XML 54 R43.htm IDEA: XBRL DOCUMENT
v3.21.2

Leases - Summary of Operating Leases (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Lessee Lease Description [Line Items] |  |
Operating lease right of use assets, gross | $ 158,827 | $ 159,454
Amortization of right-of-use assets | (54,904) | (32,322)
Total operating lease right-of-use assets | 103,923 | 127,132
Real Estate Facilities |  |
Lessee Lease Description [Line Items] |  |
Operating lease right of use assets, gross | 156,020 | 157,010
Office Equipment |  |
Lessee Lease Description [Line Items] |  |
Operating lease right of use assets, gross | 2,117 | 1,864
Other |  |
Lessee Lease Description [Line Items] |  |
Operating lease right of use assets, gross | $ 690 | $ 580

X
- Definition Operating lease right of use asset amortization. + References No definition available. + Details
Name: | icfi_OperatingLeaseRightOfUseAssetAmortization
Namespace Prefix: | icfi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Operating lease right of use asset gross. + References No definition available. + Details
Name: | icfi_OperatingLeaseRightOfUseAssetGross
Namespace Prefix: | icfi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_LesseeLeaseDescriptionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977 + Details
Name: | us-gaap_OperatingLeaseRightOfUseAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=icfi_RealEstateFacilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_OfficeEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=icfi_OtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |