Restructuring and Severance Charges - Additional Information (Detail) $ in Millions	12 Months Ended
	Oct. 01, 2017 USD ($)
Schedule of Status of Facilities by Location [Line Items]
Document Fiscal Year Focus	2017
Employee Severance
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Reversal of Prior Provision	$ 14.7
Other Associated Costs
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Settlement and Impairment Provisions	1.9
Other Facilities
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Settlement and Impairment Provisions	23.6
Reversal of prior provision	(0.4)
Other Facilities | Employee Severance
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Settlement and Impairment Provisions	15.0
Reversal of prior provision	(0.3)
Other Facilities | Contract Termination Costs
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Settlement and Impairment Provisions	6.7
Reversal of prior provision	(0.1)
Other Facilities | Other Associated Costs
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Settlement and Impairment Provisions	1.9
Reversal of prior provision	$ 0.0