Length of Loan Extension

No definition available.

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- Definition

Long Term Debt, Debt Replaced by New Debt

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of Loan Extensions

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of Properties Collateralized

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

The percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Decrease for amounts repaid on the debt instrument for the period.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 4

-Section 08

-Paragraph f

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(f))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase for additional borrowings on the debt instrument during the period.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

-SubTopic 10

-Section S99

-Paragraph 1

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

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Details

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Balance Type:	na
Period Type:	duration

- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Decrease for amounts repaid on the credit facility for the period.

+ References

+ Details

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- Definition

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 16

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20, 22

-Article 5

+ Details

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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

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-Section 50

-Paragraph 4

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-Topic 230

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-Paragraph 3

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MORTGAGES NOTES PAYABLE (Details) (USD $)				3 Months Ended		6 Months Ended	1 Months Ended										1 Months Ended
MORTGAGES NOTES PAYABLE (Details) (USD $)	Jun. 30, 2012	Dec. 31, 2011	Mar. 31, 2012 Chicago Illinois Four Property Portfolio properties	Mar. 31, 2012 Secured Credit Facilities - Variable-Rate Fund III revolving subscription line of credit Line of Credit	Jun. 30, 2012 Secured Credit Facilities - Variable-Rate Fund III revolving subscription line of credit Line of Credit	Jun. 30, 2012 Secured Credit Facilities - Variable-Rate Fund II Line of Credit	Jun. 30, 2012 LIBOR Plus 2.95% Mortgage Note Mortgages	Jun. 30, 2012 LIBOR Plus 2.95% Mortgage Note Mortgages LIBOR	Jun. 30, 2012 6.35% Mortgage Note Washington, D.C. Shopping Center Mortgages	Jun. 30, 2012 Disposal Property Loan, Mortgage Note Mortgages	May 31, 2012 3.68% Mortgage Note Mortgages	Apr. 30, 2012 LIBOR Plus 2.25% Construction Loan Construction Loans extension_options	Apr. 30, 2012 LIBOR Plus 2.25% Construction Loan Construction Loans LIBOR	Apr. 30, 2012 Mortgage Notes Maturing April 2012 [Member] Mortgages	Apr. 30, 2012 Mortgage Notes Maturing April 2012 [Member] Chicago Illinois Lincoln Park Centre Fund III revolving subscription line of credit Mortgages	Apr. 30, 2012 LIBOR Plus 1.9% Mortgage Note Mortgages	Apr. 30, 2012 LIBOR Plus 1.9% Mortgage Note Mortgages LIBOR	Mar. 31, 2012 5.62% Mortage Note Chicago Illinois Four Property Portfolio Mortgages	Mar. 31, 2012 5.55% Mortage Note Chicago Illinois Four Property Portfolio Mortgages	Feb. 29, 2012 6.26% Mortage Note Cambridge Massachusetts Single Tenant Property Mortgages extension_options	Feb. 29, 2012 Mortgage Notes Payable - Variable-Rate Mortgages LIBOR
Debt Instrument [Line Items]
Line of credit facility, repayments				$ 53,100,000		$ 7,600,000
Line of credit facility, amount outstanding					82,900,000	32,400,000
Mortgages payable	853,924,000	779,650,000					22,800,000				4,300,000	69,600,000		73,900,000		15,500,000
Business Acquisition, Debt Assumption									16,500,000						19,800,000			14,500,000	1,500,000	7,000,000
Interest rate									6.35%		3.68%				5.85%			5.62%	5.55%	6.26%
Repayments of Long-term Debt										8,300,000
Long Term Debt, Debt Replaced by New Debt												56,500,000
Debt Instrument, Increase, Additional Borrowings														$ 23,600,000
Number of Properties Collateralized (in properties)			4
Number of loan extensions (in extension options)												2								1
Length of loan extension option							1 year				5 years	1 year								5 years
LIBOR								LIBOR					LIBOR				LIBOR				LIBOR
Basis Spread								2.95%					2.25%				1.90%				2.00%