Note 5 - Changes Warranty Liability (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Balance of accrued warranty at January 1	$ 9,237	$ 7,579
Warranties issued during the period	3,413	4,323
Cash settlements made during the period	(5,297)	(3,238)
Changes in liability for pre-existing warranties during the period, including expirations	3,886	(607)
Balance of accrued warranty at September 30	$ 11,239	$ 9,488