Retirement Benefits (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
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| Defined Benefit Pension Plans | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | $ 82.5 | $ 85.6 | $ 166.2 | $ 169.4 |
| Interest cost | 175.0 | 165.7 | 347.8 | 330.7 |
| Expected return on plan assets | (271.6) | (277.9) | (541.1) | (555.5) |
| Amortization of prior service cost (benefit) | 0.5 | 0.5 | 1.0 | 1.0 |
| Recognized actuarial gain (loss) | 21.9 | 31.8 | 42.8 | 62.4 |
| Net periodic cost (benefit) | 8.3 | 5.7 | 16.7 | 8.0 |
| Retiree Health Benefit Plans | ||||
| Defined Benefit Plan Disclosure [Line Items] | ||||
| Service cost | 8.1 | 9.5 | 16.4 | 17.7 |
| Interest cost | 16.2 | 15.6 | 32.0 | 31.1 |
| Expected return on plan assets | (46.2) | (48.0) | (92.4) | (96.1) |
| Amortization of prior service cost (benefit) | (0.1) | (1.4) | (0.2) | (2.8) |
| Recognized actuarial gain (loss) | (1.1) | (0.7) | (1.9) | (1.3) |
| Net periodic cost (benefit) | $ (23.1) | $ (25.0) | $ (46.1) | $ (51.4) |
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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. 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. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of cost recognized for passage of time related to defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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