Revenues - Location of Customer (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
Americas
Disaggregation of Revenue [Line Items]
Revenues	1,601,543	1,531,978	1,533,773
Americas | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	981,822	925,647	937,741
Americas | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	619,721	606,331	596,032
EMEA
Disaggregation of Revenue [Line Items]
Revenues	584,736	495,653	481,566
EMEA | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	294,129	214,763	220,511
EMEA | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	290,607	280,890	261,055
APAC
Disaggregation of Revenue [Line Items]
Revenues	399,089	361,012	341,333
APAC | Enterprise Solutions
Disaggregation of Revenue [Line Items]
Revenues	239,615	215,895	213,556
APAC | Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenues	$ 159,474	$ 145,117	$ 127,777