Consolidation and Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified				3 Months Ended
	Mar. 31, 2013 States Property	Dec. 31, 2012	Mar. 31, 2013 Development Properties [Member] Communities Property	Mar. 31, 2013 Mid America Multifamily Fund I, LLC Apartments Property	Mar. 31, 2013 Mid America Multifamily Fund II, LLC Apartments Property	Mar. 31, 2013 Under Development sqft	Mar. 31, 2013 Expected Costs [Member]	Mar. 31, 2013 Costs Incurred to Date [Member]	Mar. 31, 2013 Maximum [Member]	Mar. 31, 2013 Minimum [Member]
Real Estate Properties [Line Items]
Number of units under development community	774
Number of owned or owned interests of apartment communities	166		2			4
Number of apartments included in a community	49,697		106
Capital improvements in progress	$ 51,625	$ 52,455					$ 101,300	$ 56,300
Number of Development Properties	3
Number of states in which apartment units are located	13
Square Footage of Real Estate Property						107,000
Percentage Of Ownership Interests									100.00%	96.00%
Number Of Properties Acquired				1	4
Number Of Units Acquired In Real Estate Property				316	1,156