| **Long-Term Debt (Tables)**                       | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
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| **Long-term Debt, Unclassified [Abstract]**       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Long-term debt                                    | Long-term debt outstanding as of December 31, was comprised of the following: (Millions of dollars)      2015 2014  Balance Avg. Rate Balance Avg. RateMedium-term notes $20,611 2.4% $23,094 2.4%Unamortized discount (1)   (4)  Medium-term notes, net 20,610   23,090  Bank borrowings 995 4.0% 1,484 3.4%Total $21,605   $24,574            |
| Aggregate amounts of maturities of long-term debt |  Long-term debt outstanding as of December 31, 2015, matures as follows: (Millions of dollars) 2016$5,36220175,86620184,15420192,53120201,125Thereafter2,567Total$21,605                                                                                                                                                                                                                                                                                                                                                                                          |

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No definition available.
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| - Definition
Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.
+ References
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| - Definition
Tabular disclosure of the combined aggregate amount of maturities and sinking fund requirements for all long-term borrowings for each of the five years following the date of the latest balance sheet date presented.
+ References
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