Investments In Unconsolidated Real Estate Funds Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013 Number_of_funds_managed	Mar. 31, 2012
Number of Real Estate Funds owned and managed	2
Additional interest acquired, value	$ 8.0	$ 33.4
Commitments assumed in business combination step acquisition of equity method investee	$ 1.4	$ 3.2
Percentage of amounts related to the Fund	100.00%
Fund X [Member]
Additional interest acquired, percent	3.30%	16.30%
Partnership X [Member]
Additional interest acquired, percent	0.90%

In a business combination achieved in stages, this element represents the acquisition-date fair value of the equity interest in the acquiree held by the acquirer immediately before the acquisition date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Number 141R

-Paragraph 68

-Subparagraph q(1)

-Name Statement of Financial Accounting Standard (FAS)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (g)(1)

-URI http://asc.fasb.org/extlink&oid=6909870&loc=d3e1392-128463

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant