Schedule I - Condensed Financial Information - Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Current Assets
Cash and temporary cash investments	$ 1,324	$ 1,189
Tax receivable	145	1
Accounts receivable from affiliated companies	2,440	2,418
Accrued unbilled revenue	848	722
Prepayments	445	470
Other current assets	194	125
TOTAL CURRENT ASSETS	6,664	6,537
Investments in subsidiaries and others	1,126	999
Goodwill	408	408
Pension and retiree benefits - asset	3,791	3,275
Other deferred charges and noncurrent assets	10,607	9,187
TOTAL ASSETS	70,562	66,331	$ 69,065
Current Liabilities
Notes payable	2,170	2,288
Accounts payable	1,676	1,775
Accrued taxes	70	73
Other current liabilities	481	411
TOTAL CURRENT LIABILITIES	6,433	6,462
Shareholders’ Equity
TOTAL LIABILITIES AND EQUITY	70,562	66,331
Parent Company
Current Assets
Cash and temporary cash investments	1	3
Other receivables, net allowance for uncollectible accounts	64	103
Tax receivable	145	1
Accounts receivable from affiliated companies	300	343
Accrued unbilled revenue	3	4
Prepayments	13	109
Other current assets	1	3
TOTAL CURRENT ASSETS	527	566
Investments in subsidiaries and others	21,706	20,778
Goodwill	406	406
Pension and retiree benefits - asset	6	5
Other deferred charges and noncurrent assets	356	249
TOTAL ASSETS	23,001	22,004
Current Liabilities
Notes payable	348	339
Other current liabilities	9	8
TOTAL CURRENT LIABILITIES	1,036	841
Other noncurrent liabilities	4	5
Total Liabilities	1,040	846
Shareholders’ Equity
Common stock, including additional paid-in capital	10,024	9,898
Retained earnings	11,937	11,260
Equity	21,961	21,158
TOTAL LIABILITIES AND EQUITY	23,001	22,004
Parent Company | Nonrelated Party
Current Liabilities
Accounts payable	17	30
Accrued taxes	2	15
Parent Company | Related Party
Current Liabilities
Accounts payable	14	12
Accrued taxes	$ 646	$ 437