Goodwill and Intangible Assets - Narrative (Details)			3 Months Ended	12 Months Ended
	Jul. 03, 2017 USD ($) reporting_unit	Jun. 30, 2014	Sep. 27, 2015 USD ($)	Oct. 01, 2017 USD ($)	Oct. 02, 2016 USD ($)	Sep. 27, 2015 USD ($)
Goodwill [Line Items]
Impairment of goodwill	$ 0		$ 58,100,000
Number of reporting units having fair value in excess of carrying value of less than 20%. | reporting_unit	0
Impairment of goodwill and other intangible assets			60,800,000	$ 0	$ 0	$ 60,763,000
Impairment of goodwill and other intangible assets, net of tax			57,300,000
Identifiable intangible assets that were determined not to be recoverable			$ 2,700,000
Minimum
Goodwill [Line Items]
Percentage of excess of fair value over carrying value	20.00%
WEI
Goodwill [Line Items]
Gross amounts of goodwill				324,100,000	304,400,000
Accumulated impairment				82,400,000	82,400,000
RME
Goodwill [Line Items]
Gross amounts of goodwill				532,400,000	529,200,000
Accumulated impairment				$ 33,200,000	$ 33,200,000
GMP | RME
Goodwill [Line Items]
Percentage of decline in revenue			25.00%
Annual revenue growth rate (as a percent)		3.00%