Note 4 - Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Warrant [Member]
Dilutive effect of weighted-average outstanding common share equivalents
Warrants (in shares)	539,201	566,405	495,785	456,274
Employee Stock Option [Member]
Dilutive effect of weighted-average outstanding common share equivalents
Warrants (in shares)	92,455	139,867	87,737	124,249
Restricted Stock Units (RSUs) [Member]
Dilutive effect of weighted-average outstanding common share equivalents
Warrants (in shares)	141,990	53,525	132,966	37,043
Net Income (Loss) Attributable to Parent	$ 34,831	$ 45,200	$ 80,994	$ 81,180	$ 81,000
Basic weighted-average number of common shares outstanding (in shares)	78,846,237	79,939,197	79,290,378	79,887,699
Diluted weighted-average number of common shares outstanding (in shares)	79,619,883	80,698,994	80,006,866	80,505,265
Average stock options and warrants with anti-dilutive effect (in shares)	177,642	939,615	268,593	1,246,123
Basic (in dollars per share)	$ 0.44	$ 0.57	$ 1.02	$ 1.02
Diluted (in dollars per share)	$ 0.44	$ 0.56	$ 1.01	$ 1.01