SEGMENT AND GEOGRAPHIC INFORMATION - Operating Segments Revenue and Operating Income (Loss) (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2023 USD ($) segment	Mar. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)
SEGMENT INFORMATION
Number of segments | segment			2
Revenue	$ 151,463	$ 140,313	$ 274,217	$ 224,524	$ 547,656
Operating Income (Loss)	(2,125)	7,868	(92,703)	(25,773)
Interest expense	(10,515)	(7,547)	(20,965)	(12,375)
Other expense (income)	545	(139)	(1,333)	(57,866)
(Loss) income before income taxes	(12,095)	182	(115,001)	(96,014)
Service
SEGMENT INFORMATION
Revenue	58,752	49,584	108,800	87,760
Product
SEGMENT INFORMATION
Revenue	92,711	90,729	165,417	136,764
Intersegment
SEGMENT INFORMATION
Revenue	3,262	1,997	4,387	2,317
Discovery and Safety Assessment Segment (DSA)
SEGMENT INFORMATION
Operating Income (Loss)	1,924	3,752	4,296	9,794
Discovery and Safety Assessment Segment (DSA) | Service
SEGMENT INFORMATION
Revenue	46,145	38,062	86,116	69,937
Discovery and Safety Assessment Segment (DSA) | Product
SEGMENT INFORMATION
Revenue	878	992	2,000	1,942
Research Models And Services Segment (RMS)
SEGMENT INFORMATION
Operating Income (Loss)	12,725	22,562	(58,547)	22,642
Research Models And Services Segment (RMS) | Service
SEGMENT INFORMATION
Revenue	12,607	11,522	22,684	17,823
Research Models And Services Segment (RMS) | Product
SEGMENT INFORMATION
Revenue	91,833	89,737	163,417	134,822
Unallocated Corporate Segment
SEGMENT INFORMATION
Operating Income (Loss)	$ (16,774)	$ (18,446)	$ (38,452)	$ (58,209)