NET LOSS PER SHARE - Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares (in shares)	13,859	9,710	13,859	9,710
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares (in shares)	2,788	3,496	2,788	3,496
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares (in shares)	10,334	5,854	10,334	5,854
Contingently issuable shares (hold-back shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares (in shares)	350	0	350	0
Potential shares to be issued from ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive shares (in shares)	387	360	387	360