Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Statutory federal income tax rate	21.00%	21.00%	35.00%
Uncertain tax positions	$ 0	$ 0	$ 0
Interest and penalties	0	$ 0	$ 0
Internal Revenue Service (IRS)
Income Tax Disclosure [Line Items]
Federal net operating losses annual limitation amount	1,300,000
MidSouth Bank
Income Tax Disclosure [Line Items]
Net operating losses acquired from acquisition	$ 8,346,000