Note 11 - Warranty Accrual - Warranty Accrual and Payment Activity (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Balance at beginning of period	$ 17,217,000	$ 17,253,000	$ 15,328,000	$ 18,346,000
Expense provisions	2,390,000	1,536,000	6,147,000	3,980,000
Cash payments	(2,723,000)	(2,708,000)	(7,828,000)	(6,032,000)
Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties	1,825,000	0	5,062,000	(213,000)
Balance at end of period	$ 18,709,000	$ 16,081,000	$ 18,709,000	$ 16,081,000