Investments in Unconsolidated Real Estate Entities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended			9 Months Ended		12 Months Ended									12 Months Ended
	Dec. 31, 2012 Property	Dec. 31, 2011	Dec. 31, 2010	Sep. 24, 2010 Mixed-Use LP [Member]	Sep. 30, 2010 Mixed-Use LP [Member]	Dec. 31, 2012 Land LLC [Member]	Dec. 31, 2012 Land LLC [Member] Atlanta Condominium Project [Member]	Dec. 31, 2012 Apartment LLCs [Member] Property	Dec. 31, 2011 Apartment LLCs [Member]	Dec. 31, 2010 Apartment LLCs [Member]	Dec. 31, 2012 Apartment LLCs Minimum [Member]	Dec. 31, 2012 Apartment LLCs Maximum [Member]	Dec. 31, 2012 Atlanta, Georgia [Member] Apartment LLCs [Member] Property	Dec. 31, 2012 Washington, D.C. [Member] Apartment LLCs [Member] Property	Dec. 31, 2012 Apartment LLC Sold [Member]	Dec. 31, 2010 Deferred Gain On Early Extinguishment Of Debt Amount [Member] Atlanta Condominium Project [Member]	Dec. 31, 2010 Impairment Loss [Member] Atlanta Condominium Project [Member]	Dec. 31, 2012 3.50% Mortgage Note Payable [Member]	Dec. 31, 2012 5.63% Mortgage Notes Payable [Member]	Dec. 31, 2012 5.71% Mortgage Notes Payable [Member] Y
Real Estate Properties [Line Items]
Equity method investment, ownership percentage					49.00%						25.00%	35.00%			35.00%
Number of real estate properties	60							4					3	1
Investment in owned subsidiaries	$ 4,533	$ 7,344
Investments in unconsolidated real estate entities	16,297	15,945						16,297	15,945
Investment over equity underlying net assets								2,830
Net proceeds from sale of entire community															50,500
Mortgage note payable								177,723	206,495						29,272			51,000	85,724	41,000
Equity in income (loss) of unconsolidated real estate entities, net	7,995	1,001	18,739	18,104				7,995	1,001	635					6,055	23,596	5,492
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
Payments on indebtedness	282,979	197,806	151,151				49,793
Gain on debt extinguishment	$ (4,318)	$ (6,919)	$ 2,845			$ 2,845