Loans Receivable and Related Allowance for Loan Losses (4) (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021	Mar. 31, 2021
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	$ 808,037	$ 913,824	$ 986,428
Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	752,459	839,631
Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	43,035	58,053
Substandard [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	12,543	16,140
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	101,354	115,246	94,706
Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	95,347	106,910
Commercial and Industrial [Member] | Substandard [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	6,007	8,336
Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	177,669	198,710	218,165
Residential Mortgage [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	174,594	195,658
Residential Mortgage [Member] | Substandard [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	3,075	3,052
Construction and Development - Residential and Commercial [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	25,558	61,492	76,257
Construction and Development - Residential and Commercial [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	25,558	61,492
Construction and Development - Land [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	4,603	2,204	3,596
Construction and Development - Land [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	4,603	2,204
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	400,974	426,915	482,611
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	357,298	376,721
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	42,972	48,705
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	704	1,489
Commercial Farmland [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	15,624	10,297	7,344
Commercial Farmland [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	13,392	8,043
Commercial Farmland [Member] | Substandard [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	2,232	2,254
Commercial Multi Family [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	54,789	66,332	67,122
Commercial Multi Family [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	54,789	57,052
Commercial Multi Family [Member] | Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross		9,280
Commercial - Other [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	7,977	10,954	9,927
Commercial - Other [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	7,977	10,954
Consumer - Home Equity Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	12,283	13,491	15,936
Consumer - Home Equity Lines of Credit [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	12,107	13,390
Consumer - Home Equity Lines of Credit [Member] | Substandard [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	176	101
Consumer - Second Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	4,969	5,884	8,114
Consumer - Second Mortgages [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	4,560	4,908
Consumer - Second Mortgages [Member] | Special Mention [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	63	68
Consumer - Second Mortgages [Member] | Substandard [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	346	908
Consumer - Other [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	2,237	2,299	$ 2,650
Consumer - Other [Member] | Pass [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	2,234	$ 2,299
Consumer - Other [Member] | Substandard [Member]
Financing Receivable, Impaired [Line Items]
Loans and Leases, gross	$ 3