Geographic Information (Schedule Of Revenue By Geographic Area) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 185,345	$ 158,047
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	63,595	49,106
Japan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	29,555	26,925
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	20,541	16,960
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	3,138	2,950
Other European [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	41,856	39,205
Other International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 26,660	$ 22,901