Business Segments (Details Textual) $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($) Units Property Segment	Sep. 30, 2015 USD ($)
Business Segments (Textual) [Abstract]
Number of reportable segments | Segment	2
Conventional Real Estate Operations [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	130
Number of apartment homes in apartment communities | Units	37,772
Affordable Real Estate Operations [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	46
Number of apartment homes in apartment communities | Units	7,610
Operating Segments [Member] | Conventional Real Estate Operations [Member]
Business Segments (Textual) [Abstract]
Capital additions related to segments | $	$ 245.7	$ 258.7
Operating Segments [Member] | Affordable Real Estate Operations [Member]
Business Segments (Textual) [Abstract]
Capital additions related to segments | $	$ 6.4	$ 6.5