Organization (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Apr. 01, 2014 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) community building apartment project shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General partner ownership interest (in hundredths)		96.70%	96.70%
Limited partner - ownership percentage		3.30%	3.30%
Operating Partnership units outstanding (in shares) | shares		2,214,545	2,168,158
Redemption value of Operating Partnership units outstanding | $		$ 530,200	$ 447,900
Number of apartment communities owned | community		246
Apartment units owned | apartment		59,160
Ownership interests, number of commercial buildings | building		4
Ownership interests, number of active development projects | project		8
Business Acquisition [Line Items]
Merger and integration expenses | $		$ 3,798	$ 53,530	$ 4,284
Share price	$ 174
Share price after deducting special dividend and cash consideration	$ 164
BRE Properties, Inc. [Member]
Business Acquisition [Line Items]
Common shares conversion ratio in connection with merger | shares	0.2971
Share price (in dollars per share)	$ 7.18
Merger and integration expenses | $	$ 4,300,000
Special dividend declared per share	$ 5.15
Cash consideration per share before special dividend	$ 12.33
Common stock issued as consideration by general partner in merger (in shares) | shares	23,100,000
Share price	$ 61
Share price after deducting special dividend and cash consideration	$ 48.67