Retirement Plans - Schedule of Fair Values of Plan Assets (Detail) - USD ($) $ in Millions	Oct. 02, 2020	Sep. 27, 2019
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 301.1	$ 254.2
Mutual funds - equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	41.1	51.9
Mutual funds - debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	139.3	112.5
Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets		4.0
Mutual funds - real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	44.4	43.9
Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	40.6	27.1
Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	13.3	13.0
Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	9.3
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	13.1	1.8
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	13.1	1.8
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Mutual funds - equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Mutual funds - debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0.0
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Mutual funds - real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	13.1	1.8
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	288.0	252.4
Significant Other Observable Inputs (Level 2) | Mutual funds - equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	41.1	51.9
Significant Other Observable Inputs (Level 2) | Mutual funds - debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	139.3	112.5
Significant Other Observable Inputs (Level 2) | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets		4.0
Significant Other Observable Inputs (Level 2) | Mutual funds - real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	44.4	43.9
Significant Other Observable Inputs (Level 2) | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	40.6	27.1
Significant Other Observable Inputs (Level 2) | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	13.3	13.0
Significant Other Observable Inputs (Level 2) | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	9.3
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0.0
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Mutual funds - equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Mutual funds - debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0.0
Significant Unobservable Inputs (Level 3) | Mutual funds - real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Significant Unobservable Inputs (Level 3) | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0
Significant Unobservable Inputs (Level 3) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 0.0	$ 0.0