Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs - Summary of Notes Payable (Parenthetical) (Detail) (USD $)	12 Months Ended																														1 Months Ended	12 Months Ended							0 Months Ended	12 Months Ended
	Dec. 31, 2013 Metro Pike Center	Dec. 31, 2013 White Oak Shopping Center	Dec. 31, 2013 Beacon Center	Dec. 31, 2013 Northrock	Dec. 31, 2012 7.67% due October 2012 Metro Pike Center	Dec. 31, 2012 6.12% due January 2013 Cruse Market Place	Dec. 31, 2012 7.88% due January 2013 Seabreeze Plaza	Dec. 31, 2013 7.45% due June 2015 Shops at Fairfax and Boulevard	Dec. 31, 2013 6.01% due February 2018 Washington Square	Dec. 31, 2013 5.88% due January 2019 Broadlands Village, The Glen and Kentlands Square I Store	Dec. 31, 2013 5.76% due May 2019 Olde Forte Village	Dec. 31, 2013 5.62% due July 2019 Countryside	Dec. 31, 2013 5.79% due September 2019 Briggs Chancy MarketPlace	Dec. 31, 2013 5.22% due January 2020 Shops at Monocacy	Dec. 31, 2013 5.60% due May 2020 Boca Valley Plaza	Dec. 31, 2013 5.30% due June 2020 Palm Springs Center	Dec. 31, 2013 5.83% due July 2020 Thruway	Dec. 31, 2013 5.81% due February 2021 Jamestown Place	Dec. 31, 2013 6.01% due August 2021 Hunt Club Corners	Dec. 31, 2013 5.62% due June 2022 Landsowne Town Center	Dec. 31, 2013 6.08% due September 2022 Orchard Park	Dec. 31, 2013 6.43% due April 2023 BJs Wholesale	Dec. 31, 2013 6.28% due February 2024 Great Falls Shopping Center Note	Dec. 31, 2013 7.35% due June 2024 Leesburg Pike	Dec. 31, 2013 7.60% due June 2024 Village Center	Dec. 31, 2013 7.02% due July 2024 White Oak Shopping Center	Dec. 31, 2013 7.45% due July 2024 Avenel Business Park	Dec. 31, 2013 7.30% due January 2025 Ashburn Village	Dec. 31, 2013 6.18% due January 2026 Ravenwood	Dec. 31, 2013 5.31% due April 2026 Clarendon Center	Sep. 23, 2011 4.30% due October2026 Severna Park Market Place	Dec. 31, 2013 4.30% due October2026 Severna Park Market Place	Dec. 31, 2013 4.53% due November 2026 Kentlands Square II	Dec. 31, 2013 4.70% due December 2026 Cranberry Square	Dec. 31, 2013 5.84% due May 2027 Seven Corners	Dec. 31, 2013 4.04% due April 2028 Hampshire Langley	Dec. 31, 2013 3.51% due June 2028 Beacon Center	Dec. 31, 2013 3.99% due September 2028 Seabreeze Plaza	Oct. 25, 2013 4.88% due September 2032 Park Van Ness	Dec. 31, 2013 4.88% due September 2032 Park Van Ness	Dec. 31, 2013 Revolving credit facility	Dec. 31, 2013 Revolving credit facility One-month LIBOR	Dec. 31, 2013 Northrock loan Northrock
Notes Payable [Line Items]
Principal and interest payments	$ 48,000				$ 86,000	$ 56,000	$ 102,000	$ 156,000	$ 264,000	$ 306,000	$ 98,000	$ 133,000	$ 133,000	$ 112,000	$ 75,000	$ 75,000	$ 289,000	$ 66,000	$ 42,000	$ 230,000	$ 73,000	$ 80,000	$ 138,000	$ 135,000	$ 119,000	$ 193,000	$ 246,000	$ 240,000	$ 111,000	$ 753,000		$ 207,000	$ 240,000	$ 113,000	$ 463,200	$ 95,400	$ 203,200	$ 94,900		$ 413,500			$ 47,000
Amortization period	25 years	25 years	20 years	25 years	25 years	24 years	26 years	23 years	27 years 6 months	25 years	25 years	25 years	25 years	25 years	30 years	25 years	25 years	25 years	30 years	30 years	30 years	30 years	26 years	25 years	25 years	24 years 4 months 24 days	25 years	25 years	25 years	25 years	25 years	25 years	25 years	25 years	25 years	25 years	20 years	25 years	25 years	25 years
Debt instrument final payment	14,800,000	18,500,000		14,200,000	15,600,000	6,800,000	13,300,000	15,200,000	28,000,000	28,400,000	9,000,000	12,300,000	12,200,000	10,600,000	9,100,000	7,100,000	34,800,000	6,100,000	5,000,000	28,200,000	8,600,000	9,300,000	6,300,000	11,500,000	10,100,000	18,500,000	20,900,000	20,500,000	10,100,000	70,500,000		20,300,000	23,100,000	10,900,000	42,300,000	9,500,000	11,400,000	9,500,000	39,600,000				14,200,000
Amortization of principal	206,000							670,000	1,100,000	1,500,000	469,000	644,000	621,000	566,000	262,000	367,000	962,000	285,000	126,000	718,000	199,000	194,000	649,000	346,000	291,000	482,000	616,000	596,000	332,000	2,700,000	911,000		996,000	451,000	1,400,000	282,000	609,000	105,000					161,000
Number of shopping centers										3
Number of notes																							3
Debt instrument amount	$ 15,600,000	$ 10,500,000		$ 15,000,000																						$ 10,500,000				$ 125,000,000		$ 38,000,000	$ 43,000,000	$ 20,000,000	$ 73,000,000	$ 18,000,000	$ 35,000,000	$ 18,000,000		$ 71,580,000	$ 175,000,000
Interest rate spread on LIBOR	1.65%			1.65%																																						1.90%
Debt maturity extension period																																									1 year
Debt instrument fee																																									0.20%
Debt instrument frequency of periodic payment																																									Monthly