Cost in Excess of Net Assets of Companies Acquired - Intangibles (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			12 Months Ended
	Apr. 02, 2016		Mar. 28, 2015	Dec. 31, 2015
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 622,143			$ 613,390
Accumulated Amortization	(238,640)			(224,064)
Net	383,503			$ 389,326
Amortization of Intangible Assets	12,913		$ 11,107
Amortization of intangible assets, net of tax	$ 10,634		$ 9,029
Amortization of intangible assets, per share basic	$ 0.12		$ 0.09
Amortization of intangible assets, per share diluted	$ 0.11		$ 0.09
Customer Relationships [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life	10 years			10 years
Gross Carrying Amount	$ 501,895			$ 498,319
Accumulated Amortization	(227,733)			(215,263)
Net	$ 274,162			$ 283,056
Developed Technology [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life	5 years			5 years
Gross Carrying Amount	$ 13,625			$ 13,154
Accumulated Amortization	(8,975)			(7,894)
Net	4,650			5,260
Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,623	[1]		917	[2]
Accumulated Amortization	(1,932)	[1]		(907)	[2]
Net	3,691	[1]		10	[2]
Trade Names [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	101,000			101,000
Accumulated Amortization	0			0
Net	$ 101,000			$ 101,000
Minimum [Member] | Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life	2 years
Maximum [Member] | Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life	3 years

[1] Consists of non-competition agreements and sales backlog with useful lives ranging from two to three years.

[2] Consists of non-competition agreements with useful lives ranging from two to three years.