Loans - Additional Information (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	$ 357,057,000		$ 325,992,000
Additional committed impared loans	0		0
Loans modified as troubled debt restructurings	0		0
Troubled debt restructurings within past twelve months for which there was a default	0	$ 0
Overdrawn deposit account reclassified as loan	13,000,000		106,000,000
Loans and leases receivable, net amount	$ 354,740,000		323,789,000
Covid Nineteen [Member] | Payment Deferral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing recievable threshold past due	30 days
Loans and leases receivable, net amount	$ 4,600,000
Financing receivable deferral amount	245,000
Doubtful [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total Loans	0		0
Other Financial Institutions [Member]
Loans and Leases Receivable Disclosure [Line Items]
Participation loans transferred	$ 30,400,000		$ 32,100,000