Loans - Recorded Investment for Consumer Loans, Credit Quality based on Status of Loan and Payment Activity (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans after net deferred loan fees and costs	$ 1,302,990	$ 1,218,999
Performing	148	152
Consumer - Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Performing	3,670	4,091
Consumer - Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Performing	48,991	45,318
Performing [Member] | Consumer - Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Performing	3,660	4,076
Performing [Member] | Consumer - Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Performing	48,855	44,831
Nonperforming [Member] | Consumer - Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Performing	10	15
Nonperforming [Member] | Consumer - Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Performing	136	487
Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans after net deferred loan fees and costs	175,316	164,691
Performing	42	46
Pass [Member] | Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans after net deferred loan fees and costs	171,667	160,930
5 [Member] | Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans after net deferred loan fees and costs	1,284	415
6 [Member] | Consumer Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans after net deferred loan fees and costs	$ 2,365	$ 3,346