Note 13 - Income Taxes - Components of Company's Deferred Tax Assets and Liabilities for Federal and State Income Taxes (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 27,312,000	$ 29,682,000
Income tax credit carryforwards	2,769,000	2,667,000
Stock compensation	850,000	751,000
Other	1,027,000	831,000
Total deferred tax assets	31,958,000	33,931,000
Deferred tax liabilities
Indefinite lived intangible assets		(4,730,000)
Depreciation and amortization	(419,000)	(126,000)
Total deferred tax liabilities	(419,000)	(4,856,000)
Valuation allowance	(31,539,000)	(33,805,000)
Net deferred taxes		$ (4,730,000)