Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
(Loss) income from continuing operations	$ (8,174)	$ (23,125)	$ 490,835	$ (106,152)
Income (loss) from discontinued operations	166	1,326	(10,616)	472
NET (LOSS) INCOME	(8,008)	(21,799)	480,219	(105,680)
Adjustment for basic earnings per share:
Earnings allocated to unvested shareholders	(717)	(458)	(4,241)	(1,349)
Numerator for basic earnings per share:
From continuing operations	(8,891)	(23,583)	486,594	(107,501)
From discontinued operations	166	1,326	(10,616)	472
Net income (loss) attributable to parent, basic	(8,725)	(22,257)	475,978	(107,029)
Adjustment for diluted earnings per share:
Effect of reallocating undistributed earnings of unvested shareholders			10
Numerator for diluted earnings per share:
From continuing operations	(8,891)	(23,583)	486,604	(107,501)
From discontinued operations	166	1,326	(10,616)	472
Net income (loss) attributable to parent, diluted	$ (8,725)	$ (22,257)	$ 475,988	$ (107,029)
Denominator:
Denominator for basic earnings per share – weighted-average shares	108,905	108,572	108,818	108,470
Effect of dilutive shares from stock options and restricted stock (in shares)			520
Denominator for diluted earnings per share – adjusted weighted-average shares	108,905	108,572	109,338	108,470
Basic earnings per common share:
(Loss) income from continuing operations (in dollars per share)	$ (0.08)	$ (0.22)	$ 4.47	$ (0.99)
Income (loss) from discontinued operations (in dollars per share)		0.01	(0.10)
Net (loss) income (in dollars per share)	(0.08)	(0.21)	4.37	(0.99)
Diluted earnings per common share:
(Loss) income from continuing operations (in dollars per share)	(0.08)	(0.22)	4.45	(0.99)
Income (loss) from discontinued operations (in dollars per share)		0.01	(0.10)
Net (loss) income (in dollars per share)	$ (0.08)	$ (0.21)	$ 4.35	$ (0.99)
Outstanding equity awards
Shares excluded from calculation of diluted earnings per share (in shares)	929	1,332	1,585	1,034
Weighted-average price per share (in dollars per share)	$ 75.56	$ 70.82	$ 68.51	$ 73.84