Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,321	$ 3,205
Accumulated Amortization	(3,035)	(2,895)
Net	286	310
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,014	2,898
Accumulated Amortization	(2,772)	(2,662)
Net	242	236
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	206	206
Accumulated Amortization	(193)	(170)
Net	13	36
Marketing assets and customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(70)	(63)
Net	$ 31	$ 38