v3.26.1
Retirement Benefits - Narrative (Details)
$ in Millions
 6 Months Ended
Jun. 30, 2026
USD ($)
Defined Benefit Plan Disclosure [Line Items]  
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax $ (4)
Defined Benefit Plan Amounts Recognized In Regulatory Assets Before Tax 23
Defined Benefit Plan Amounts Recognized In Regulatory Liabilities Before Tax $ 1
Pension Plan, Defined Benefit [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected return on assets 7.00%
Discount rate 5.42%
Other Postretirement Benefit Plan, Defined Benefit [Member]  
Defined Benefit Plan Disclosure [Line Items]  
Expected return on assets 6.50%
Discount rate 5.34%
Increase (Decrease) in Obligation, Pension Benefits $ 6
Increase (Decrease) in Obligation, Other Postretirement Benefits 10
Defined Benefit Plan, Plan Assets, Period Increase (Decrease) $ (2)