Business - Ownership Breakdown (Details)	Sep. 30, 2018 Property ApartmentUnit
Property/Unit schedule
Properties | Property	306
Apartment Units | ApartmentUnit	79,260
Wholly Owned Properties
Property/Unit schedule
Properties | Property	286
Apartment Units | ApartmentUnit	74,618
Master-Leased Properties - 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