Goodwill and Intangible Assets - Finite Lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Jan. 01, 2017	Dec. 27, 2015	Oct. 02, 2016
Finite-lived intangible assets
Gross Amount	$ 141,767		$ 144,044
Accumulated Amortization	(99,600)		(95,082)
Foreign currency translation adjustments	900
Amortization expense	5,900	$ 4,300
Estimated amortization expense
2017	16,286
2018	14,011
2019	6,871
2020	3,708
2021	651
Beyond	640
Total	$ 42,167
Non-compete agreements
Finite-lived intangible assets
Weighted-Average Remaining Life (in Years)	8 months 12 days
Gross Amount	$ 876		881
Accumulated Amortization	$ (858)		(840)
Client relations
Finite-lived intangible assets
Weighted-Average Remaining Life (in Years)	2 years 2 months 12 days
Gross Amount	$ 111,166		112,367
Accumulated Amortization	$ (85,982)		(83,514)
Backlog
Finite-lived intangible assets
Weighted-Average Remaining Life (in Years)	2 years
Gross Amount	$ 22,229		23,018
Accumulated Amortization	$ (9,304)		(7,536)
Technology and trade names
Finite-lived intangible assets
Weighted-Average Remaining Life (in Years)	3 years 7 months 6 days
Gross Amount	$ 7,496		7,778
Accumulated Amortization	$ (3,456)		$ (3,192)