| Current Federal Tax Expense (Benefit) | -30.40M | 2025-01-01 → 2025-12-31 |
| Current State and Local Tax Expense (Benefit) | -1.60M | 2025-01-01 → 2025-12-31 |
| Current Income Tax Expense (Benefit) | -32.00M | 2025-01-01 → 2025-12-31 |
| Deferred Federal Income Tax Expense (Benefit) | 411.40M | 2025-01-01 → 2025-12-31 |
| Deferred State and Local Income Tax Expense (Benefit) | 13.10M | 2025-01-01 → 2025-12-31 |
| Capitalized Computer Software, Amortization | 76.00M | 2025-01-01 → 2025-12-31 |
| Asset Retirement Obligation, Liabilities Incurred | 63.30M | 2025-01-01 → 2025-12-31 |
| Deferred Other Tax Expense (Benefit) | -700.00K | 2025-01-01 → 2025-12-31 |
| Asset Retirement Obligation, Liabilities Settled | 73.00M | 2025-01-01 → 2025-12-31 |
| Operating Lease, Liability, Current | 9.70M | as of 2025-12-31 |
| Asset Retirement Obligation, Revision of Estimate | 25.40M | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Amount Capitalized | 5.10M | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Expense | 40.90M | 2025-01-01 → 2025-12-31 |
| Accrual for Environmental Loss Contingencies, Gross | 82.60M | as of 2025-12-31 |
| DerivativeAssetAfterOffsetSubjectToMasterNettingArrangement | 12.90M | as of 2025-12-31 |
| Participating Securities, Distributed and Undistributed Earnings (Loss), Basic | 2.60M | 2025-01-01 → 2025-12-31 |
| Energy Related Inventory, Natural Gas in Storage | 252.00M | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | 255.40M | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Cost | 7.90M | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount | 4.90M | 2025-01-01 → 2025-12-31 |
| Energy Related Inventory, Coal | 8.50M | as of 2025-12-31 |
| Share-based Payment Arrangement, Expense, Tax Benefit | 11.10M | 2025-01-01 → 2025-12-31 |
| Financial Liabilities Fair Value Disclosure | 5.90M | as of 2025-12-31 |
| Share-based Payment Arrangement, Exercise of Option, Tax Benefit | 5.10M | 2025-01-01 → 2025-12-31 |
| Long-term Debt, Fair Value | 14.98B | as of 2025-12-31 |
| Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | 59.20M | as of 2025-12-31 |
| Debt and Equity Securities, Unrealized Gain (Loss) | 700.00K | 2025-01-01 → 2025-12-31 |
| Interest Income (Expense), Nonoperating, Net | 10.20M | 2025-01-01 → 2025-12-31 |
| LIFO Inventory Amount | 42.50M | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount | 5.50M | 2025-01-01 → 2025-12-31 |
| Weighted Average Cost Inventory Amount | 209.50M | as of 2025-12-31 |
| Excess of Replacement or Current Costs over Stated LIFO Value | 7.60M | as of 2025-12-31 |
| Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent | 153.10M | as of 2025-12-31 |
| SegmentExpenditureAdditionToLongLivedAssets | 4.05B | 2025-01-01 → 2025-12-31 |
| Dividends, Common Stock, Cash | 533.00M | 2025-01-01 → 2025-12-31 |
| Public Utilities, Property, Plant and Equipment, Plant in Service | 38.06B | as of 2025-12-31 |
| Public Utilities, Property, Plant and Equipment, Accumulated Depreciation | 9.37B | as of 2025-12-31 |
| Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities | 0 | 2025-01-01 → 2025-12-31 |
| Public Utilities, Property, Plant and Equipment, Net | 28.69B | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Amount | -18.20M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Gain (Loss) | -1.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | 8.40M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Other Adjustments, Amount | -4.40M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount | -1.20M | 2025-01-01 → 2025-12-31 |
| Guarantor Obligations, Current Carrying Value | 27.20M | as of 2025-12-31 |
| Net Income (Loss) Available to Common Stockholders, Diluted | 926.90M | 2025-01-01 → 2025-12-31 |
| Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic | 926.90M | 2025-01-01 → 2025-12-31 |
| Redemption Premium | 0 | 2025-01-01 → 2025-12-31 |
| Regulatory Assets | 2.50B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 2.40M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 2.10M | as of 2025-12-31 |
| Regulatory Liabilities | 1.77B | as of 2025-12-31 |
| Deferred Tax Assets, Operating Loss Carryforwards | 326.00M | as of 2025-12-31 |
