Business - Ownership Breakdown (Details)	Mar. 31, 2019 Property ApartmentUnit
Property/Unit schedule
Properties | Property	310
Apartment Units | ApartmentUnit	80,061
Wholly Owned Properties
Property/Unit schedule
Properties | Property	290
Apartment Units | ApartmentUnit	75,419
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