XML 62 R46.htm IDEA: XBRL DOCUMENT v3.10.0.1

Description of Business and Basis of Presentation (Details)	3 Months Ended		12 Months Ended
	Mar. 30, 2018 Business	Mar. 27, 2015 Business	Sep. 28, 2018 segment	Sep. 29, 2017	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cost-reimbursable			76.00%	81.00%	82.00%
Fixed-price			24.00%	19.00%	18.00%
Number of operating and reporting structure of business	3	4	3

X

- Definition

Number of operating and reporting structure of business.

+ References

No definition available.

+ Details

Name:	jec_NumberOfOperatingAndReportingStructureOfBusiness
Namespace Prefix:	jec_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Revenue From Cost Reimbursable Contracts Percentage

+ References

No definition available.

+ Details

Name:	jec_RevenueFromCostReimbursableContractsPercentage
Namespace Prefix:	jec_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Revenue From Fixed Price Contracts Percentage

+ References

No definition available.

+ Details

Name:	jec_RevenueFromFixedPriceContractsPercentage
Namespace Prefix:	jec_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- References

No definition available.

+ Details

Name:	us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration