BUSINESS SEGMENT AND OTHER OPERATIONS DATA - NET FINANCIAL EARNINGS LOSS RECONCILIATION (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting [Abstract]
Consolidated net financial earnings	$ 2,477	$ 4,514	$ 156,729	$ 196,295
Unrealized loss (gain) from derivative instruments and related transactions	1,188	(6,585)	(19,010)	45,811
Effects of economic hedging related to natural gas inventory	16,464	38,139	(15,751)	(3,409)
Tax adjustments	(7,715)	(12,766)	14,727	(12,497)
NET (LOSS) INCOME	$ (7,460)	$ (14,274)	$ 176,763	$ 166,390