Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 27, 2020	Sep. 27, 2019
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 992,004	$ 954,731
Less: accumulated depreciation	(440,977)	(417,299)
Property, Plant And Equipment, Net	551,027	537,432
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	41,852	41,918
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	282,779	282,924
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	75,019	66,730
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	125,793	128,525
Computer Systems and Software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	222,336	219,455
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	31,648	34,191
Equipment Leased to Other Party [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	182,257	161,372
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant And Equipment, Gross	$ 30,320	$ 19,616