NET LOSS PER SHARE - Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares	11,798	10,931
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares	2,974	3,891
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares	8,188	6,420
Potential shares to be issued from ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares	636	620