Federal Home Loan Bank Advances - Summary of Federal Home Loan Bank Advances (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank Advances total	$ 12,642	$ 30,010
Open Line of Credit [Member]
Federal Home Loan Bank, Advances [Line Items]
Advance structured note, payments due monthly, maturing February 2030		2.61%
Federal Home Loan Bank Advances total		$ 5,350
Fixed Rate Fixed Term Advances [Member]
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank Advances total	$ 12,000	$ 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	$ 642	$ 660
Minimum [Member] | Fixed Rate Fixed Term Advances [Member]
Federal Home Loan Bank, Advances [Line Items]
Advance structured note, payments due monthly, maturing February 2030	1.41%	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%