| Current Federal Tax Expense (Benefit) | 10.00M | 2025-01-01 → 2025-12-31 |
| Current State and Local Tax Expense (Benefit) | -1.00M | 2025-01-01 → 2025-12-31 |
| Deferred Federal Income Tax Expense (Benefit) | 59.00M | 2025-01-01 → 2025-12-31 |
| Deferred State and Local Income Tax Expense (Benefit) | 33.00M | 2025-01-01 → 2025-12-31 |
| Asset Retirement Obligation, Liabilities Incurred | 16.00M | 2025-01-01 → 2025-12-31 |
| Asset Retirement Obligation, Liabilities Settled | 5.00M | 2025-01-01 → 2025-12-31 |
| Operating Lease, Liability, Current | 2.00M | as of 2025-12-31 |
| Asset Retirement Obligation, Revision of Estimate | -1.00M | 2025-01-01 → 2025-12-31 |
| Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability | 8.00M | 2025-01-01 → 2025-12-31 |
| Other Tax Expense (Benefit) | 0 | 2025-01-01 → 2025-12-31 |
| Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization | 190.00M | as of 2025-12-31 |
| Money Market Funds, at Carrying Value | 411.00M | as of 2025-12-31 |
| Share-based Payment Arrangement, Expense | 22.00M | 2025-01-01 → 2025-12-31 |
| Short-term Debt, Maximum Amount Outstanding During Period | 741.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | 139.00M | 2025-01-01 → 2025-12-31 |
| Energy Related Inventory, Gas Stored Underground | 49.00M | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount | 22.00M | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Expense, Tax Benefit | 3.00M | 2025-01-01 → 2025-12-31 |
| Energy Related Inventory, Other Fossil Fuel | 46.00M | as of 2025-12-31 |
| Long-term Debt, Fair Value | 11.75B | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount | 2.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount | 156.00M | 2025-01-01 → 2025-12-31 |
| EffectiveIncomeTaxRateReconciliationTaxCreditEnergyRelatedAmount | 206.00M | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | 14.00M | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount | 1.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount | 4.00M | 2025-01-01 → 2025-12-31 |
| Line of Credit Facility, Current Borrowing Capacity | 1.30B | as of 2025-12-31 |
| Line of Credit Facility, Remaining Borrowing Capacity | 1.21B | as of 2025-12-31 |
| Public Utilities, Property, Plant and Equipment, Construction Work in Progress | 1.74B | as of 2025-12-31 |
| SegmentExpenditureAdditionToLongLivedAssets | 2.48B | 2025-01-01 → 2025-12-31 |
| Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | 10.00M | as of 2025-12-31 |
| SegmentReportingOtherItemAmount | 33.00M | 2025-01-01 → 2025-12-31 |
| Public Utilities, Property, Plant and Equipment, Accumulated Depreciation | 6.69B | as of 2025-12-31 |
| Public Utilities, Property, Plant and Equipment, Net | 19.69B | as of 2025-12-31 |
| Dividends, Common Stock | 521.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Other Adjustments, Amount | 0 | 2025-01-01 → 2025-12-31 |
| Public Utilities, Property, Plant and Equipment, Present Value of Regulated Asset for Plant Abandonment | 0 | as of 2025-12-31 |
| Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service | 2.54B | as of 2025-12-31 |
| Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation | 1.06B | as of 2025-12-31 |
| Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress | 27.00M | as of 2025-12-31 |
| Deferred Credits and Other Liabilities | 4.58B | as of 2025-12-31 |
| Regulatory Assets | 2.27B | as of 2025-12-31 |
| Regulatory Liabilities | 1.20B | as of 2025-12-31 |
| Deferred Tax Assets, Operating Loss Carryforwards, State and Local | 19.00M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Credit Carryforwards | 669.00M | as of 2025-12-31 |
| Lease, Cost | 9.00M | 2025-01-01 → 2025-12-31 |
| Right-of-Use Asset Obtained in Exchange for Finance Lease Liability | 1.00M | 2025-01-01 → 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year One | 9.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Two | 10.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Three | 10.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Four | 10.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Five | 10.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, after Year Five | 328.00M | as of 2025-12-31 |
