Equity Transactions (Details) (USD $)	1 Months Ended	12 Months Ended			3 Months Ended
	Apr. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2011	Sep. 30, 2006	Jun. 30, 2014
Class of Stock [Line Items]
Stock-based compensation expense		$ 8,740,000	$ 4,508,000	$ 4,141,000
Shares issued (in shares)	23,067,446
Issue price (in dollars per share)	$ 163.82
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest		96.70%	94.60%
Redemption value of operating partnership units outstanding		455,000,000	309,000,000
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Proceeds from Issuance of Common Stock		532,770,000	138,366,000	357,720,000
Series H 7.125% Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Shares Authorized (in shares)		8,000,000	8,000,000
Shares Outstanding (in shares)		2,950,000	2,950,000
Liquidation Preference		73,800,000	73,750,000
Cumulative dividend rate (in hundredths)		7.125%	7.125%
Shares issued (in shares)					2,950,000
Issue price (in dollars per share)					$ 25.00
Net proceeds					71,200,000
Beginning date of called period					Apr. 13, 2016
4.875% Series G Cumulative Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Shares Outstanding (in shares)			178,249				178,249
Liquidation Preference		4,500,000	4,456,000
Number of shares sold (in shares)						5,980,000
Cumulative dividend rate (in hundredths)		4.875%	4.875%
Gross proceeds from sale of shares						149,500,000
Conversion rate into shares of common stock (in shares)						0.1830	0.19301
Liquidation preference per share (in dollars per share)						$ 25
Initial conversion price per share of common stock (in dollars per share)						$ 136.62
Common Stock [Member]
Class of Stock [Line Items]
Shares Outstanding (in shares)							34,403
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common Stock, Number of shares sold		2,964,315
Proceeds from Issuance of Common Stock		534,000,000	138,400,000	357,700,000
Average Share Price		$ 181.56
Stock Issued During Period, Shares, New Issues			913,344	2,404,096
Operating Partnership Units [Member]
Class of Stock [Line Items]
Shares Outstanding (in shares)		2,110,462	2,031,612
Long Term Incentive Plan "LTIP" Units [Member]
Class of Stock [Line Items]
Shares Outstanding (in shares)		91,348	118,190
BRE Properties, Inc. [Member]
Class of Stock [Line Items]
Allocated Share-based Compensation Expense		3,600,000
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Merger and integration expenses		$ 1,700,000