Revenues - Products and Services (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 668,639	$ 610,633	$ 1,274,204	$ 1,162,014
Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	396,893	348,804	746,025	663,082
Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	271,746	261,829	528,179	498,932
Products
Disaggregation of Revenue [Line Items]
Revenues	627,438	566,730	1,192,235	1,074,382
Products | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	379,416	330,670	712,160	626,639
Products | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	248,022	236,060	480,075	447,743
Support & Services
Disaggregation of Revenue [Line Items]
Revenues	41,201	43,903	81,969	87,632
Support & Services | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	17,477	18,134	33,865	36,443
Support & Services | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	$ 23,724	$ 25,769	$ 48,104	$ 51,189