Business Segments (Details Textual) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Business Segments (Textual) [Abstract]
Number of reportable segments	2
Conventional Real Estate Operations [Member]
Business Segments (Textual) [Abstract]
Capital additions related to segments	$ 270.4	$ 249.8
Affordable Real Estate Operations [Member]
Business Segments (Textual) [Abstract]
Capital additions related to segments	$ 6.6	$ 7.0
Affordable Real Estate [Member]
Business Segments (Textual) [Abstract]
Number of owned apartment communities in segments	61
Number of Apartment Homes in Apartment Communities	9,142
Conventional Real Estate [Member]
Business Segments (Textual) [Abstract]
Number of owned apartment communities in segments	143
Number of Apartment Homes in Apartment Communities	43,306