EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income (loss), as reported	$ 123,699	$ 34,929
Basic earnings per share
Weighted average shares of common stock outstanding-basic (shares)	86,996,000	86,084,000
Basic earnings per common share (usd per share)	$ 1.42	$ 0.41
Diluted earnings per share
Weighted average shares of common stock outstanding-basic (shares)	86,996,000	86,084,000
Incremental shares	351,000	771,000
Weighted average shares of common stock outstanding-diluted (shares)	87,347,000	86,855,000
Diluted (loss) earnings per common share (usd per share)	$ 1.42	$ 0.40
Anti-dilutive shares excluded from the calculation of diluted earnings per share	0	0