v3.25.1
Accumulated Other Comprehensive Income (Loss), Net of Tax - Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Reclassification out of Accumulated Other Comprehensive Income [Line Items]      
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax $ (2) $ (4)  
Reclassification from Accumulated Other Comprehensive Income, Current Period, Tax 0 2  
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (2) (2)  
Cash Flow Hedges [Member]      
Reclassification out of Accumulated Other Comprehensive Income [Line Items]      
Cash Flow Hedge, Pre-tax 1 3  
Cash Flow Hedge, Tax (1) (1)  
Cash Flow Hedge, After Tax 0 2  
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax 1   $ 13
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) 0 2 $ 9
Pension and OPEB Plans [Member]      
Reclassification out of Accumulated Other Comprehensive Income [Line Items]      
Reclassification Adjustment from AOCI, Pension and OPEB, Pre-Tax (2) (3)  
Reclassification Adjustment from AOCI, Pension and OPEB, Tax 1 1  
Reclassification Adjustment from AOCI, Pension and OPEB, After-Tax (1) (2)  
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (1) (2)  
Available-for-Sale Securities [Member]      
Reclassification out of Accumulated Other Comprehensive Income [Line Items]      
Reclassification for Available for Sale Securities, Pre-Tax (1) (4)  
Reclassification for Available for Sale Securities, Tax 0 2  
Reclassification for Available for Sale Securities, After-Tax (1) (2)  
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (1) (2)  
Interest Expense [Member] | Cash Flow Hedges [Member]      
Reclassification out of Accumulated Other Comprehensive Income [Line Items]      
Cash Flow Hedge, Pre-tax 1 3  
Cash Flow Hedge, Tax (1) (1)  
Cash Flow Hedge, After Tax 0 2  
Non-Operating Pension and OPEB Credits (Costs) [Member] | Pension and OPEB Plans [Member]      
Reclassification out of Accumulated Other Comprehensive Income [Line Items]      
Amortization of Net Actuarial Loss, Pre-Tax (2) (3)  
Amortization of Net Actuarial Loss, Tax 1 1  
Amortization of Net Actuarial Loss, After-Tax (1) (2)  
Net Gains (Losses) on Trust Investments [Member] | Available-for-Sale Securities [Member]      
Reclassification out of Accumulated Other Comprehensive Income [Line Items]      
Reclassification for Available for Sale Securities, Pre-Tax (1) (4)  
Reclassification for Available for Sale Securities, Tax 0 2  
Reclassification for Available for Sale Securities, After-Tax $ (1) $ (2)