Organization and Basis of Presentation - Additional Information (Detail) ft² in Millions	3 Months Ended
	Mar. 31, 2018 ft² Property
Organization And Significant Accounting Policies [Line Items]
Outstanding common units of aggregate limited partnership interest owned percentage	83.00%
Wholly Owned Operating Properties [Member]
Organization And Significant Accounting Policies [Line Items]
Number of properties	46
Aggregate area of land | ft²	3.7
Wholly Owned Operating Properties [Member] | Government [Member]
Organization And Significant Accounting Policies [Line Items]
Number of properties	44
Wholly Owned Operating Properties [Member] | Private Tenants [Member]
Organization And Significant Accounting Policies [Line Items]
Number of properties	2
Wholly Owned Properties Under Development [Member]
Organization And Significant Accounting Policies [Line Items]
Number of properties	3
Aggregate area of land | ft²	0.3