Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share
Net income	$ 22,186	$ 18,898
Income allocated to participating securities	(12)	(13)
Net income available to common stockholders	$ 22,174	$ 18,885
Total basic average common shares outstanding	135,627,043	135,397,691
Effect of dilutive stock options	0	1,193
Total diluted average common shares outstanding	135,627,043	135,398,884
Net EPS:
Basic	$ 0.16	$ 0.14
Diluted	$ 0.16	$ 0.14
Antidilutive stock options, excluded from the diluted average common shares outstanding calculation	543,761	431,212
Average Common Shares Outstanding [Member]
Earnings Per Share
Total basic average common shares outstanding	135,626,594	135,397,242
Average Committed ESOP Shares Outstanding [Member]
Earnings Per Share
Total basic average common shares outstanding	449	449