XML 76 R54.htm IDEA: XBRL DOCUMENT
v3.25.3

Basis of Presentation - Cash and Cash Equivalents and Accounts Receivable (Details) | 12 Months Ended
--- | ---
Sep. 28, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Maximum term of original maturity to classify instrument as cash equivalent | 90 days
Period for billing and collecting unbilled receivables | 12 months

X
- Definition Represents the maximum original term to maturity of an instrument to classify it as a cash equivalent. + References No definition available. + Details
Name: | ttek_MaximumTermOfOriginalMaturityToClassifyAnInstrumentAsCashEquivalent
Namespace Prefix: | ttek_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the period within which substantially all unbilled receivables are expected to be billed and collected. + References No definition available. + Details
Name: | ttek_UnbilledContractsReceivablePeriodForBillingAndCollection
Namespace Prefix: | ttek_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration