Goodwill and Intangible Assets - Narrative (Details) - USD ($)		3 Months Ended	12 Months Ended
	Jul. 01, 2019	Sep. 29, 2019	Sep. 29, 2019	Sep. 30, 2018	Oct. 01, 2017
Goodwill [Line Items]
Impairment of goodwill	$ 0	$ (7,800,000)	$ (7,755,000)	$ 0	$ 0
Percentage of excess of fair value over carrying value (more than)		25.00%	25.00%
Carrying value		$ 2,147,408,000	$ 2,147,408,000	1,959,421,000
Goodwill		924,820,000	924,820,000	798,820,000	740,886,000
Foreign currency translation adjustments			300,000	900,000
Amortization expense for intangible assets			11,600,000	18,200,000	22,800,000
GSG
Goodwill [Line Items]
Impairment of goodwill			0
Goodwill		441,802,000	441,802,000	389,741,000	361,761,000
Gross amounts of goodwill		459,500,000	459,500,000	407,400,000
Accumulated impairment		17,700,000	17,700,000	17,700,000
CIG
Goodwill [Line Items]
Impairment of goodwill			(7,755,000)
Goodwill		483,018,000	483,018,000	409,079,000	$ 379,125,000
Gross amounts of goodwill		588,700,000	588,700,000	507,000,000.0
Accumulated impairment		105,700,000	105,700,000	$ 97,900,000
RFS Reporting Unit
Goodwill [Line Items]
Impairment of goodwill			(7,800,000)
Carrying value		61,000,000	61,000,000
Goodwill		$ 48,800,000	$ 48,800,000