Goodwill - Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 586,405		$ 586,405		$ 593,037
Accumulated Amortization	(279,020)		(279,020)		(256,155)
Net	307,385		307,385		$ 336,882
Amortization of Intangible Assets	12,645	$ 13,893	$ 37,909	$ 41,252
Customer Relationships [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life			10 years		10 years
Gross Carrying Amount	476,656		$ 476,656		$ 476,176
Accumulated Amortization	(274,847)		(274,847)		(247,206)
Net	201,809		$ 201,809		$ 228,970
Developed Technology [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life			5 years		5 years
Gross Carrying Amount	6,340		$ 6,340		$ 9,140
Accumulated Amortization	(2,973)		(2,973)		(4,435)
Net	3,367		$ 3,367		4,705
Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted-Average Life			5 years
Gross Carrying Amount	2,409		$ 2,409		6,721	[1]
Accumulated Amortization	(1,200)		(1,200)		(4,514)	[1]
Net	1,209		1,209		2,207	[1]
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
Maximum [Member] | Other Intangible Assets [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life					5 years

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