Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended
Dec. 28, 2019	Dec. 29, 2018	Sep. 28, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (42.3)
Changes in foreign currency translation adjustment	8.3	$ (3.2)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent		0.0
Changes in value of hedged interest rate swaps and interest rate caps, net of tax of $1.7 and $0.5 for the three months ended December 28, 2019 and December 29, 2018.	4.0	(3.9)
Accumulated other comprehensive loss	(28.7)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(41.4)	(26.6)
Changes in foreign currency translation adjustment	8.3	(3.2)
Amounts reclassified to statement of income	0.0	0.0
Accumulated other comprehensive loss	(33.1)	(29.8)
Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Debt Securities, Available-for-sale, Adjustment, after Tax			$ 3.5
Changes in unrealized holding gains and losses on available-for-sale securities, net of tax of$0.2 for the three months ended December 30, 2017:	4.0
Amounts reclassified to statement of income	0.0
Pension Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(1.7)	(1.1)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	0.0
Amounts reclassified to statement of income	0.0	0.0
Accumulated other comprehensive loss	(1.7)	(1.1)
Hedged Interest Rate Caps
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(2.7)	2.2
Changes in value of hedged interest rate swaps and interest rate caps, net of tax of $1.7 and $0.5 for the three months ended December 28, 2019 and December 29, 2018.	0.0	(3.9)
Amounts reclassified to statement of income	(1.3)	(0.7)
Accumulated other comprehensive loss	(1.4)	(1.0)
Total
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(42.3)	(25.5)
Other Comprehensive Income (Loss) before Reclassifications, Tax	12.3	(7.1)
Amounts reclassified to statement of income	(1.3)	(0.7)
Accumulated other comprehensive loss	(28.7)	$ (31.9)
Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ 7.5

Amount, after tax, of accumulated unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature, attributable to parent entity.

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