Other Financial Statement Data (Schedule Of Changes In Deferred Warranty Revenue) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Movement in Extended Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 275	$ 218
Revenue deferrals	231	238
Amortization of deferred revenue	(183)	(224)
Total deferred warranty revenue	323	232
Current portion of deferred warranty revenue	(209)	(214)
Long-term deferred warranty revenue	$ 114	$ 18