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Benefit Plans (Tables) | 12 Months Ended
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Dec. 31, 2025
Retirement Benefits [Abstract] |
Schedule of Components of Net Periodic Benefit Cost | The components of net periodic benefit cost and other amounts recognized in OCI were as follows:
| Pension benefits |  | Other retirement benefits
($ in millions) | 2025 |  | 2024 |  | 2023 |  | 2025 |  | 2024 |  | 2023
Net periodic benefit cost: |  |  |  |  |  |  |  |  |  |  |
Service cost | $ | 1.3 |  |  | $ | 1.2 |  |  | $ | 1.1 |  |  | $ | — |  |  | $ | — |  |  | $ | — |
Interest cost | 2.4 |  |  | 2.1 |  |  | 2.4 |  |  | 0.2 |  |  | 0.2 |  |  | 0.2 |
Expected return on plan assets | (1.2) |  |  | (1.3) |  |  | (1.2) |  |  | — |  |  | — |  |  | — |
Amortization of actuarial loss (gain) | 0.9 |  |  | 0.6 |  |  | 0.6 |  |  | (1.3) |  |  | (1.6) |  |  | (2.0) |
Settlement loss | — |  |  | — |  |  | 0.1 |  |  | — |  |  | — |  |  | — |
Other | — |  |  | 1.0 |  |  | 0.3 |  |  | — |  |  | — |  |  | 0.4 |
Net periodic benefit cost | $ | 3.4 |  |  | $ | 3.6 |  |  | $ | 3.3 |  |  | $ | (1.1) |  |  | $ | (1.4) |  |  | $ | (1.4) |
Other changes in plan assets and benefit obligations recognized in OCI, pre-tax: |  |  |  |  |  |  |  |  |  |  |
Net (gain) loss arising during period | $ | (3.4) |  |  | $ | (0.7) |  |  | $ | (1.4) |  |  | $ | (0.3) |  |  | $ | (0.5) |  |  | $ | (0.5) |
Amortization of actuarial (loss) gain | (0.9) |  |  | (0.6) |  |  | (0.3) |  |  | 1.3 |  |  | 1.6 |  |  | 2.0 |
Settlement loss | — |  |  | — |  |  | (0.1) |  |  | — |  |  | — |  |  | — |
Foreign currency translation | 0.7 |  |  | (0.2) |  |  | 0.7 |  |  | — |  |  | — |  |  | — |
Other | — |  |  | — |  |  | 0.4 |  |  | — |  |  | — |  |  | — |
Total recognized in OCI | $ | (3.6) |  |  | $ | (1.5) |  |  | $ | (0.7) |  |  | $ | 1.0 |  |  | $ | 1.1 |  |  | $ | 1.5 |
Total recognized in net periodic benefit cost and OCI | $ | (0.2) |  |  | $ | 2.1 |  |  | $ | 2.6 |  |  | $ | (0.1) |  |  | $ | (0.3) |  |  | $ | 0.1 |
Net periodic benefit cost by geographic location is as follows:
| Pension benefits |  | Other retirement benefits
($ in millions) | 2025 |  | 2024 |  | 2023 |  | 2025 |  | 2024 |  | 2023
U.S. plans | $ | 0.4 |  |  | $ | 1.1 |  |  | $ | 0.8 |  |  | $ | (1.1) |  |  | $ | (1.4) |  |  | $ | (1.4) |
International plans | 3.0 |  |  | 2.5 |  |  | 2.5 |  |  | — |  |  | — |  |  | — |
Net periodic benefit cost | $ | 3.4 |  |  | $ | 3.6 |  |  | $ | 3.3 |  |  | $ | (1.1) |  |  | $ | (1.4) |  |  | $ | (1.4) |
Schedule of Changes in Projected Benefit Obligation, Fair Value of Plan Assets and Funded Status | The following table presents the changes in the benefit obligation and the fair value of plan assets, as well as the funded status of the plans:
