REPORTING SEGMENT AND OTHER OPERATIONS DATA - NET FINANCIAL EARNINGS LOSS RECONCILIATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting [Abstract]
Net financial earnings	$ 240,321	$ 207,712	$ 165,333
Less:
Unrealized (gain) loss on derivative instruments and related transactions	(59,906)	54,203	(9,644)
Tax effect	14,248	(12,887)	2,296
Effects of economic hedging related to natural gas inventory	19,939	(42,405)	12,690
Tax effect	(4,738)	10,078	(3,016)
(Gain on) impairment of equity method investment	(5,521)	92,000	0
Tax effect	1,377	(11,167)	0
NET INCOME	$ 274,922	$ 117,890	$ 163,007