Mergers and Acquisitions - Acquisition Narrative (Details)		3 Months Ended			12 Months Ended
	Oct. 02, 2017 employee	Apr. 02, 2017 USD ($) employee	Mar. 27, 2016 USD ($) employee	Jun. 28, 2015 USD ($)	Sep. 27, 2015 USD ($)	Oct. 01, 2017 USD ($)	Oct. 02, 2016 USD ($)
Business acquisition
Contingent earn-out liability					$ 0	$ 2,400,000
Aggregate maximum of contingent consideration						$ 8,900,000
CEG
Business acquisition
Aggregate fair value of purchase prices					15,900,000
Cash paid to the sellers					11,800,000
Contingent earn-out liability		$ 1,800,000		$ 4,100,000	4,100,000		$ 3,900,000
Aggregate maximum of contingent consideration				$ 9,800,000	$ 9,800,000
Earn-out period				3 years
Coffey
Business acquisition
Aggregate fair value of purchase prices			$ 76,100,000
Number of employees | employee			3,300
Assumed debt			$ 65,100,000
Secured bank debt assumed			37,100,000
Unsecured corporate bonds assumed			28,000,000
INDUS
Business acquisition
Aggregate fair value of purchase prices			18,700,000
Cash paid to the sellers			14,000,000
Contingent earn-out liability		0	4,700,000				$ 4,900,000
Aggregate maximum of contingent consideration			$ 8,000,000
Earn-out period			2 years
ELA
Business acquisition
Aggregate fair value of purchase prices		9,900,000
Cash paid to the sellers		8,300,000
Contingent earn-out liability		1,600,000
Aggregate maximum of contingent consideration		$ 1,700,000
Number of employees | employee		160
Earn-out period		2 years
Glumac | Subsequent Event
Business acquisition
Number of employees | employee	300