Fair Value Measurements - Summary of Fair Value Information for Financial Instruments (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Carrying Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans receivable, net $ 109,425 $ 117,721
Revolving credit facilities 15,181 35,120
Convertible Notes, net (1) 695,957 0
Mortgages and notes payable 3,658,496 3,743,098
Estimated Fair Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans receivable, net 115,747 131,587
Revolving credit facilities 15,254 34,911
Convertible Notes, net (1) 729,231 0
Mortgages and notes payable $ 3,899,950 $ 3,892,621