XML 132 R116.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Business Segment and Geographical Information - Distribution of Income from Operations, Excluding Restructuring, by Geographical Area (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Segment Reporting Information [Line Items] |  |  |
Income from operations, excluding restructuring and other items | $ 607,897 | $ 408,830 | $ 433,406
Ireland |  |  |
Segment Reporting Information [Line Items] |  |  |
Income from operations, excluding restructuring and other items | 161,862 | 295,360 | 314,287
Rest of Europe |  |  |
Segment Reporting Information [Line Items] |  |  |
Income from operations, excluding restructuring and other items | 183,436 | 35,402 | 37,997
U.S. |  |  |
Segment Reporting Information [Line Items] |  |  |
Income from operations, excluding restructuring and other items | 231,971 | 56,921 | 60,272
Other |  |  |
Segment Reporting Information [Line Items] |  |  |
Income from operations, excluding restructuring and other items | $ 30,628 | $ 21,147 | $ 20,850

X
- Definition Operating Income (Loss) Before Restructuring Charges, Transaction And Integration Expenses + References No definition available. + Details
Name: | iclr_OperatingIncomeLossBeforeRestructuringChargesTransactionAndIntegrationExpenses
Namespace Prefix: | iclr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_StatementGeographicalAxis=country_IE
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=iclr_RestOfEuropeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=iclr_OtherCountriesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |