Note 11 - Warranty Accrual (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Product Warranty, First Term for Performing Work			2 years
Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties	$ (425)	$ 1,825	$ (375)	$ 5,062
Minimum [Member]
Product Warranty, Term for Paying for Work			3 years
Maximum [Member]
Product Warranty, Term for Paying for Work			10 years