DERIVATIVE INSTRUMENTS - OFFSETTING OF ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Energy Services
Derivative assets:
Amounts Presented on the Balance Sheets	$ 36,572	$ 26,510
Offsetting Derivative Instruments	(34,191)	(17,982)
Financial Collateral Received/Pledged	19,832	(200)
Net Amounts	22,213	8,328
Derivative liabilities:
Amounts Presented in Balance Sheets	100,613	46,859
Offsetting Derivative Instruments	(34,191)	(17,982)
Financial Collateral Received/Pledged	0	0
Net Amounts	66,422	28,877
Energy Services | Physical commodity contracts
Derivative assets:
Amounts Presented on the Balance Sheets	3,151	7,718
Offsetting Derivative Instruments	(894)	(3,587)
Financial Collateral Received/Pledged	(700)	(200)
Net Amounts	1,557	3,931
Derivative liabilities:
Amounts Presented in Balance Sheets	37,829	32,441
Offsetting Derivative Instruments	(894)	(3,587)
Financial Collateral Received/Pledged	0	0
Net Amounts	36,935	28,854
Energy Services | Financial commodity contracts
Derivative assets:
Amounts Presented on the Balance Sheets	33,294	18,708
Offsetting Derivative Instruments	(33,294)	(14,311)
Financial Collateral Received/Pledged	20,532	0
Net Amounts	20,532	4,397
Derivative liabilities:
Amounts Presented in Balance Sheets	62,781	14,311
Offsetting Derivative Instruments	(33,294)	(14,311)
Financial Collateral Received/Pledged	0	0
Net Amounts	29,487	0
Energy Services | Foreign currency contracts
Derivative assets:
Amounts Presented on the Balance Sheets	127	84
Offsetting Derivative Instruments	(3)	(84)
Financial Collateral Received/Pledged		0
Net Amounts	124	0
Derivative liabilities:
Amounts Presented in Balance Sheets	3	107
Offsetting Derivative Instruments	(3)	(84)
Financial Collateral Received/Pledged	0	0
Net Amounts	0	23
Natural Gas Distribution
Derivative assets:
Amounts Presented on the Balance Sheets	2,082	149
Offsetting Derivative Instruments	(21)	(136)
Financial Collateral Received/Pledged	0	0
Net Amounts	2,061	13
Derivative liabilities:
Amounts Presented in Balance Sheets	29	358
Offsetting Derivative Instruments	(21)	(136)
Financial Collateral Received/Pledged	0	0
Net Amounts	8	222
Natural Gas Distribution | Physical commodity contracts
Derivative assets:
Amounts Presented on the Balance Sheets	36	78
Offsetting Derivative Instruments	(8)	(65)
Financial Collateral Received/Pledged	0	0
Net Amounts	28	13
Derivative liabilities:
Amounts Presented in Balance Sheets	16	76
Offsetting Derivative Instruments	(8)	(65)
Financial Collateral Received/Pledged	0	0
Net Amounts	8	11
Natural Gas Distribution | Financial commodity contracts
Derivative assets:
Amounts Presented on the Balance Sheets	2,046	71
Offsetting Derivative Instruments	(13)	(71)
Financial Collateral Received/Pledged	0	0
Net Amounts	2,033	0
Derivative liabilities:
Amounts Presented in Balance Sheets	13	282
Offsetting Derivative Instruments	(13)	(71)
Financial Collateral Received/Pledged	0	0
Net Amounts	$ 0	$ 211