Loans Receivable - Summary of Loans Receivable (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Real estate loans:
Total Loans	$ 1,759,590	$ 1,699,050
Less allowance for credit losses	15,306	18,525
Net loans	1,744,284	1,680,525
Commercial [Member]
Real estate loans:
Total Loans	36,799	48,143
Real Estate Loans [Member] | Residential [Member]
Real estate loans:
Total Loans	721,505	713,326
Less allowance for credit losses	4,897
Real Estate Loans [Member] | Construction [Member]
Real estate loans:
Total Loans	14,851	16,768
Less allowance for credit losses	183
Real Estate Loans [Member] | Commercial [Member]
Real estate loans:
Total Loans	884,621	821,958
Less allowance for credit losses	11,983
Real Estate Loans [Member] | Commercial [Member]
Real estate loans:
Less allowance for credit losses	941
Obligations of States and Political Subdivisions [Member]
Real estate loans:
Total Loans	48,570	48,118
Less allowance for credit losses	110
Home Equity Loans and Lines of Credit [Member]
Real estate loans:
Total Loans	51,306	48,212
Less allowance for credit losses	346
Auto Loans [Member]
Real estate loans:
Total Loans	65	523
Less allowance for credit losses	2
Other [Member]
Real estate loans:
Total Loans	1,873	$ 2,002
Less allowance for credit losses	$ 22