Business Segments (Details Textual)	6 Months Ended
	Jun. 30, 2019 Property apartment_home Segment
Business Segments (Textual) [Abstract]
Number of reportable segments | Segment	4
Wholly And Partially Owned Consolidated Properties [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	124
Number of apartment homes in apartment communities | apartment_home	33,678
Wholly And Partially Owned Consolidated Properties [Member] | Same Store [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	95
Number of apartment homes in apartment communities | apartment_home	27,640
Wholly And Partially Owned Consolidated Properties [Member] | Redevelopment and Development [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	7
Number of apartment homes in apartment communities | apartment_home	3,134
Wholly And Partially Owned Consolidated Properties [Member] | Acquisition [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	7
Number of apartment homes in apartment communities | apartment_home	1,590
Wholly And Partially Owned Consolidated Properties [Member] | Other Real Estate [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	15
Number of apartment homes in apartment communities | apartment_home	1,315
Unconsolidated Properties [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	4
Number of apartment homes in apartment communities | apartment_home	142