Segment Information - Schedule of Transaction Costs Associated With Acquisition (Details) - CH2M HILL Companies, Ltd. $ in Millions	3 Months Ended
Dec. 29, 2017 USD ($)
Business Acquisition [Line Items]
Personnel costs	$ 41,222
Professional service, real estate-related, and other expenses	26,675
Total	$ 67,897

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

No definition available.

Name:	us-gaap_BusinessCombinationIntegrationRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration