Cost in Excess of Net Assets of Companies Acquired - Intangibles (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended			12 Months Ended
	Mar. 28, 2015		Mar. 29, 2014	Dec. 31, 2014
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 526,526			$ 513,561
Accumulated Amortization	(184,939)			(177,850)
Net	341,587			335,711
Amortization of Intangible Assets	11,107		10,947
Amortization of intangible assets, net of tax	9,029		8,907
Amortization of intangible assets, per share basic	$ 0.09		$ 0.09
Amortization of intangible assets, per share diluted	$ 0.09		$ 0.09
Customer Relationships [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life	10 years			10 years
Gross Carrying Amount	411,160			402,036
Accumulated Amortization	(178,098)			(171,071)
Net	233,062			230,965
Developed Technology [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life	5 years			5 years
Gross Carrying Amount	13,223			8,806
Accumulated Amortization	(5,970)			(5,444)
Net	7,253			3,362
Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,143	[1]		1,719	[1]
Accumulated Amortization	(871)	[1]		(1,335)	[1]
Net	272	[1]		384	[1]
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 with useful lives ranging from two to three years.