Long term debt (Tables)

12 Months Ended

Dec. 31, 2023

Long-Term Debt, Unclassified [Abstract]

Schedule of Long-term Debt Instruments [Table Text Block]

Long-term debt consists of the following (in millions):

	As of December 31,
	2023		2022
First Mortgage Bonds, rates range from 1.82% to 6.88%, with a weighted average rate of 4.32% in 2023 and 4.09% in 2022, due at various dates through 2059.	$	3,880	$	3,280
Unsecured term bank loans, variable rate of approximately 5.30% at December 31, 2022	—		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

Schedule of Maturities of Long-term Debt [Table Text Block]

As of December 31, 2023, the future minimum principal payments on long-term debt are as follows (in millions):

Years ending December 31:
2024	$	80
2025	—
2026	—
2027	160
2028	100
Thereafter	3,659
	$	3,999

Lessee, Operating Lease, Liability, Maturity

As of December 31, 2023, the future minimum payments on the financing arrangement are as follows (in millions):

Years ending December 31:
2024	$	2
2025	5
2026	5
2027	5
2028	5
Thereafter	64
Total Payments	86
Less: Imputed Interest	(57)
Present value of minimum payments	$	29