XML 43 R31.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Basis of Presentation (Details) | 9 Months Ended
--- | ---
Jul. 01, 2018 segment
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Number of renamed reportable segments | 2

X
- Definition Number Of Renamed Reportable Segments + References No definition available. + Details
Name: | ttek_NumberOfRenamedReportableSegments
Namespace Prefix: | ttek_
Data Type: | xbrli:integerItemType
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