Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,081	$ 2,975
Accumulated Amortization	(2,668)	(2,537)
Net	413	438
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,673	2,567
Accumulated Amortization	(2,433)	(2,351)
Net	240	216
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	206	206
Accumulated Amortization	(104)	(82)
Net	102	124
Marketing assets and customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(42)	(33)
Net	59	68
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(89)	(71)
Net	$ 12	$ 30