Note 2 - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares
Outstanding (in shares) | shares	3,766,868
Outstanding (in dollars per share) | $ / shares	$ 13.28
Options granted (in shares) | shares
Options granted (in dollars per share) | $ / shares
Options forfeited (in shares) | shares	(46,346)
Options forfeited (in dollars per share) | $ / shares	$ 33.13
Options exercised (in shares) | shares	(74,121)
Options exercised (in dollars per share) | $ / shares	$ 9.99
Outstanding (in shares) | shares	3,646,401
Outstanding (in dollars per share) | $ / shares	$ 13.10
Exercisable (in shares) | shares	3,377,368
Exercisable (in dollars per share) | $ / shares	$ 11.51
Exercisable	5 years 36 days
Exercisable | $	$ 61,718