SEGMENT AND GEOGRAPHIC INFORMATION - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023
SEGMENT INFORMATION
Revenue	$ 135,501	$ 122,754
Long-lived assets	191,536		$ 191,068
United States
SEGMENT INFORMATION
Revenue	111,769	99,009
Long-lived assets	175,950		178,021
Netherlands
SEGMENT INFORMATION
Revenue	18,062	15,222
Long-lived assets	6,873		6,656
Other
SEGMENT INFORMATION
Revenue	5,670	$ 8,523
Long-lived assets	$ 8,713		$ 6,391