Schedule of Fair Values of Plan Assets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 28, 2012	Sep. 30, 2011
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 142.6	$ 125.5
Corporate Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0.1
Mutual Funds Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	40.3	32.4
Mutual Funds Debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	23.2	20.6
Mutual Funds Real Estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	3.5	3.2
Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	73.3	67.9
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	2.3	1.3
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	2.3	1.4
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Corporate Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0.1
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Mutual Funds Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	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
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Mutual Funds Real Estate
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
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	2.3	1.3
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	140.3	124.1
Significant Other Observable Inputs (Level 2) | Corporate Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0
Significant Other Observable Inputs (Level 2) | Mutual Funds Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	40.3	32.4
Significant Other Observable Inputs (Level 2) | Mutual Funds Debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	23.2	20.6
Significant Other Observable Inputs (Level 2) | Mutual Funds Real Estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	3.5	3.2
Significant Other Observable Inputs (Level 2) | Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	73.3	67.9
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
Significant Unobservable Inputs (Level 3) | Corporate Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0
Significant Unobservable Inputs (Level 3) | Mutual Funds Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Significant Unobservable Inputs (Level 3) | Mutual Funds Debt
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
Significant Unobservable Inputs (Level 3) | Insurance Contracts
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