Business - Ownership Breakdown (Details)	Jun. 30, 2018 Property ApartmentUnit
Property/Unit schedule
Properties | Property	304
Apartment Units | ApartmentUnit	78,645
Wholly Owned Properties
Property/Unit schedule
Properties | Property	284
Apartment Units | ApartmentUnit	74,003
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