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Basis of Presentation and Preparation - Goodwill and Intangible Assets (Details) | 12 Months Ended
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Oct. 01, 2023 level
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Number of levels below operating/reportable segments at which goodwill impairment testing is performed | 1

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- Definition Represents the number of levels below reportable segments at which the reporting units reside for which goodwill impairment testing is performed. + References No definition available. + Details
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Namespace Prefix: | ttek_
Data Type: | xbrli:integerItemType
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Period Type: | duration

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- References No definition available. + Details
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