Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,246	$ 3,205
Accumulated Amortization	(2,988)	(2,895)
Net	258	310
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,939	2,898
Accumulated Amortization	(2,735)	(2,662)
Net	204	236
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	206	206
Accumulated Amortization	(185)	(170)
Net	21	36
Marketing assets and customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(68)	(63)
Net	$ 33	$ 38