Goodwill and Intangible Assets - Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Oct. 01, 2017
Finite-lived intangible assets
Gross Amount	$ 86,237	$ 118,995
Accumulated Amortization	(70,114)	(92,307)
Estimated amortization expense
2019	9,016
2020	3,366
2021	2,271
2022	1,037
2023	433
Total	$ 16,123
Non-compete agreements
Finite-lived intangible assets
Weighted- Average Remaining Life (in years)	0 years
Gross Amount	$ 83	495
Accumulated Amortization	$ (83)	(493)
Client relations
Finite-lived intangible assets
Weighted- Average Remaining Life (in years)	2 years 7 months 6 days
Gross Amount	$ 54,639	90,297
Accumulated Amortization	$ (46,449)	(75,074)
Backlog
Finite-lived intangible assets
Weighted- Average Remaining Life (in years)	6 months
Gross Amount	$ 23,371	21,518
Accumulated Amortization	$ (20,007)	(13,301)
Technology and trade names
Finite-lived intangible assets
Weighted- Average Remaining Life (in years)	3 years 2 months 12 days
Gross Amount	$ 8,144	6,685
Accumulated Amortization	$ (3,575)	$ (3,439)