Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Property, Plant and Equipment
Utility	$ 7,034	$ 6,520
Non-utility	7,316	7,153
Total property, plant and equipment	14,350	13,673
Distribution
Property, Plant and Equipment
Utility	6,024	5,595
Transmission
Property, Plant and Equipment
Utility	134	125
General and other
Property, Plant and Equipment
Utility	746	706
Work in process
Property, Plant and Equipment
Utility	130	94
Non-utility	150	258
Land
Property, Plant and Equipment
Non-utility	202	172
Buildings and improvements
Property, Plant and Equipment
Non-utility	$ 445	429
Buildings and improvements \| Minimum
Property, Plant and Equipment
Estimated Useful Life	10 years
Buildings and improvements \| Maximum
Property, Plant and Equipment
Estimated Useful Life	40 years
Transportation equipment
Property, Plant and Equipment
Non-utility	$ 242	233
Transportation equipment \| Minimum
Property, Plant and Equipment
Estimated Useful Life	3 years
Transportation equipment \| Maximum
Property, Plant and Equipment
Estimated Useful Life	10 years
Equipment, primarily cylinders and tanks
Property, Plant and Equipment
Non-utility	$ 4,052	3,985
Equipment, primarily cylinders and tanks \| Minimum
Property, Plant and Equipment
Estimated Useful Life	5 years
Equipment, primarily cylinders and tanks \| Maximum
Property, Plant and Equipment
Estimated Useful Life	30 years
Electric generation
Property, Plant and Equipment
Non-utility	$ 48	48
Electric generation \| Minimum
Property, Plant and Equipment
Estimated Useful Life	25 years
Electric generation \| Maximum
Property, Plant and Equipment
Estimated Useful Life	40 years
Pipeline and related assets
Property, Plant and Equipment
Non-utility	$ 1,710	1,598
Pipeline and related assets \| Minimum
Property, Plant and Equipment
Estimated Useful Life	25 years
Pipeline and related assets \| Maximum
Property, Plant and Equipment
Estimated Useful Life	40 years
Other
Property, Plant and Equipment
Non-utility	$ 467	$ 430
Other \| Minimum
Property, Plant and Equipment
Estimated Useful Life	1 year
Other \| Maximum
Property, Plant and Equipment
Estimated Useful Life	12 years

Amount, before accumulated depreciation and amortization, of property, plant, and equipment and finance lease right-of-use asset.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (a)
-SubTopic 20
-Topic 842
-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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