Summary of Significant Accounting Policies (Detail) - USD ($)		3 Months Ended		6 Months Ended
	Jan. 01, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		$ 67,000	$ 11,055,000	$ 67,000	$ 11,055,000	$ 0	$ 0
Interest costs capitalized		1,100,000	1,100,000	1,943,000	1,682,000
Real estate taxes and insurance costs capitalized		300,000	400,000	$ 600,000	600,000
REIT annual taxable income distribution requirement percentage				90.00%
Adjustment to rental income resulting from lease collectability assessment		(1,100,000)	(400,000)	$ 1,500,000	(500,000)
Cumulative effect of adoption of ASC 842					(222,000)
Income tax provision				0	0
Construction Employees
Summary Of Significant Accounting Policies [Line Items]
Compensation costs capitalized		$ 1,000,000.0	$ 600,000	$ 2,000,000.0	$ 1,300,000
Minimum | Office Leases
Summary Of Significant Accounting Policies [Line Items]
Estimated remaining life				10 years
Minimum | Site Improvements
Summary Of Significant Accounting Policies [Line Items]
Estimated remaining life				5 years
Maximum | Office Leases
Summary Of Significant Accounting Policies [Line Items]
Estimated remaining life				30 years
Maximum | Site Improvements
Summary Of Significant Accounting Policies [Line Items]
Estimated remaining life				20 years
Measurement Input, Discount Rate | Minimum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		5.75%		5.75%
Measurement Input, Discount Rate | Maximum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		7.00%		7.00%
Measurement Input, Cap Rate | Minimum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		4.75%		4.75%
Measurement Input, Cap Rate | Maximum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		5.75%		5.75%
Property Average Lease Up Period | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated average lease-up period				6 months
Property Average Lease Up Period | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated average lease-up period				9 months
Estimate of Fair Value Measurement | Minimum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		3.00%		3.00%
Estimate of Fair Value Measurement | Maximum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		3.75%		3.75%
Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect of adoption of ASC 842	$ 200,000
Rent Relief Agreement, COVID-19 [Member]
Summary Of Significant Accounting Policies [Line Items]
Application of Security Deposits		$ 4,200,000		$ 4,200,000
Acceleration of Concessions		800,000		800,000
Deferral of Base Rent		$ 3,600,000		$ 3,600,000