Goodwill and Intangible Assets Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 27, 2016	Mar. 27, 2016	Sep. 27, 2015
Goodwill
Balance at beginning of the period		$ 601,379
Goodwill additions		104,454
Goodwill adjustments		2,000
Foreign exchange impact		8,411
Balance at end of the period	$ 716,244	716,244
CEG
Goodwill
Goodwill adjustments	2,000
Coffey and INDUS
Goodwill
Balance at end of the period	104,454	104,454
WEI
Goodwill
Balance at beginning of the period		210,748
Goodwill additions		9,030
Foreign exchange impact		713
Balance at end of the period	220,491	220,491
Gross amounts of goodwill	302,900	302,900	$ 293,100
Accumulated impairment	82,400	82,400	82,400
WEI | Coffey and INDUS
Goodwill
Goodwill additions	9,000
RME
Goodwill
Balance at beginning of the period		390,631
Goodwill additions		95,424
Goodwill adjustments		2,000
Foreign exchange impact		7,698
Balance at end of the period	495,753	495,753
Gross amounts of goodwill	529,000	529,000	423,800
Accumulated impairment	33,200	$ 33,200	$ 33,200
RME | Coffey and INDUS
Goodwill
Goodwill additions	$ 95,400