REPORTING SEGMENT AND OTHER OPERATIONS DATA - NET FINANCIAL EARNINGS (LOSS) RECONCILIATION (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting [Abstract]
Net financial earnings (loss)	$ 44,657	$ 34,931
Less:
Unrealized gain on derivative instruments and related transactions	(37,491)	(41,766)
Tax effect	8,913	9,931
Effects of economic hedging related to natural gas inventory	(7,532)	(8,887)
Tax effect	1,790	2,112
NFE tax adjustment	(2,068)	(2,211)
NET INCOME	$ 81,045	$ 75,752