Note 10 - Rentals (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leases, Rent Expense	$ 1.1	$ 1.1	$ 0.3
Operating Leases, Future Minimum Payments Due	2.1
Operating Leases, Future Minimum Payments Due, Next Twelve Months	0.9
Operating Leases, Future Minimum Payments, Due in Two Years	0.6
Operating Leases, Future Minimum Payments, Due in Three Years	0.5
Operating Leases, Future Minimum Payments, Due in Four Years	$ 0.1