Other Financial Statement Data (Schedule Of Amortization Expense For Intangible Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 157	$ 178
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 113	112
Intangible assets acquired, Weighted Average Life (in years)	2 years
Software [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 30	29
Intangible assets acquired, Weighted Average Life (in years)	2 years 2 months 12 days
Marketing Assets and Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 9	12
Intangible assets acquired, Weighted Average Life (in years)	5 years 2 months 12 days
Non-compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 5	$ 25