Geographic And Customer Information (Comparison Of Property And Equipment, Net, By Geographic Region) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	$ 266,125	$ 295,570
U.S. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	261,837	287,986
EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	$ 4,288	$ 7,584