COMMITMENTS AND CONTINGENT LIABILITIES - SCHEDULE OF FUTURE COMMITTED EXPENSES (Details) $ in Thousands	6 Months Ended
Mar. 31, 2020 USD ($)
Long-term Purchase Commitment [Line Items]
Current charges recoverable through BGSS	$ 127,500
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	432,118
2021	233,954
2022	213,848
2023	167,500
2024	142,013
Thereafter	644,441
Energy Services
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	261,940
2021	75,559
2022	49,111
2023	28,547
2024	19,413
Thereafter	45,994
Energy Services \| Natural gas purchases
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	169,895
2021	0
2022	0
2023	0
2024	0
Thereafter	0
Energy Services \| Storage demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	24,464
2021	14,228
2022	11,983
2023	4,727
2024	2,173
Thereafter	1,872
Energy Services \| Pipeline demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	67,581
2021	61,331
2022	37,128
2023	23,820
2024	17,240
Thereafter	44,122
Natural Gas Distribution
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	170,178
2021	158,395
2022	164,737
2023	138,953
2024	122,600
Thereafter	598,447
Natural Gas Distribution \| Natural gas purchases
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	42,700
2021	31,414
2022	30,092
2023	30,719
2024	30,819
Thereafter	14,630
Natural Gas Distribution \| Storage demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	36,051
2021	27,347
2022	26,554
2023	14,056
2024	11,483
Thereafter	4,634
Natural Gas Distribution \| Pipeline demand fees
Natural Gas Purchases and Future Demand Fees, Next Five Fiscal Years
2020	91,427
2021	99,634
2022	108,091
2023	94,178
2024	80,298
Thereafter	$ 579,183
Minimum \| Energy Services
Long-term Purchase Commitment [Line Items]
Storage and pipeline capacity, contract term	1 year
Maximum \| Energy Services
Long-term Purchase Commitment [Line Items]
Storage and pipeline capacity, contract term	10 years

Current Charges Recoverable Through Basic Gas Supply Service as shown for the reporting period

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Storage and Pipeline Capacity, Term of Contract

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Minimum amount of purchase arrangement maturing after the fifth fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the fourth fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the next fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the second fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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Minimum amount of purchase arrangement maturing in the third fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

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