STOCKHOLDERS' EQUITY - Stock-Based Compensation Expense By Statement Of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based employee compensation expense	$ 70,878	$ 44,508	$ 29,176
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based employee compensation expense	19,712	12,313	6,625
Selling and Marketing Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based employee compensation expense	20,205	11,951	6,630
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based employee compensation expense	22,580	14,717	11,944
Service | Cost of Sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based employee compensation expense	5,330	3,752	2,636
Other revenue | Cost of Sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based employee compensation expense	$ 3,051	$ 1,775	$ 1,341