Real Estate Investments Real Estate Investments, Business Combinations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 19, 2013
One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		$ 255,705
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		85,036
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		8,637
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net		332,104
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt		238,082
Business Combination, return of capital on equity method investment		(30,424)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other		10,423
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		(946)
Business Combination, Total Cash Payment at Settlement		73,075
Leases, Acquired-in-Place [Member] \| One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		80,916
Above Market Leases [Member] \| One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		4,120
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 10 months 24 days
Below Market Lease [Member] \| One and Two Commerce Square [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		$ (8,637)
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 6 months
One and Two Commerce Square [Member] \| Leases, Acquired-in-Place [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years 10 months 24 days

Business Combination, return of capital on equity method investment

No definition available.

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- Definition

Business Combination, Total Cash Payment at Settlement

+ References

No definition available.

+ Details

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- Details

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- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16265-109275

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- Definition

This element represents the fair value of the noncontrolling interest in the acquiree at the acquisition date.

+ References

+ Details

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- Definition

Amount of other assets expected to be realized or consumed before one year or the normal operating cycle, if longer, acquired at the acquisition date.

+ References

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- Definition

The amount of identifiable intangible assets recognized as of the acquisition date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=39739317&loc=d3e4845-128472

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 55

-Paragraph 37

-URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464

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- Definition

Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

+ References

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- Definition

Amount of long-term debt due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

+ References

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- Definition

Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

+ References

+ Details

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- Definition

The amount of property, plant, and equipment recognized as of the acquisition date.

+ References

+ Details

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