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Employee Benefits - Net Periodic Pension Benefit Cost Assumptions (Details) - ICON Development Solutions Limited pension plan - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected rate of return on plan assets | 3.80% |  |
United Kingdom |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Discount rate | 1.50% | 2.10% | 2.90%
Rate of compensation increase | 3.40% | 3.30% | 3.70%
Expected rate of return on plan assets | 3.40% | 4.00% | 2.10%
Other comprehensive income |  |  |
Actuarial (gain)/loss - benefit obligation | $ (2,097) | $ 5,294 | $ 4,756
Actuarial gain – plan assets | (1,176) | (878) | (2,930)
Actuarial loss recognized in net periodic benefit cost | (625) | (160) | (67)
Total | $ (3,898) | $ 4,256 | $ 1,759

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- Definition Weighted average rate for present value of future retirement benefits cash flows, 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)(1) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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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 Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related 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)(2) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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