Relationship with Vornado: Summary of Fees (Details) (Affiliated Entity [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Related Party Transaction [Line Items]
Fees to Related Party	$ 1,963	$ 2,828
Company Management Fees [Member]
Related Party Transaction [Line Items]
Fees to Related Party	700	750
Development fees [Member]
Related Party Transaction [Line Items]
Fees to Related Party	0	188
Leasing Fees [Member]
Related Party Transaction [Line Items]
Fees to Related Party	386	623
Property Management Fees [Member]
Related Party Transaction [Line Items]
Fees to Related Party	$ 877	$ 1,267

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 57

-Paragraph 2

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 850

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

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