Variable Interest Entities - Summary of Consolidated VIEs (Details)	Dec. 31, 2018 community Property apartment_home Entity	Dec. 31, 2017 Property apartment_home Entity
Variable Interest Entity [Line Items]
Apartment communities owned by VIEs | community	6
Apartment homes in communities owned by VIEs	1,480
Real Estate Portfolio | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
VIEs with interests in apartment communities | Entity	9	14
Apartment communities owned by VIEs | Property	9	14
Apartment homes in communities owned by VIEs	3,592	4,321
Consolidated Partnerships Served by the Asset Management Business | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
VIEs with interests in apartment communities | Entity	0	49
Apartment communities owned by VIEs | Property	0	37
Apartment homes in communities owned by VIEs	0	5,893