Real Estate Acquired - Allocation of Purchase Prices to Acquired Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2014
Business Acquisition [Line Items]
Land	$ 9,432	$ 66,047
Buildings	874	4,873
Below Market Rent	(63)	(5,069)
Total Purchase Price	10,336	67,950
In-place Leases
Business Acquisition [Line Items]
Intangible assets	93	2,099
Above Market Rent
Business Acquisition [Line Items]
Intangible assets	0	0
700 N. Glebe Road
Business Acquisition [Line Items]
Land	7,236
Buildings	0
Below Market Rent	0
Total Purchase Price	7,236
700 N. Glebe Road \| In-place Leases
Business Acquisition [Line Items]
Intangible assets	0
700 N. Glebe Road \| Above Market Rent
Business Acquisition [Line Items]
Intangible assets	0
Thruway Pad
Business Acquisition [Line Items]
Land	2,196
Buildings	874
Below Market Rent	(63)
Total Purchase Price	3,100
Thruway Pad \| In-place Leases
Business Acquisition [Line Items]
Intangible assets	93
Thruway Pad \| Above Market Rent
Business Acquisition [Line Items]
Intangible assets	$ 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]
Intangible assets		513
1580 Rockville Pike \| Above Market Rent
Business Acquisition [Line Items]
Intangible assets		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]
Intangible assets		849
1582 Rockville Pike \| Above Market Rent
Business Acquisition [Line Items]
Intangible assets		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]
Intangible assets		449
750 N. Glebe Road \| Above Market Rent
Business Acquisition [Line Items]
Intangible assets		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]
Intangible assets		39
730 N. Glebe Road \| Above Market Rent
Business Acquisition [Line Items]
Intangible assets		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]
Intangible assets		249
1584 Rockville Pike \| Above Market Rent
Business Acquisition [Line Items]
Intangible assets		$ 0

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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.

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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=73531372&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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