Investments - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2014
State
Property
Dec. 31, 2013
Property
Investment [Line Items]    
Real estate properties and loans, gross $ 7,383,475,000 [1] $ 7,235,732,000 [1]
Real estate assets held for sale 2,287 2,186
Properties dispersed geographically 48  
Number of states exceeding disclosure threshold 1  
Minimum percentage of investment in real estate properties 10.00%  
Number of owned real estate properties 2,142 2,041
Securing mortgage properties 145 145
Securing mortgage properties carrying amount 115,400,000 117,300,000
Other Loan Receivable with aggregate carrying value $ 400,000 $ 400,000
Properties vacant
   
Investment [Line Items]    
Number of properties 24 21
Property Held For Sale
   
Investment [Line Items]    
Number of properties 5 6
Texas
   
Investment [Line Items]    
Percentage of investment in real estate properties 13.10%  
[1] The dollar amount of investments includes the gross investment in land, buildings and lease intangibles, as adjusted for any impairment, related to properties owned and the carrying amount of loans receivable and real estate assets held under direct financing leases.