Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Dec. 27, 2013	Sep. 27, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Corporate debt security	$ 74.0	$ 62.7
Derivative assets	3.0
Option to purchase a company	1.4	1.4
Total assets measured at fair value	98.4	114.1
Derivative liabilities	(0.5)	(1.1)
Contingent consideration	(2.3)	(2.5)
Total liabilities measured at fair value	(2.8)	(3.6)
Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	20.0	50.0
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Corporate debt security	0	0
Derivative assets	0
Option to purchase a company	0	0
Total assets measured at fair value	20.0	50.0
Derivative liabilities	0	0
Contingent consideration	0	0
Total liabilities measured at fair value	0	0
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	20.0	50.0
Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Corporate debt security	0	0
Derivative assets	3.0
Option to purchase a company	0	0
Total assets measured at fair value	3.0	0
Derivative liabilities	(0.5)	(1.1)
Contingent consideration	0	0
Total liabilities measured at fair value	(0.5)	(1.1)
Significant Other Observable Inputs (Level 2) | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Corporate debt security	74.0	62.7
Derivative assets	0
Option to purchase a company	1.4	1.4
Total assets measured at fair value	75.4	64.1
Derivative liabilities	0	0
Contingent consideration	(2.3)	(2.5)
Total liabilities measured at fair value	(2.3)	(2.5)
Significant Unobservable Inputs (Level 3) | Money market funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 0	$ 0