CONVERTIBLE SENIOR NOTES AND CAPPED CALL - Interest Expense (Details) - Convertible Debt - Aggregate Notes - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Contractual interest expense	$ 453	$ 400	$ 1,359	$ 1,119
Amortization of debt discount	4,198	3,551	12,399	9,926
Amortization of issuance costs	59	40	174	92
Total interest expense	$ 4,710	$ 3,991	$ 13,932	$ 11,137