Long-Term and Short-Term Debt (Schedule of Principal Payments of Long-Term Debt) (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
2024	$ 230
2025	0
2026	0
2027	0
2028	92
Thereafter	4,165
Total	$ 4,487	$ 3,987
Weighted-average coupon, 2024	3.05%
Weighted-average coupon, 2028	4.14%
Weighted-average coupon, Thereafter	5.22%
First Mortgage Bonds
Debt Instrument [Line Items]
2024	$ 0
2025	0
2026	0
2027	0
2028	53
Thereafter	4,081
Total	4,134
Tax Exempt Financings
Debt Instrument [Line Items]
2024	0
2025	0
2026	0
2027	0
2028	39
Thereafter	83
Total	122
Other Debt
Debt Instrument [Line Items]
2024	230
2025	0
2026	0
2027	0
2028	0
Thereafter	1
Total	$ 231

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