Other Financial Statement Data (Schedule Of Changes In Estimated Warranty Liability) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 790	$ 645	$ 839
Accrual for warranties	582	688	441
Warranty revision	7	(53)	(19)
Settlements made during the period	(612)	(490)	(616)
Balance at end of period	767	790	645
Current portion of estimated warranty liability	(713)	(717)	(584)
Long-term estimated warranty liability	$ 54	$ 73	$ 61