Goodwill and Intangible Assets - Narrative (Details) - USD ($)		1 Months Ended	3 Months Ended			12 Months Ended
	Jun. 29, 2020	Sep. 27, 2020	Sep. 27, 2020	Jun. 28, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019	Sep. 30, 2018
Goodwill [Line Items]
Impairment of goodwill	$ 0		$ 15,800,000		$ 7,800,000	$ 15,800,000	$ 7,755,000	$ 0
Carrying value		$ 2,378,558,000	2,378,558,000		2,147,408,000	2,378,558,000	2,147,408,000
Goodwill		993,498,000	993,498,000		924,820,000	993,498,000	924,820,000	798,820,000
Foreign currency translation adjustments						400,000	300,000
Amortization expense for intangible assets						11,600,000	11,600,000	18,200,000
Australia
Goodwill [Line Items]
Percentage negative growth				7.00%
GSG
Goodwill [Line Items]
Impairment of goodwill						0	0
Goodwill		516,315,000	516,315,000		441,802,000	516,315,000	441,802,000	389,741,000
Gross amounts of goodwill		534,000,000.0	534,000,000.0		459,500,000	534,000,000.0	459,500,000
Accumulated impairment		17,700,000	17,700,000		17,700,000	17,700,000	17,700,000
CIG
Goodwill [Line Items]
Impairment of goodwill						15,800,000	7,755,000
Goodwill		477,183,000	477,183,000		483,018,000	477,183,000	483,018,000	$ 409,079,000
Gross amounts of goodwill		598,700,000	598,700,000		588,700,000	598,700,000	588,700,000
Accumulated impairment		121,500,000	121,500,000		105,700,000	121,500,000	105,700,000
All reporting units excluding ASP reporting unit
Goodwill [Line Items]
Percentage of excess of fair value over carrying value	80.00%
ASP
Goodwill [Line Items]
Impairment of goodwill		15,800,000
Carrying value		144,900,000	144,900,000			144,900,000
Goodwill		$ 95,500,000	$ 95,500,000			$ 95,500,000
ASP | CIG
Goodwill [Line Items]
Percentage of excess of fair value over carrying value	20.00%
RFS
Goodwill [Line Items]
Impairment of goodwill					7,800,000
Carrying value					61,000,000		61,000,000
Goodwill					$ 48,800,000		$ 48,800,000