Note 7 - Commitments and Contingencies (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Purchase Obligation, Total	$ 1.2
Selling, General and Administrative Expenses [Member]
Operating Leases, Rent Expense, Total	0.3	$ 0.3
Cost of Sales [Member]
Operating Leases, Rent Expense, Total	$ 0.8	$ 0.7
Maximum [Member]
Lessee, Operating Lease, Term of Contract		5 years