Current report filing

Financial Information by Geographic Area (Detail)

v2.4.0.8
Financial Information by Geographic Area (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [Line Items]                  
Total operating revenue $ 533.8 $ 520.0 $ 513.3 $ 490.8 $ 472.3 $ 471.5 $ 2,073.0 $ 1,893.2 $ 1,797.5
Percentage of operating revenues             100.00% 100.00% 100.00%
Long-lived assets 3,981.4     3,060.5     3,981.4 3,060.5  
Percentage of consolidated long-lived assets             100.00%    
UNITED STATES
                 
Revenues from External Customers and Long-Lived Assets [Line Items]                  
Total operating revenue             1,561.9 1,374.3 1,290.2
Percentage of operating revenues             76.00% 72.00% 72.00%
Long-lived assets 3,453.6     2,542.4     3,453.6 2,542.4  
Percentage of consolidated long-lived assets             87.00% 83.00%  
Canada
                 
Revenues from External Customers and Long-Lived Assets [Line Items]                  
Total operating revenue             153.9 151.3 138.4
Percentage of operating revenues             7.00% 8.00% 8.00%
Long-lived assets 63.9     70.7     63.9 70.7  
Percentage of consolidated long-lived assets             1.00% 2.00%  
UNITED KINGDOM
                 
Revenues from External Customers and Long-Lived Assets [Line Items]                  
Total operating revenue             133.5 124.1 104.7
Percentage of operating revenues             6.00% 7.00% 6.00%
Long-lived assets       121.5       121.5  
Percentage of consolidated long-lived assets             3.00% 4.00%  
BRAZIL
                 
Revenues from External Customers and Long-Lived Assets [Line Items]                  
Total operating revenue             0 35.4 84.1
Percentage of operating revenues             0.00% 2.00% 4.00%
Long-lived assets 70.8     77.2     70.8 77.2  
Percentage of consolidated long-lived assets             2.00% 3.00%  
Other Countries
                 
Revenues from External Customers and Long-Lived Assets [Line Items]                  
Total operating revenue             223.7 208.1 180.1
Percentage of operating revenues             11.00% 11.00% 10.00%
Long-lived assets $ 270.8     $ 248.7     $ 270.8 $ 248.7  
Percentage of consolidated long-lived assets             7.00% 8.00%