Organization and Summary of Significant Accounting Policies (Textual) (Details) (USD $)	12 Months Ended									12 Months Ended																					12 Months Ended
	Dec. 31, 2012 Communities	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2012 Development Properties [Member] Communities Apartments	Dec. 31, 2012 Mid-America Multifamily Fund I, LLC [Member]	Dec. 31, 2007 Mid-America Multifamily Fund I, LLC [Member]	Dec. 31, 2012 Real Estate Investment [Member] Property	Dec. 31, 2012 Mid-America Multifamily Fund II, LLC [Member]	Dec. 31, 2012 Retail [Member] sqft Property	Dec. 31, 2012 Additional Paid-in Capital	Dec. 31, 2012 Accumulated Distributions in Excess of Net Income	Dec. 31, 2012 Noncontrolling Interest	Dec. 31, 2012 Land improvements and buildings [Member] Y	Dec. 31, 2012 Land improvements and buildings [Member] Year	Dec. 31, 2012 Furniture, fixtures and equipment [Member] Year	Dec. 31, 2012 Furniture, fixtures and equipment [Member] Y	Dec. 31, 2012 Computer and software [Member] Y	Dec. 31, 2012 Leases, Acquired-in-Place [Member]	Dec. 31, 2011 Leases, Acquired-in-Place [Member]	Dec. 31, 2010 Leases, Acquired-in-Place [Member]	Dec. 31, 2012 Dividend Declared [Member]	Dec. 31, 2011 Dividend Declared [Member]	Dec. 31, 2010 Dividend Declared [Member]	Dec. 31, 2012 Real Estate Taxes [Member]	Dec. 31, 2011 Real Estate Taxes [Member]	Dec. 31, 2010 Real Estate Taxes [Member]	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2010 Cedar Mill [Member] Property	Dec. 31, 2012 Out Of Period Adjustment [Member]
Real Estate Properties [Line Items]
Number of apartment communities owned (properties)	160
Interest in real estate joint ventures (percent)						33.33%	33.33%		33.33%
Number of operating apartment communities owned (properties)								6
Number of development communities (communities)					2
Number of units under development community					774
Expected cumulative development costs					$ 101,100,000
Development costs incurred to date					43,900,000
Number of properties with retail components (properties)										4
Square footage of real estate property (square foot)										108,000
Percentage of ownership interests of all consolidated subsidiaries (percent)																												95.00%	100.00%
Advertising expenses	8,800,000	8,700,000	7,200,000
Minimum estimated useful lives (years)														8	8			3
Maximum estimated useful lives (years)														40	40			5
Estimated useful lives (years)																5	5
Total interest capitalized during period	2,318,000	1,156,000	66,000
Amortization period of in-place leases and residential relationships (months)																			6 months
Gross real estate assets	3,707,582,000	3,359,095,000																	1,600,000	1,800,000	1,800,000
Depreciation and amortization	126,136,000	110,870,000	98,384,000	[1]															3,700,000	3,500,000	3,000,000
Accumulated amortization	1,027,618,000	961,724,000																	1,000,000	700,000	1,000,000
Number of impaired units in a community as a result of purchase offer received and long term considerations (units)																														276
Asset impairment	0	0	1,914,000
Accrued expenses and other liabilities	94,719,000	91,718,000																				30,600,000	27,000,000	23,400,000	27,900,000	25,400,000	19,900,000
Development and capital improvements in progress	52,455,000	53,790,000
Prior period adjustment	0										27,032,000	(24,870,000)	(2,162,000)																		(655,000)
Maximum self insurance reserve for general liability claims																													45,000
Maximum self insurance reserve for workers' compensation claims																													500,000
Reclassification adjustment	$ 1,300,000
Description of prior period adjustments																															In the twelve months ended December 31, 2011, we recorded a $1.8 million non-cash adjustment to general and administrative expenses related to restricted stock grants issued to certain employees. This adjustment was made during the second quarter of 2011. This error correction represents a cumulative adjustment for the 3.5 year period ended June 30, 2011, required by Accounting Standards Codification, or ASC, 718to record expense under certain of our restricted stock grant based incentive plans using liability accounting rather than treating these grants as equity awards.

[1] The 2010 column shows the segment break down based on the 2011 same store portfolios. A comparison using the 2012 same store portfolio would not be comparative due to the nature of the classifications.