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Property, Plant and Equipment - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Property Plant And Equipment [Abstract]      
Net Cost of Assets under capital leases $ 1 $ 3  
Depreciation charge 838 930 1,068
Capital investment funding 3 1 11
Reduction in depreciation charges due to public funding 6 10 12
Cash proceeds from sale of equipment $ 12 $ 16 $ 26