Summary of Significant Accounting Policies (Detail) - USD ($)		3 Months Ended
	Jan. 01, 2019	Mar. 31, 2020	Mar. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Interest costs capitalized		$ 882,000	$ 629,000
Real estate taxes and insurance costs capitalized		$ 300,000	200,000
REIT annual taxable income distribution requirement percentage		90.00%
Adjustment to rental income resulting from lease collectability assessment		$ 400,000	100,000
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	$ 700,000
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%
Measurement Input, Discount Rate | Maximum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		6.50%
Measurement Input, Cap Rate | Minimum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		4.75%
Measurement Input, Cap Rate | Maximum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		5.50%
Property Average Lease Up Period | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated average lease-up period		6 months
Estimate of Fair Value Measurement [Member] | Minimum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		3.21%
Estimate of Fair Value Measurement [Member] | Maximum
Summary Of Significant Accounting Policies [Line Items]
Acquired property, measurement input		3.75%
Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect of adoption of ASC 842	$ 200,000