XML 62 R52.htm IDEA: XBRL DOCUMENT
v3.23.1

Income Taxes - Additional Information (Details) | 3 Months Ended
--- | ---
Mar. 31, 2023 | Mar. 31, 2022
Income Taxes [Line Items] |  |
Effective income tax rate reconciliation, percent | 23.50% | 27.50%
Internal Revenue Service (IRS) | Latest Tax Year |  |
Income Taxes [Line Items] |  |
Open tax year | 2021 |
Internal Revenue Service (IRS) | Earliest Tax Year |  |
Income Taxes [Line Items] |  |
Open tax year | 2019 |
State Local and Foreign Jurisdictions | Latest Tax Year |  |
Income Taxes [Line Items] |  |
Open tax year | 2021 |
State Local and Foreign Jurisdictions | Earliest Tax Year |  |
Income Taxes [Line Items] |  |
Open tax year | 2018 |

X
- Definition Income taxes. + References No definition available. + Details
Name: | icfi_IncomeTaxesLineItems
Namespace Prefix: | icfi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32687-109319 + Details
Name: | us-gaap_EffectiveIncomeTaxRateContinuingOperations
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tax year that remains open to examination under enacted tax laws, in YYYY format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (e) -URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319 + Details
Name: | us-gaap_OpenTaxYear
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:gYearListItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeTaxAuthorityNameAxis=us-gaap_InternalRevenueServiceIRSMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TaxPeriodAxis=us-gaap_LatestTaxYearMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TaxPeriodAxis=us-gaap_EarliestTaxYearMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityNameAxis=icfi_StateAndForeignJurisdictionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |