RESTRUCTURING CHARGES - Schedule of Accrued Liability for the Restructuring and Related Charges (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2024	Mar. 31, 2023
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	$ 12,999	$ 19,658	$ 483	$ 650	$ 19,658	$ 650
Restructuring charges	2,401	12,400	78,334
Cash payment	(2,527)	(10,577)	(2,127)	(167)
Non-cash charges		(8,482)	(59,118)
Accrued liability ending balance	12,873	12,999	17,572	483	12,873	17,572
Personnel related costs
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	8,739	14,107	312	386	14,107	386
Restructuring charges	482	1,847	8,050
Cash payment	(608)	(7,215)	(244)	(74)
Non-cash charges		0	0
Accrued liability ending balance	8,613	8,739	8,118	312	8,613	8,118
Facilities & Exit Costs
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	4,260	5,551	171	264	5,551	264
Restructuring charges	1,919	2,071	11,166
Cash payment	(1,919)	(3,362)	(1,883)	(93)
Non-cash charges		0	0
Accrued liability ending balance	4,260	4,260	9,454	171	4,260	9,454
Non-cash facility and other
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	0	0	0	0	0	0
Restructuring charges	0	8,482	59,118
Cash payment	0	0	0	0
Non-cash charges		(8,482)	(59,118)
Accrued liability ending balance	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0