Geographic And Customer Information (Comparison Of Geographic Revenues) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 1,010,117	$ 965,087	$ 873,592
U.S. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	616,125	585,201	530,111
EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	182,897	169,767	135,084
Asia Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	133,748	129,664	130,648
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 77,347	$ 80,455	$ 77,749