Loans - Summary of Additional Information Pertaining to the Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	$ 200	$ 284
Allowance for non-impaired loans	3,071	2,955
Total allowance for loan losses	3,271	3,239	$ 3,544
Impaired loans	5,614	6,703
Non-impaired loans	329,472	280,399
Total loans	335,086	287,102
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for non-impaired loans	37	72
Total allowance for loan losses	37	72	51
Impaired loans		16
Non-impaired loans	2,067	2,024
Total loans	2,067	2,040
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for non-impaired loans	145	53
Total allowance for loan losses	145	53	38
Non-impaired loans	6,578	2,602
Total loans	6,578	2,602
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	190	254
Allowance for non-impaired loans	828	822
Total allowance for loan losses	1,018	1,076	1,368
Impaired loans	4,506	4,961
Non-impaired loans	174,519	161,522
Total loans	179,025	166,483
Second Mortgages and HELOC [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	2	2
Allowance for non-impaired loans	434	510
Total allowance for loan losses	436	512	488
Impaired loans	276	277
Non-impaired loans	35,117	32,982
Total loans	35,393	33,259
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	8	28
Allowance for non-impaired loans	1,402	1,339
Total allowance for loan losses	1,410	1,367
Impaired loans	832	1,449
Non-impaired loans	87,562	73,462
Total loans	88,394	74,911
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for non-impaired loans	225	159
Total allowance for loan losses	225	159	$ 60
Non-impaired loans	23,629	7,807
Total loans	$ 23,629	$ 7,807