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Business Combination, Restructuring and Integration Related Costs, Before Tax

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Restructuring pre-tax net charges.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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Restructuring and Other Charges - Narrative (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 30, 2018 Business	Mar. 27, 2015 Business	Sep. 28, 2018 USD ($) segment	Sep. 29, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring pre-tax net charges				$ 22.6
Restructuring and integration related costs, before tax			$ 190.8
Net realizable value write-offs on contract accounts receivables				16.5
Statutory redundancy and severance costs				1.4
Other liabilities				$ 4.7
Number of lines of business	3	4	3
CH2M HILL Companies, Ltd.
Restructuring Cost and Reserve [Line Items]
Restructuring pre-tax net charges			$ 101.7
Integration related costs			$ 89.2