Consolidation and Basis of Presentation and Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
Mar. 31, 2012 States Communities Property
Real Estate Properties [Line Items]
Number of units under development community	1,020
Number of owned or owned interests of apartment communities	167
Number of apartments included in a community	48,685
Number of states in which apartment units are located	13
Cumulative adjustments due to error corrections from prior periods	655
Development Properties [Member]
Real Estate Properties [Line Items]
Number of owned or owned interests of apartment communities	3
Number of apartments included in a community	148
Mid America Multifamily Fund I, LLC
Real Estate Properties [Line Items]
Number of owned or owned interests of apartment communities	2
Number of apartments included in a community	626
Mid America Multifamily Fund II, LLC
Real Estate Properties [Line Items]
Number of owned or owned interests of apartment communities	5
Number of apartments included in a community	1,635
Under Development
Real Estate Properties [Line Items]
Number of owned or owned interests of apartment communities	3
Square Footage of Real Estate Property	81,000

- Definition

Description of a prior period adjustment to previously issued financial statements, including an adjustment that is a correction of an error. At a minimum, the description may include the nature and reasons for the adjustment and the periods affected by the adjustment, as well as (1) the effect of the correction on each financial statement line item and any per-share amounts affected for each prior period presented (2) the cumulative effect of the change on retained earnings or other appropriate components of equity or net assets in the statement of financial position, as of the beginning of the earliest period presented, and (3) the effect of the prior period adjustment (both gross and net of applicable income tax) on the net income of each prior period presented in the entity's annual report for the year in which the adjustments are made.

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