SEGMENT AND GEOGRAPHIC INFORMATION - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022
SEGMENT INFORMATION
Revenue	$ 157,468	$ 172,666	$ 431,685	$ 397,190	$ 547,656
Long-lived assets	189,879		189,879		186,199
United States
SEGMENT INFORMATION
Revenue	132,265	150,540	361,254	340,875
Long-lived assets	175,451		175,451		173,417
Netherlands
SEGMENT INFORMATION
Revenue	15,682	12,894	42,426	31,549
Long-lived assets	6,625		6,625		5,824
Other
SEGMENT INFORMATION
Revenue	9,521	$ 9,232	28,005	$ 24,766
Long-lived assets	$ 7,803		$ 7,803		$ 6,958