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DERIVATIVE INSTRUMENTS - VOLUME (Details) - Bcf	Jun. 30, 2021	Sep. 30, 2020
Natural Gas Distribution | Long | Futures
Derivative [Line Items]
Notional amount	18.1	23.7
Natural Gas Distribution | Long | Physical Commodity
Derivative [Line Items]
Notional amount	9.4	6.0
Energy Services | Long | Physical Commodity
Derivative [Line Items]
Notional amount	3.5	5.0
Energy Services | Short | Futures
Derivative [Line Items]
Notional amount	22.1	27.5
Energy Services | Short | Swaps
Derivative [Line Items]
Notional amount	0.5	1.8

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

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