Leases - Additional Information (Detail)		3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 11, 2024 USD ($) Property	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) Number	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Lessee Lease Description [Line Items]
Loss on disposition of equipment				$ 2,522,000
Future lease payments		$ 9,837,000		9,837,000
Finance lease liability		1,523,000		1,523,000
Operating lease, Right-of-use asset		5,719,000		5,719,000		$ 587,000
Operating lease liability		5,719,000		$ 5,719,000		$ 587,000
Branch Office and Certain Equipment Expires in June 2039
Lessee Lease Description [Line Items]
Lease expiration month and year				2039-06
Future lease payments		9,300,000		$ 9,300,000
Finance lease liability		1,500,000		1,500,000
Operating lease, Right-of-use asset		5,200,000		5,200,000
Operating lease liability		5,200,000		5,200,000
Sale-leaseback transaction resulted pre-tax gain				2,500,000
Operating lease expense		131,000	$ 0	160,000	$ 0
ATM Related Equipment Expires in August 2030
Lessee Lease Description [Line Items]
Lease expiration month and year						2030-08
Loss on disposition of equipment						$ (2,000)
Future lease payments		451,000		451,000
Operating lease expense		19,000	6,000	$ 57,000	6,000
Branch Office Expires in August 2027
Lessee Lease Description [Line Items]
Lease expiration month and year				2027-08
Future lease payments		123,000		$ 123,000
Operating lease expense		$ 10,000	$ 10,000	$ 29,000	$ 27,000
Real estate and equipment [Member] | Maximum [Member]
Lessee Lease Description [Line Items]
Operating leases remaining lease terms		15 years		15 years
Office and Branch [Member]
Lessee Lease Description [Line Items]
Aggregate cash purchase price	$ 7,500,000
Number of properties owned and operated | Property	4
Number of lease renewal | Number				1
Branch Office and Certain Equipment [Member]
Lessee Lease Description [Line Items]
Operating lease, renewal term		15 years		15 years
Operating lease initial term				15 years
Annual rent escalation percentage				2.50%