Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Oct. 02, 2015	Sep. 26, 2014
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	$ 93.0	$ 75.6
Non-U.S. government security
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	0.7
Fair Value, Measurements, Recurring
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Derivative assets		1.5
Total assets measured at fair value	93.0	77.1
Contingent consideration	(4.1)	(7.5)
Total liabilities measured at fair value	(4.1)	(7.5)
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Derivative assets		0.0
Total assets measured at fair value	0.0	0.0
Contingent consideration	0.0	0.0
Total liabilities measured at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Derivative assets		1.5
Total assets measured at fair value	9.1	1.5
Contingent consideration	0.0	0.0
Total liabilities measured at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Derivative assets		0.0
Total assets measured at fair value	83.9	75.6
Contingent consideration	(4.1)	(7.5)
Total liabilities measured at fair value	(4.1)	(7.5)
Fair Value, Measurements, Recurring | Corporate debt securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	92.3	75.6
Fair Value, Measurements, Recurring | Corporate debt securities | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	0.0	0.0
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Other Observable Inputs (Level 2)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	8.4	0.0
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Unobservable Inputs (Level 3)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	83.9	$ 75.6
Fair Value, Measurements, Recurring | Non-U.S. government security
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	0.7
Fair Value, Measurements, Recurring | Non-U.S. government security | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	0.0
Fair Value, Measurements, Recurring | Non-U.S. government security | Significant Other Observable Inputs (Level 2)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	0.7
Fair Value, Measurements, Recurring | Non-U.S. government security | Significant Unobservable Inputs (Level 3)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	$ 0.0