Investments In Joint Ventures (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended	1 Months Ended	3 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	May 31, 2013 Sale of 14 operating properties within an unconsolidated joint venture in May 2013 [Member]	Sep. 30, 2013 Sale of 14 operating properties within an unconsolidated joint venture in May 2013 [Member]	Jun. 30, 2013 Sale of 14 operating properties within an unconsolidated joint venture in May 2013 [Member]
Number of joint ventures accounted for under equity method investments				3
Equity method investment ownership percentage	20.00%			20.00%
Maximum guaranteed amount of loans utilized for construction and development activities for joint ventures	$ 0			$ 0
Fees earned for property and asset management, construction, development, and other services to joint ventures	2,400,000	2,800,000		7,500,000	8,800,000
Number of operating properties sold	2		2			11	14
Number of apartment homes in operating properties sold	500		1,296			3,213	3,098
Proceeds from sale of 14 operating properties							200,200,000
Gain on sale of unconsolidated JV property							13,000,000
Promoted equity interest in assets sold during period								$ 1,200,000	$ 3,800,000