Segments (Schedule Of Revenues Net, Long-Lived Assets Excluding Goodwill Foreign Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net	$ 140,160	$ 134,213	$ 134,213	$ 111,005	$ 106,547	$ 111,655	$ 111,437	$ 104,202	$ 519,591	$ 433,841	$ 354,073
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net									348,784	287,794	227,373
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net									$ 170,807	$ 146,047	$ 126,700