REPORTING SEGMENT AND OTHER OPERATIONS DATA - NET FINANCIAL EARNINGS (LOSS) RECONCILIATION (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting [Abstract]
Net financial earnings (loss)	$ 130,206		$ 170,604		$ 195,976	$ 215,261
Less:
Unrealized loss (gain) on derivative instruments and related transactions	42,022		29,255		(40,169)	(8,235)
Tax effect	(9,980)		(6,954)		9,556	1,958
Effects of economic hedging related to natural gas inventory	1,155		(7,209)		24,732	(14,741)
Tax effect	(274)		1,713		(5,877)	3,503
NFE tax adjustment	1,248		3,990		387	1,922
NET INCOME	$ 96,035	$ 111,312	$ 149,809	$ 81,045	$ 207,347	$ 230,854