Savings And Deferred Compensation Plans (Savings Plans) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Sep. 27, 2013	Sep. 28, 2012	Sep. 30, 2011
Savings And Deferred Compensation Plans [Abstract]
Savings plans contributions	$ 74,686	$ 70,211	$ 61,065

Defined Contribution Plan Savings Plans Contributions

No definition available.

Name:	jec_DefinedContributionPlanSavingsPlansContributions
Namespace Prefix:	jec_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration