Minimum period the individual is required to perform services to be fully vested under the deferred compensation arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Retirement Plans - Additional Information (Detail) $ in Millions	12 Months Ended
	Sep. 29, 2017 USD ($) plan	Sep. 30, 2016 USD ($)	Oct. 02, 2015 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total retirement, post-retirement benefit plan and defined benefit plan expense	$ 30.1	$ 29.8	$ 28.7
Accumulated benefit obligation for defined benefit pension plans	$ 199.0	$ 190.1
Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target percentage allocation	30.00%
Debt and fixed income assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target percentage allocation	60.00%
Real Estate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target percentage allocation	3.00%
Other
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target percentage allocation	7.00%
U.K. Savings Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of plans \| plan	5
Defined Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	1.40%	1.03%
Rate of projected compensation increase (as a percent)	2.40%	2.33%
Contributions by employer	$ 8.2	$ 8.0	$ 6.7
Expected total contribution to the defined benefit plans for the next year	$ 8.7
Defined Benefit Plans \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	0.60%
Rate of projected compensation increase (as a percent)	1.75%
Defined Benefit Plans \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	2.70%
Rate of projected compensation increase (as a percent)	3.70%
Defined Benefit Plans \| Domestic Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum eligible participant compensation that company matches under defined contribution plan (as a percent)	6.00%
Defined Benefit Plans \| Domestic Plan \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, annual contributions per employee (percent)	1.00%
Defined Benefit Plans \| Domestic Plan \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, annual contributions per employee (percent)	25.00%
Contribution as percentage on after-tax basis (as a percent)	15.00%
Defined Benefit Plans \| U.K. Savings Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Maximum eligible participant compensation that company matches under defined contribution plan (as a percent)	6.00%
Defined Benefit Plans \| U.K. Savings Plan \| Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, annual contributions per employee (percent)	4.00%
Defined Benefit Plans \| U.K. Savings Plan \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, annual contributions per employee (percent)	100.00%
Other Postretirement Benefits Plan \| Domestic Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Years of service for 100% vesting	1 year