EQUITY, STOCK-BASED COMPENSATION AND EARNINGS (LOSS) PER SHARE - Basic and diluted net loss per share (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
	Sep. 27, 2021	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Consolidated net loss		$ (48,079)		$ (9,629)		$ (63,907)	$ (96,561)
Less: Net income (loss) attributable to noncontrolling interests		0		365		(440)	756
Net loss attributable to common shareholders		$ (48,079)	$ (15,388)	$ (9,994)	$ (87,323)	$ (63,467)	$ (97,317)
Denominator:
Weighted-average shares outstanding - Basic (in shares)		25,831,000		25,687,000		25,797,000	25,645,000
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Weighted-average shares outstanding - Diluted (in shares)		25,831,000		25,687,000		25,797,000	25,645,000
Shares excluded in computing of earnings (in shares)		5,664,000		5,549,000		5,664,000	5,549,000
Shares issuable upon conversion (in shares)	3,040,268