Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,250	$ 3,162
Accumulated Amortization	(2,955)	(2,829)
Net	295	333
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,842	2,754
Accumulated Amortization	(2,630)	(2,533)
Net	212	221
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	206	206
Accumulated Amortization	(163)	(141)
Net	43	65
Marketing assets and customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(61)	(54)
Net	40	47
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(101)	(101)
Net	$ 0	$ 0