FHLB Advances - Summary of Federal Home Loan Bank Advances (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank Advances total	$ 30,010	$ 34,693
Open Line of Credit [Member]
Federal Home Loan Bank, Advances [Line Items]
Advance structured note, payments due monthly, maturing February 2030	2.61%	0.88%
Federal Home Loan Bank Advances total	$ 5,350	$ 10,000
Fixed Rate Fixed Term Advances [Member]
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank Advances total	$ 24,000	$ 24,000
Advance Structured Note [Member]
Federal Home Loan Bank, Advances [Line Items]
Advance structured note, payments due monthly, maturing February 2030	7.47%	7.47%
Federal Home Loan Bank Advances total	$ 660	$ 693
Minimum [Member] | Fixed Rate Fixed Term Advances [Member]
Federal Home Loan Bank, Advances [Line Items]
Advance structured note, payments due monthly, maturing February 2030	1.13%	1.13%
Maximum [Member] | Fixed Rate Fixed Term Advances [Member]
Federal Home Loan Bank, Advances [Line Items]
Advance structured note, payments due monthly, maturing February 2030	1.50%	1.50%