Revenue from Contracts with Customers Revenue from Contracts with Customers (Additional Information) (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 30, 2019	Oct. 01, 2018	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract with Customer, Refund Liability	$ 23,400
Contract with Customer, Asset, Reclassified to Receivable	14,100
Contract with Customer, Asset, Additions during Period	7,500
Deferred Revenue, Revenue Recognized	246,100
Deferred Revenue, Additions	$ 280,400
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption			$ 367,378
Accounting Standards Update 2014-09 | Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect Of New Accounting Principle In Period Of Adoption, Gross		$ 431,900
Cumulative Effect of New Accounting Principle in Period of Adoption		367,400	$ 367,378
Cumulative Effect Of New Accounting Principle In Period Of Adoption, Related To Deferral Of Commission Expenses		70,000
Cumulative Effect Of New Accounting Principle In Period Of Adoption, Related To Offsetting Current Liability		$ 2,800
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percent of standalone selling price for subscriptions that contains license	50.00%
Percent of standalone selling price for subscriptions that contains support	45.00%
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percent of standalone selling price for subscriptions that contains license	55.00%
Percent of standalone selling price for subscriptions that contains support	50.00%
Other Current Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Capitalized Contract Cost, Net	$ 20,100
Other Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Capitalized Contract Cost, Net	$ 57,600