Loans Receivable - Schedule of Loan Modifications (Details) - Term Extension - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2024	Jun. 30, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term Extension	$ 48,231	$ 94,109
% of Total Loan Class Balance	0.23%	0.45%
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term Extension	$ 47,668	$ 93,546
% of Total Loan Class Balance	0.20%	0.76%
Commercial loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term Extension	$ 23,435	$ 23,502
% of Total Loan Class Balance	0.63%	0.63%
Wtd. Avg. Term Extension	36 months	36 months
Commercial loans | Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term Extension	$ 24,233	$ 56,891
% of Total Loan Class Balance	1.01%	2.38%
Wtd. Avg. Term Extension	9 months	8 months
Commercial loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term Extension		$ 13,153
% of Total Loan Class Balance		0.91%
Wtd. Avg. Term Extension		15 months
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term Extension	$ 563	$ 563
% of Total Loan Class Balance	0.01%	0.01%
Consumer loans | Single-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term Extension	$ 563	$ 563
% of Total Loan Class Balance	0.01%	0.01%
Wtd. Avg. Term Extension	6 months	6 months