Real Estate Acquired - Allocation of Purchase Prices to Acquired Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]
Land	$ 2,300	$ 30,400
Buildings	2,000	3,800
Below Market Rents		(700)	(5,500)
In-Place Leases
Business Acquisition [Line Items]
Intangible assets		500
Above Market Rents
Business Acquisition [Line Items]
Intangible assets			28
Kentlands Square II
Business Acquisition [Line Items]
Land	20,500
Buildings	51,973
Below Market Rents	(676)
Total Purchase Price	74,500
Kentlands Square II | In-Place Leases
Business Acquisition [Line Items]
Intangible assets	2,697
Kentlands Square II | Above Market Rents
Business Acquisition [Line Items]
Intangible assets	6
Severna Park Market Place
Business Acquisition [Line Items]
Land	12,700
Buildings	50,554
Below Market Rents	(4,691)
Total Purchase Price	61,000
Severna Park Market Place | In-Place Leases
Business Acquisition [Line Items]
Intangible assets	2,433
Severna Park Market Place | Above Market Rents
Business Acquisition [Line Items]
Intangible assets	4
Cranberry Square
Business Acquisition [Line Items]
Land	6,700
Buildings	24,878
Below Market Rents	(95)
Total Purchase Price	33,000
Cranberry Square | In-Place Leases
Business Acquisition [Line Items]
Intangible assets	1,499
Cranberry Square | Above Market Rents
Business Acquisition [Line Items]
Intangible assets	18
Three Property
Business Acquisition [Line Items]
Land	39,900
Buildings	127,405
Below Market Rents	(5,462)
Total Purchase Price	168,500
Three Property | In-Place Leases
Business Acquisition [Line Items]
Intangible assets	6,629
Three Property | Above Market Rents
Business Acquisition [Line Items]
Intangible assets	$ 28