Revenue from Contracts with Customers - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 27, 2020	Jun. 30, 2021	Jun. 27, 2020	Sep. 30, 2020
Revenue from External Customer [Line Items]
Contract with customer, asset, expected to be transferred to receivables within the next 12 months and therefore	$ 5,900,000		$ 5,900,000
Contract with customer, asset, reclassified to receivable			6,600,000
Contract with customer, asset, increase in contract assets related to revenue recognized			5,300,000
Impairments of the contract cost asset	0	$ 0	0	$ 0
Deferred revenue, revenue recognized			368,800,000
Deferred revenue, additions			400,400,000
Short term and long term accounts receivable	601,500,000		601,500,000		$ 511,300,000
Refund liability	41,500,000		41,500,000		34,500,000
Allowance for doubtful accounts receivable	400,000		400,000		500,000
Amortization expense related to costs to obtain a contract with a customer	11,700,000	$ 9,000,000.0	33,100,000	$ 25,200,000
Deferred revenue	473,613,000		473,613,000		426,465,000
Revenue, remaining performance obligation, amount	1,323,600,000		1,323,600,000
Unrecorded
Revenue from External Customer [Line Items]
Revenue, remaining performance obligation, amount	850,000,000.0		850,000,000.0
Other Current Assets
Revenue from External Customer [Line Items]
Capitalized contract cost, net	41,700,000		41,700,000		33,900,000
Other Assets
Revenue from External Customer [Line Items]
Capitalized contract cost, net	$ 73,900,000		73,900,000		$ 72,900,000
Arena Solutions
Revenue from External Customer [Line Items]
Deferred revenue increased			15,500,000
Deferred revenue fair value adjustment net			$ 10,400,000