Note 2 - Earnings Per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net income (loss)	$ 14,673	$ 10,796
Weighted average shares outstanding
Total weighted average shares outstanding, basic (in shares)	45,565,381	45,274,540
Dilutive potential common shares (in shares)	1,863,962	393,025
Total weighted average shares outstanding, diluted (in shares)	47,429,343	45,667,565
Net income per share available to common stockholders
Basic (in dollars per share)	$ 0.32	$ 0.24
Diluted (in dollars per share)	$ 0.31	$ 0.24