Geographic And Customer Information (Comparison Of Geographic Revenues) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 873,592	$ 771,978	$ 680,578
U.S. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	530,111	472,700	419,315
EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	135,084	109,680	92,351
APAC [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	130,648	116,999	103,494
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 77,749	$ 72,599	$ 65,418