Real Estate Acquisitions and Dispositions Real Estate Acquisitions and Dispositions - Additional Information (Details)	Dec. 31, 2018 a ft² apartmentunits
Sync 36 I [Member] [Member]
Significant Acquisitions and Disposals [Line Items]
Number of units in real estate property | apartmentunits	374
Hue [Member]
Significant Acquisitions and Disposals [Line Items]
Square footage of real estate property (square foot) | ft²	7,500
Long Point Road - Houston [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land	9
Westminster - Denver [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land	10
Craft Farms Residential - Outparcel [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land	3
Randal Park - Outparcel [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land	34
CG at Azure - Outparcel [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land	29
Spring Hill - Outparcel [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land	7
Spring Hill - Outparcel 2 [Member]
Significant Acquisitions and Disposals [Line Items]
Area of Land	3