RESTRUCTURING CHARGES - Summary of Accrued Liability for the Restructuring and Related Charges (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2020 USD ($)
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	$ 2,965
Restructuring charges	10,800
Cash payments	(4,132)
Non-cash charges	(5,794)
Accrued liability ending balance	3,839
Personnel related costs
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	2,701
Restructuring charges	2,482
Cash payments	(1,598)
Non-cash charges	0
Accrued liability ending balance	3,585
Facilities, exit costs and other
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	264
Restructuring charges	2,524
Cash payments	(2,534)
Non-cash charges	0
Accrued liability ending balance	254
Facility and Other Costs
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	0
Restructuring charges	5,794
Cash payments	0
Non-cash charges	(5,794)
Accrued liability ending balance	$ 0