Commitments and Contingencies (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015	Dec. 31, 2014
300 properties designed and built in violation of accessibility requirements	300
Loss Contingency Accrual, Period Increase (Decrease)	$ 1,000,000
Loss Contingency Accrual	5,000,000
Projects in various stages of development	15
Units in various stages of development	5,273
Consolidated Project Under Development Commitment Fund	1,300,000,000
Various stages of development with estimated completion dates ranging through September 30, 2017	Sep. 30, 2017
Number Of Unconsolidated Projects	2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	5,968,000	130,300,000
Investment in Joint Venture	339,400,000
Noncontrolling Interests - Partially Owned Properties	122,661,000		124,909,000
Company's Portion [Member]
Land purchase price	76,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	102,500,000
Joint Venture Partner [Member]
Land purchase price	57,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	75,700,000
Noncontrolling Interests - Partially Owned Properties	$ 117,400,000