Revenue Disaggregated Revenue by Geography (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 312,282	$ 360,460	$ 643,214	$ 732,493
EMEA [Member]
Disaggregation of Revenue [Line Items]
Revenues	32,978	33,867	65,356	73,391
Other foreign countries [Member]
Disaggregation of Revenue [Line Items]
Revenues	51,594	51,777	102,955	102,709
Foreign [Member]
Disaggregation of Revenue [Line Items]
Revenues	84,572	85,644	168,311	176,100
UNITED STATES
Disaggregation of Revenue [Line Items]
Revenues	$ 227,710	$ 274,816	$ 474,903	$ 556,393