Fair Value Information for Financial Instruments (Detail) (USD $)
Jun. 30, 2014
Carrying Value
Dec. 31, 2013
Carrying Value
Jun. 30, 2014
Estimated Fair Value
Dec. 31, 2013
Estimated Fair Value
Jun. 30, 2014
Convertible Senior Notes
May 20, 2014
Convertible Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]            
Loans receivable, net $ 113,321,000 $ 117,721,000 $ 121,670,000 $ 131,587,000    
Revolving credit facilities, net 15,528,000 35,120,000 15,711,000 34,911,000    
Mortgages and notes payable, net 3,202,853,000 3,743,098,000 3,279,436,000 3,892,621,000    
Convertible senior notes, net (1) 691,711,000 [1] 0 [1] 747,066,000 [1] 0 [1]    
Value of the embedded conversion premium, included in net debt (discount)         $ 55,800,000 $ 56,700,000
[1] The carrying amount of the convertible senior notes is net of an embedded conversion premium totaling $55.8 million.