Organization, Basis of Presentation and Significant Accounting Policies (Details)	Sep. 30, 2018 state community home
Accounting Policies [Abstract]
Number of operating apartment communities | community	271
Number of apartment homes included in operating apartment communities owned | home	78,383
Number of states where operating apartment communities owned are located | state	12
Number of Communities with Apartments under Reconstruction | community	15
Number of Apartment Homes under Reconstruction | home	6,242
Number of owned communities under construction | community	19
Expected number of apartment homes under construction | home	6,107
Communities under development rights | community	25
Estimated number of apartment homes in communities to be developed | home	8,600