Revenue Recognition (Comparison Of Geographic Revenues) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,231,661	$ 1,214,969	$ 1,165,095
U.S. [Member]
Disaggregation of Revenue [Line Items]
Total revenues	772,586	756,907	707,906
EMEA [Member]
Disaggregation of Revenue [Line Items]
Total revenues	206,975	212,699	211,349
CHINA
Disaggregation of Revenue [Line Items]
Total revenues	119,291	106,841	106,526
Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues	$ 132,809	$ 138,522	$ 139,314