Note 9 - Income Taxes (Details) - USD ($) $ in Thousands  | 
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2016  | 
Jun. 30, 2015  | 
Jun. 30, 2016  | 
Jun. 30, 2015  | 
|
| Benefit from income tax | $ (236) | $ (177) | $ (227) | $ (250) | 
| Effective income tax rate | 6.30% | 2.00% | 2.90% | 1.60% | 
| X | ||||||||||
- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
  | 
| X | ||||||||||
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
  |