Property, Plant and Equipment - (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Property, Plant and Equipment
Utility	$ 4,265	$ 3,938
Non-utility	6,393	6,135
Total property, plant and equipment	10,658	10,073
Distribution
Property, Plant and Equipment
Utility	3,630	3,366
Transmission
Property, Plant and Equipment
Utility	111	106
General and other
Property, Plant and Equipment
Utility	425	389
Work in process
Property, Plant and Equipment
Utility	99	77
Non-utility	196	102
Land
Property, Plant and Equipment
Non-utility	191	184
Buildings and improvements
Property, Plant and Equipment
Non-utility	431	404
Transportation equipment
Property, Plant and Equipment
Non-utility	248	258
Equipment, primarily cylinders and tanks
Property, Plant and Equipment
Non-utility	3,712	3,455
Electric generation
Property, Plant and Equipment
Non-utility	211	327
Pipeline and related assets
Property, Plant and Equipment
Non-utility	1,098	1,150
Other
Property, Plant and Equipment
Non-utility	$ 306	$ 255