Organization - Summary of Disaggregated Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation Of Revenue [Line Items]
Rental income	$ 135,965	$ 128,565	$ 393,701	$ 381,625
Operating revenues other than rental income	20,345	17,069	56,565	45,561
Total operating revenues	156,310	145,634	450,266	427,186
Management and Acquisition Fee Income [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues other than rental income	4,518	3,809	13,107	10,156
Revenues Related to Tenant Reinsurance [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues other than rental income	11,616	9,170	32,508	23,948
Other Operating Income [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues other than rental income	$ 4,211	$ 4,090	$ 10,950	$ 11,457