EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income, as reported	$ 81,045	$ 75,752
Basic earnings per share
Weighted average shares of common stock outstanding-basic (in shares)	96,114,000	91,911,000
Basic earnings per common share (usd per share)	$ 0.84	$ 0.82
Diluted earnings per share
Weighted average shares of common stock outstanding-basic (in shares)	96,114,000	91,911,000
Equity forward sale agreement (in shares)	0	106,000
Other (in shares)	301,000	303,000
Weighted average shares of common stock outstanding-diluted (in shares)	96,415,000	92,320,000
Diluted earnings per common share (usd per share)	$ 0.84	$ 0.82
Share-based Payment Arrangement
Diluted earnings per share
Anti-dilutive shares excluded from the calculation of diluted earnings per share (in shares)	32,317