Basis of Presentation and Summary of Significant Accounting Policies (Details Textual) $ in Thousands	Sep. 30, 2015 USD ($) Entity Units Property	Dec. 31, 2014 USD ($)
Variable Interest Entity [Line Items]
Net real estate related to VIEs	$ 5,580,271	$ 5,472,779
Non-recourse property debt related to VIEs	$ 3,807,699	4,022,809
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of consolidated variable interest entities | Entity	61
Number of Apartment Communities | Property	47
Number of apartment homes owned by VIEs | Units	7,459
Net real estate related to VIEs	$ 342,568	360,160
Non-recourse property debt related to VIEs	$ 327,403	$ 336,471