Pension and Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
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| Defined Benefit Plan Disclosure [Line Items] | |||
| COVID-19 related regulatory asset | $ 2,477.3 | $ 2,460.2 | |
| Pension Plan | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Defined Benefit Plan, Accumulated Benefit Obligation | 1,278.4 | 1,390.9 | |
| Funded status of plan | (49.1) | (25.0) | |
| Employer contributions | 2.4 | 3.1 | |
| Settlement loss | 7.2 | $ 9.2 | $ 12.4 |
| Expected contribution | $ 2.3 | ||
| Expected return on plan assets | 7.02% | 7.00% | 4.80% |
| Other Postretirement Benefits | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Funded status of plan | $ 193.1 | $ 232.3 | |
| Employer contributions | 23.6 | 23.4 | |
| Settlement loss | 0.0 | $ 0.0 | $ 0.0 |
| Expected contribution | $ 21.3 | ||
| Expected return on plan assets | 7.06% | 6.96% | 5.72% |
| Unrecognized Pension Benefit And Other Postretirement Benefit Costs | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| COVID-19 related regulatory asset | $ 485.3 | $ 561.6 | |
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- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of contribution received by defined benefit plan from employer which increases plan assets. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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