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Retirement Plans - Reconciliation of Balances of Pension Benefit Obligation and Fair Value of Plan Assets (Detail) - USD ($) | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Change in pension benefit obligation: |  |  |
Benefit obligation at beginning of year | $ 216,000,000.0 | $ 211,900,000 |
Service cost | 600,000 | 3,300,000 | $ 500,000
Interest cost | $ 9,900,000 | $ 10,700,000 | 6,800,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] | Compensation expense | Compensation expense |
Merger of the Buck U.S. pension plan | $ 95,400,000 |  |
Net actuarial loss (gain) | (10,500,000) | $ 8,800,000 |
Benefits paid | (15,400,000) | (18,700,000) |
Benefit obligation at end of year | 296,000,000.0 | 216,000,000.0 | 211,900,000
Change in plan assets: |  |  |
Fair value of plan assets at beginning of year | 228,900,000 | 212,500,000 |
Actual (loss) return on plan assets | 15,300,000 | 35,100,000 |
Merger of the Buck U.S. pension plan | 83,700,000 |  |
Contributions by the Company | 0 | 0 | 0
Benefits paid | (15,400,000) | (18,700,000) |
Fair value of plan assets at end of year | 312,500,000 | 228,900,000 | $ 212,500,000
Funded status of the plan (underfunded) | 16,500,000 | 12,900,000 |
Amounts recognized in the consolidated balance sheet consist of: |  |  |
Noncurrent assets - prepaid pension asset | 16,500,000 | 12,900,000 |
Accumulated other comprehensive income | 17,700,000 | 37,300,000 |
Net amount included in retained earnings | $ 34,200,000 | $ 50,200,000 |

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- Definition Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 10A -Subparagraph (j) -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-10A Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 10A -Subparagraph (k) -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-10A Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 10A -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-10A Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (j) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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