EARNINGS (LOSS) PER COMMON SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator:
Income (loss) from continuing operations	$ (154,621)	$ (8,174)	$ (74,400)	$ 490,835
Income (loss) from discontinued operations	(62)	166	(433)	(10,616)
Net income (loss)	(154,683)	(8,008)	(74,833)	480,219
Adjustment for basic earnings per share
Earnings allocated to unvested shareholders	(772)	(717)	(2,332)	(4,241)
Numerator for basic earnings (loss) per share:
From continuing operations	(155,393)	(8,891)	(76,732)	486,594
From discontinued operations	(62)	166	(433)	(10,616)
Net income (loss) attributable to parent, basic	(155,455)	(8,725)	(77,165)	475,978
Adjustment for diluted earnings (loss) per share:
Effect of reallocating undistributed earnings of unvested shareholders	0	0	0	10
Numerator for diluted earnings (loss) per share:
From continuing operations	(155,393)	(8,891)	(76,732)	486,604
From discontinued operations	(62)	166	(433)	(10,616)
Net income (loss) attributable to parent, diluted	$ (155,455)	$ (8,725)	$ (77,165)	$ 475,988
Denominator:
Denominator for basic earnings (loss) per share – weighted-average shares (in shares)	109,425	108,905	109,324	108,818
Effect of dilutive shares from stock options, restricted stock and performance share units (in shares)	0	0	0	520
Denominator for diluted earnings (loss) per share – adjusted weighted-average shares (in shares)	109,425	108,905	109,324	109,338
Basic earnings (loss) per common share:
Income (loss) from continuing operations (in dollars per share)	$ (1.42)	$ (0.08)	$ (0.71)	$ 4.47
Loss from discontinued operations (in dollars per share)	0	0	0	(0.10)
Net income (loss) (in dollars per share)	(1.42)	(0.08)	(0.71)	4.37
Diluted earnings (loss) per common share:
Income (loss) from continuing operations (in dollars per share)	(1.42)	(0.08)	(0.71)	4.45
Loss from discontinued operations (in dollars per share)	0	0	0	(0.10)
Net income (loss) (in dollars per share)	$ (1.42)	$ (0.08)	$ (0.71)	$ 4.35
Outstanding equity awards
Shares excluded from calculation of diluted earnings (loss) per share (in shares)	2,753	929	2,768	1,585
Weighted-average price per share (in dollars per share)	$ 64.22	$ 75.56	$ 64.21	$ 68.51