Real Estate Acquired and Sold - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended	1 Months Ended		1 Months Ended				1 Months Ended		1 Months Ended
	Apr. 30, 2014 Olney Center sqft	Sep. 30, 2014 Olney Center	Apr. 30, 2014 Giant Center sqft	Mar. 31, 2014 Giant Center	Aug. 31, 2013 Kentlands Pad sqft	Dec. 31, 2013 Hunt Club Pad sqft	Jan. 31, 2014 1580 Rockville Pike sqft	Jan. 31, 2014 1580 Rockville Pike In-place Lease	Apr. 30, 2014 1582 Rockville Pike sqft	Apr. 30, 2014 1582 Rockville Pike In-place Lease	Aug. 31, 2014 Glebe Road sqft	Apr. 30, 2014 Glebe Road	Aug. 31, 2014 Glebe Road In-place Lease
Business Acquisition [Line Items]
Name of property	Olney Center		Giant Center		Kentlands Pad	Hunt Club Pad	1580 Rockville Pike
Purchase price					$ 4,300,000	$ 800,000	$ 8,000,000		$ 11,000,000		$ 40,000,000
Property type					retail pad	retail pad
Area of real estate property (in sq ft)	53,765		70,040		7,100	5,500	12,100		40,700		16,900
Location of property	Olney, Maryland		Milford Mill, Maryland		Gaithersburg, Maryland	Apopka, Florida	Rockville, Maryland		Rockville, Maryland
Property acquisition costs					99,000		163,000		200,000			355,000
Remaining life of the lease							10 years
Purchase Price Allocation:
Land							9,600,000		9,742,000		38,224,000
Building							2,200,000		828,000		1,327,000
In-place lease								513,000		849,000			449,000
Below-market rents							(4,313,000)		(419,000)
Total acquisition cost							8,000,000
Proceeds from sale of real estate	11,000,000	11,000,000	7,500,000
Lease term	P20Y
Sale leaseback, option to purchase the property	14,600,000
Sales price of property	11,000,000
Annual increase in rental payments, percentage	1.50%
Gain on sale of real estate			6,100,000
Assets held-for-sale				500,000
Liabilities of assets held-for-sale				$ 100,000