COMPUTATION OF EARNINGS (LOSS) PER COMMON SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net income (loss)	$ (49,504)	$ 22,221	$ (10,723)	$ 63,082
Denominator:
Weighted average common shares-basic (in shares)	32,075	32,242	32,384	32,260
Dilutive effect of employee equity incentive plans (in shares)	0	584	0	635
Weighted average common shares-diluted (in shares)	32,075	32,826	32,384	32,895
Basic earnings (loss) per common share (in dollars per share)	$ (1.54)	$ 0.69	$ (0.33)	$ 1.96
Diluted earnings (loss) per common share (in dollars per share)	$ (1.54)	$ 0.68	$ (0.33)	$ 1.92
Potentially dilutive securities excluded from diluted earnings per common share because their effect is anti-dilutive	968	473	1,107	573