Retirement Plans - Schedule of Fair Values of Plan Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Oct. 02, 2015
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 202.9	$ 189.9
Mutual funds - equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	52.3	42.7
Mutual funds - debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	27.2	35.5
Mutual funds - real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.7	4.4
Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	2.9	3.4
Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	115.5	102.9
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.3	1.0
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.3	1.0
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) | 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) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.3	1.0
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	202.6	188.9
Significant Other Observable Inputs (Level 2) | Mutual funds - equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	52.3	42.7
Significant Other Observable Inputs (Level 2) | Mutual funds - debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	27.2	35.5
Significant Other Observable Inputs (Level 2) | Mutual funds - real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.7	4.4
Significant Other Observable Inputs (Level 2) | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	2.9	3.4
Significant Other Observable Inputs (Level 2) | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	115.5	102.9
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	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) | 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) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 0.0	$ 0.0