| Financing Receivable, Allowance for Credit Loss, Recovery | 15.40M | 2025-01-01 → 2025-12-31 |
| Financing Receivable, Allowance for Credit Loss, Writeoff | 65.80M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Credit Carryforwards, General Business | 77.30M | as of 2025-12-31 |
| Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided | 499.30M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits | 32.00M | as of 2025-12-31 |
| Operating Lease, Cost | 14.30M | 2025-01-01 → 2025-12-31 |
| Lease, Cost | 47.70M | 2025-01-01 → 2025-12-31 |
| Right-of-Use Asset Obtained in Exchange for Finance Lease Liability | 50.20M | 2025-01-01 → 2025-12-31 |
| Right-of-Use Asset Obtained in Exchange for Operating Lease Liability | 13.90M | 2025-01-01 → 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year One | 32.60M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Two | 27.40M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Three | 26.20M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Four | 21.30M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, Year Five | 22.30M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities | 49.60M | as of 2025-12-31 |
| Finance Lease, Liability, to be Paid, after Year Five | 368.10M | as of 2025-12-31 |
| Finance Lease, Liability, Payment, Due | 497.90M | as of 2025-12-31 |
| Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease) | 16.50M | 2025-01-01 → 2025-12-31 |
| Finance Lease, Liability, Undiscounted Excess Amount | 223.90M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year One | 10.70M | as of 2025-12-31 |
| Regulated Operating Revenue, Other | 119.40M | 2025-01-01 → 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Two | 5.10M | as of 2025-12-31 |
| Regulated Operating Revenue | 6.64B | 2025-01-01 → 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Three | 3.80M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Four | 3.20M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Five | 2.10M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, after Year Five | 5.60M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid | 30.50M | as of 2025-12-31 |
| Deferred Tax Assets, Other | 19.40M | as of 2025-12-31 |
| Utilities Operating Expense, Maintenance and Operations | 1.71B | 2025-01-01 → 2025-12-31 |
| Deferred Tax Asset, Interest Carryforward | 8.40M | as of 2025-12-31 |
| Deferred Tax Assets, Gross | 708.10M | as of 2025-12-31 |
| Deferred Tax Assets, Valuation Allowance | 14.80M | as of 2025-12-31 |
| Net Assets | 17.90M | as of 2025-12-31 |
| Deferred Tax Assets, Net of Valuation Allowance | 693.30M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, Undiscounted Excess Amount | 3.60M | as of 2025-12-31 |
| Deferred Tax Liabilities, Gross | 3.19B | as of 2025-12-31 |
| Long-term Debt, Gross | 15.48B | as of 2025-12-31 |
| Assets, Fair Value Disclosure | 173.40M | as of 2025-12-31 |
| Other Comprehensive Income (Loss), before Reclassifications, Net of Tax | 24.50M | 2025-01-01 → 2025-12-31 |
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax | -300.00K | 2025-01-01 → 2025-12-31 |
| Deferred Tax Liabilities, Net | 2.50B | as of 2025-12-31 |
| Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount | 0 | as of 2025-12-31 |
| Defined Contribution Plan, Cost | 59.00M | 2025-01-01 → 2025-12-31 |
| Capitalization, Long-term Debt and Equity | 27.12B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss | 0 | as of 2025-12-31 |
| Operating Loss Carryforwards | 21.70M | as of 2025-12-31 |
| Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net | -141.50M | as of 2025-12-31 |
| Contractual Obligation | 52.00M | as of 2025-12-31 |
| Unrecognized Tax Benefits | 21.70M | as of 2025-12-31 |
| Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions | 0 | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions | 0 | 2025-01-01 → 2025-12-31 |
| Income (Loss) from Continuing Operations before Income Taxes, Domestic | 1.22B | 2025-01-01 → 2025-12-31 |
| Allowance for Funds Used During Construction, Capitalized Interest | 32.70M | 2025-01-01 → 2025-12-31 |
| Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 9.30M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Amortized Cost | 145.80M | as of 2025-12-31 |