Foreclosed Assets - Summary of Foreclosed Properties Activity (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	$ 3,369	$ 2,397	$ 2,397
Foreclosure	241		4,312
Sales	(88)	(1,666)	(3,461)
Reduction in Values	(5)		(10)
Gain (Loss) on Sale	16		131
Ending Balance	3,533		3,369
Multi-Family [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance		1,775	1,775
Sales			(1,761)
Gain (Loss) on Sale			(14)
One-to-Four Family Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	169	135	135
Foreclosure	241		1,069
Sales	(88)		(1,182)
Reduction in Values	(5)
Gain (Loss) on Sale	16		147
Ending Balance	333		169
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance		28	28
Sales			(18)
Reduction in Values			(10)
Land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	3,200
Foreclosure			3,200
Ending Balance	$ 3,200		3,200
Non-Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance		$ 459	459
Foreclosure			43
Sales			(500)
Gain (Loss) on Sale			$ (2)