Condensed Parent Company Financial Statements (Condensed Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Other	$ 160	$ 223
Total current assets	1,272	1,250
Investments:
Other	216	201
Total investments	602	559
Other assets	2,206	2,107
Total assets	21,237	20,163	$ 18,553
Current liabilities:
Commercial paper	475	642
Other	302	351
Total current liabilities	2,304	2,363
Long-term debt, net	8,225	7,668
Other liabilities	617	518
Common Equity:
Retained earnings	3,756	3,509
Accumulated other comprehensive income	1	0
Shares in deferred compensation trust	(13)	(13)
Total common equity	6,777	6,276
Total liabilities and equity	21,237	20,163
Parent Company [Member]
Current assets:
Notes receivable from affiliated companies	96	65
Other	1	1
Total current assets	97	66
Investments:
Investments in consolidated subsidiaries	8,405	7,801
Other	2	2
Total investments	8,407	7,803
Other assets	90	97
Total assets	8,594	7,966
Current liabilities:
Commercial paper	157	352
Notes payable to affiliated companies	1,068	1,318
Other	10	10
Total current liabilities	1,235	1,680
Long-term debt, net	568	0
Other liabilities	2	1
Common Equity:
Common stock and additional paid-in capital	3,033	2,780
Retained earnings	3,768	3,518
Accumulated other comprehensive income	1	0
Shares in deferred compensation trust	(13)	(13)
Total common equity	6,789	6,285
Total liabilities and equity	$ 8,594	$ 7,966