Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Operating and maintenance expenses	$ 343	$ 313	$ 279
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	7	7	7
Interest cost	23	22	22
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(32)	(32)	(32)
Defined Benefit Plan, Amortization of Gain (Loss)	3	3	2
Net periodic pension cost	1	0	(1)
Defined Benefit Plan, Costs Not Recognized Due To Regulation	2	(1)	5
Net benefit cost recognized for financial reporting	$ 3	$ (1)	$ 4
Discount rate (as a percent)	5.88%	5.49%	5.80%
Expected average long-term increase in compensation level (as a percent)	4.25%	4.25%	4.25%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	7.03%	6.97%	6.96%
Net loss	$ 162	$ 165
Prior service credit	(1)	(1)
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Total	161	164
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Current Regulatory Assets	5	4
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Noncurrent Regulatory Assets	156	160
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Current Regulatory Liabilities	0	0
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Noncurrent Regulatory Liabilities	0	0
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	1	1	$ 1
Interest cost	1	1	1
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(2)	(2)	(1)
Defined Benefit Plan, Amortization of Gain (Loss)	(1)	0	0
Net periodic pension cost	(1)	0	1
Defined Benefit Plan, Costs Not Recognized Due To Regulation	0	0	0
Net benefit cost recognized for financial reporting	$ (1)	$ 0	$ 1
Discount rate (as a percent)	5.88%	5.54%	5.80%
Expected average long-term increase in compensation level (as a percent)	0.00%	0.00%	0.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	6.25%	5.00%	5.00%
Net loss	$ (15)	$ (19)
Prior service credit	0	0
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Total	(15)	(19)
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Current Regulatory Assets	0	0
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Noncurrent Regulatory Assets	0	0
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Current Regulatory Liabilities	0	(1)
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Noncurrent Regulatory Liabilities	$ (15)	$ (18)