Fair Value Measurements - Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 30, 2017	Sep. 30, 2017
Assets:
Assets measured at fair value on a recurring basis	$ 5.7
Interest Rate Cash Flow Hedge Asset at Fair Value		$ 4.8
Liabilities:
Liabilities measured at fair value on a recurring basis	52.3
Foreign Exchange Contract [Member]
Assets:
Foreign Currency Contract, Asset, Fair Value Disclosure	0.4
Deferred compensation liabilities
Liabilities:
Liabilities measured at fair value on a recurring basis	49.7
Quoted Prices in Active Market for Identical Assets (Level 1)
Assets:
Assets measured at fair value on a recurring basis	0.0
Liabilities:
Liabilities measured at fair value on a recurring basis	49.7
Quoted Prices in Active Market for Identical Assets (Level 1) | Interest rate cap - derivative
Assets:
Assets measured at fair value on a recurring basis	0.0
Interest Rate Cash Flow Hedge Asset at Fair Value	5.3
Quoted Prices in Active Market for Identical Assets (Level 1) | Foreign Exchange Contract [Member]
Assets:
Assets measured at fair value on a recurring basis	0.0
Quoted Prices in Active Market for Identical Assets (Level 1) | Deferred compensation liabilities
Liabilities:
Liabilities measured at fair value on a recurring basis	49.7
Quoted Prices in Active Market for Identical Assets (Level 1) | Forward Contracts [Member]
Liabilities:
Foreign Currency Contracts, Liability, Fair Value Disclosure	0.0
Significant Other Observable Inputs (Level 2)
Assets:
Assets measured at fair value on a recurring basis	5.7
Liabilities:
Liabilities measured at fair value on a recurring basis	2.6
Significant Other Observable Inputs (Level 2) | Interest rate cap - derivative
Assets:
Assets measured at fair value on a recurring basis	5.3
Significant Other Observable Inputs (Level 2) | Foreign Exchange Contract [Member]
Assets:
Assets measured at fair value on a recurring basis	0.4
Significant Other Observable Inputs (Level 2) | Deferred compensation liabilities
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0
Significant Other Observable Inputs (Level 2) | Forward Contracts [Member]
Liabilities:
Foreign Currency Contracts, Liability, Fair Value Disclosure	2.6
Significant Unobservable Inputs (Level 3)
Assets:
Assets measured at fair value on a recurring basis	0.0
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0
Significant Unobservable Inputs (Level 3) | Interest rate cap - derivative
Assets:
Assets measured at fair value on a recurring basis	0.0
Significant Unobservable Inputs (Level 3) | Foreign Exchange Contract [Member]
Assets:
Assets measured at fair value on a recurring basis	0.0
Significant Unobservable Inputs (Level 3) | Deferred compensation liabilities
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0
Significant Unobservable Inputs (Level 3) | Forward Contracts [Member]
Liabilities:
Foreign Currency Contracts, Liability, Fair Value Disclosure	$ 0.0