Note 6 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2015
Tax Credit Carryforward, Amount	$ 2,700,000	$ 2,600,000	$ 2,600,000
Unrecognized Tax Benefits, Period Increase (Decrease)	$ (540,000)
Earliest Tax Year [Member] | Other Tax Credit Carryforwards [Member]
Operating Loss Carryforwards, Expiration Year	2024
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards	$ 32,600,000	30,100,000	29,400,000
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Earliest Tax Year [Member]
Operating Loss Carryforwards, Expiration Year	2025
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	$ 21,900,000	20,300,000	$ 20,400,000
State and Local Jurisdiction [Member] | Earliest Tax Year [Member]
Operating Loss Carryforwards, Expiration Year	2017
Foreign Tax Authority [Member]
Operating Loss Carryforwards	$ 200,000	$ 200,000