COMPUTATION OF EARNINGS PER COMMON SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income (loss)	$ (21,589)	$ (41,734)	$ (86,709)	$ 14,471	$ 9,854	$ (49,504)	$ 19,953	$ 18,828	$ (135,561)	$ (869)	$ 82,599
Earnings Per Share, Basic and Diluted
Weighted average common shares-basic									37,569	32,345	32,279
Dilutive effect of employee equity incentive plans									0	0	684
Weighted average common shares-diluted									37,569	32,345	32,963
Basic (in dollars per share)	$ (0.55)	$ (1.06)	$ (2.21)	$ 0.43	$ 0.30	$ (1.54)	$ 0.59	$ 0.58	$ (3.61)	$ (0.03)	$ 2.56
Diluted (in dollars per share)	$ (0.55)	$ (1.06)	$ (2.21)	$ 0.42	$ 0.29	$ (1.54)	$ 0.59	$ 0.57	$ (3.61)	$ (0.03)	$ 2.51
Potentially dilutive securities excluded from diluted earnings (loss) per share because their effect is anti-dilutive									616	543	574