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Fair Value of Pension Plan Assets (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | $ 428.7 |
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Assets Transferred into (out of) Level 3 | 0.0 | $ 314.5
Fair Value of Plan Assets (Period End) | 379.3 | 428.7
Investment funds |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 6.7 |
Fair Value of Plan Assets (Period End) | 5.4 | 6.7
Limited partnerships |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Fixed income securities |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 9.2 |
Fair Value of Plan Assets (Period End) | 9.7 | 9.2
Insurance contracts |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 335.8 |
Fair Value of Plan Assets (Period End) | 292.3 | 335.8
Other plan assets |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 10.7 |
Fair Value of Plan Assets (Period End) | 16.7 | 10.7
Total plan assets subject to leveling |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 362.4 |
Fair Value of Plan Assets (Period End) | 324.1 | 362.4
Investments measured at net asset value |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 106.5 |
Fair Value of Plan Assets (Period End) | 64.2 | 106.5
Non-benefit obligation liabilities |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | (40.2) |
Fair Value of Plan Assets (Period End) | (9.0) | (40.2)
Level 1 | Investment funds |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 6.7 |
Fair Value of Plan Assets (Period End) | 5.4 | 6.7
Level 1 | Limited partnerships |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 1 | Fixed income securities |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 9.2 |
Fair Value of Plan Assets (Period End) | 9.7 | 9.2
Level 1 | Insurance contracts |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 1 | Other plan assets |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 10.7 |
Fair Value of Plan Assets (Period End) | 16.7 | 10.7
Level 1 | Total plan assets subject to leveling |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 26.6 |
Fair Value of Plan Assets (Period End) | 31.8 | 26.6
Level 2 | Investment funds |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 2 | Limited partnerships |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 2 | Fixed income securities |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 2 | Insurance contracts |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 1.4 |
Fair Value of Plan Assets (Period End) | 1.3 | 1.4
Level 2 | Other plan assets |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 2 | Total plan assets subject to leveling |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 1.4 |
Fair Value of Plan Assets (Period End) | 1.3 | 1.4
Level 3 | Investment funds |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 3 | Limited partnerships |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Actual return on plan assets | (43.4) | 19.9
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 3 | Fixed income securities |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 3 | Insurance contracts |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 334.4 |
Fair Value of Plan Assets (Period End) | 291.0 | 334.4
Level 3 | Other plan assets |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 0.0 |
Fair Value of Plan Assets (Period End) | 0.0 | 0.0
Level 3 | Total plan assets subject to leveling |  |
Fair value assets and liabilities measured on recurring basis |  |
Fair Value of Plan Assets (Period Start) | 334.4 | 0.0
Fair Value of Plan Assets (Period End) | $ 291.0 | $ 334.4

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- Definition Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets still held. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(A) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan, for assets transferred into (out of) Level 3 of fair value hierarchy. Includes, but is not limited to, transfer due to change in observability of significant inputs. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(C) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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