Segment Information (Schedule Of Revenue From Unaffiliated Customers By Geographic Area) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 segment	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of reportable segments									1
Revenue from unaffiliated customers	$ 187,438	$ 166,944	$ 151,512	$ 147,758	$ 154,817	$ 135,717	$ 120,787	$ 102,079	$ 653,652	$ 513,400	$ 353,633
Americas [Member]
Segment Reporting Information [Line Items]
Revenue from unaffiliated customers									333,925	284,752	196,414
Germany [Member]
Segment Reporting Information [Line Items]
Revenue from unaffiliated customers									87,021	51,245	39,748
Other EMEA [Member]
Segment Reporting Information [Line Items]
Revenue from unaffiliated customers									109,066	82,536	60,939
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Revenue from unaffiliated customers									$ 123,640	$ 94,867	$ 56,532