Business - Ownership Breakdown (Details)	Dec. 31, 2018 Property ApartmentUnit
Property/Unit schedule
Properties | Property	307
Apartment Units | ApartmentUnit	79,482
Wholly Owned Properties
Property/Unit schedule
Properties | Property	287
Apartment Units | ApartmentUnit	74,840
Master-Leased Property – Consolidated
Property/Unit schedule
Properties | Property	1
Apartment Units | ApartmentUnit	162
Partially Owned Properties – Consolidated
Property/Unit schedule
Properties | Property	17
Apartment Units | ApartmentUnit	3,535
Partially Owned Properties – Unconsolidated
Property/Unit schedule
Properties | Property	2
Apartment Units | ApartmentUnit	945