Note 14 - Equity Incentive Plans - Status of Non-vested Shares (Details) - $ / shares	Mar. 31, 2019	Jan. 01, 2019
Shares underlying stock options (in shares)	872,500	1,682,500
Weighted average grant date fair value (in dollars per share)	$ 0.27	$ 0.24

Weighted average grant-date fair value of non-vested options outstanding.

No definition available.

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant