Goodwill - Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended			12 Months Ended
	Oct. 01, 2016		Sep. 26, 2015	Oct. 01, 2016		Sep. 26, 2015	Dec. 31, 2015
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 609,728			$ 609,728			$ 613,390
Accumulated Amortization	(253,760)			(253,760)			(224,064)
Net	355,968			355,968			$ 389,326
Amortization of Intangible Assets	13,893		$ 14,269	$ 41,252		$ 39,293
Customer Relationships [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life				10 years			10 years
Gross Carrying Amount	485,493			$ 485,493			$ 498,319
Accumulated Amortization	(238,987)			(238,987)			(215,263)
Net	246,506			$ 246,506			$ 283,056
Developed Technology [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life				5 years			5 years
Gross Carrying Amount	16,220			$ 16,220			$ 13,154
Accumulated Amortization	(10,993)			(10,993)			(7,894)
Net	5,227			5,227			5,260
Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,015	[1]		7,015	[1]		917	[2]
Accumulated Amortization	(3,780)	[1]		(3,780)	[1]		(907)	[2]
Net	3,235	[1]		3,235	[1]		10	[2]
Trade Names [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	101,000			101,000			101,000
Accumulated Amortization	0			0			0
Net	$ 101,000			$ 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			2 years
Maximum [Member] | Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life				5 years			3 years

[1] Consists of non-competition agreements, sales backlog, and an amortizable trade name with useful lives ranging from two to five years.

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