Derivative Financial Instruments - Income (loss) related to derivative financial instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Derivative Financial Instruments
Income (loss) related to derivative financial instruments	$ 555	$ 7,648	$ 609	$ 8,517
Interest rate lock commitments
Derivative Financial Instruments
Income (loss) related to derivative financial instruments	986	(4,663)	1,585	(4,490)
Forward mortgage loan sale contracts
Derivative Financial Instruments
Income (loss) related to derivative financial instruments	$ (431)	$ 12,311	$ (976)	$ 13,007