SHAREHOLDERS' EQUITY - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Numerator for basic and diluted earnings per share attributable to common stockholders:
Net income (loss) attributable to common stockholders					$ 23,773	$ 13,600	$ 31,289
Denominator:
Basic (in shares)					14,580,398	13,993,638	14,017,279
Effect of diluted securities (in shares)					200,000,000	25,205,000	0
Denominator for diluted earnings per share-adjusted weighted average shares and assumed conversions (in shares)					14,780,398	14,018,843	14,017,279
Basic earnings (loss) per share (in dollars per share)	$ (0.20)	$ (0.33)	$ 1.77	$ 0.45	$ 1.63	$ 0.97	$ 2.23
Diluted earnings (loss) per share (in dollars per share)	$ (0.20)	$ (0.33)	$ 1.75	$ 0.45	$ 1.61	$ 0.97	$ 2.23