Note 1 - Stock Option Activity (Details)	9 Months Ended
	Sep. 30, 2015 $ / shares shares
Outstanding at (in shares)	1,118,058
Outstanding at (in dollars per share) | $ / shares	$ 6.63
Granted (in shares)	153,618
Granted (in dollars per share) | $ / shares	$ 18.11
Exercised (in shares)	(255,332)
Exercised (in dollars per share) | $ / shares	$ 7.03
Lapsed (in shares)	(5,900)
Lapsed (in dollars per share) | $ / shares	$ 5.64
Cancelled (in shares)	(520)
Cancelled (in dollars per share) | $ / shares	$ 17.40
Outstanding at (in shares)	1,009,924
Outstanding at (in dollars per share) | $ / shares	$ 8.27