Fair Value Measurements and Disclosures about Fair Value of Financial Instruments (Carrying Value And Estimated Fair Value Of Financial Instruments) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Financial assets:
Cash and due from banks	$ 11,524	$ 14,191
Interest-bearing deposits with banks	24,820	28,083
Securities available for sale	186,260	184,373
Securities held to maturity	2,570	2,607
Loans, net	734,061	704,271
Loan servicing rights (included in other assets)	2,554	2,405	$ 1,746	$ 1,389
Derivative assets (included in other assets)	658	421
Financial liabilities:
Deposits	832,073	811,112
Short-term repurchase agreements	1,352	1,352
Borrowings from FHLB	107,019	90,000
Accrued interest payable	996	743
Advance payments by borrowers for taxes and insurance	855	1,218
Derivative Liability	132	0
Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and due from banks	11,524	14,191
Interest-bearing deposits with banks	24,820	28,083
Interest-bearing time deposits	0	0
Securities available for sale	0	0
Securities held to maturity	0	0
Loans, net	0	0
Accrued interest receivable	0	0
Loan servicing rights (included in other assets)	0	0
Derivative assets (included in other assets)	0	0
Financial liabilities:
Deposits	0	0
Short-term repurchase agreements	0	0
Borrowings from FHLB	0	0
Subordinated note	0	0
Accrued interest payable	0	0
Advance payments by borrowers for taxes and insurance	0	0
Derivative Liability	0
Fair Value, Inputs, Level 1 [Member] | Small Business Administration Loans [Member]
Financial assets:
Loans, net	0	0
Fair Value, Inputs, Level 1 [Member] | Residential mortgage loans held for sale [Member]
Financial assets:
Loans, net	0	0
Fair Value, Inputs, Level 2 [Member]
Financial assets:
Cash and due from banks	0	0
Interest-bearing deposits with banks	0	0
Interest-bearing time deposits	2,978	2,494
Securities available for sale	186,260	184,373
Securities held to maturity	2,897	2,896
Loans, net	0	0
Accrued interest receivable	4,808	4,287
Loan servicing rights (included in other assets)	0	0
Derivative assets (included in other assets)	0	41
Financial liabilities:
Deposits	0	0
Short-term repurchase agreements	1,352	1,352
Borrowings from FHLB	102,984	84,175
Subordinated note	19,678	19,661
Accrued interest payable	996	743
Advance payments by borrowers for taxes and insurance	855	1,218
Derivative Liability	132
Fair Value, Inputs, Level 2 [Member] | Small Business Administration Loans [Member]
Financial assets:
Loans, net	0	23,488
Fair Value, Inputs, Level 2 [Member] | Residential mortgage loans held for sale [Member]
Financial assets:
Loans, net	15,920	10,476
Fair Value, Inputs, Level 3 [Member]
Financial assets:
Cash and due from banks	0	0
Interest-bearing deposits with banks	0	0
Interest-bearing time deposits	0	0
Securities available for sale	0	0
Securities held to maturity	0	0
Loans, net	698,595	673,652
Accrued interest receivable	0	0
Loan servicing rights (included in other assets)	2,614	2,405
Derivative assets (included in other assets)	658	380
Financial liabilities:
Deposits	830,814	809,305
Short-term repurchase agreements	0	0
Borrowings from FHLB	0	0
Subordinated note	0	0
Accrued interest payable	0	0
Advance payments by borrowers for taxes and insurance	0	0
Derivative Liability	0
Fair Value, Inputs, Level 3 [Member] | Small Business Administration Loans [Member]
Financial assets:
Loans, net	24,128	0
Fair Value, Inputs, Level 3 [Member] | Residential mortgage loans held for sale [Member]
Financial assets:
Loans, net	0	0
Estimate of Fair Value Measurement [Member]
Financial assets:
Cash and due from banks	11,524	14,191
Interest-bearing deposits with banks	24,820	28,083
Interest-bearing time deposits	2,991	2,501
Securities available for sale	186,260	184,373
Securities held to maturity	2,570	2,607
Loans, net	734,061	704,271
FRB and FHLB stock	10,196	9,621
Accrued interest receivable	4,808	4,287
Loan servicing rights (included in other assets)	2,554	2,405
Derivative assets (included in other assets)	658	421
Financial liabilities:
Deposits	832,073	811,112
Short-term repurchase agreements	1,352	1,352
Borrowings from FHLB	107,019	90,000
Subordinated note	19,678	19,661
Accrued interest payable	996	743
Advance payments by borrowers for taxes and insurance	855	1,218
Derivative Liability	132
Estimate of Fair Value Measurement [Member] | Small Business Administration Loans [Member]
Financial assets:
Loans, net	22,032	21,659
Estimate of Fair Value Measurement [Member] | Residential mortgage loans held for sale [Member]
Financial assets:
Loans, net	$ 15,920	$ 10,466