Commitments and Contingencies (Details Textual) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 Units	Dec. 31, 2012 Units
Long-term Purchase Commitment [Line Items]
Number of apartment homes	536	3,046
Commitments and Contingencies (Textual) [Abstract]
Commitments related to capital spending activities	$ 146.2
Long-term Purchase Commitment, Time Period	12 months
Term of commitments to purchase goods or services related to the operations of properties	one year or less
Range of remaining compliance periods for tax credit syndication arrangements	less than one year to 13 years
One Canal Project [Member]
Long-term Purchase Commitment [Line Items]
Number of stories in real estate development project	12
Expected investment in development project	190.0
Expected Development Period	two years
Number of apartment homes	310
Square feet of rentable commercial space	22,000
Term of ground lease	99 years 0 months
Prepaid ground rent	$ 13.0