Retirement Plans - Schedule of Fair Values of Plan Assets (Detail) - USD ($) $ in Millions	Oct. 02, 2015	Sep. 26, 2014
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 189.9	$ 188.6
Mutual funds - equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	42.7	51.7
Mutual funds - debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	35.5	32.5
Mutual funds - real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.4	3.6
Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	3.4
Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	102.9	99.1
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1.0	1.7
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1.0	1.7
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
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	1.0	1.7
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	188.9	186.9
Significant Other Observable Inputs (Level 2) | Mutual funds - equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	42.7	51.7
Significant Other Observable Inputs (Level 2) | Mutual funds - debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	35.5	32.5
Significant Other Observable Inputs (Level 2) | Mutual funds - real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.4	3.6
Significant Other Observable Inputs (Level 2) | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	3.4
Significant Other Observable Inputs (Level 2) | Insurance contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	102.9	99.1
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
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