Revenues - Major Product Category (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenues	$ 2,585,368	$ 2,388,643	$ 2,356,672
Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	1,515,566	1,356,305	1,371,808
Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	1,069,802	1,032,338	984,864
Cable And Connectivity
Disaggregation of Revenue [Line Items]
Revenues	1,709,486	1,652,979	1,594,261
Cable And Connectivity | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	1,046,744	1,024,090	1,003,799
Cable And Connectivity | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	662,742	628,889	590,462
Networking, Software & Security
Disaggregation of Revenue [Line Items]
Revenues	875,882	735,664	762,411
Networking, Software & Security | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	468,822	332,215	368,009
Networking, Software & Security | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	$ 407,060	$ 403,449	$ 394,402