Property Acquisitions, Discontinued Operations, And Assets Held For Sale (Narrative) (Details) (USD $)	1 Months Ended		3 Months Ended
	Jan. 31, 2012	Dec. 31, 2011	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Property Acquisitions, Discontinued Operations, And Assets Held For Sale [Abstract]
Percentage of voting interests acquired	80.00%
Number of unconsolidated equity method investments acquired	12		12
Number of apartment units in wholly owned property acquired	4,034
Gain on acquisition of controlling interest in joint ventures			$ 40,191,000		$ 0
Pro Forma Property Revenues of Acquiree since Acquisition Date, Actual			8,700,000
Pro Forma Property Expenses of Acquiree since Acquisition Date, Actual			$ 3,600,000
Number of operating properties sold		2	3	4
Number of apartment homes in operating properties sold		788	1,033
Number of assets classified as held for sale			0