STOCKHOLDERS' EQUITY - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) $ in Thousands	9 Months Ended
	Jun. 30, 2019 USD ($) shares
Shares
Beginning balance (in shares) | shares	2,207,242
Granted (in shares) | shares	1,771,529
Vested (in shares) | shares	(485,169)
Forfeited (in shares) | shares	(119,523)
Ending balance (in shares) | shares	3,374,079
Weighted Average Grant Date Fair Value
Beginning balance | $	$ 7,302
Granted | $	5,305
Vested | $	(2,034)
Forfeited | $	(389)
Ending balance | $	$ 10,184