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Note 16 - Retirement Benefit Plans (Details Textual) $ in Millions |  | 12 Months Ended
--- | --- | ---
Jan. 01, 2025 | Dec. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($)
Number of Plans |  | 2 |  |
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay |  | 5.00% |  |
Defined Contribution Plan, Employer Matching Contribution, Additional One Time Percent Match |  | 1.00% |  |
Defined Contribution Plan, Cost |  | $ 10.1 | $ 8.1 | $ 8.6
Expected Rate of Return on Plan Assets |  | 4.10% |  |
Pension Plan [Member] |  |  |  |
Defined Benefit Plan Surplus On Triennial Valuation Of H G P S |  | $ 2.4 |  |
Defined Benefit Plan, Benefit Obligation, Payment for Settlement |  | 9.6 |  |
Defined Benefit Plan, Plan Assets, Amount |  | $ 625.1 | $ 696.4 | 660.5
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage |  | 100.00% | 100.00% |
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss) |  | $ (11.7) | $ 39.6 |
Expected Rate of Return on Plan Assets |  |  | 4.40% |
Defined Benefit Plan, Plan Assets, Contributions by Employer, Excluding Credits to Member's Money Purchase Accounts |  | 2.4 |  |
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year |  | 2.4 |  |
Pension Plan [Member] | JHG-managed Funds [Member] |  |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 93.9 | $ 103.4 |
Pension Plan [Member] | Bulk Annuity Policy [Member] |  |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 217.7 | 240.7 |
Defined Benefit Plan, Change in Financial Condition |  | (21.9) |  |
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss) |  | 4.2 |  |
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Purchase, Sale, and Settlement |  | 14.5 |  |
Defined Benefit Plan, Interest on Bulk Annuity Asset |  | 9.9 |  |
Defined Benefit Plan Change in Financial Conditions |  | 7.6 |  |
Defined Benefit Plan Change in Demographic Assumptions |  | 0.1 |  |
Foreign Plan [Member] |  |  |  |
Defined Contribution Plan, Contribution Amount |  | $ 17.3 | $ 14.0 | $ 15.7
Subsequent Event [Member] |  |  |  |
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay | 6.00% |  |  |

X
- Definition Increase (decrease) in defined benefit plan assets due to changes in demographic assumptions. + References No definition available. + Details
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- Definition The amount of change in financial condition to the defined benefit plan + References No definition available. + Details
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- Definition Increase (decrease) in defined benefit plan assets due to changes in financial conditions. + References No definition available. + Details
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- Definition The amount of interest expense on bulk annuity assets under the defined benefit plan during the reporting period. + References No definition available. + Details
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- Definition Amount of contribution received by defined benefit plan from employer excluding credits to member's money purchase accounts, which increases plan assets. + References No definition available. + Details
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- Definition The amount of surplus on a technical provisions basis of latest triennial valuation of Henderson Group Pension Scheme (HGPS). + References No definition available. + Details
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- Definition Amount of contributions to a defined contribution plan. + References No definition available. + Details
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- Definition The additional percentage of the additional one time percent match or the contribution plan. + References No definition available. + Details
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- Definition Percentage of expected rate of return on plan assets derived by taking the weighted average of the long term expected rate of return on each of the asset classes in HGPS's target asset allocation. + References No definition available. + Details
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- Definition The number of benefit plans. + References No definition available. + Details
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- Definition Amount of payment, which decreases benefit obligation of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract. Excludes decreases to benefit obligation for remeasurement due to settlement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a)(10) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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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. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-18 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (g) -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 of foreign currency translation gain (loss) which increases (decreases) plan assets of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Amount, measured using unobservable input, of increase (decrease) in plan asset of defined benefit plan from purchase, sale and settlement of trade associated with underlying investment. + 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)(B) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 70 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480794/715-70-50-1 + Details
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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
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