| Pension benefits |  | Other retirement benefits
($ in millions) | 2025 |  | 2024 |  | 2025 |  | 2024
Change in benefit obligation: |  |  |  |  |  |  |
Benefit obligation, January 1 | $ | (53.2) |  |  | $ | (57.5) |  |  | $ | (3.2) |  |  | $ | (3.7) |
Service cost | (1.3) |  |  | (1.2) |  |  | — |  |  | — |
Interest cost | (2.4) |  |  | (2.1) |  |  | (0.2) |  |  | (0.2) |
Participants’ contributions | — |  |  | (0.1) |  |  | (0.2) |  |  | (0.2) |
Actuarial gain | 1.8 |  |  | 2.2 |  |  | 0.3 |  |  | 0.6 |
Benefits paid | 4.1 |  |  | 3.4 |  |  | 0.3 |  |  | 0.3 |
Foreign currency translation | (5.1) |  |  | 2.1 |  |  | — |  |  | — |
Benefit obligation, December 31 | $ | (56.1) |  |  | $ | (53.2) |  |  | $ | (3.0) |  |  | $ | (3.2) |
Change in plan assets: |  |  |  |  |  |  |
Fair value of assets, January 1 | $ | 29.2 |  |  | $ | 32.3 |  |  | $ | — |  |  | $ | — |
Actual return on plan assets | 1.6 |  |  | (0.6) |  |  | — |  |  | — |
Employer contribution | 1.2 |  |  | 0.7 |  |  | 0.1 |  |  | 0.1 |
Participants’ contributions | — |  |  | 0.1 |  |  | 0.2 |  |  | 0.2 |
Benefits paid | (2.3) |  |  | (2.5) |  |  | (0.3) |  |  | (0.3) |
Foreign currency translation | 2.6 |  |  | (0.8) |  |  | — |  |  | — |
Fair value of assets, December 31 | $ | 32.3 |  |  | $ | 29.2 |  |  | $ | — |  |  | $ | — |
Funded status at end of year | $ | (23.8) |  |  | $ | (24.0) |  |  | $ | (3.0) |  |  | $ | (3.2) |
Schedule of Amounts Recognized in Balance Sheet | Amounts recognized in the balance sheet were as follows:
| Pension benefits |  | Other retirement benefits
($ in millions) | 2025 |  | 2024 |  | 2025 |  | 2024
Noncurrent assets | $ | 4.0 |  |  | $ | 2.9 |  |  | $ | — |  |  | $ | — |
Current liabilities | (1.4) |  |  | (1.4) |  |  | (0.4) |  |  | (0.5) |
Noncurrent liabilities | (26.4) |  |  | (25.5) |  |  | (2.6) |  |  | (2.7) |
| $ | (23.8) |  |  | $ | (24.0) |  |  | $ | (3.0) |  |  | $ | (3.2) |
Schedule of Amounts Recognized in Other Comprehensive Loss | The amounts in accumulated other comprehensive loss, pre-tax, consisted of:
| Pension benefits |  | Other retirement benefits
($ in millions) | 2025 |  | 2024 |  | 2025 |  | 2024
Net actuarial loss (gain) | $ | 10.8 |  |  | $ | 14.4 |  |  | $ | (1.6) |  |  | $ | (2.6) |
Prior service credit | (1.2) |  |  | (1.2) |  |  | — |  |  | — |
Total | $ | 9.6 |  |  | $ | 13.2 |  |  | $ | (1.6) |  |  | $ | (2.6) |
Schedule of Expected Benefit Payments | Benefit payments expected to be paid under our defined benefit pension and other retirement benefit plans in the next ten years are as follows. The expected benefit payments listed correspond to regular ongoing benefit payments expected to be made by the plans during future years.
