Note 9 - Intangible Assets, Patents (Tables)
|9 Months Ended|
Sep. 30, 2018
|Schedule of Finite-Lived Intangible Assets [Table Text Block]||
Tabular disclosure of assets, excluding financial assets and goodwill, lacking physical substance with a finite life, by either major class or business segment.
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef