Income Taxes - Net Deferred Tax Asset (Liability) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Deferred tax assets
Allowance for credit losses	$ 46,191	$ 47,426
REO reserves	300	329
Non-accrual loan interest	1,797	1,104
Deferred compensation	2,901	6,841
Stock based compensation	3,089	2,636
Lease liability	5,367	6,207
Other	2,804	1,329
Total deferred tax assets	62,449	65,872
Deferred tax liabilities
FHLB stock dividends	9,741	9,826
Valuation adjustment on available-for-sale securities and cash flow hedges	13,933	15,765
Loan origination fees and costs	11,471	10,918
Premises and equipment	18,155	20,132
Lease right-of-use assets	4,841	5,992
Equity investments	4,244	5,323
Acquired intangibles	4,798	4,116
Other	483	25
Total deferred tax liabilities	67,666	72,097
Net deferred tax asset (liability)	(5,217)	(6,225)
Current tax asset (liability)	13,696	2,920
Net tax asset (liability)	$ 8,479	$ (3,305)