Loans Receivable, Net - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018 USD ($) SecurityLoan	Dec. 31, 2017 USD ($) SecurityLoan	Dec. 31, 2016 USD ($) SecurityLoan Borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment in impaired loans	$ 11,954,000	$ 20,328,000	$ 31,600,000
Interest income recognized on impaired loans	993,000	598,000	1,600,000
Non-accrual loans	1,430,000	1,285,000
Total loans past due more than 90 days and still accruing interest	0	88,000	0
Interest income foregone on non accrual loans	127,000	100,000	108,000
Loans that have been modified as TDRs, subsequently defaulted	0	0	0
Commitments to lend additional funds to borrower	$ 0	$ 0	$ 0
Number of loans modified as TDR | SecurityLoan	2	0	4
Number of borrowers received financial concessions | Borrower			1
Troubled debt restructurings outstanding balance of four loans			$ 1,000,000
Loans to officers and directors	$ 5,204,000	$ 5,933,000	$ 4,894,000
Funds undisbursed to officers and directors	300,000	1,500,000
Impaired Loans Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,400,000	1,300,000
Officers and Directors [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to officers and directors	5,200,000	5,900,000
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 8,000	3,000
Consumer Loans [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	1 year
Consumer Loans [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	5 years
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 525,000	459,000
Commercial Loans [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	1 year
Commercial Loans [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	5 years
Multi-Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans modified as TDR | SecurityLoan			3
Multi-Family [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	5 years
Multi-Family [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans amortization period	20 years
Owner Occupied Properties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Secured non-residential real estate loans	$ 96,600,000	95,600,000	$ 78,700,000
Non Owner Occupied Properties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Secured non-residential real estate loans	145,800,000	129,400,000	$ 104,200,000
One-to-Four Family Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 62,000	266,000
Total loans past due more than 90 days and still accruing interest		88,000
One-to-Four Family Mortgages [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable maturity period	30 years
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 98,000	402,000
Home Equity Line of Credit [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable maturity period	10 years
Home Equity Line of Credit [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable maturity period	15 years
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans amortization period	20 years
Non-accrual loans	$ 152,000
Construction [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable maturity period	12 months
Construction [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable maturity period	24 months
Recreational Land Development Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans amortization period	20 years
Recreational Land Development Loans [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	1 year
Recreational Land Development Loans [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	5 years
Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans		$ 111,000
Farmland [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	5 years
Farmland [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable maturity period	20 years
Fixed rate of interest period	10 years
Non-Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable maturity period	20 years
Non-accrual loans	$ 581,000
Number of loans modified as TDR | SecurityLoan			1
Non-Residential Real Estate [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	5 years
Non-Residential Real Estate [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate of interest period	10 years
Real Estate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable in percentage	84.80%	84.80%