XML 78 R62.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Goodwill and Intangible Assets - Narrative (Details) |  |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jul. 03, 2017 USD ($) reporting_unit | Jun. 30, 2014 | Sep. 27, 2015 USD ($) | Oct. 01, 2017 USD ($) | Oct. 02, 2016 USD ($) | Sep. 27, 2015 USD ($)
Goodwill [Line Items] |  |  |  |  |  |
Impairment of goodwill | $ 0 |  | $ 58,100,000 |  |  |
Number of reporting units having fair value in excess of carrying value of less than 20%. | reporting_unit | 0 |  |  |  |  |
Impairment of goodwill and other intangible assets |  |  | 60,800,000 | $ 0 | $ 0 | $ 60,763,000
Impairment of goodwill and other intangible assets, net of tax |  |  | 57,300,000 |  |  |
Identifiable intangible assets that were determined not to be recoverable |  |  | $ 2,700,000 |  |  |
Minimum |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Percentage of excess of fair value over carrying value | 20.00% |  |  |  |  |
WEI |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Gross amounts of goodwill |  |  |  | 324,100,000 | 304,400,000 |
Accumulated impairment |  |  |  | 82,400,000 | 82,400,000 |
RME |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Gross amounts of goodwill |  |  |  | 532,400,000 | 529,200,000 |
Accumulated impairment |  |  |  | $ 33,200,000 | $ 33,200,000 |
GMP | RME |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Percentage of decline in revenue |  |  | 25.00% |  |  |
Annual revenue growth rate (as a percent) |  | 3.00% |  |  |  |

X
- Definition Amount of impairment loss resulting from write-down of assets, including financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value. + References No definition available. + Details
Name: | ttek_ImpairmentOfIntangibleAssetsIndefiniteLivedIncludingGoodwill
Namespace Prefix: | ttek_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of impairment loss after tax resulting from write-down of assets, including financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value. + References No definition available. + Details
Name: | ttek_ImpairmentOfIntangibleAssetsIndefiniteLivedIncludingGoodwillNetOfTax
Namespace Prefix: | ttek_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents number of units with goodwill determined to have fair value in excess of carrying value of less than 20%. + References No definition available. + Details
Name: | ttek_NumberOfReportingUnitsHavingFairValueInExcessOfCarryingValueOfLessThanTwentyPercent
Namespace Prefix: | ttek_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage by which revenue had declined. + References No definition available. + Details
Name: | ttek_PercentageOfDeclineInRevenue
Namespace Prefix: | ttek_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of assumed long-term growth in revenues, used as an input to measure fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueInputsLongTermRevenueGrowthRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a,h) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
Name: | us-gaap_GoodwillGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a,h) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
Name: | us-gaap_GoodwillImpairedAccumulatedImpairmentLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13854-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13777-109266 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
Name: | us-gaap_GoodwillImpairmentLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of an intangible asset (excluding goodwill) to fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
Name: | us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of fair value of reporting unit in excess of carrying amount. + References No definition available. + Details
Name: | us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ttek_WaterEnvironmentAndInfrastructureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ttek_ResourceManagementAndEnergyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsegmentsAxis=ttek_GlobalMiningPracticeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |