Real Estate Investments Joint Venture Developments (Details) (USD $)	12 Months Ended						1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2014 unit project community		Dec. 31, 2013 unit		Dec. 31, 2012		Jul. 31, 2014 apartment	Dec. 31, 2014	Dec. 31, 2011 joint_venture community unit sqft	May 31, 2013 unit
Schedule of Equity Method Investments [Line Items]
Loans Assumed	$ 72,568,000	[1]	$ 0	[1]	$ 82,133,000	[1]
Number Of Apartment Communities Owned	239							239
Number Of Development Projects	2
Ownership interests, number of active development projects	12							12
Number Of Units Acquired	1,480		1,079
Co-investment	1,036,411,000		677,133,000					1,036,411,000
Payments to Acquire Equity Method Investments	246,006,000		162,578,000		260,153,000
Basis spread on rate (in hundredths)					2.50%
One South Market [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage										55.00%
Estimated cost active development projects	145,000,000							145,000,000
Active development projects Estimated costs to be expended	25,000,000							25,000,000
Remaining Estimated cost to be contributed by Company	13,800,000							13,800,000
Number Of Units To Be Developed										312
Century Towers [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage							50.00%
Estimated cost active development projects	172,000,000						172,000,000	172,000,000
Active development projects Estimated costs to be expended	132,000,000							132,000,000
Remaining Estimated cost to be contributed by Company	66,000,000							66,000,000
Number Of Units To Be Developed							376
Co-investment	12,000,000						27,000,000	12,000,000
Preferred Stock Dividend Rate Percentage In First Five Years							8.10%
Canada Pension Plan Investment Board (CPPIB) I [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Development Projects	7
Number Of Units Acquired	1,424
Estimated cost active development projects	650,000,000							650,000,000
Active development projects Estimated costs to be expended	205,000,000							205,000,000
Remaining Estimated cost to be contributed by Company	111,300,000							111,300,000
CPPIB Epic Phase I and II [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Units Acquired	309
CPPIB Epic Phase I [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Units Acquired	280
CPPIB Epic Phase II [Member] [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Units Acquired	289
Real Estate Under Development Activities [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interests, number of active development projects	10							10
Real Estate predevelopment projects [Member]
Schedule of Equity Method Investments [Line Items]
Estimated cost active development projects	1,500,000,000							1,500,000,000
Active development projects Estimated costs to be expended	420,000,000							420,000,000
Remaining Estimated cost to be contributed by Company	250,000,000							250,000,000
Number Of Units To Be Developed	2,920							2,920
Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%							50.00%
Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	55.00%							55.00%
Mortgages [Member] | Century Towers [Member]
Schedule of Equity Method Investments [Line Items]
Mortgage Loans on Real Estate							90,000,000
Debt Instrument, Term Of Interest Rate							3 years
Debt Instrument, Interest Rate, Number Of Extensions							2
Debt Instrument, Term Of Interest Rate Per Extension							1 year
SIFMA [Member] | The Huxley And The Dylan [Member]
Schedule of Equity Method Investments [Line Items]
Derivative, Basis Spread on Variable Rate									1.50%
London Interbank Offered Rate (LIBOR) [Member] | Mortgages [Member] | Century Towers [Member]
Schedule of Equity Method Investments [Line Items]
Basis spread on rate (in hundredths)							1.75%
Equity Method Investments [Member]
Schedule of Equity Method Investments [Line Items]
Redemption of preferred equity investments	101,000,000							101,000,000
Gain from redemption penalties due to early redemption of preferred equity investments								5,300,000
Equity Method Investments [Member] | The Huxley And The Dylan [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Apartment Communities Owned									2
Number Of Development Projects									2
Number Of Units To Be Developed									371
Area of Real Estate Property									30,950
Equity Method Investment, Aggregate Cost									14,800,000
Equity Method Investment Ownership Percentage By Partners									50.00%
Mortgage Loans on Real Estate									114,400,000
Mortgage loan on property acquired, maturity date									Oct. 31, 2046
Derivative, Maturity Date									Sep. 30, 2016
Equity Method Investments [Member] | The Huxley [Member]
Schedule of Equity Method Investments [Line Items]
Rental Properties	72,200,000.0							72,200,000.0
Equity Method Investments [Member] | The Dylan [Member]
Schedule of Equity Method Investments [Line Items]
Rental Properties	74,100,000.0							74,100,000.0
Equity Method Investments [Member] | Los Angeles II [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Apartment Communities Owned			3
Co-investment			22,800,000
Gain from redemption penalties due to early redemption of preferred equity investments			900,000
Equity Method Investments [Member] | Anaheim, CA [Member]
Schedule of Equity Method Investments [Line Items]
Maximum Term Extended (in years)			1 year
Income related to the restructured investment			400,000
Equity Method Investments [Member] | Cupertino California [Member]
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Equity Method Investments					14,000,000
Cumulative dividend rate (in hundredths)					9.50%
Preferred Equity Investment Additional funding, Maximum					$ 4,000,000
Equity Method Investments [Member] | Canada Pension Plan Investment Board (CPPIB) I [Member]
Schedule of Equity Method Investments [Line Items]
Number Of Development Projects	7
Number Of Communities To Be Developed	7
Equity Method Investments [Member] | Minimum [Member] | Anaheim, CA [Member]
Schedule of Equity Method Investments [Line Items]
Preferred Stock Dividend Rate Percentage Thereafter			9.00%
Equity Method Investments [Member] | Maximum [Member] | Anaheim, CA [Member]
Schedule of Equity Method Investments [Line Items]
Preferred Stock Dividend Rate Percentage Thereafter			13.00%

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