Impairments (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
item
Impairments    
Provisions for impairment $ 2.1 $ 1.7
Number of impaired properties sold   4
Restaurants - casual dining industry    
Impairments    
Number of impaired properties sold 1 2
Number of impaired properties held-for-sale 1  
Number of impaired properties from disposal of building 1  
Consumer electronics    
Impairments    
Number of impaired properties sold   1
Home furnishings    
Impairments    
Number of impaired properties sold   1