Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Dec. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 36,523
Amortization of Intangible Assets	11,500	$ 6,800
Finite-Lived Intangible Assets, Gross	376,957		$ 372,670
Finite-Lived Intangible Assets, Accumulated Amortization	(218,451)		(207,334)
Finite-Lived Intangible Assets, Amortization Expense, Year Two	30,105
Finite-Lived Intangible Assets, Amortization Expense, Year Three	28,435
Finite-Lived Intangible Assets, Amortization Expense, Year Four	25,398
Finite-Lived Intangible Assets, Amortization Expense, Year Five	19,475
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	18,570
Finite-Lived Intangible Assets, Net	$ 158,506
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years	5 years 2 months
Finite-Lived Intangible Assets, Gross	$ 333,922		330,496
Finite-Lived Intangible Assets, Accumulated Amortization	$ (180,081)		(171,005)
Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	1 month	9 months
Finite-Lived Intangible Assets, Gross	$ 20,138		19,689
Finite-Lived Intangible Assets, Accumulated Amortization	$ (19,913)		(18,081)
Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	4 years 1 month	4 years 2 months
Finite-Lived Intangible Assets, Gross	$ 22,897		22,485
Finite-Lived Intangible Assets, Accumulated Amortization	(18,457)		(18,248)
Tradenames And Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	$ 629,007		$ 615,090