Segment Information (Schedule Of Revenue From Unaffiliated Customers By Geographic Area) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)
Number of reportable segments | segment	1
Revenue from unaffiliated customers	$ 165,888	$ 156,431
United States
Revenue from unaffiliated customers	82,730	77,872
Other Americas
Revenue from unaffiliated customers	1,817	2,419
EMEA
Revenue from unaffiliated customers	57,416	52,958
Asia Pacific
Revenue from unaffiliated customers	$ 23,925	$ 23,182