Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

+ Details

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- Definition

Represents the portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing the amount excluded from the assessment of hedge effectiveness.

+ References

No definition available.

+ Details

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- Definition

Represents the number of derivative agreements entered into by the entity during the reporting period.

+ References

No definition available.

+ Details

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Namespace Prefix:	ttek_
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Balance Type:	na
Period Type:	duration

- Definition

Average fixed interest rate related to the group of interest rate derivatives.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Estimated period for the anticipated transfer of gain (loss), net, from accumulated other comprehensive income into earnings, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Details

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Namespace Prefix:	us-gaap_
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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 29, 2013 item	Jun. 29, 2014	Sep. 29, 2013 item
Not Designated as Hedging Instrument [Member]
Derivative financial instruments
Number of derivative instruments		0	0
Interest Rate Swap [Member]
Derivative financial instruments
Notional Amount		$ 205.0
Weighted average fixed rate		1.32%
Interest Rate Swap [Member] \| Designated as Hedging Instrument [Member]
Derivative financial instruments
Amounts excluded from effectiveness testing		$ 0
Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| Designated as Hedging Instrument [Member]
Derivative financial instruments
Number of derivative agreements	2		3
Period of reclassification from accumulated other comprehensive income to interest expense		12 months