Mergers and Acquisitions - Narrative (Details)	3 Months Ended				6 Months Ended		12 Months Ended
	Apr. 01, 2018 USD ($) employee	Dec. 31, 2017 USD ($) employee	Apr. 02, 2017 USD ($) employee	Mar. 27, 2016 USD ($)	Apr. 01, 2018 USD ($)	Apr. 02, 2017 USD ($)	Oct. 02, 2016 USD ($)
Mergers and Acquisitions
Contingent earn-out liability	$ 30,100,000				$ 30,100,000
Aggregate maximum of contingent consideration	$ 43,400,000				43,400,000
Increase (decrease) in contingent consideration					1,900,000	$ (7,100,000)
Gain (loss) on change in contingent consideration					$ (1,900,000)	7,100,000
Minimum
Mergers and Acquisitions
Earn-out period					2 years
Minimum | Existing customer contracts
Mergers and Acquisitions
Useful life of intangible assets					1 year
Minimum | Trade names
Mergers and Acquisitions
Useful life of intangible assets					3 years
Maximum
Mergers and Acquisitions
Earn-out period					3 years
Maximum | Existing customer contracts
Mergers and Acquisitions
Useful life of intangible assets					10 years
Maximum | Trade names
Mergers and Acquisitions
Useful life of intangible assets					5 years
Norman Disney & Young
Mergers and Acquisitions
Number of employees acquired in acquisition | employee	700
Fair value of acquisition purchase price	$ 56,100,000
Cash paid to the former owners	46,300,000
Amount held in escrow	1,600,000				$ 1,600,000
Purchase price payable	600,000
Contingent earn-out liability	7,600,000				7,600,000
Aggregate maximum of contingent consideration	$ 20,200,000				$ 20,200,000
Earn-out period	3 years
Glumac
Mergers and Acquisitions
Number of employees acquired in acquisition | employee		300
Fair value of acquisition purchase price		$ 38,400,000
Cash paid to the former owners		19,000,000
Amount held in escrow		1,000,000
Contingent earn-out liability		18,400,000
Aggregate maximum of contingent consideration		$ 20,000,000
Earn-out period		3 years
Eco Logical Australia
Mergers and Acquisitions
Number of employees acquired in acquisition | employee			160
Fair value of acquisition purchase price			$ 9,900,000
Cash paid to the former owners			8,300,000
Contingent earn-out liability			1,600,000			1,600,000
Aggregate maximum of contingent consideration			$ 1,700,000			1,700,000
Earn-out period			2 years
INDUS
Mergers and Acquisitions
Contingent earn-out liability			$ 0	$ 4,700,000		0	$ 4,900,000
Aggregate maximum of contingent consideration				$ 8,000,000
Earn-out period				2 years
Increase (decrease) in contingent consideration						(5,000,000)
Gain (loss) on change in contingent consideration			5,000,000			5,000,000
Potential earn-out to be paid each year				$ 4,000,000
Estimated potential earn-out (as a percent)				50.00%			59.00%
Minimum operating income threshold to earn contingent consideration during year one			3,200,000	$ 3,200,000
Minimum operating income threshold to earn contingent consideration during year two			$ 3,600,000	3,600,000
Operating income to earn maximum consideration during the first year				3,600,000
Operating income to earn maximum consideration during the second year				$ 4,000,000
CEG
Mergers and Acquisitions
Increase (decrease) in contingent consideration						(2,100,000)
Gain (loss) on change in contingent consideration						$ 2,100,000