Note 4 - Changes Warranty Liability (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Balance of accrued warranty at January 1	$ 9,237	$ 7,579
Warranties issued during the period	2,097	2,336
Cash settlements made during the period	(3,601)	(1,958)
Changes in liability for pre-existing warranties during the period, including expirations	2,018	(607)
Balance of accrued warranty at June 30	$ 9,751	$ 8,564