Note 3 - Intangible Assets - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Gross Carrying Amount	$ 4,911	$ 4,897
Accumulated Amortization	(3,248)	(3,059)
Net Carrying Amount	1,663	1,838
Patents [Member]
Gross Carrying Amount	591	577
Accumulated Amortization	(290)	(274)
Net Carrying Amount	$ 301	303
Patents [Member] \| Minimum [Member]
Useful Lives (Year)	3 years
Patents [Member] \| Maximum [Member]
Useful Lives (Year)	17 years
Computer Software, Intangible Asset [Member]
Gross Carrying Amount	$ 405	405
Accumulated Amortization	(393)	(383)
Net Carrying Amount	$ 12	22
Useful Lives (Year)	3 years
Customer Relationships [Member]
Gross Carrying Amount	$ 3,370	3,370
Accumulated Amortization	(2,110)	(1,974)
Net Carrying Amount	$ 1,260	1,396
Useful Lives (Year)	12 years
Permits [Member]
Gross Carrying Amount	$ 545	545
Accumulated Amortization	(455)	(428)
Net Carrying Amount	$ 90	$ 117
Useful Lives (Year)	10 years