($ in millions) | Domestic |  | International |  | Total
2026 | $ | 1.0 |  |  | $ | 3.1 |  |  | $ | 4.1 |
2027 | 0.9 |  |  | 3.4 |  |  | 4.3 |
2028 | 0.9 |  |  | 3.3 |  |  | 4.2 |
2029 | 0.9 |  |  | 4.3 |  |  | 5.2 |
2030 | 0.8 |  |  | 3.0 |  |  | 3.8 |
2031 to 2035 | 3.5 |  |  | 21.1 |  |  | 24.6 |
| $ | 8.0 |  |  | $ | 38.2 |  |  | $ | 46.2 |
Schedule of Assumptions Used | Weighted average assumptions used to determine net periodic benefit cost were as follows:
| Pension benefits |  | Other retirement benefits
| 2025 |  | 2024 |  | 2023 |  | 2025 |  | 2024 |  | 2023
Discount rate | 4.38 | % |  | 3.95 | % |  | 4.35 | % |  | 5.60 | % |  | 5.20 | % |  | 5.55 | %
Rate of compensation increase | 3.07 | % |  | 3.08 | % |  | 3.09 | % |  | — |  |  | — |  |  | — |
Expected long-term rate of return on assets | 3.77 | % |  | 4.01 | % |  | 4.22 | % |  | — |  |  | — |  |  | — |
Weighted average assumptions used to determine the benefit obligations were as follows:
| Pension benefits |  | Other retirement benefits
| 2025 |  | 2024 |  | 2025 |  | 2024
Discount rate | 4.58 | % |  | 4.38 | % |  | 5.30 | % |  | 5.60 | %
Rate of compensation increase | 2.97 | % |  | 3.07 | % |  | — |  |  | — |
The weighted average interest crediting rating used to determine net periodic benefit cost by geographic location for our pension plans, at December 31, were as follows:
| 2025 |  | 2024 |  | 2023
U.S. plans | 4.00 | % |  | 4.00 | % |  | 4.00 | %
International plans | 2.34 | % |  | 1.13 | % |  | 1.13 | %
Schedule of Allocation of Plan Assets | The weighted average asset allocations by asset category for our pension plans, at December 31, were as follows:
| 2025 |  | 2024
Equity securities | 22 | % |  | 21 | %
Debt securities | 74 | % |  | 75 | %
Other | 4 | % |  | 4 | %
| 100 | % |  | 100 | %
The following are the target asset allocations and acceptable allocation ranges across:
| Target allocation |  | Allocation range
Equity securities | 19% |  | 15% - 20%
Debt securities | 79% |  | 75% - 85%
Other | 2% |  | 2% - 5%
The following tables present the fair value of our pension plan assets, utilizing the fair value hierarchy discussed in Note 12, Fair Value Measurements. In accordance with U.S. GAAP, certain pension plan assets measured at net asset value (“NAV”) have not been classified in the fair value hierarchy.
| Balance at |  |
| December 31, |  | Basis of Fair Value Measurements
($ in millions) | 2025 |  | Level 1 |  | Level 2 |  | Level 3
Cash | $ | 0.7 |  |  | $ | 0.7 |  |  | $ | — |  |  | $ | — |
Equity securities: |  |  |  |  |  |  |
International mutual funds | 7.1 |  |  | — |  |  | 7.1 |  |  | — |
Fixed income securities: |  |  |  |  |  |  |
International mutual funds | 24.0 |  |  | — |  |  | 24.0 |  |  | — |
Other mutual funds | 0.5 |  |  | — |  |  | 0.5 |  |  | — |
Pension plan assets in the fair value hierarchy | $ | 32.3 |  |  | $ | 0.7 |  |  | $ | 31.6 |  |  | $ | — |
Pension plan assets measured at NAV | — |  |  |  |  |  |  |
Pension plan assets at fair value | $ | 32.3 |  |  |  |  |  |  |
| Balance at |  |
| December 31, |  | Basis of Fair Value Measurements
($ in millions) | 2024 |  | Level 1 |  | Level 2 |  | Level 3
Cash | $ | 0.6 |  |  | $ | 0.6 |  |  | $ | — |  |  | $ | — |
Equity securities: |  |  |  |  |  |  |
International mutual funds | 6.2 |  |  | — |  |  | 6.2 |  |  | — |
Fixed income securities: |  |  |  |  |  |  |
International mutual funds | 21.8 |  |  | — |  |  | 21.8 |  |  | — |
Other mutual funds | 0.6 |  |  | — |  |  | 0.6 |  |  | — |
Pension plan assets in the fair value hierarchy | $ | 29.2 |  |  | $ | 0.6 |  |  | $ | 28.6 |  |  | $ | — |
Pension plan assets measured at NAV | — |  |  |  |  |  |  |
Pension plan assets at fair value | $ | 29.2 |  |  |  |  |  |  |

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