Commitments to Acquire/Dispose of Real Estate - Separate Agreements to Dispose (Details) $ in Thousands	Mar. 31, 2019 USD ($) Property ApartmentUnit
Property/Unit schedule
Properties | Property	3
Apartment Units | ApartmentUnit	1,037
Sales Price	$ 539,650
Rental Properties Disposed [Member] | Consolidated [Member]
Property/Unit schedule
Properties | Property	2
Apartment Units | ApartmentUnit	593
Sales Price	$ 282,250
Rental Properties Disposed [Member] | Unconsolidated [Member]
Property/Unit schedule
Properties | Property	1
Apartment Units | ApartmentUnit	444
Sales Price	$ 255,500
Land [Member]
Property/Unit schedule
Sales Price	$ 1,900