Note 6 - Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net income	$ (10,554)	$ 7,195	$ 225	$ 20,885
Basic (in shares)	165,162	162,357	164,812	158,259
Effect of dilutive securities: Stock options, restricted shares and performance based shares (in shares)		1,448	2,903	1,683
Diluted (in shares)	165,162	163,805	167,715	159,942
Net (loss) income per common share - basic (in dollars per share)	$ (0.06)	$ 0.04	$ 0	$ 0.13
Net (loss) income per common share - diluted (in dollars per share)	$ (0.06)	$ 0.04	$ 0	$ 0.13