Note 13 - Employee Equity Incentive Plans - Weighted Average Grant Date Fair Value Activity (Details) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Stock options granted during the period (in dollars per share)	$ 0.21	$ 0.19
Stock options vested during the period (in dollars per share)	0.20	0.21
Stock options forfeited during the period (in dollars per share)	$ 0.13	$ 0.28

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration