DERIVATIVE INSTRUMENTS - OFFSETTING OF ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Energy Services
Derivative assets:
Amounts Presented in Balance Sheets	$ 18,644	$ 26,510
Offsetting Derivative Instruments	(9,359)	(17,982)
Financial Collateral Received/Pledged	(200)	(200)
Net Amounts	9,085	8,328
Derivative liabilities:
Amounts Presented in Balance Sheets	44,107	46,859
Offsetting Derivative Instruments	(9,359)	(17,982)
Financial Collateral Received/Pledged	0	0
Net Amounts	34,748	28,877
Energy Services | Physical commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	5,032	7,718
Offsetting Derivative Instruments	(1,757)	(3,587)
Financial Collateral Received/Pledged	(200)	(200)
Net Amounts	3,075	3,931
Derivative liabilities:
Amounts Presented in Balance Sheets	36,505	32,441
Offsetting Derivative Instruments	(1,757)	(3,587)
Financial Collateral Received/Pledged	0	0
Net Amounts	34,748	28,854
Energy Services | Financial commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	13,355	18,708
Offsetting Derivative Instruments	(7,573)	(14,311)
Financial Collateral Received/Pledged		0
Net Amounts	5,782	4,397
Derivative liabilities:
Amounts Presented in Balance Sheets	7,573	14,311
Offsetting Derivative Instruments	(7,573)	(14,311)
Financial Collateral Received/Pledged	0	0
Net Amounts	0	0
Energy Services | Foreign currency contracts
Derivative assets:
Amounts Presented in Balance Sheets	257	84
Offsetting Derivative Instruments	(29)	(84)
Financial Collateral Received/Pledged		0
Net Amounts	228	0
Derivative liabilities:
Amounts Presented in Balance Sheets	29	107
Offsetting Derivative Instruments	(29)	(84)
Financial Collateral Received/Pledged	0	0
Net Amounts	0	23
Natural Gas Distribution
Derivative assets:
Amounts Presented in Balance Sheets	766	149
Offsetting Derivative Instruments	(89)	(136)
Financial Collateral Received/Pledged	0	0
Net Amounts	677	13
Derivative liabilities:
Amounts Presented in Balance Sheets	89	358
Offsetting Derivative Instruments	(89)	(136)
Financial Collateral Received/Pledged	0	0
Net Amounts	0	222
Natural Gas Distribution | Physical commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	177	78
Offsetting Derivative Instruments	(1)	(65)
Financial Collateral Received/Pledged	0	0
Net Amounts	176	13
Derivative liabilities:
Amounts Presented in Balance Sheets	1	76
Offsetting Derivative Instruments	(1)	(65)
Financial Collateral Received/Pledged		0
Net Amounts	0	11
Natural Gas Distribution | Financial commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	589	71
Offsetting Derivative Instruments	(88)	(71)
Financial Collateral Received/Pledged	0	0
Net Amounts	501	0
Derivative liabilities:
Amounts Presented in Balance Sheets	88	282
Offsetting Derivative Instruments	(88)	(71)
Financial Collateral Received/Pledged		0
Net Amounts	$ 0	$ 211