Investments in Real Estate Entities (Details) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended	9 Months Ended				3 Months Ended				9 Months Ended	3 Months Ended				3 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 community	Sep. 30, 2013	Sep. 30, 2014 Fund I community	Sep. 30, 2014 Fund I RutherfordStation [Member] home	Sep. 30, 2014 Fund I Weymouth Place home	Sep. 30, 2014 Fund I South Hills [Member] home	Sep. 30, 2014 Fund I Springs home	Sep. 30, 2014 Joint Venture Partners [Member] Springs	Sep. 30, 2014 Fund II	Sep. 30, 2014 Fund II Avalon Bellevue Park [Member] home	Sep. 30, 2014 Fund II Avalon Fair Oaks home	Sep. 30, 2014 CVP I, LLC [Member] sqft	Sep. 30, 2014 CVP I, LLC [Member] home sqft	Sep. 30, 2014 Equity Method Investee [Member]	Sep. 30, 2014 Unconsolidated real estate entities entity	Sep. 30, 2014 Unconsolidated real estate entities Minimum	Sep. 30, 2014 Unconsolidated real estate entities Maximum	Sep. 30, 2014 Residual JV	Sep. 30, 2014 Residual JV	Jun. 30, 2014 Secured notes	Sep. 30, 2014 Secured notes Notes payable maturing in 2014 Fund I Springs
Investment in Real Estate Entities
Number of unconsolidated real estate entities																	7
Ownership interest percentage														20.00%	20.00%			15.20%	31.30%
Number of Apartment Communities Sold			3		4
Number of apartment homes sold						108	211	85	320			220	491		361
Area of Real Estate Property														71,000	71,000
Proceeds from sale of real estate						$ 34,250,000	$ 25,750,000	$ 21,800,000	$ 43,200,000			$ 58,750,000	$ 108,200,000	$ 365,000,000						$ 8,249,000	$ 51,361,000
Gain on sale of communities	327,539,000	5,395,000	333,221,000	70,662,000		345,000	545,000	54,000	2,373,000	14,132,000		8,450,000	13,174,000	50,478,000							7,548,000
Equity Method Investment, Underlying Equity in Net Assets														57,489,000	57,489,000
Percentage of gain (loss) from sale of real estate recognized in income									100.00%
Gain on sale of land	0	0	0	240,000					16,656,000
Noncontrolling interest, ownership percentage by noncontrolling owners									84.80%
Repayments of secured mortgages											42,023,000					198,961,000						5,914,000	21,748,000
Gains (Losses) on Extinguishment of Debt	$ 0	$ 0	$ (412,000)	$ 0												$ 2,339,000
Fixed rate (as a percent)																							6.06%