Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Oct. 02, 2015
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	$ 95.3	$ 93.0
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
Total assets measured at fair value	95.3	93.0
Contingent consideration	(1.3)	(4.1)
Total liabilities measured at fair value	(1.3)	(4.1)
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Instruments (Level 1)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
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
Total assets measured at fair value	0.0	9.1
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
Total assets measured at fair value	95.3	83.9
Contingent consideration	(1.3)	(4.1)
Total liabilities measured at fair value	(1.3)	(4.1)
Fair Value, Measurements, Recurring | Corporate debt securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities:	95.3	92.3
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:	0.0	8.4
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:	$ 95.3	83.9
Fair Value, Measurements, Recurring | Non-U.S. government security
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Non-U.S. government security		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
Non-U.S. government security		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
Non-U.S. government security		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
Non-U.S. government security		$ 0.0