The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 59

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=6909708&loc=d3e1043-128460

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- Definition

The number of units or percentage investment held by the managing member or general partner of the LLC or LP.

+ References

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

-Publisher AICPA

-Name Practice Bulletin (PB)

-Number 14

-Paragraph 15

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Name Accounting Standards Codification

-Topic 272

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (b)

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- Definition

The amount of debt that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 32

-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 FASB

-Name Accounting Standards Codification

-Topic 230

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- Definition

The amount of square footage related to a real estate property.

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ACQUISITION AND DISPOSITION OF PROPERTIES AND DISCONTINUED OPERATIONS Acquisitions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	1 Months Ended				3 Months Ended		1 Months Ended
	Mar. 31, 2012 Core Portfolio [Member]	Jan. 31, 2012 1520 North Milwaukee Avenue [Member] Chicago Illinois [Member] Core Portfolio [Member] sqft	Feb. 29, 2012 Single Tenant Property [Member] Cambridge Massachusetts [Member] Core Portfolio [Member] sqft	Feb. 29, 2012 Second Single Tenant Property [Member] Cambridge Massachusetts [Member] Core Portfolio [Member] sqft	Mar. 31, 2012 Four Property Portfolio [Member] Chicago Illinois [Member] Core Portfolio [Member]	Mar. 31, 2012 Fund III [Member]	Mar. 31, 2012 Fund III [Member] Opportunity Funds [Member]	Feb. 29, 2012 Fund III [Member] 640 Broadway [Member] New York New York [Member] Opportunity Funds [Member] sqft
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price		$ 3.8	$ 12.2	$ 6.7	$ 18.8			$ 16.3
In-Place Mortgage Debt Assumption			7.0		16.0
Square Footage of Real Estate Property (in square feet)		3,100	40,000	13,300				45,700
Business Combination, Acquisition Related Costs	$ 0.4						$ 0.6
Ownership Interest By General Partner or Managing Partner						19.90%		50.00%