INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Deferred tax assets
Net operating loss carryforwards	$ 61,740	$ 40,465
Net operating loss carryforwards	15,573	11,761
Stock-based compensation	9,006	6,389
Reserves and allowances	5,697	3,181
Fixed assets and intangibles	2,709	378
Gross deferred tax assets	94,725	62,174
Valuation allowance	(65,948)	(62,174)
Total deferred tax assets	28,777	0
Deferred tax liabilities
Deferred sales commissions	(12,221)	0
Convertible debt	(16,556)	0
Net deferred taxes	$ 0	$ 0