EARNINGS (LOSSES) PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Loss from continuing operations	$ (46,007)			$ (154,621)			$ (435,746)	$ (74,400)
Income (loss) from discontinued operations	408			(62)			212	(433)
Net loss	(45,599)	$ (420,540)	$ 30,605	(154,683)	$ 60,891	$ 18,959	(435,534)	(74,833)
Adjustment for basic loss per share
Loss allocated to unvested shareholders	(331)			(772)			(2,327)	(2,332)
Numerator for basic loss per share:
From continuing operations	(46,338)			(155,393)			(438,073)	(76,732)
From discontinued operations	408			(62)			212	(433)
Net income (loss) attributable to parent, basic	(45,930)			(155,455)			(437,861)	(77,165)
Adjustment for diluted loss per share:
Effect of reallocating undistributed earnings of unvested shareholders	0			0			0	0
Numerator for diluted loss per share:
From continuing operations	(46,338)			(155,393)			(438,073)	(76,732)
From discontinued operations	408			(62)			212	(433)
Net income (loss) attributable to parent, diluted	$ (45,930)			$ (155,455)			$ (437,861)	$ (77,165)
Denominator:
Denominator for basic loss per share – weighted-average shares (in shares)	107,439			109,425			108,185	109,324
Effect of dilutive shares from stock options, restricted stock and performance share units (in shares)	0			0			0	0
Denominator for diluted loss per share – adjusted weighted-average shares (in shares)	107,439			109,425			108,185	109,324
Basic loss per common share:
Loss from continuing operations (in dollars per share)	$ (0.43)			$ (1.42)			$ (4.05)	$ (0.71)
Loss from discontinued operations (in dollars per share)	0			0			0	0
Net loss (in dollars per share)	(0.43)			(1.42)			(4.05)	(0.71)
Diluted loss per common share:
Loss from continuing operations (in dollars per share)	(0.43)			(1.42)			(4.05)	(0.71)
Loss from discontinued operations (in dollars per share)	0			0			0	0
Net loss (in dollars per share)	$ (0.43)			$ (1.42)			$ (4.05)	$ (0.71)