Commitments and Contingencies (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
300 properties designed and built in violation of accessibility requirements	300
Loss Contingency Accrual, Period Increase (Decrease)	$ 1,000
Loss Contingency Accrual	$ 5,000
Projects in various stages of development	15
Units in various stages of development	5,211
Consolidated Project Under Development Commitment Fund	$ 1,100,000
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	$ 136,243
Investment in Joint Venture	342,200
Noncontrolling Interests - Partially Owned Properties	122,368	$ 124,909
Company's Portion [Member]
Land purchase price	76,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	102,500
Joint Venture Partner [Member]
Land purchase price	57,900
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	75,700
Noncontrolling Interests - Partially Owned Properties	$ 117,400