Note 5 - Acquisition (Details) - Changes in the Carrying Amount of Goodwill (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Aug. 08, 2014
Goodwill [Line Items]      
Balance as of December 31, 2013   $ 2,117  
Balance as of December 31, 2014 16,659 2,117  
Alpine Biosciences, Inc. [Member]      
Goodwill [Line Items]      
Balance as of December 31, 2013     14,542
Goodwill recorded in connection with the acquisition of Alpine 14,542    
Balance as of December 31, 2014     $ 14,542