Consolidation and Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified				6 Months Ended
	Jun. 30, 2013 States Property	Dec. 31, 2012	Jun. 30, 2013 Development Properties [Member] Communities Property	Jun. 30, 2013 Mid America Multifamily Fund II, LLC Apartments Property	Jun. 30, 2013 Under Development sqft Property	Jun. 30, 2013 Expected Costs [Member]	Jun. 30, 2013 Costs Incurred to Date [Member]	Jun. 30, 2013 Maximum [Member]	Jun. 30, 2013 Minimum [Member]
Real Estate Properties [Line Items]
Number of units under development community	564
Number of owned or owned interests of apartment communities	164		2		4
Number of apartments included in a community	49,113		96
Capital improvements in progress	$ 47,662	$ 52,455				$ 73,800	$ 37,800
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				4
Number Of Units Acquired In Real Estate Property				1,156