REPORTING SEGMENT AND OTHER OPERATIONS DATA - NET FINANCIAL EARNINGS (LOSS) RECONCILIATION (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting [Abstract]
Net financial earnings (loss)	$ 112,310		$ 130,206		$ 222,594	$ 195,976
Less:
Unrealized loss (gain) on derivative instruments and related transactions	13,971		42,022		(17,532)	(40,169)
Tax effect	(3,320)		(9,980)		4,167	9,556
Effects of economic hedging related to natural gas inventory	(11,203)		1,155		12,769	24,732
Tax effect	2,662		(274)		(3,035)	(5,877)
Gain on equity method investment	(200)		0		(200)	0
Tax effect	50		0		50	0
NFE tax adjustment	103		1,248		207	387
NET INCOME	$ 110,247	$ 115,921	$ 96,035	$ 111,312	$ 226,168	$ 207,347