Business (Details)	Mar. 31, 2013
Property/Unit schedule
Wholly Owned Properties	390
Partially Owned Consolidated Properties	20
Partially Owned Unconsolidated Properties	1
Military Housing Properties	2
Wholly Owned Units	108,579
Master Leased Properties Acquired	3
Master Leased Units	853
Partially Owned Consolidated Units	3,917
Partially Owned Unconsolidated Units	336
Military Housing Units	5,093
Business (Textuals) [Abstract]
Number of Real Estate Properties	416
Number of Units in Real Estate Property	118,778
Number of States in which Entity Operates	13
Noncontrolling Interest, Ownership Percentage by Parent	96.20%
Archstone Transaction [Member]
Property/Unit schedule
Master Leased Properties Acquired	3