Inventories - Components of Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Inventory
Total inventories	$ 618	$ 665	$ 548
Non-utility LPG and natural gas
Inventory
Total inventories	310	335	352
Gas Utility natural gas
Inventory
Total inventories	129	166	65
Energy certificates
Inventory
Total inventories	78	70	60
Materials, supplies and other
Inventory
Total inventories	$ 101	$ 94	$ 71