Loans Receivable and Related Allowance for Loan Losses (6) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Current	$ 979,050	$ 1,035,788
Past Due	23,458	3,213
Total Loans Receivable	1,002,508	1,039,001	$ 1,001,763
Accruing 90 Days or More Past Due	775	58
30 to 59 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	21,062	225
60 to 89 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	574	728
Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	1,822	2,260
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Current	98,898	116,584
Past Due	2,954
Total Loans Receivable	101,852	116,584	99,494
Commercial and Industrial [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	2,954
Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Current	228,711	239,623
Past Due	3,770	2,467
Total Loans Receivable	232,481	242,090	234,738
Accruing 90 Days or More Past Due	710
Residential Mortgage [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	1,678	68
Residential Mortgage [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	520	694
Residential Mortgage [Member] | Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	1,572	1,705
Construction and Development - Residential and Commercial Receivables [Member]
Financing Receivable, Impaired [Line Items]
Current	73,000	65,703
Total Loans Receivable	73,000	65,703	49,095
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Current	464,949	495,087
Past Due	13,859	311
Total Loans Receivable	478,808	495,398	521,495
Commercial Real Estate [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	13,859
Commercial Real Estate [Member] | Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due		311
Commercial Farmland [Member]
Financing Receivable, Impaired [Line Items]
Current	5,091	7,517
Past Due	2,287
Total Loans Receivable	7,378	7,517	7,563
Commercial Farmland [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	2,287
Commercial Multi Family Receivable [Member]
Financing Receivable, Impaired [Line Items]
Current	67,457	67,767
Total Loans Receivable	67,457	67,767	43,473
Commercial - Other Receivable [Member]
Financing Receivable, Impaired [Line Items]
Current	10,010	10,142
Total Loans Receivable	10,010	10,142	8,569
Consumer - Home Equity Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Current	16,230	17,080
Past Due	159	48
Total Loans Receivable	16,389	17,128	18,372
Accruing 90 Days or More Past Due		48
Consumer - Home Equity Lines of Credit [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	86
Consumer - Home Equity Lines of Credit [Member] | Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	73	48
Consumer - Second Mortgages Receivable [Member]
Financing Receivable, Impaired [Line Items]
Current	8,669	10,325
Past Due	428	386
Total Loans Receivable	9,097	10,711	13,179
Accruing 90 Days or More Past Due	65	10
Consumer - Second Mortgages Receivable [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	197	157
Consumer - Second Mortgages Receivable [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	54	33
Consumer - Second Mortgages Receivable [Member] | Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	177	196
Consumer - Other Receivable [Member]
Financing Receivable, Impaired [Line Items]
Current	2,387	2,850
Past Due	1	1
Total Loans Receivable	2,388	2,851	2,160
Consumer - Other Receivable [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due	1
Consumer - Other Receivable [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Impaired [Line Items]
Past Due		1
Construction and Development - Land Receivable [Member]
Financing Receivable, Impaired [Line Items]
Current	3,648	3,110
Total Loans Receivable	$ 3,648	$ 3,110	$ 3,625