Note 5 - Stock Option Plan (Details) - Stock option activity (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Stock option activity [Abstract]
Outstanding at beginning of period	5,209	4,262
Outstanding at beginning of period (in Dollars per share)	$ 6.40	$ 5.69
Granted	585	1,697
Granted (in Dollars per share)	$ 7.25	$ 6.98
Exercised	(122)	(407)
Exercised (in Dollars per share)	$ 5.51	$ 3.18
Forfeited or expired	(580)	(206)
Forfeited or expired (in Dollars per share)	$ 5.73	$ 4.60
Outstanding at period end	5,092	5,346
Outstanding at period end (in Dollars per share)	$ 6.60	$ 6.24
Exercisable at period end	2,732	2,340
Exercisable at period end (in Dollars per share)	$ 6.82	$ 6.57