Comprehensive Income (Details) (USD $) In Thousands	3 Months Ended	9 Months Ended
Jul. 03, 2011	Jun. 27, 2010	Jul. 03, 2011	Jun. 27, 2010
Comprehensive Income
Net income including noncontrolling interests	$ 24,748	$ 20,639	$ 65,583	$ 53,678
Other comprehensive income:
Foreign currency translation adjustment	1,947	(987)	22,532	5,089
Foreign currency hedge	5	112	(320)	(242)
Comprehensive income including noncontrolling interests	26,700	19,764	87,795	58,525
Net income attributable to noncontrolling interests	(909)		(1,944)
Foreign currency translation adjustment	(68)		(815)
Comprehensive income attributable to noncontrolling interests	(977)		(2,759)
Comprehensive income attributable to Tetra Tech	$ 25,723	$ 19,764	$ 85,036	$ 58,525

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The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to noncontrolling interests, if any. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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The portion of net income (loss) attributable to the noncontrolling interest (if any) deducted in order to derive the portion attributable to the parent.

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Adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity, net of tax.

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Adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity, net of tax, attributable to noncontrolling interest.

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Change in accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges, net of tax effect. The after tax effect change includes an entity's share of an equity investee's increase (decrease) in deferred hedging gains or losses.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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