Note 12 - Commitments and Contingencies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Estimated Litigation Liability	$ 91,000	$ 138,000
Operating Leases, Rent Expense	$ 1,500,000	$ 1,600,000	$ 1,500,000