Related Party Transactions (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Related Party Transactions [Abstract]
Management and other fees from affiliates including management, property management, development and redevelopment fees from co-investments, net of intercompany amounts eliminated by company	$ 10,900,000	$ 6,100,000	$ 4,100,000
Property acquisition fee			500,000
Related Party Transaction [Line Items]
Debt instrument, basis spread on variable rate (in hundredths)	2.50%
Number of units acquired	2,052	386
Cost of acquired entity	551,100,000	103,300,000
Redemption price per partnership unit (in dollars per share)			$ 106.76
Redemption price discount from the closing price of the company's common stock (in hundredths)			2.00%
Partnership units purchased from related party (in shares)			187,334
Limited partnership units exchange ratio to Company's common stock			one-for-one
Executive Vice President of the Company invested			4,000,000
Limited partnership interest in partnership investments (in hundredths)			3.00%
Marcus and Millichamp Company TMMC Affiliate [Member]
Related Party Transaction [Line Items]
Brokerage commissions revenue	400,000
Wesco III [Member]
Related Party Transaction [Line Items]
Short term bridge loan	26,000,000
SummerHill Apartment Communities [Member]
Related Party Transaction [Line Items]
Preferred equity interest investment in a related party entity	8,600,000
Preferred return on investment in related party investee during first five years (in hundredths)	9.50%
Pacific Urban Residential [Member]
Related Party Transaction [Line Items]
Preferred equity interest investment in a related party entity	14,000,000
Additional preferred equity interest investment related party entity	4,000,000
Preferred return on investment in related party investee during first five years (in hundredths)	9.50%
Maturity date	May 31, 2016
Montebello [Member]
Related Party Transaction [Line Items]
Number of units acquired	248
Cost of acquired entity	52,000,000
TMCC [Member]
Related Party Transaction [Line Items]
Preferred equity interest investment in a related party entity	12,000,000
Preferred return on investment in related party investee during first five years (in hundredths)	13.00%
Units in the community	768
Preferred return on investment in related party investee after year five (in hundredths)	15.00%
TMCC and Wesco I [Member]
Related Party Transaction [Line Items]
Units in the community	156
Cost of acquired entity	$ 38,300,000