Other Financial Statement Data (Schedule Of Changes In Deferred Warranty Revenue) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Movement in Extended Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 346	$ 199
Revenue deferrals	321	490
Amortization of deferred revenue	(325)	(330)
Total deferred warranty revenue	342	359
Current portion of deferred warranty revenue	(301)	(278)
Long-term deferred warranty revenue	$ 41	$ 81