Note 4 - Earnings (Loss) Per Share - Basic and Diluted Weighted Average Number of Shares of Common Stock and Potential Common Stock Equivalents (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Net income (loss)		$ 74,297	$ (93,212)	$ 202,329	$ (26,910)
Computation of Basic EPS:
Weighted Average Shares Outstanding used in Computing Basic EPS (in shares)		168,795	168,313	168,679	168,216
Basic earnings (loss) per share (in dollars per share)		$ 0.44	$ (0.55)	$ 1.20	$ (0.16)
Computation of Diluted EPS:
Weighted Average Shares Outstanding used in Computing Basic EPS (in shares)		168,795	168,313	168,679	168,216
Effect of stock awards (in shares)		519		568
Weighted Average Shares used in Computing Diluted EPS (1) (in shares)	[1]	169,314	168,313	169,247	168,216
Diluted earnings (loss) per share (in dollars per share)		$ 0.44	$ (0.55)	$ 1.20	$ (0.16)

[1] Common stock equivalents not included in the computation of diluted earnings per share because the impact would have been anti-dilutive were 0 shares for the three month periods ended December 31, 2017 and 2018, respectively, and 121 shares and 8 shares for the nine months ended December 31, 2017 and 2018, respectively.