Accumulated Other Comprehensive Loss (Details) - USD ($)
$ in Millions
 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Dec. 31, 2014
Accumulated Other Comprehensive Income Loss [Line Items]        
Accumulated other comprehensive loss $ (2,541) $ (2,592) $ (2,702) $ (2,116)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax (157) (679)    
Other Comprehensive Income (Loss), Before Reclassifications, Tax (346) 92    
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax 664 111    
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent 161 (476)    
Translation Adjustments Other Than Translation Of Balance Sheet Tax Benefit Expense (53) 23    
Pension and other postretirement benefit adjustments, tax cost (252) 50    
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax (1) 2    
Accumulated Translation Adjustment [Member]        
Accumulated Other Comprehensive Income Loss [Line Items]        
Accumulated other comprehensive loss (1,562) (1,219) (1,332) (628)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax (157) (679)    
Other Comprehensive Income (Loss), Before Reclassifications, Tax (73) 88    
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax 0 0    
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent (230) (591)    
Accumulated Defined Benefit Plans Adjustment [Member]        
Accumulated Other Comprehensive Income Loss [Line Items]        
Accumulated other comprehensive loss (988) (1,383) (1,379) (1,492)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax 0 0    
Other Comprehensive Income (Loss), Before Reclassifications, Tax (267) 40    
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax 658 69    
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent 391 109    
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]        
Accumulated Other Comprehensive Income Loss [Line Items]        
Accumulated other comprehensive loss 9 10 $ 9 $ 4
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax 0 0    
Other Comprehensive Income (Loss), Before Reclassifications, Tax (6) (36)    
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax 6 42    
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent $ 0 $ 6