Real Estate (Significant Acquisitions and Disposition) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012 ResidentialPropertyAdjacentToSantanaRow [Member]	Dec. 27, 2011 Montrose Crossing [Member]	Dec. 27, 2011 Montrose Crossing [Member] New Mortgage Debt [Member]	Dec. 30, 2011 Plaza El Segundo [Member]
Real Estate Investments [Line Items]
Business Acquisition Cost of Acquired Entity Cash Paid and Total Debt Assumed		$ 141.5
Business Acquisition, Percentage of Voting Interests Acquired		89.90%		48.20%
Business Acquisition Cost of Acquired Entity Cash Paid and Share of Debt Assumed		127.2
Debt Instrument, Fair Value Disclosure			80.0
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets		2.9		7.5
Business Acquisition Purchase Price Allocation Amortizable Intangible Below Market Lease Liabilities		3.8		2.3
NumberofRealEstatePropertiesAcquired	3
NumberofResidentialUnits	47
Business Acquisition Purchase Price	9.0			192.7
Business Acquisition, Cost of Acquired Entity, Cash Paid				8.5
Debt Instrument, Face Amount				$ 175.0