Note 4 - Stockholders' Equity - Stock Options Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Outstanding, January 1, 2016 (in shares)	1,764
Outstanding, January 1, 2016 (in dollars per share) | $ / shares	$ 7.88
Granted (weighted average fair value of $4.82 per share) (in shares)	75
Exercised (in shares)	(150)
Exercised (in dollars per share) | $ / shares	$ 7.55
Canceled (in shares)	(28)
Canceled (in dollars per share) | $ / shares	$ 13.68
Expired (in shares)	(75)
Expired (in dollars per share) | $ / shares	$ 13.78
Outstanding, September 30, 2016 (in shares)	1,586
Outstanding, September 30, 2016 (in dollars per share) | $ / shares	$ 7.77
Outstanding, September 30, 2016	4 years 200 days
Outstanding, September 30, 2016 | $	$ 16,565
Vested and expected to vest, September 30, 2016 (in shares)	1,577
Vested and expected to vest, September 30, 2016 (in dollars per share) | $ / shares	$ 7.74
Vested and expected to vest, September 30, 2016	4 years 193 days
Vested and expected to vest, September 30, 2016 | $	$ 16,520
Exercisable, September 30, 2016 (in shares)	1,452
Exercisable, September 30, 2016 (in dollars per share) | $ / shares	$ 7.22
Exercisable, September 30, 2016	4 years 54 days
Exercisable, September 30, 2016 | $	$ 15,943