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Employee Benefits - Expected Rate of Return and Actual Plan Asset Allocation (Details) - ICON Development Solutions Limited pension plan | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items] |  |  |
High yield percentage of corporate bond investment | 50.00% |  |
44561 | 3.80% |  |
Actual plan asset allocations | 100.00% | 100.00% |
Corporate Bonds (including 50% high yield bonds) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
44561 | 2.80% | 2.80% |
Actual plan asset allocations | 37.00% | 40.00% |
Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
44561 | 5.50% | 5.20% |
Actual plan asset allocations | 24.00% | 21.00% |
Secured Loans and Multi Asset Credit |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
44561 | 3.00% | 3.00% |
Actual plan asset allocations | 39.00% | 39.00% |
United Kingdom |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
44561 | 3.40% | 4.00% | 2.10%

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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2919-114920 + 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 -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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