATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 33,539	$ 33,265	$ 28,594
Income tax benefit	(10,768)	(10,950)	(8,451)
Total stock-based compensation expense, net of tax	22,771	22,315	20,143
Cost of revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	3,244	3,306	2,583
Research, development and engineering
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	8,616	9,908	8,053
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	21,679	20,051	17,958
Stock-based compensation expense included in operating expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 30,295	$ 29,959	$ 26,011