Goodwill and Other Intangible Assets - Summary of Other Intangible Assets (Details) - USD ($) $ in Thousands		Dec. 26, 2020	Sep. 26, 2020
Finite Lived Intangible Assets [Line Items]
Other intangible assets, gross		$ 560,281	$ 557,333
Accumulated amortization		(487,370)	(473,193)
Other intangible assets, net		72,911	84,140
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Other intangible assets, gross	[1]	519,374	517,676
Accumulated amortization		(453,255)	(439,507)
Non-compete Agreements [Member]
Finite Lived Intangible Assets [Line Items]
Other intangible assets, gross	[1]	38,940	37,690
Accumulated amortization		(32,560)	(32,154)
Other [Member]
Finite Lived Intangible Assets [Line Items]
Other intangible assets, gross		1,967	1,967
Accumulated amortization		$ (1,555)	$ (1,532)

[1] Reflects the impact from acquisitions (See Note 4).