Schedule I - Condensed Financial Information - Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current Assets
Cash and temporary cash investments	$ 1,189	$ 1,282
Taxes receivable	1	10
Accounts receivable from affiliated companies	2,418	2,192
Accrued unbilled revenue	722	702
Prepayments	470	264
Other current assets	124	176
TOTAL CURRENT ASSETS	6,537	12,972
Investments in subsidiaries and others	999	841
Goodwill	408	408
Pension and retiree benefits - asset	3,275	3,269
Other deferred charges and noncurrent assets	9,187	8,486
TOTAL ASSETS	66,331	69,065	$ 63,116
Current Liabilities
Long-term debt due within one year	250	649
Notes payable	2,288	2,640
Accounts payable	1,775	1,955
Accrued taxes	73	102
Accrued interest	170	153
Other current liabilities	411	444
TOTAL CURRENT LIABILITIES	6,462	11,336
Shareholders’ Equity
Equity	21,158	20,687
TOTAL LIABILITIES AND EQUITY	66,331	69,065
Parent Company
Current Assets
Cash and temporary cash investments	3	191
Other receivables, net allowance for uncollectible accounts	103	4
Taxes receivable	1	5
Accounts receivable from affiliated companies	343	1,337
Accrued unbilled revenue	4	0
Prepayments	109	9
Other current assets	3	32
TOTAL CURRENT ASSETS	566	1,578
Investments in subsidiaries and others	20,778	20,839
Goodwill	406	406
Pension and retiree benefits - asset	5	5
Other deferred charges and noncurrent assets	249	2
TOTAL ASSETS	22,004	22,830
Current Liabilities
Long-term debt due within one year	0	649
Term loan	0	400
Notes payable	339	282
Accrued interest	0	7
Other current liabilities	8	7
TOTAL CURRENT LIABILITIES	841	1,908
Deferred income taxes and unamortized investment tax credits	0	235
Other noncurrent liabilities	5	0
Total Liabilities	846	2,143
Shareholders’ Equity
Common stock, including additional paid-in capital	9,898	9,840
Retained earnings	11,260	10,847
Equity	21,158	20,687
TOTAL LIABILITIES AND EQUITY	22,004	22,830
Parent Company | Nonrelated Party
Current Liabilities
Accounts payable	30	39
Accrued taxes	15	7
Parent Company | Related Party
Current Liabilities
Accounts payable	12	11
Accrued taxes	$ 437	$ 506