Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Foreclosed assets	$ 0	$ 0
Other comprehensive income (loss) tax	18,000	0
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of the Income Tax Effects of the Tax Cuts and Jobs Act from accumulated other comprehensive loss		130,000
AOCI Attributable to Parent [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of the Income Tax Effects of the Tax Cuts and Jobs Act from accumulated other comprehensive loss		(130,000)
Residential Real Estate [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans in process of foreclosure	$ 161,000	$ 205,000