Real Estate Acquired and Sold - Purchase Price Allocation (Details) $ in Thousands	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Land	$ 66,048
Buildings	4,874
Below Market Rent	(5,070)
Total Purchase Price	67,950
In-place Leases
Business Acquisition [Line Items]
Finite-lived Intangibles	2,099
Above Market Rent
Business Acquisition [Line Items]
Finite-lived Intangibles	0
1580 Rockville Pike
Business Acquisition [Line Items]
Land	9,600
Buildings	2,200
Below Market Rent	(4,313)
Total Purchase Price	8,000
1580 Rockville Pike \| In-place Leases
Business Acquisition [Line Items]
Finite-lived Intangibles	513
1580 Rockville Pike \| Above Market Rent
Business Acquisition [Line Items]
Finite-lived Intangibles	0
1582 Rockville Pike
Business Acquisition [Line Items]
Land	9,742
Buildings	828
Below Market Rent	(419)
Total Purchase Price	11,000
1582 Rockville Pike \| In-place Leases
Business Acquisition [Line Items]
Finite-lived Intangibles	849
1582 Rockville Pike \| Above Market Rent
Business Acquisition [Line Items]
Finite-lived Intangibles	0
750 N. Glebe Road
Business Acquisition [Line Items]
Land	38,224
Buildings	1,327
Below Market Rent	0
Total Purchase Price	40,000
750 N. Glebe Road \| In-place Leases
Business Acquisition [Line Items]
Finite-lived Intangibles	449
750 N. Glebe Road \| Above Market Rent
Business Acquisition [Line Items]
Finite-lived Intangibles	0
730 N. Glebe Road
Business Acquisition [Line Items]
Land	2,683
Buildings	78
Below Market Rent	0
Total Purchase Price	2,800
730 N. Glebe Road \| In-place Leases
Business Acquisition [Line Items]
Finite-lived Intangibles	39
730 N. Glebe Road \| Above Market Rent
Business Acquisition [Line Items]
Finite-lived Intangibles	0
1584 Rockville Pike
Business Acquisition [Line Items]
Land	5,798
Buildings	440
Below Market Rent	(337)
Total Purchase Price	6,150
1584 Rockville Pike \| In-place Leases
Business Acquisition [Line Items]
Finite-lived Intangibles	249
1584 Rockville Pike \| Above Market Rent
Business Acquisition [Line Items]
Finite-lived Intangibles	$ 0

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Below Market Lease

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of facility held for productive use including, but not limited to, office, production, storage and distribution facilities, acquired at 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)

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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 10

-Section 55

-Paragraph 37

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

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Amount of real estate acquired, at the acquisition date.

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

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