Restructuring and Severance Charges - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 02, 2016	Sep. 27, 2015	Sep. 28, 2014
Schedule of Status of Facilities by Location [Line Items]
Recorded severance accruals	$ 4.2	$ 3.4
Restructuring and severance charges	60.7	15.4	$ 31.5
Employee Severance
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Reversal of Prior Provision	52.0
Restructuring, Settlement and Impairment Provisions	55.4
Contract Termination Costs
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Settlement and Impairment Provisions	5.1
Restructuring Reserve, Accrual Adjustment	(0.3)
Other Associated Costs
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Settlement and Impairment Provisions	4.2	4.0
Other Facilities
Schedule of Status of Facilities by Location [Line Items]
Restructuring, Settlement and Impairment Provisions	64.7
Restructuring Reserve, Accrual Adjustment	(3.9)
Payments for Restructuring	36.2
Restructuring Reserve, Settled without Cash	26.3
Recorded severance accruals	7.5	6.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Restructuring Liabilities	3.0
Other Facilities | Employee Severance
Schedule of Status of Facilities by Location [Line Items]
Restructuring Reserve, Accrual Adjustment	(3.4)
Payments for Restructuring	32.4
Restructuring Reserve, Settled without Cash	22.9
Recorded severance accruals	2.5	2.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Restructuring Liabilities	2.9
Other Facilities | Contract Termination Costs
Schedule of Status of Facilities by Location [Line Items]
Payments for Restructuring	2.9
Restructuring Reserve, Settled without Cash	0.5
Recorded severance accruals	4.6	3.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Restructuring Liabilities	0.0
Other Facilities | Other Associated Costs
Schedule of Status of Facilities by Location [Line Items]
Restructuring Reserve, Accrual Adjustment	(0.2)
Payments for Restructuring	0.9
Restructuring Reserve, Settled without Cash	2.9
Recorded severance accruals	0.4	$ 0.1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Restructuring Liabilities	0.1
Vitesse | Employee Severance
Schedule of Status of Facilities by Location [Line Items]
Restructuring and severance charges	$ 45.6