Derivative Financial Instruments and Hedging Activities - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Notional Amount	$ 64,800	$ 154,300
Derivative assets held for sale	113,600	97,100
Mortgage derivative asset	1,876	5,293
Mortgage derivative liability	75	1,600
A before income tax gain on terminated cash flow hedges	6,200
Payment of advances that were associated with hedges	115,000
Hedged Instrument [Member]
Derivative [Line Items]
Derivative assets held for sale	$ 169,500	$ 225,000