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Goodwill and Intangible Assets - Narrative (Details) - USD ($)		3 Months Ended		12 Months Ended
	Jul. 02, 2018	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Oct. 02, 2016
Goodwill [Line Items]
Impairment of goodwill	$ 0	$ 0	$ 0
Percentage of excess of fair value over carrying value (more than)		30.00%		30.00%
Foreign currency translation adjustments				$ 900,000	$ 100,000
Amortization expense for intangible assets				18,200,000	22,800,000	$ 22,100,000
GSG
Goodwill [Line Items]
Gross amounts of goodwill		$ 407,400,000	379,500,000	407,400,000	379,500,000
Accumulated impairment		17,700,000	17,700,000	17,700,000	17,700,000
CIG
Goodwill [Line Items]
Gross amounts of goodwill		507,000,000	477,000,000	507,000,000	477,000,000
Accumulated impairment		$ 97,900,000	$ 97,900,000	$ 97,900,000	$ 97,900,000