Fair Value Measurements - Carrying Value and Estimated Fair Value of Financial Instruments Not Recorded at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Aug. 31, 2012
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Loans receivable	$ 113,308	$ 211,250
Mortgage loans payable	325,026	280,576
Senior notes payable	86,250	86,250	86,250
Secured financings	29,150	52,920
Notes payable	1,645	1,676
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Loans receivable
Mortgage loans payable
Senior notes payable	90,252	89,183
Secured financings
Notes payable
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Loans receivable
Mortgage loans payable
Senior notes payable
Secured financings
Notes payable
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Loans receivable	124,636	222,246
Mortgage loans payable	315,888	270,923
Senior notes payable
Secured financings	29,406	53,253
Notes payable	1,645	1,676
Fair Value [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Loans receivable	124,636	222,246
Mortgage loans payable	315,888	270,923
Senior notes payable	90,252	89,183
Secured financings	29,406	53,253
Notes payable	$ 1,645	$ 1,676