Note 3 - Intangible Assets - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Gross Carrying Amount	$ 4,906	$ 4,897
Accumulated Amortization	(3,153)	(3,059)
Net Carrying Amount	1,753	1,838
Patents [Member]
Gross Carrying Amount	586	577
Accumulated Amortization	(282)	(274)
Net Carrying Amount	$ 304	303
Patents [Member] \| Minimum [Member]
Useful Lives (Year)	3 years
Patents [Member] \| Maximum [Member]
Useful Lives (Year)	17 years
Computer Software, Intangible Asset [Member]
Useful Lives (Year)	3 years
Gross Carrying Amount	$ 405	405
Accumulated Amortization	(388)	(383)
Net Carrying Amount	$ 17	22
Customer Relationships [Member]
Useful Lives (Year)	12 years
Gross Carrying Amount	$ 3,370	3,370
Accumulated Amortization	(2,042)	(1,974)
Net Carrying Amount	$ 1,328	1,396
Permits [Member]
Useful Lives (Year)	10 years
Gross Carrying Amount	$ 545	545
Accumulated Amortization	(441)	(428)
Net Carrying Amount	$ 104	$ 117