Real Estate Investments Co-Investments (Details) (USD $)	12 Months Ended						0 Months Ended		1 Months Ended
	Dec. 31, 2014 community unit project		Dec. 31, 2013 unit community		Dec. 31, 2012 community		Oct. 31, 2014	Apr. 01, 2014	Dec. 31, 2010 unit	Dec. 31, 2011	Mar. 31, 2011
Business Acquisition [Line Items]
Number Of Development Projects	2
Payments to Acquire Equity Method Investments	$ 246,006,000		$ 162,578,000		$ 260,153,000
Loans Assumed	72,568,000	[1]	0	[1]	82,133,000	[1]
Number Of Apartment Communities Owned	239
Number Of Units Acquired	1,480		1,079
Number of communities sold	4		3		2
Sales of Real Estate	120,400,000		57,500,000		28,300,000
Gain on sale of real estate	43,600,000		29,200,000		10,900,000
Ownership interests, number of active development projects	12
Palm Valley Apartments [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage							50.00%
Payments to Acquire Equity Method Investments							180,000,000
Mortgage Loan Including Amount Attributable To Non-controlling Interest							220,000,000
Debt Instrument, Interest Rate, Stated Percentage							5.60%
Loans Assumed							110,000,000
Rental Property, Including Amount Attributable To Non-controlling Interests	370,800,000
Wesco I LLC And Wesco III [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage										50.00%
Pro rata share in earnings	50.00%
Equity Method Investment Each Partners Equity Commitment	270,000,000
Wesco I LLC [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Number Of Apartment Communities Owned	9
Rental Properties	682,400,000
Wesco III [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Number Of Apartment Communities Owned	6
Number Of Units Acquired	993
Rental Properties	230,700,000
Wesco IV LLC [Member]
Business Acquisition [Line Items]
Units in the community	1,116
Wesco IV LLC [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Percentage of voting interests acquired								50.00%
Percent debt in merger								50.00%
Number of apartment communities	5
BEXAEW [Member]
Business Acquisition [Line Items]
Units in the community	2,723
BEXAEW [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Pro rata share in earnings								50.00%
Percentage of voting interests acquired								50.00%
Percentage of voting interests retained by institutional partner								50.00%
Percent debt in merger								60.00%
Number of apartment communities	9
Santa Monica at La Brea [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage										50.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners										50.00%
Membership interest in Wesco IV [Member]
Business Acquisition [Line Items]
Company's share of equity	297,900,000
Membership interest in BEXAEW [Member]
Business Acquisition [Line Items]
Company's share of equity	519,200,000
Essex Apartment Value Fund II LP Fund II [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	28.20%
Equity Method Investment, Aggregate Cost	75,000,000
Number of communities sold	2		5		7
Sales of Real Estate	47,300,000		320,400,000		413,000,000
Sales Of Real Estate, Promote Income	9,500,000
Payments of Debt Extinguishment Costs	200,000		400,000		2,300,000
Gains (Losses) on Sales of Investment Real Estate	23,300,000
Pro rata gain on sale of property of joint venture	6,600,000		38,800,000		29,100,000
Gain on sale of real estate			146,800,000		106,000,000
Expo formerly Queen Anne [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage											50.00%
Number Of Units Acquired									275
Company's share of equity	65,300,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners											50.00%
Real Estate Under Development Activities [Member]
Business Acquisition [Line Items]
Ownership interests, number of active development projects	10
Wesco I LLC [Member] | Equity Method Investments [Member]
Business Acquisition [Line Items]
Number Of Units Acquired	2,713
Real Estate predevelopment projects [Member]
Business Acquisition [Line Items]
Number Of Units To Be Developed	2,920
Estimated cost active development projects	1,500,000,000
Active development projects Estimated costs to be expended	420,000,000
Remaining Estimated cost to be contributed by Company	$ 250,000,000

[1] See note 2(r) for details of noncash investing and financing activities related to the BRE merger.