Revenues - Summary of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Rental revenue	$ 188,079	$ 185,074	$ 551,835	$ 545,475
Fee income:
Total fee income	7,159	4,079	17,371	12,953
Other income	3,079	3,443	9,486	9,858
Total fee and other income	10,238	7,522	26,857	22,811
Total revenues	198,317	192,596	578,692	568,286
Property Management Fees [Member]
Fee income:
Total fee income	1,692	1,476	4,933	4,468
Asset Management Fees [Member]
Fee income:
Total fee income	2,665	2,222	7,273	5,655
Acquisition, Disposition and Leasing Fee [Member]
Fee income:
Total fee income	2,104		3,435	1,750
Other Fee Income [Member]
Fee income:
Total fee income	$ 698	$ 381	$ 1,730	$ 1,080