Commitments and Contingencies (Details) (USD $)	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
300 properties designed and built in violation of accessibility requirements	300
Projects in various stages of development	11
Units in various stages of development	2,488
Consolidated Project Under Development Commitment Fund	$ 432,819,000
Various stages of development with estimated completion dates ranging through June 30, 2015	Jun. 30, 2015
Number Of Unconsolidated Projects	4
Number Of Apartments Units Under Development Unconsolidated Projects	1,513
Estimated completion period of project	Sep. 30, 2014
Business Acquisition, Cost of Acquired Entity, Purchase Price	108,000,000
Investment in Joint Venture	230,725,964
Noncontrolling Interests - Partially Owned Properties	107,493,000	77,688,000
Joint Venture Partner [Member]
Land purchase price	57,900,000
Business Acquisition, Cost of Acquired Entity, Purchase Price	75,700,000
Noncontrolling Interests - Partially Owned Properties	90,775,479
Company's Portion [Member]
Land purchase price	76,100,000
Business Acquisition, Cost of Acquired Entity, Purchase Price	102,500,000
Enclave at Wellington [Domain]
Business Acquisition, Percentage of Voting Interests Acquired	95.00%
Parkside at Emeryville [Domain]
Guarantor Obligations, Maximum Exposure	$ 19,700,000