Fair Value Measurements - Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 26, 2020	Sep. 28, 2019
Assets:
Assets measured at fair value on a recurring basis	$ 11.2	$ 7.7
Liabilities:
Liabilities measured at fair value on a recurring basis	113.0	9.2
Quoted Prices in Active Market for Identical Assets (Level 1)
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0	0.0
Significant Other Observable Inputs (Level 2)
Assets:
Assets measured at fair value on a recurring basis	11.2	7.7
Liabilities:
Liabilities measured at fair value on a recurring basis	31.2	0.1
Significant Unobservable Inputs (Level 3)
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Liabilities:
Liabilities measured at fair value on a recurring basis	81.8	9.1
Interest rate caps - derivative
Assets:
Interest rate caps - derivative	0.0	0.1
Interest rate caps - derivative | Quoted Prices in Active Market for Identical Assets (Level 1)
Assets:
Interest rate caps - derivative		0.0
Interest rate caps - derivative | Significant Other Observable Inputs (Level 2)
Assets:
Interest rate caps - derivative		0.1
Interest rate caps - derivative | Significant Unobservable Inputs (Level 3)
Assets:
Interest rate caps - derivative		0.0
Interest rate caps - derivative | Assets
Assets:
Interest rate caps - derivative		0.1
Interest Rate Swap [Member]
Assets:
Assets measured at fair value on a recurring basis	31.2	4.7
Interest rate caps - derivative	31.2
Interest Rate Swap [Member] | Quoted Prices in Active Market for Identical Assets (Level 1)
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Interest Rate Swap [Member] | Significant Other Observable Inputs (Level 2)
Assets:
Assets measured at fair value on a recurring basis	31.2	4.7
Interest Rate Swap [Member] | Significant Unobservable Inputs (Level 3)
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Stock Options
Assets:
Forward foreign currency contracts	10.1	2.0
Stock Options | Assets | Quoted Prices in Active Market for Identical Assets (Level 1)
Assets:
Forward foreign currency contracts	0.0	0.0
Stock Options | Assets | Significant Other Observable Inputs (Level 2)
Assets:
Forward foreign currency contracts	10.1	2.0
Stock Options | Assets | Significant Unobservable Inputs (Level 3)
Assets:
Forward foreign currency contracts	0.0	0.0
Forward foreign currency contracts
Liabilities:
Liabilities measured at fair value on a recurring basis		0.1
Forward foreign currency contracts | Quoted Prices in Active Market for Identical Assets (Level 1)
Liabilities:
Liabilities measured at fair value on a recurring basis		0.0
Forward foreign currency contracts | Significant Other Observable Inputs (Level 2)
Liabilities:
Liabilities measured at fair value on a recurring basis		0.1
Forward foreign currency contracts | Significant Unobservable Inputs (Level 3)
Liabilities:
Liabilities measured at fair value on a recurring basis		0.0
Forward foreign currency contracts | Assets
Assets:
Forward foreign currency contracts	1.1	0.9
Forward foreign currency contracts | Assets | Quoted Prices in Active Market for Identical Assets (Level 1)
Assets:
Forward foreign currency contracts	0.0	0.0
Forward foreign currency contracts | Assets | Significant Other Observable Inputs (Level 2)
Assets:
Forward foreign currency contracts	1.1	0.9
Forward foreign currency contracts | Assets | Significant Unobservable Inputs (Level 3)
Assets:
Forward foreign currency contracts	0.0	0.0
contingent consideration
Liabilities:
Liabilities measured at fair value on a recurring basis	81.8	9.1
contingent consideration | Quoted Prices in Active Market for Identical Assets (Level 1)
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0	0.0
contingent consideration | Significant Other Observable Inputs (Level 2)
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0	0.0
contingent consideration | Significant Unobservable Inputs (Level 3)
Liabilities:
Liabilities measured at fair value on a recurring basis	$ 81.8	$ 9.1