EARNINGS (LOSSES) PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net income	$ 95,173	$ 97,145
Adjustment for basic earnings per share
Earnings allocated to unvested shareholders	(1,248)	(992)
Numerator for basic earnings per share	93,925	96,153
Adjustment for diluted earnings per share
Effect of reallocating undistributed earnings of unvested shareholders	2	0
Numerator for diluted earnings per share	$ 93,927	$ 96,153
Denominator:
Denominator for basic earnings (loss) per share - weighted-average shares (in shares)	99,143	105,248
Effect of dilutive shares from stock options, restricted stock and performance share units (in shares)	485	856
Denominator for diluted earnings (loss) per share - adjusted weighted-average shares (in shares)	99,628	106,104
Earnings per common share, basic (in dollars per share)	$ 0.95	$ 0.92
Earnings per common share, diluted (in dollars per share)	$ 0.94	$ 0.91