Earnings (Loss) Per Share of Common Stock - Reconciliation of Numerator and Denominator for Basic and Diluted Earnings (loss) Per Share Calculation (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
Earnings Per Share [Abstract]
Net income (loss) available to common stockholders	$ 31,709	$ (1,397)	$ 19,276	$ (4,139)
Weighted average number of common shares outstanding – basic	102,828	77,025	102,705	77,046
Basic earnings (loss) per share	$ 0.31	$ (0.02)	$ 0.19	$ (0.05)
Weighted average number of common shares outstanding – diluted	102,999	77,025	103,300	77,046
Diluted earnings (loss) per share	$ 0.31	$ (0.02)	$ 0.19	$ (0.05)
Weighted average number of anti-dilutive options and restricted stock	6,356	130	6,406	43