Other Financial Statement Data (Schedule Of Changes In Estimated Warranty Liability) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 767	$ 790
Accrual for warranties	399	362
Warranty revision	(30)	(23)
Settlements made during the period	(368)	(413)
Balance at end of period	768	716
Current portion of estimated warranty liability	(713)	(691)	$ (713)
Long-term estimated warranty liability	$ 55	$ 25