Long-term Debt Schedule of Long Term Debt Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
First Mortgage Bonds, rates range from 1.82% to 6.88%, with a weighted average rate of 4.09% in 2022 and 4.11% in 2021, due at various dates through 2051	$ 3,880	$ 3,280
Other Loans Payable, Long-Term, Noncurrent	0	260
Pollution Control Revenue Bonds, rates at 2.13% and 2.38%, due 2033	119	119
Total long-term debt	3,999	3,659
Less: Unamortized debt expense	(14)	(13)
Less: current portion of long-term debt	(80)	(260)
Long-term debt, net of current portion	$ 3,905	$ 3,386
First mortgage Bonds - minimum rate	1.82%
First Mortgage Bonds - maximum rate	6.88%
Debt, Weighted Average Interest Rate	4.32%	4.09%