Segment Reporting (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Capital expenditures for each segment
Capital Expenditures	$ 15,040	$ 4,217	$ 28,506	$ 7,643
Retail [Member]
Capital expenditures for each segment
Capital Expenditures	4,292	1,574	11,734	2,521
Office [Member]
Capital expenditures for each segment
Capital Expenditures	10,381	1,638	15,737	3,850
Multifamily [Member]
Capital expenditures for each segment
Capital Expenditures	259	335	782	472
Mixed-Use [Member]
Capital expenditures for each segment
Capital Expenditures	$ 108	$ 670	$ 253	$ 800

Total expenditures for additions to long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets of the reportable segment; if the amount: (a) is included in the determination of segment assets reviewed by the chief operating decision maker or (b) is otherwise regularly provided to the chief operating decision maker, even if not included in the determination of segment assets.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 28

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Name:	us-gaap_AdditionsToNoncurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration