Note 3 - Summary of Significant Accounting Policies (Details Textual)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) shares	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) shares
Number of Operating Segments			2
Allowance for Doubtful Accounts Receivable, Ending Balance	$ 10,000		$ 10,000		$ 10,000
Impairment of Long-Lived Assets Held-for-use			0		$ 0
Income from Non-employee Options			6,000	$ 6,000
Employee Stock Option [Member]
Allocated Share-based Compensation Expense, Total	82,000	$ 110,000	164,000	244,000
Non-employee Options [Member]
Allocated Share-based Compensation Expense, Total	$ 3,000	$ 11,000	$ 7,000	$ 7,000
Options and Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares			3,518,668		3,710,335