Allowance for Credit Losses on Loans - Past Due Information of Loan Portfolio by Class (Detail) - USD ($)	Jun. 30, 2026	Dec. 31, 2025
Financing Receivable Impaired [Line Items]
Total Past Due Loans	$ 692,231,000	$ 689,562,000
Total Loans	692,231,000	689,562,000
Accruing Loans 90 Days or More Past Due	0	0
Loans 30-89 Days Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	1,572,000	700,000
Nonaccrual Loans
Financing Receivable Impaired [Line Items]
Total Past Due Loans	771,000	378,000
Financial Asset, Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	2,343,000	1,078,000
Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	689,888,000	688,484,000
Real Estate - Commercial [Member]
Financing Receivable Impaired [Line Items]
Total Loans	253,193,000	255,944,000
Accruing Loans 90 Days or More Past Due	0	0
Real Estate - Commercial [Member] \| Loans 30-89 Days Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	119,000
Real Estate - Commercial [Member] \| Financial Asset, Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	119,000
Real Estate - Commercial [Member] \| Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	253,074,000	255,944,000
Other Real Estate Construction [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	64,119,000	57,247,000
Total Loans	64,119,000	57,247,000
Accruing Loans 90 Days or More Past Due	0	0
Other Real Estate Construction [Member] \| Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	64,119,000	57,247,000
Real Estate 1 - 4 Family Construction [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	20,447,000	19,453,000
Total Loans	20,447,000	19,453,000
Accruing Loans 90 Days or More Past Due	0	0
Real Estate 1 - 4 Family Construction [Member] \| Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	20,447,000	19,453,000
Real Estate - Residential [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	152,888,000	159,274,000
Total Loans	152,888,000	159,274,000
Accruing Loans 90 Days or More Past Due	0	0
Real Estate - Residential [Member] \| Loans 30-89 Days Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	1,373,000	561,000
Real Estate - Residential [Member] \| Nonaccrual Loans
Financing Receivable Impaired [Line Items]
Total Past Due Loans	489,000	179,000
Real Estate - Residential [Member] \| Financial Asset, Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	1,862,000	740,000
Real Estate - Residential [Member] \| Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	151,026,000	158,534,000
Home Equity [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	76,779,000	73,262,000
Total Loans	76,779,000	73,262,000
Accruing Loans 90 Days or More Past Due	0	0
Home Equity [Member] \| Loans 30-89 Days Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	57,000	104,000
Home Equity [Member] \| Nonaccrual Loans
Financing Receivable Impaired [Line Items]
Total Past Due Loans	259,000	199,000
Home Equity [Member] \| Financial Asset, Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	316,000	303,000
Home Equity [Member] \| Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	76,463,000	72,959,000
Other Loans [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	5,089,000	4,683,000
Total Loans	5,089,000	4,683,000
Accruing Loans 90 Days or More Past Due	0	0
Other Loans [Member] \| Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	5,089,000	4,683,000
Commercial [Member]
Financing Receivable Impaired [Line Items]
Total Loans	110,491,000	110,088,000
Accruing Loans 90 Days or More Past Due	0	0
Commercial [Member] \| Loans 30-89 Days Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	15,000	22,000
Commercial [Member] \| Financial Asset, Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	15,000	22,000
Commercial [Member] \| Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	110,476,000	110,066,000
Consumer Loans [Member]
Financing Receivable Impaired [Line Items]
Total Loans	9,225,000	9,611,000
Accruing Loans 90 Days or More Past Due	0	0
Consumer Loans [Member] \| Loans 30-89 Days Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	8,000	13,000
Consumer Loans [Member] \| Nonaccrual Loans
Financing Receivable Impaired [Line Items]
Total Past Due Loans	23,000
Consumer Loans [Member] \| Financial Asset, Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	31,000	13,000
Consumer Loans [Member] \| Financial Asset, Not Past Due [Member]
Financing Receivable Impaired [Line Items]
Total Past Due Loans	$ 9,194,000	$ 9,598,000