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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
	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%

X

- Definition

Defined Benefit Plan, Plan Assets, Corporate Bonds Target Allocation, High Yield Percentage

+ References

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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

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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)
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