Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Aug. 31, 2012
Carrying value and estimated fair value of financial instruments not recorded at fair value on recurring basis
Loan receivable	$ 130,212	$ 211,250
Mortgage loans payable	278,824	280,576
Senior notes payable	86,250	86,250	86,250
Secured financings	42,803	52,920
Notes payable	1,660	1,676
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Carrying value and estimated fair value of financial instruments not recorded at fair value on recurring basis
Loan receivable
Mortgage loans payable
Senior notes payable	89,700	89,183
Secured financings
Notes payable
Significant Other Observable Inputs (Level 2) [Member]
Carrying value and estimated fair value of financial instruments not recorded at fair value on recurring basis
Loan receivable
Mortgage loans payable
Senior notes payable
Secured financings
Notes payable
Significant Unobservable Inputs (Level 3) [Member]
Carrying value and estimated fair value of financial instruments not recorded at fair value on recurring basis
Loan receivable	143,247	222,246
Mortgage loans payable	269,423	270,923
Senior notes payable
Secured financings	43,098	53,253
Notes payable	1,660	1,676
Fair Value [Member]
Carrying value and estimated fair value of financial instruments not recorded at fair value on recurring basis
Loan receivable	143,247	222,246
Mortgage loans payable	269,423	270,923
Senior notes payable	89,700	89,183
Secured financings	43,098	53,253
Notes payable	$ 1,660	$ 1,676