Note 6 - Employee Benefits Plans - Stock Options Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares
Outstanding (in shares)	1,027
Outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 9.75
Granted (in shares)	30
Exercised (in shares)	(87)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 5.98
Canceled (in shares)	(3)
Canceled, weighted average exercise price (in dollars per share) | $ / shares	$ 14.41
Expired (in shares)	(10)
Expired, weighted average exercise price (in dollars per share) | $ / shares	$ 16.70
Outstanding (in shares)	957
Outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 10.05
Outstanding, weighted average remaining contractual term (Year)	4 years 226 days
Outstanding, aggregate intrinsic value | $	$ 3,191
Vested and expected to vest (in shares)	936
Vested and expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 9.99
Vested and expected to vest, weighted average remaining contractual term (Year)	4 years 189 days
Vested and expected to vest, aggregate intrinsic value | $	$ 3,167
Exercisable (in shares)	713
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 9.03
Exercisable, weighted average remaining contractual term (Year)	3 years 62 days
Exercisable, aggregate intrinsic value | $	$ 2,932