Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 26, 2020	Sep. 27, 2019
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 1,003,725	$ 954,731
Less: accumulated depreciation	(457,075)	(417,299)
Property, Plant And Equipment, Net	546,650	537,432
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	41,925	41,918
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	284,373	282,924
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	81,797	66,730
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	130,906	128,525
Computer Systems and Software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	229,297	219,455
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	31,742	34,191
Equipment Leased to Other Party [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	189,179	161,372
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 14,506	$ 19,616