Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,333	$ 2,139
Accumulated Amortization	(1,952)	(1,814)
Net	381	325
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,041	1,832
Accumulated Amortization	(1,678)	(1,542)
Net	363	290
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	206	206
Accumulated Amortization	(206)	(200)
Net	0	6
Marketing assets and customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	86	101
Accumulated Amortization	(68)	(72)
Net	$ 18	$ 29