Name:	ttek_BusinessCombinationContingentConsiderationPaymentPeriod
Namespace Prefix:	ttek_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents a number of financial institutions, in any such number of which the entity limits the amount of investment exposure in order to control credit risk.

No definition available.

Name:	ttek_ConcentrationOfCreditRiskNumberOfFinancialInstitutionsForInvestmentExposure
Namespace Prefix:	ttek_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ttek_GoodwillAndIntangibleAssetsAbstract
Namespace Prefix:	ttek_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Represents the number of levels below reportable segments at which the reporting units reside for which goodwill impairment testing is performed.

No definition available.

Name:	ttek_NumberOfLevelsBelowReportableSegmentsForGoodwillImpairmentTesting
Namespace Prefix:	ttek_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of steps involved in the process of goodwill annual impairment test.

No definition available.

Name:	ttek_NumberOfStepsInvolvedInProcessOfGoodwillAnnualImpairmentTest
Namespace Prefix:	ttek_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of accounts receivable due from various agencies of the U.S. federal government.

No definition available.

Name:	ttek_PercentageOfAccountReceivablesDueFromAgencies
Namespace Prefix:	ttek_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The maximum useful life of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar either by their nature or by their use in the operations of a company.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 35

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6904245&loc=d3e15217-109273

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 35

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6904245&loc=d3e15300-109273

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 35

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6904245&loc=d3e15211-109273

Name:	us-gaap_FiniteLivedIntangibleAssetsUsefulLifeMaximum
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

The minimum useful life of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar either by their nature or by their use in the operations of a company.