Restructuring and Other Charges - Additional Information (Details) $ in Thousands		3 Months Ended			9 Months Ended
	Oct. 02, 2019 USD ($)	Jun. 27, 2020 USD ($)	Jun. 29, 2019 USD ($)	Dec. 28, 2018 USD ($) Employee	Jun. 27, 2020 USD ($) Employee	Jun. 29, 2019 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net		$ (62)	$ 9		$ (32,338)	$ (45,464)
Restructuring charges		200			(26,764)	(42,962)
Restructuring Reserve		16,084	28,771		16,084	28,771	$ 31,086	$ 2,415
Impairment and Accretion Exited Lease Facilities
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net					(4,900)
Accelerated Depreciation Planned Facility Exit
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net		(300)			(600)
Prior Headquarters Relocation Charge
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net					$ 4,500	(2,500)
Lease expiration, month and year					2022-11
Employee Severance and Related Benefits
Restructuring Cost And Reserve [Line Items]
Restructuring charges					$ (31,155)	(15,719)
Restructuring Reserve		9,728	328		9,728	328	298	0
Employee Severance and Related Benefits | Restructuring Plan 2020
Restructuring Cost And Reserve [Line Items]
Restructuring charges					$ (31,300)
Number of employees | Employee					255
Employee Severance and Related Benefits | Restructuring Plan 2019
Restructuring Cost And Reserve [Line Items]
Restructuring charges				$ (16,300)	$ 200
Number of employees | Employee				240
Facility Closures and Related Costs
Restructuring Cost And Reserve [Line Items]
Restructuring charges					4,391	(27,243)
Restructuring Reserve		6,356	28,443		6,356	28,443	$ 30,788	$ 2,415
Facility Closures and Related Costs | Accrued Expenses and Other Current Liabilities
Restructuring Cost And Reserve [Line Items]
Restructuring Reserve		2,600	12,100		2,600	12,100
Facility Closures and Related Costs | Other Noncurrent Liabilities
Restructuring Cost And Reserve [Line Items]
Restructuring Reserve		$ 3,800	$ 16,300		$ 3,800	16,300
Facility Closures and Related Costs | Accounting Standards Update 2016-02
Restructuring Cost And Reserve [Line Items]
ASC 842 adoption	$ 16,500
Facility Closures and Related Costs | Accounting Standards Update 2016-02 | Operating Lease ROU Asset
Restructuring Cost And Reserve [Line Items]
ASC 842 adoption	7,600
Facility Closures and Related Costs | Accounting Standards Update 2016-02 | Operating Lease Short Term Lease Obligation
Restructuring Cost And Reserve [Line Items]
ASC 842 adoption	9,200
Facility Closures and Related Costs | Accounting Standards Update 2016-02 | Operating Lease Long Term Lease Obligation
Restructuring Cost And Reserve [Line Items]
ASC 842 adoption	$ 14,900
Facility Closures and Related Costs | Prior Headquarters
Restructuring Cost And Reserve [Line Items]
Depreciation						1,900
Operating Leases, Rent Expense						$ 600