Notes Payable (Detail) - Future Principal Payments On The Notes Payable	9 Months Ended
	Sep. 30, 2020 USD ($)
Period One [Member]
Principal Payments	$ 48,654,000
Period Two [Member]
Principal Payments	2,087,000
Period Three [Member]
Principal Payments	2,252,000
Period Four [Member]
Principal Payments	2,498,000
Period Five [Member]
Principal Payments	15,283,000
Thereafter [Member]
Principal Payments	88,674,000
Less unamortized loan issuance costs [Member]
Less unamortized loan issuance costs	(1,257,000)
Total [Member]
Principal Payments	$ 158,191,000