Note 5 - Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net income (loss)	$ 41,443	$ (25,455)
Basic (in shares)	169,723	166,041
Stock options and restricted shares (in shares)
Denominator for diluted earnings per share – adjusted weighted-average shares and assumed exercise of options and restricted shares (in shares)	169,723	166,041
Net income (loss) per common share - basic (in dollars per share)	$ 0.24	$ (0.15)
Net income (loss) per common share - diluted (in dollars per share)	$ 0.24	$ (0.15)