Increase (Decrease) Revenue From Contracts With Customers

No definition available.

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Namespace Prefix:	iclr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130531-203044

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130532-203044

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130549-203045

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
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-Section 55
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-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

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-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Impact of New Accounting Pronouncements (Details) - USD ($)	6 Months Ended
	Dec. 31, 2021	Jul. 01, 2021	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill	$ 9,037,931,000		$ 936,257,000	$ 883,170,000
Accounting Standards Update 2021-08
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Goodwill		$ 16,000,000
Contract with customer, liability		$ 16,000,000
Contract with customer, liability, revenue recognized	4,000,000
Increase (decrease) in revenue from contracts with customers	$ 0