Fair Value Measurements - Summary of Assets and Liabilities at Carrying Value and Estimated Fair Value on a Nonrecurring Basis (Detail) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Financial Assets:
Cash and due from banks		$ 7,404	$ 7,685	[1]
Certificates of deposit		3,746	3,746	[1]
Federal funds sold		182	625	[1]
Restricted securities		7,804	7,600	[1]
Loans receivable, net		910,762	894,191	[1]
Loans held for sale	[1]		368
Accrued interest receivable		3,274	3,172	[1]
Financial Liabilities:
Savings and interest-bearing demand deposits		371,587	359,400	[1]
Time deposits		372,751	368,670	[1]
Securities sold under repurchase agreements		7,220	6,089	[1]
FHLB advances		100,000	100,000	[1]
Subordinated notes, net		6,897	6,893	[1]
Fair Value, Inputs, Level 1
Financial Assets:
Cash and due from banks		7,404	7,685
Interest-earning deposits		23,091	18,981
Federal funds sold		182	625
Financial Liabilities:
Noninterest-bearing demand deposits		112,315	114,122
Savings and interest-bearing demand deposits		330,690	359,400
Securities sold under repurchase agreements		7,220	6,089
Fair Value, Inputs, Level 2
Financial Assets:
Certificates of deposit		3,746	3,746
Loans held for sale			368
Accrued interest receivable		3,274	3,172
Financial Liabilities:
FHLB advances		99,773	99,727
Fair Value, Inputs, Level 3
Financial Assets:
Restricted securities		7,804	7,600
Loans receivable, net		896,740	877,114
Financial Liabilities:
Time deposits		372,921	369,347
Subordinated notes, net		7,045	7,046
Carrying Value
Financial Assets:
Cash and due from banks		7,404	7,685
Interest-earning deposits		23,091	18,981
Certificates of deposit		3,746	3,746
Federal funds sold		182	625
Restricted securities		7,804	7,600
Loans receivable, net		910,762	894,191
Loans held for sale			368
Accrued interest receivable		3,274	3,172
Financial Liabilities:
Noninterest-bearing demand deposits		112,315	114,122
Savings and interest-bearing demand deposits		371,587	359,400
Time deposits		372,751	368,670
Securities sold under repurchase agreements		7,220	6,089
FHLB advances		100,000	100,000
Subordinated notes, net		6,897	6,893
Fair Value
Financial Assets:
Cash and due from banks		7,404	7,685
Interest-earning deposits		23,091	18,981
Certificates of deposit		3,746	3,746
Federal funds sold		182	625
Restricted securities		7,804	7,600
Loans receivable, net		896,740	877,114
Loans held for sale			368
Accrued interest receivable		3,274	3,172
Financial Liabilities:
Noninterest-bearing demand deposits		112,315	114,122
Savings and interest-bearing demand deposits		330,690	359,400
Time deposits		372,921	369,347
Securities sold under repurchase agreements		7,220	6,089
FHLB advances		99,773	99,727
Subordinated notes, net		$ 7,045	$ 7,046

[1] Derived from audited December 31, 2018 Consolidated Financial Statements.