Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,047	$ 2,975
Accumulated Amortization	(2,623)	(2,537)
Net	424	438
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,639	2,567
Accumulated Amortization	(2,402)	(2,351)
Net	237	216
Software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	206	206
Accumulated Amortization	(98)	(82)
Net	108	124
Marketing assets and customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(39)	(33)
Net	62	68
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	101
Accumulated Amortization	(84)	(71)
Net	$ 17	$ 30