| Finance Lease, Right-of-Use Asset, before Accumulated Amortization | 193.00M | as of 2025-12-31 |
| Finance Lease, Right-of-Use Asset, Accumulated Amortization | 53.00M | as of 2025-12-31 |
| Current Federal Tax Expense (Benefit) | 34.00M | 2025-01-01 → 2025-12-31 |
| Current State and Local Tax Expense (Benefit) | 9.00M | 2025-01-01 → 2025-12-31 |
| Current Income Tax Expense (Benefit) | 43.00M | 2025-01-01 → 2025-12-31 |
| Deferred Federal Income Tax Expense (Benefit) | 107.00M | 2025-01-01 → 2025-12-31 |
| Deferred State and Local Income Tax Expense (Benefit) | 100.00M | 2025-01-01 → 2025-12-31 |
| Asset Retirement Obligation, Liabilities Incurred | 31.00M | 2025-01-01 → 2025-12-31 |
| Asset Retirement Obligation, Liabilities Settled | 73.00M | 2025-01-01 → 2025-12-31 |
| Operating Lease, Liability, Current | 3.00M | as of 2025-12-31 |
| Other Inventory, Supplies, Gross | 329.00M | as of 2025-12-31 |
| Asset Retirement Obligation, Revision of Estimate | 73.00M | 2025-01-01 → 2025-12-31 |
| Other Tax Expense (Benefit) | -4.00M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries | 898.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | 262.00M | 2025-01-01 → 2025-12-31 |
| Energy Related Inventory, Gas Stored Underground | 427.00M | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount | 77.00M | 2025-01-01 → 2025-12-31 |
| Energy Related Inventory, Other Fossil Fuel | 35.00M | as of 2025-12-31 |
| EffectiveIncomeTaxRateReconciliationTaxCreditEnergyRelatedAmount | 68.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount | 6.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount | 3.00M | 2025-01-01 → 2025-12-31 |
| SegmentExpenditureAdditionToLongLivedAssets | 3.97B | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Contingency, Amount | 9.00M | 2025-01-01 → 2025-12-31 |
| SegmentReportingOtherItemAmount | -59.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Amount | -15.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount | -42.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Other Adjustments, Amount | -4.00M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Credit Carryforwards, General Business | 120.00M | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year One | 2.38B | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two | 1.67B | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three | 1.40B | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four | 1.33B | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year Five | 1.31B | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, after Year Five | 12.47B | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation | 20.57B | as of 2025-12-31 |
| Operating Lease, Cost | 4.00M | 2025-01-01 → 2025-12-31 |
| Short-term Lease, Cost | 25.00M | 2025-01-01 → 2025-12-31 |
| Variable Lease, Cost | 115.00M | 2025-01-01 → 2025-12-31 |
| Lease, Cost | 170.00M | 2025-01-01 → 2025-12-31 |
| Right-of-Use Asset Obtained in Exchange for Finance Lease Liability | 22.00M | 2025-01-01 → 2025-12-31 |
| Right-of-Use Asset Obtained in Exchange for Operating Lease Liability | 1.00M | 2025-01-01 → 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year One | 23.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Two | 23.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Three | 22.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Four | 23.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Five | 23.00M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, after Year Five | 202.00M | as of 2025-12-31 |
| Finance Lease, Liability, Payment, Due | 316.00M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals | 16.00M | as of 2025-12-31 |
| Finance Lease, Liability, Undiscounted Excess Amount | 175.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year One | 4.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Two | 2.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Three | 2.00M | as of 2025-12-31 |
| Deferred Tax Assets, Regulatory Assets and Liabilities | 294.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Four | 2.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Five | 1.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, after Year Five | 27.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid | 38.00M | as of 2025-12-31 |
| Deferred Tax Assets, Gross | 449.00M | as of 2025-12-31 |
| Deferred Tax Assets, Valuation Allowance | 2.00M | as of 2025-12-31 |
| Deferred Tax Assets, Net of Valuation Allowance | 447.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, Undiscounted Excess Amount | 16.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Gross | 3.70B | as of 2025-12-31 |
| Long-term Debt, Gross | 18.94B | as of 2025-12-31 |
| Debt Instrument, Face Amount | 3.46B | as of 2025-12-31 |
| Deferred Tax Liabilities, Property, Plant and Equipment | 2.83B | as of 2025-12-31 |
| Deferred Tax Liabilities, Inventory | 24.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Regulatory Assets and Liabilities | 137.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Other | 147.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Net | 3.25B | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year One | 950.00M | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Two | 888.00M | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Three | 1.88B | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Four | 1.26B | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Five | 812.00M | as of 2025-12-31 |
| Debt Instrument, Unamortized Discount (Premium), Net | 28.00M | as of 2025-12-31 |
| Debt Issuance Costs, Net | 154.00M | as of 2025-12-31 |
| Unrecognized Tax Benefits | 29.00M | as of 2025-12-31 |
| Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions | 7.00M | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions | 2.00M | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations | 4.00M | 2025-01-01 → 2025-12-31 |
| Lessor, Operating Lease, Payment to be Received, Year One | 18.00M | as of 2025-12-31 |