Note 9 - Product Warranty Obligations - Recognition of Deferred Revenue Related to Extended Warranties 2 (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Revenue performance obligation	$ 68,340
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue performace obligation, expected timing (Year)	1 year
Revenue performance obligation	$ 13,438
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue performace obligation, expected timing (Year)	1 year
Revenue performance obligation	$ 13,547
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue performace obligation, expected timing (Year)	1 year
Revenue performance obligation	$ 12,178
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue performace obligation, expected timing (Year)	1 year
Revenue performance obligation	$ 9,756
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue performace obligation, expected timing (Year)
Revenue performance obligation	$ 19,421