Real Estate Acquired and Sold - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
Jul. 25, 2012 West Park Shopping Center sqft	Dec. 31, 2012 Belvedere Shopping Center sqft	Dec. 31, 2012 1500 Rockville Pike	Dec. 31, 2012 5541 Nicholson Lane
Business Acquisition [Line Items]
Business acquisition, property purchase price			$ 22.4	$ 11.7
Property acquisition costs			0.6	0.5
Proceeds from sale of real estate property	2.0	4.0
Area of real estate property	77,000	54,900
Gain on sale of real estate property	$ 1.1	$ 3.4

Area of a real estate property.

No definition available.

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- Definition

Amount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition.

+ References

No definition available.

+ Details

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- Details

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- Definition

Amount of difference between the carrying amount and the sales price of real estate properties sold as part of discontinued operations.

+ References

No definition available.

+ Details

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- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

+ Details

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- Definition

Cash received for the sale of real estate that is not part of an investing activity during the current period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

+ Details

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