Business Combinations (Textual) (Details) $ / shares in Units, $ in Thousands, shares in Millions		12 Months Ended
	Oct. 01, 2013 USD ($) ft² Communities properties $ / shares	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($) shares	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Business Combinations, Other Consideration	$ 7,300
Business Combination, Merger and Integration Related Expenses		$ 11,500	$ 37,500
Parent Company [Member]
Business Acquisition [Line Items]
Acquired properties, purchase price		$ 0	(2,162,876)	$ 0
Parent Company [Member] | Colonial
Business Acquisition [Line Items]
Number of Apartment Communities Acquired in Real Estate Property | Communities	115
Number Of Units Acquired In Real Estate Property | Communities	34,370
Number of Commercial Properties Acquired in Real Estate Property | properties	4
Acquired properties, purchase price	$ (2,162,876)		$ (2,162,876)
Share Price | $ / shares	$ 62.56
Stock Issued During Period, Shares, Acquisitions | shares			31.9
Parent Company [Member] | Commercial
Business Acquisition [Line Items]
Square footage of real estate property (square foot) | ft²	806,000
Noncontrolling Interest
Business Acquisition [Line Items]
Stock Issued During Period, Shares, Acquisitions | shares			2.6