v3.25.4

Income Taxes - (Amounts of Cash Income Taxes Paid) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2025	Dec. 27, 2024	Dec. 29, 2023
Income Tax Paid, by Individual Jurisdiction [Line Items]
Federal	$ 5,600
Total income taxes paid, net of refunds	13,147	$ 11,638	$ 13,257
All other states
Income Tax Paid, by Individual Jurisdiction [Line Items]
State and local	3,392
Other Foreign Jurisdiction [Member]
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign	702
Foreign Tax Jurisdiction [Member] \| New Jersey
Income Tax Paid, by Individual Jurisdiction [Line Items]
State and local	790
Foreign Tax Jurisdiction [Member] \| United Kingdom
Income Tax Paid, by Individual Jurisdiction [Line Items]
Foreign	$ 2,663

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

+ Details

Name:	us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after income tax refund received, of cash paid to federal (national) tax jurisdiction for tax on income.

+ References

+ Details

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

- Definition

Amount, after income tax refund received, of cash paid to foreign tax jurisdiction for tax on income.

+ References

+ Details

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

- Definition

Amount, after income tax refund received, of cash paid to state and local tax jurisdictions for tax on income.

+ References

+ Details

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

- Definition

Amount, after refund, of cash paid to foreign, federal, state, and local jurisdictions as income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-2A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 23
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-22

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-2

+ Details

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

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalTaxJurisdictionOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignTaxJurisdictionOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignCountryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_NJ
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_GB
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

HACKETT GROUP, INC. 10-K