SEGMENT AND GEOGRAPHIC INFORMATION - Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
SEGMENT INFORMATION
Depreciation and amortization:	$ 12,990	$ 9,831	$ 26,253	$ 15,866
Capital expenditures:	8,471	9,547	16,840	15,202
Discovery and Safety Assessment Segment (DSA)
SEGMENT INFORMATION
Depreciation and amortization:	3,611	3,414	7,591	5,958
Capital expenditures:	3,970	3,431	7,264	6,417
Research Models And Services Segment (RMS)
SEGMENT INFORMATION
Depreciation and amortization:	9,379	6,417	18,662	9,908
Capital expenditures:	$ 4,501	$ 6,116	$ 9,576	$ 8,785