Real Estate and Lease Intangibles - Real Estate Acquisitions and Dispositions (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) Property ApartmentUnit
Properties acquired | Property	2
Property Units acquired | ApartmentUnit	357
Purchase Price	$ 199,700
Properties disposed | Property	4
Property Units disposed | ApartmentUnit	786
Sales Price	$ 292,720
Rental Properties - Consolidated [Member]
Properties acquired | Property	2
Property Units acquired | ApartmentUnit	357
Purchase Price	$ 199,700
Properties disposed | Property	4
Property Units disposed | ApartmentUnit	786
Sales Price	$ 290,020
Land [Member]
Purchase Price	49,100
Sales Price	$ 2,700