Business Combinations (Textual) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014
Business Acquisition [Line Items]
Business Combinations, Conversion Rate of Shares and Units	36.00%
Business Combinations, Other Consideration	$ 7,300,000
Stock Issued During Period, Shares, Acquisitions	31,916,765
Parent Company [Member]
Business Acquisition [Line Items]
Business Combination, Merger and Integration Related Expenses	5,900,000
Parent Company [Member] | Colonial [Member]
Business Acquisition [Line Items]
Real Estate Acquired, Number of Units	34,370
Number of Apartment Communities Acquired in Real Estate Property	115
Number of Commercial Properties Acquired in Real Estate Property	4
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 2,162,876,000
Share Price	$ 62.56
Stock Issued During Period, Shares, Acquisitions	31,900,000
Noncontrolling Interest [Member]
Business Acquisition [Line Items]
Stock Issued During Period, Shares, Acquisitions	2,574,631
Commercial [Member] | Parent Company [Member]
Business Acquisition [Line Items]
Square Footage of Real Estate Property	806,000