Utility Regulatory Assets and Liabilities and Regulatory Matters - Schedule of Regulatory Assets and Liabilities (Details) - Utilities - USD ($) $ in Millions	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Regulatory Assets
Regulatory assets	$ 393	$ 340	$ 412
Regulatory Liabilities
Regulatory liabilities	320	335	346
Postretirement benefit overcollections
Regulatory Liabilities
Regulatory liabilities	11	11	13
Deferred fuel and power refunds
Regulatory Liabilities
Regulatory liabilities	3	3	1
State tax benefits — distribution system repairs
Regulatory Liabilities
Regulatory liabilities	39	38	33
Excess federal deferred income taxes
Regulatory Liabilities
Regulatory liabilities	264	279	285
Other
Regulatory Liabilities
Regulatory liabilities	3	4	14
Income taxes recoverable
Regulatory Assets
Regulatory assets	93	83	145
Underfunded pension plans
Regulatory Assets
Regulatory assets	114	114	106
Environmental costs
Regulatory Assets
Regulatory assets	36	37	57
Deferred fuel and power costs
Regulatory Assets
Regulatory assets	71	32	29
Removal costs, net
Regulatory Assets
Regulatory assets	25	22	23
Other
Regulatory Assets
Regulatory assets	$ 54	$ 52	$ 52