Revenues - Summary of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Rental revenue	$ 181,140	$ 182,722	$ 363,756	$ 360,401
Fee income:
Total fee income	4,213	5,409	10,212	8,874
Other income	3,230	3,288	6,407	6,415
Total fee and other income	7,443	8,697	16,619	15,289
Total revenues	188,583	191,419	380,375	375,690
Property Management Fees [Member]
Fee income:
Total fee income	1,599	1,490	3,241	2,992
Asset Management Fees [Member]
Fee income:
Total fee income	2,290	1,823	4,608	3,433
Acquisition, Disposition and Leasing Fee [Member]
Fee income:
Total fee income		1,750	1,331	1,750
Other Fee Income [Member]
Fee income:
Total fee income	$ 324	$ 346	$ 1,032	$ 699