Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Commitments And Contingencies [Line Items]
Reserve for off-balance sheet credits	$ 420	$ 426
Reserve for sold mortgages	304
Letter of Credit [Member]
Commitments And Contingencies [Line Items]
Reserve for off-balance sheet credits	$ 338
Minimum [Member]
Commitments And Contingencies [Line Items]
Term of letter of credit	1 year
Maximum [Member]
Commitments And Contingencies [Line Items]
Term of letter of credit	5 years
Maximum [Member] | Letter of Credit [Member]
Commitments And Contingencies [Line Items]
Off-balance sheet risks, amount, liability	$ 44,400