Goodwill and Intangible Assets - Summary (Details)			3 Months Ended	12 Months Ended
	Jun. 27, 2016 USD ($) item	Jun. 30, 2014	Sep. 27, 2015 USD ($)	Oct. 02, 2016 USD ($)	Sep. 27, 2015 USD ($)
Goodwill
Balance at beginning of the period				$ 601,379,000	$ 714,190,000
Goodwill additions				107,618,000	6,272,000
Foreign exchange translation				7,304,000	(60,965,000)
Goodwill impairment	$ 0				(58,118,000)
Goodwill adjustment				1,687,000
Balance at end of the period			$ 601,379,000	717,988,000	601,379,000
Number of reporting units having fair value in excess of carrying value of less than 20%. | item	0
Impairment of goodwill and other intangible assets			60,800,000		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
Percentage of excess of fair value over carrying value	20.00%
WEI
Goodwill
Balance at beginning of the period				210,748,000	281,930,000
Goodwill additions				9,080,000
Foreign exchange translation				2,125,000	(27,479,000)
Goodwill impairment					(43,703,000)
Balance at end of the period			210,748,000	221,953,000	210,748,000
Gross amounts of goodwill			293,100,000	304,400,000	293,100,000
Accumulated impairment			82,400,000	82,400,000	82,400,000
RME
Goodwill
Balance at beginning of the period				390,631,000	432,260,000
Goodwill additions				98,538,000	6,272,000
Foreign exchange translation				5,179,000	(33,486,000)
Goodwill impairment					(14,415,000)
Goodwill adjustment				1,687,000
Balance at end of the period			390,631,000	496,035,000	390,631,000
Gross amounts of goodwill			423,800,000	529,200,000	423,800,000
Accumulated impairment			$ 33,200,000	$ 33,200,000	$ 33,200,000
GMP | RME
Goodwill
Percentage of decline in revenue			25.00%
Annual revenue growth rate (as a percent)		3.00%