LEASES - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Lease, Cost [Abstract]
Weighted average remaining lease term, Operating leases	24 years		24 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	$ 11,349	$ 9,375	$ 22,704	$ 18,976
Short-term lease expense	7,661	7,594	14,216	17,550
Variable lease expense	3,909	3,198	7,865	6,807
Finance lease expense:
Amortization of right-of-use assets	679	606	1,252	1,213
Interest on lease liabilities	488	391	875	788
Less: sublease income	(4,134)	(7,121)	(8,057)	(16,725)
Total	$ 19,952	$ 14,043	$ 38,855	$ 28,609