| Finance Lease, Liability, Payment, Due | 377.00M | as of 2025-12-31 |
| Regulated Operating Revenue, Electric, Non-Nuclear | 3.70B | 2025-01-01 → 2025-12-31 |
| Regulated Operating Revenue, Gas | 525.00M | 2025-01-01 → 2025-12-31 |
| Finance Lease, Liability, Undiscounted Excess Amount | 187.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year One | 3.00M | as of 2025-12-31 |
| Regulated Operating Revenue, Other | 51.00M | 2025-01-01 → 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Two | 3.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Three | 3.00M | as of 2025-12-31 |
| Unregulated Operating Revenue | 89.00M | 2025-01-01 → 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Four | 3.00M | as of 2025-12-31 |
| Regulated and Unregulated Operating Revenue | 140.00M | 2025-01-01 → 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Five | 2.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, after Year Five | 13.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid | 27.00M | as of 2025-12-31 |
| Utilities Operating Expense, Gas and Petroleum Purchased | 263.00M | 2025-01-01 → 2025-12-31 |
| Utilities Operating Expense, Fuel Used | 742.00M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Other | 143.00M | as of 2025-12-31 |
| Deferred Tax Assets, Gross | 831.00M | as of 2025-12-31 |
| Deferred Tax Assets, Valuation Allowance | 7.00M | as of 2025-12-31 |
| Deferred Tax Assets, Net of Valuation Allowance | 824.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, Undiscounted Excess Amount | 6.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Gross | 3.13B | as of 2025-12-31 |
| Long-term Debt, Gross | 12.13B | as of 2025-12-31 |
| Deferred Tax Liabilities, Property, Plant and Equipment | 2.83B | as of 2025-12-31 |
| Defined Benefit Plan, Expected Future Benefit Payment, Year One | 91.00M | as of 2025-12-31 |
| Defined Benefit Plan, Expected Future Benefit Payment, Year Two | 90.00M | as of 2025-12-31 |
| Defined Benefit Plan, Expected Future Benefit Payment, Year Three | 90.00M | as of 2025-12-31 |
| Defined Benefit Plan, Expected Future Benefit Payment, Year Four | 88.00M | as of 2025-12-31 |
| Defined Benefit Plan, Expected Future Benefit Payment, Year Five | 83.00M | as of 2025-12-31 |
| Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years | 381.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Other | 167.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Net | 2.31B | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year One | 1.07B | as of 2025-12-31 |
| Defined Contribution Plan, Cost | 30.00M | 2025-01-01 → 2025-12-31 |
| Long-Term Debt, Maturity, Year Two | 675.00M | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Three | 1.38B | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Four | 950.00M | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Five | 400.00M | as of 2025-12-31 |
| Purchase Obligation, to be Paid, Year One | 404.00M | as of 2025-12-31 |
| Purchase Obligation, to be Paid, Year Two | 249.00M | as of 2025-12-31 |
| Purchase Obligation, to be Paid, Year Three | 199.00M | as of 2025-12-31 |
| Purchase Obligation, to be Paid, Year Four | 149.00M | as of 2025-12-31 |
| Purchase Obligation, to be Paid, Year Five | 106.00M | as of 2025-12-31 |
| Purchase Obligation, to be Paid, after Year Five | 262.00M | as of 2025-12-31 |
| Debt Instrument, Unamortized Discount (Premium), Net | 27.00M | as of 2025-12-31 |
| Purchase Obligation | 1.37B | as of 2025-12-31 |
| Short-term Debt, Average Outstanding Amount | 349.00M | 2025-01-01 → 2025-12-31 |
| Debt Issuance Costs, Net | 70.00M | as of 2025-12-31 |
| Other Receivables | 104.00M | as of 2025-12-31 |
| FinancingReceivableYearOneOriginatedCurrentFiscalYearWriteoff | 16.00M | 2025-01-01 → 2025-12-31 |
| FinancingReceivableYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff | 12.00M | 2025-01-01 → 2025-12-31 |
| FinancingReceivableYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff | 1.00M | 2025-01-01 → 2025-12-31 |