Non-Recourse Property Debt and Credit Agreement (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Estimated Fair Value Of Unencumbered Real Estate	$ 380,000,000
Credit Agreement
Revolving loan commitments	600,000,000
Initial interest rate for credit facility	LIBOR, plus 1.875%, or, at our option, Prime plus 0.5%
Credit facility maturity date	Sep. 01, 2017
Credit Facility Extension option	an additional one-year period
Revolving credit facility borrowings	50,400,000	0
Remaining borrowing capacity under credit facility	505,000,000
Amount outstanding for undrawn letters of credit issued under revolving credit facility	44,600,000
Line of Credit Facility, Interest Rate at Period End	3.75%
Property Notes Payable
Debt Instrument [Line Items]
Debt Instrument, Collateral Amount	7,251,100,000
Property tax-exempt bonds payable
Debt Instrument [Line Items]
Debt Instrument, Collateral Amount	$ 514,200,000
Fixed Rate | Property Notes Payable
Non-Recourse Property Debt (Textual) [Abstract]
Debt Instrument, Maximum Maturity Date	Jan. 31, 2055
Fixed Rate | Property tax-exempt bonds payable
Non-Recourse Property Debt (Textual) [Abstract]
Debt Instrument, Maximum Maturity Date	Feb. 28, 2061
Variable Rate | Property Notes Payable
Non-Recourse Property Debt (Textual) [Abstract]
Debt Instrument, Maximum Maturity Date	Jan. 31, 2016
Variable Rate | Property tax-exempt bonds payable
Non-Recourse Property Debt (Textual) [Abstract]
Debt Instrument, Maximum Maturity Date	Jul. 31, 2033
Unencumbered Real Estate Property [Member]
Debt Instrument [Line Items]
Number of apartment communities	7
Pledged as collateral [Member] | Property Notes Payable
Debt Instrument [Line Items]
Number of apartment communities	186
Pledged as collateral [Member] | Property tax-exempt bonds payable
Debt Instrument [Line Items]
Number of apartment communities	20