Concentration of Risk (Details)	12 Months Ended
Dec. 31, 2012 tenants	Dec. 31, 2011 tenants	Dec. 31, 2010 tenants
Concentration Risk [Line Items]
Number of tenants representing more than 10% of rental revenue	0	0	0
Maximum [Member] \| Tenant Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk percentage	10.00%	10.00%	10.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

-SubTopic 10

-Section 50

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

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-Section 50

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

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-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13531-108611

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 275

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-Section 50

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-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

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