Segment Information (Schedule Of Revenue From Unaffiliated Customers By Geographic Area) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) segment	Sep. 30, 2015 USD ($)
Number of reportable business segments | segment			1
Revenue from unaffiliated customers	$ 156,362	$ 151,574	$ 467,028	$ 482,800
Operating Segments [Member] | Americas [Member]
Revenue from unaffiliated customers	86,890	80,724	253,981	257,382
Operating Segments [Member] | Germany [Member]
Revenue from unaffiliated customers	16,796	18,972	56,225	61,567
Operating Segments [Member] | Other EMEA [Member]
Revenue from unaffiliated customers	26,948	26,063	83,704	84,475
Operating Segments [Member] | Asia Pacific [Member]
Revenue from unaffiliated customers	$ 25,728	$ 25,815	$ 73,118	$ 79,376