Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Income tax benefit for deferred tax temporary differences		$ 300,000
Amount for which no federal income tax provision has been made	$ 6,000,000.0	6,000,000.0	$ 6,000,000.0
Unrecognized tax benefits	0	$ 0
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 71,200,000
Operating loss carryforwards, expiration year	2021
Minimum [Member]
Income Tax Contingency [Line Items]
Open tax years	2017