Investments in Unconsolidated Real Estate Entities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended					6 Months Ended					1 Months Ended	6 Months Ended
	Jun. 30, 2013 Property	Jun. 30, 2012	Jun. 30, 2013 Property	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Unconsolidated Properties [Member] Property	Jun. 30, 2012 Unconsolidated Properties [Member]	Jun. 30, 2013 Unconsolidated Properties [Member] Property	Jun. 30, 2012 Unconsolidated Properties [Member]	Dec. 31, 2012 Unconsolidated Properties [Member]	Jun. 30, 2013 Unconsolidated Properties [Member] Minimum [Member]	Jun. 30, 2013 Unconsolidated Properties [Member] Maximum [Member]	Jun. 30, 2013 3.50% Mortgage Note Payable [Member]	Jun. 30, 2013 5.63% Mortgage Notes Payable [Member]	Jun. 30, 2013 5.71% Mortgage Notes Payable [Member] Y	Jun. 30, 2013 Atlanta, Georgia [Member] Unconsolidated Properties [Member] Property	Jun. 30, 2013 Washington, D.C. [Member] Unconsolidated Properties [Member] Property	Feb. 29, 2012 Unconsolidated Property Sold [Member]	Jun. 30, 2012 Unconsolidated Property Sold [Member]
Real Estate Properties [Line Items]
Equity method investment, ownership percentage											25.00%	35.00%						35.00%
Number of real estate properties	61		61			4		4								3	1
Investment in owned subsidiaries	$ 4,458		$ 4,458		$ 4,533
Investments in unconsolidated real estate entities	16,518		16,518		16,297	16,518		16,518		16,297
Investment over equity underlying net assets						2,784		2,784
Net proceeds from sale of entire community																		50,500
Mortgage note payable						177,723		177,723		177,723			51,000	85,724	41,000			29,272
Equity in income of unconsolidated real estate entities, net	$ 477	$ 495	$ 955	$ 6,941		$ 477	$ 495	$ 955	$ 6,941										$ 6,055
Mortgage notes payable bearing interest rate													3.50%	5.63%	5.71%
Automatic extension period (in years)															1
Mortgage note payable maturity date													2019	2017	January 2018