Investments in Partially Owned Entities - Summary of Companys Investment in Unconsolidated Entities (Parenthetical) (Details)	3 Months Ended
	Mar. 31, 2019 ApartmentUnit JointVenture
Variable Interest Entity [Line Items]
Apartment units	80,061
Operating Property [Member] | Unconsolidated Non-VIE [Member]
Variable Interest Entity [Line Items]
Apartment units	945
Number of joint ventures under agreements | JointVenture	2