v3.8.0.1
Income Taxes (Narrative) (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Sep. 30, 2015
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Tax Disclosure [Abstract]        
Tax rate   35.00%    
Total income tax expense (benefit)   $ 2,880    
Tax benefit from the reduction in net deferred tax liabilities   1,592    
Tax benefit from the adoption of a modified territorial international tax system   1,785    
Tax expense related to the one-time toll tax   497    
Tax expense related to remeasuring Korea’s deferred tax assets and liabilities   26    
AFE change in tax law, tax benefit       $ 108
Tax expense reversal resulting from AFE       108
DRD constituting non-taxable investment income   280 $ 266 296
Non-taxable investment income   $ 369 352 341
Percent of income tax expense (benefit)   5.00%    
Tax expense (benefit) $ (3)      
Income (loss) from domestic operations   $ 2,541 1,242 4,235
Income (loss) from foreign operations   $ 3,945 $ 4,463 $ 3,534