INCOME TAXES - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Statutory rate	21.00%	27.60%	34.00%
State income taxes, net	22.90%	(3.70%)	(4.50%)
Impact of 2017 tax reform	0.00%	(107.00%)	0.00%
Meals and entertainment	2.70%	(1.80%)	(1.50%)
Stock-based compensation	16.10%	22.60%	0.00%
Research and development credits	7.30%	22.40%	(0.00%)
Other	1.50%	(2.00%)	0.20%
Effective rate before valuation allowance	71.50%	(41.90%)	28.20%
Change in valuation allowance	(27.20%)	38.70%	(28.50%)
Effective tax rate	44.30%	(3.20%)	(0.30%)