Subsequent Events (Details) (Subsequent event, USD $)	0 Months Ended	1 Months Ended
Jan. 13, 2013 Mezzanine loan	Jan. 31, 2013 Mezzanine loan	Feb. 28, 2013 Refinancing 1515 Broadway
Subsequent Events
Percentage of loan sold	50.00%	50.00%
Face amount of loan sold		$ 118,200,000	$ 775,000,000
Consideration from sale of loan		57,800,000
Additional income recognized on repayment of debt		12,900,000
Mortgage on properties assumed			$ 900,000,000
Term of refinanced mortgage			12 years
Interest rate (as a percent)			3.93%

Represents the term of the debt instrument.

No definition available.

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- Definition

Represents the amount of consideration from sale of mortgage loan on real estate.

+ References

No definition available.

+ Details

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- Definition

Represents the percentage of mortgage loan on real estate sold by the entity.

+ References

No definition available.

+ Details

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- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

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-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

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- Definition

Interest rate stated in the contractual debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

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- Definition

The difference between the reacquisition price and the net carrying amount of the extinguished debt recognized currently as a component of income in the period of extinguishment, net of tax.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 145

-Paragraph A5

-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.

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-Publisher AICPA

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-Publisher FASB

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- Definition

Total amount of new mortgage loans on real estate during the reporting period.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

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-Paragraph 1

-Subparagraph (SX 210.12-29.6)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Subparagraph Schedule IV

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