Note 11 - Warranty Costs - Warranty Accrual (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Warranty accrual	$ 43,932	$ 40,691
Warranty costs accrued during the period	16,097	16,903
Warranty costs paid during the period	(18,303)	(15,088)
Warranty accrual	$ 41,726	$ 42,506