Business Segments (Details Textual)	3 Months Ended
	Mar. 31, 2020 Property apartment_home Segment office_building
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	120
Number of apartment homes in apartment communities | apartment_home	32,704
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	28,095
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	6
Number of apartment homes in apartment communities | apartment_home	2,210
Wholly And Partially Owned Consolidated Properties [Member] | Acquisition [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	1
Number of apartment homes in apartment communities | apartment_home	110
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	18
Number of apartment homes in apartment communities | apartment_home	2,289
Wholly And Partially Owned Consolidated Properties [Member] | Other Real Estate [Member] | Office Building [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | office_building	1
Wholly And Partially Owned Consolidated Properties [Member] | Under Construction [Member] | Acquisition [Member]
Business Segments (Textual) [Abstract]
Number of owned and managed apartment communities in segments | Property	1
Number of apartment homes in apartment communities | apartment_home	136
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