Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,135	$ 3,095
Accumulated Amortization	(2,802)	(2,715)
Net	333	380
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,727	2,687
Accumulated Amortization	(2,515)	(2,463)
Net	212	224
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	206	206
Accumulated Amortization	(134)	(111)
Net	72	95
Marketing assets and customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(52)	(45)
Net	49	56
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(101)	(96)
Net	$ 0	$ 5