Commitments to Acquire/Dispose of Real Estate - Separate Agreements to Dispose of (Details) - Subsequent Event [Member] $ in Thousands	Feb. 16, 2018 USD ($) Property ApartmentUnit
Property/Unit schedule
Properties | Property	2
Apartment Units | ApartmentUnit	455
Sales Price | $	$ 179,720
Rental Properties Disposed [Member]
Property/Unit schedule
Properties | Property	2
Apartment Units | ApartmentUnit	455
Sales Price | $	$ 177,020
Land [Member]
Property/Unit schedule
Properties | Property	0
Apartment Units | ApartmentUnit	0
Sales Price | $	$ 2,700