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Segment Information (Revenues Earned Directly Or Indirectly From The U.S. Federal Government And Its Agencies) (Details) | 12 Months Ended
--- | ---
Sep. 30, 2011 | Oct. 01, 2010 | Oct. 02, 2009 | Sep. 26, 2008
Percentage of revenue earned from the U.S. federal government and its agencies | 24.40% | 25.40% | 20.30% |
Percentage of revenue earned |  |  |  | 10.00%
Motiva Enterprises LLC [Member] |  |  |  |
Percentage of revenue earned |  |  | 12.20% |

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- Definition Percentage of revenue earned from the U.S. federal government and their agencies + Details
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Namespace Prefix: | jec
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration