DERIVATIVE INSTRUMENTS - OFFSETTING OF ASSETS AND LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Energy Services
Derivative assets:
Amounts Presented in Balance Sheets	$ 33,910	$ 26,510
Offsetting Derivative Instruments	(11,599)	(17,982)
Financial Collateral Received/Pledged	(1,088)	(200)
Net Amounts	21,223	8,328
Derivative liabilities:
Amounts Presented in Balance Sheets	38,627	46,859
Offsetting Derivative Instruments	(11,599)	(17,982)
Financial Collateral Received/Pledged	0	0
Net Amounts	27,028	28,877
Energy Services \| Physical commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	7,575	7,718
Offsetting Derivative Instruments	(2,455)	(3,587)
Financial Collateral Received/Pledged	(200)	(200)
Net Amounts	4,920	3,931
Derivative liabilities:
Amounts Presented in Balance Sheets	29,483	32,441
Offsetting Derivative Instruments	(2,455)	(3,587)
Financial Collateral Received/Pledged	0	0
Net Amounts	27,028	28,854
Energy Services \| Financial commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	26,117	18,708
Offsetting Derivative Instruments	(9,131)	(14,311)
Financial Collateral Received/Pledged	(888)	0
Net Amounts	16,098	4,397
Derivative liabilities:
Amounts Presented in Balance Sheets	9,131	14,311
Offsetting Derivative Instruments	(9,131)	(14,311)
Financial Collateral Received/Pledged	0	0
Net Amounts	0	0
Energy Services \| Foreign currency contracts
Derivative assets:
Amounts Presented in Balance Sheets	218	84
Offsetting Derivative Instruments	(13)	(84)
Financial Collateral Received/Pledged	0	0
Net Amounts	205	0
Derivative liabilities:
Amounts Presented in Balance Sheets	13	107
Offsetting Derivative Instruments	(13)	(84)
Financial Collateral Received/Pledged	0	0
Net Amounts	0	23
Natural Gas Distribution
Derivative assets:
Amounts Presented in Balance Sheets	724	149
Offsetting Derivative Instruments	(575)	(136)
Financial Collateral Received/Pledged	0	0
Net Amounts	149	13
Derivative liabilities:
Amounts Presented in Balance Sheets	750	358
Offsetting Derivative Instruments	(575)	(136)
Financial Collateral Received/Pledged	0	0
Net Amounts	175	222
Natural Gas Distribution \| Physical commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	1	78
Offsetting Derivative Instruments	(1)	(65)
Financial Collateral Received/Pledged	0	0
Net Amounts	0	13
Derivative liabilities:
Amounts Presented in Balance Sheets	176	76
Offsetting Derivative Instruments	(1)	(65)
Financial Collateral Received/Pledged	0	0
Net Amounts	175	11
Natural Gas Distribution \| Financial commodity contracts
Derivative assets:
Amounts Presented in Balance Sheets	723	71
Offsetting Derivative Instruments	(574)	(71)
Financial Collateral Received/Pledged	0	0
Net Amounts	149	0
Derivative liabilities:
Amounts Presented in Balance Sheets	574	282
Offsetting Derivative Instruments	(574)	(71)
Financial Collateral Received/Pledged	0	0
Net Amounts	$ 0	$ 211

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