Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Public Utilities, Inventory
Total inventories	$ 433	$ 665
Non-utility LPG and natural gas
Public Utilities, Inventory
Total inventories	212	335
Gas Utility natural gas
Public Utilities, Inventory
Total inventories	55	166
Energy certificates
Public Utilities, Inventory
Total inventories	64	70
Materials, supplies and other
Public Utilities, Inventory
Total inventories	$ 102	$ 94