Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Operating Loss Carryforwards	$ 1,500,000
Unrecognized Tax Benefits	$ 0
Federal statutory rate	21.00%	21.00%	21.00%
Annual effective income tax rate, percentage	19.00%	19.00%	19.00%
Net deferred tax asset	$ 21,981,000	$ 16,862,000
Alternative minimum tax credit carryforward	0	216,000
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 0	$ 0	$ (346,000)