Condensed Parent Company Financial Statements (Condensed Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Other	$ 240	$ 123
Total current assets	1,069	887
Investments:
Other	179	154
Total investments	517	485
Other assets	1,980	2,002
Total assets	18,553	17,710	$ 16,701
Current liabilities:
Commercial paper	515	389
Other	226	207
Total current liabilities	2,054	1,297
Other liabilities	388	374
Common Equity:
Retained earnings	3,250	2,994
Shares in deferred compensation trust	(12)	(11)
Total common equity	5,990	5,688
Total liabilities and equity	18,553	17,710
Parent Company [Member]
Current assets:
Notes receivable from affiliated companies	16	32
Other	5	5
Total current assets	21	37
Investments:
Investments in consolidated subsidiaries	7,061	6,664
Other	2	2
Total investments	7,063	6,666
Other assets	96	88
Total assets	7,180	6,791
Current liabilities:
Commercial paper	279	132
Notes payable to affiliated companies	900	937
Other	4	29
Total current liabilities	1,183	1,098
Other liabilities	2	2
Common Equity:
Common stock and additional paid-in capital	2,752	2,706
Retained earnings	3,255	2,996
Shares in deferred compensation trust	(12)	(11)
Total common equity	5,995	5,691
Total liabilities and equity	$ 7,180	$ 6,791