Note 8 - Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net income (loss)	$ 15,696	$ 10,547	$ (35,660)
Weighted-average shares outstanding - basic (in shares)	51,161,059	51,015,354	49,600,396
Dilutive common stock equivalents (in shares)	143,923	14,436
Weighted-average shares outstanding - diluted (in shares)	51,304,982	51,029,790	49,600,396
Basic net income (loss) per share (in dollars per share)	$ 0.31	$ 0.21	$ (0.72)
Diluted net income (loss) per share (in dollars per share)	$ 0.31	$ 0.21	$ (0.72)
Antidulitive Shares (in shares)	568,014	1,042,579	762,021