Liabilities, Other - Summary of Liabilities, Other (Detail) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Deferred revenue, Parcel 20	$ 225,000	$ 199,000
Accrued professional fees	129,000	152,000
Deposits and prepaid rent	236,000	121,000
Accrued payroll and related costs	75,000	75,000
Other	47,000	16,000
Liabilities, other	$ 712,000	$ 563,000