Revenues - Products and Services (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 637,530	$ 668,639	$ 1,224,705	$ 1,274,204
Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	369,862	396,893	696,389	746,025
Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	267,668	271,746	528,316	528,179
Products
Disaggregation of Revenue [Line Items]
Revenues	595,710	627,438	1,142,273	1,192,235
Products | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	350,270	379,416	658,129	712,160
Products | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	245,440	248,022	484,144	480,075
Support & Services
Disaggregation of Revenue [Line Items]
Revenues	41,820	41,201	82,432	81,969
Support & Services | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	19,592	17,477	38,260	33,865
Support & Services | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	$ 22,228	$ 23,724	$ 44,172	$ 48,104