Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions		12 Months Ended
	Oct. 01, 2020 USD ($)	Sep. 30, 2020 USD ($) Segment Customer	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Oct. 01, 2019 USD ($)	Sep. 30, 2017 USD ($)
Significant Accounting Policies [Line Items]
Number of operating segments | Segment		1
Number of customers, with at least 10% of revenue | Customer		0
Number of customers, with at least 10% of accounts receivable | Customer		0
Expected dividend yield		0.00%	0.00%	0.00%
Operating lease assets		$ 443.3
Operating lease liabilities		440.9
Accounts receivable reserve		$ 19.2	$ 13.1	$ 17.6		$ 11.8
Accounting Standards Update 2016-02 [Member]
Significant Accounting Policies [Line Items]
Operating lease assets					$ 483.5
Operating lease liabilities					$ 476.0
Accounting Standards Update 2016-13 [Member] | Restatement Adjustment [Member] | Subsequent Event [Member]
Significant Accounting Policies [Line Items]
Accounts receivable reserve	$ 4.3
Retained earnings adjustment	$ 4.3
Trade Names [Member]
Significant Accounting Policies [Line Items]
Finite-lived intangible assets, amortization method		accelerated basis over a five or ten year period
Minimum [Member]
Significant Accounting Policies [Line Items]
Amortization period		5 years
Minimum [Member] | Real Estate Property [Member]
Significant Accounting Policies [Line Items]
Operating lease expiration year		2020
Minimum [Member] | Equipment [Member]
Significant Accounting Policies [Line Items]
Operating lease expiration year		2020
Minimum [Member] | Trade Names [Member]
Significant Accounting Policies [Line Items]
Amortization period		5 years
Maximum [Member]
Significant Accounting Policies [Line Items]
Amortization period		20 years
Maximum [Member] | Real Estate Property [Member]
Significant Accounting Policies [Line Items]
Operating lease expiration year		2038
Maximum [Member] | Equipment [Member]
Significant Accounting Policies [Line Items]
Operating lease expiration year		2027
Maximum [Member] | Trade Names [Member]
Significant Accounting Policies [Line Items]
Amortization period		10 years
Major Supplier Concentration Risk [Member] | Minimum [Member] | Cost of Goods, Total [Member]
Significant Accounting Policies [Line Items]
Goodwill impairment test period		3 years
Major Supplier Concentration Risk [Member] | Maximum [Member] | Cost of Goods, Total [Member]
Significant Accounting Policies [Line Items]
Goodwill impairment test period		5 years