Other Financial Statement Data (Schedule Of Changes In Deferred Warranty Revenue) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Movement in Extended Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 344	$ 275
Revenue deferrals	268	231
Amortization of deferred revenue	(221)	(183)
Total deferred warranty revenue	391	323
Current portion of deferred warranty revenue	(301)	(209)
Long-term deferred warranty revenue	$ 90	$ 114