LEASES - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Lease, Cost [Abstract]
Weighted average remaining lease term, Operating leases	23 years		23 years
Weighted average remaining lease term, Finance leases	19 years		19 years
Weighted average discount rate, Operating leases	7.68%		7.68%
Weighted average discount rate, Finance leases	7.76%		7.76%
Operating lease cost
Operating lease expense	$ 11,456	$ 9,046	$ 34,160	$ 28,022
Short-term lease expense	9,248	2,747	23,464	20,297
Variable lease expense	4,666	2,354	12,531	9,161
Finance lease expense:
Amortization of right-of-use assets	1,602	593	2,854	1,806
Interest on lease liabilities	2,067	373	2,942	1,161
Less: sublease income	(5,410)	(69)	(13,467)	(16,794)
Total	$ 23,629	$ 15,044	$ 62,484	$ 43,653