Business (Details)	Mar. 31, 2012
Property/Unit schedule
Wholly Owned Properties	404
Partially Owned Consolidated Properties	21
Military Housing Properties	2
Number of Real Estate Properties	427
Wholly Owned Units	112,181
Partially Owned Consolidated Units	3,916
Military Housing Units	4,914
Number of Units in Real Estate Property	121,011
Business (Textuals) [Abstract]
Noncontrolling Interest, Ownership Percentage by Parent	95.70%
Number of States in which Entity Operates	14