| **Fair Value Measurements (Tables)**                                                | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
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| **Fair Value Disclosures [Abstract]**                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Assets and liabilities measured at fair value                                       | Assets and liabilities measured on a recurring basis at fair value included in our Consolidated Statements of Financial Position as of March 31, 2013 and December 31, 2012 are summarized below:(Millions of dollars)        March 31, 2013 Level 1 Level 2 Level 3 Total Assets/Liabilities,at Fair ValueAssets       Derivative financial instruments, net$— $179 $— $179Total Assets$— $179 $— $179Liabilities       Guarantees$— $— $2 $2Total Liabilities$— $— $2 $2         December 31, 2012 Level 1 Level 2 Level 3 Total Assets/Liabilities,at Fair ValueAssets         Derivative financial instruments, net$— $223 $— $223Total Assets$— $223 $— $223Liabilities       Guarantees$— $— $2 $2Total Liabilities$— $— $2 $2                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Roll-forwards of assets and liabilities measured at fair value using Level 3 inputs | Below are roll-forwards of assets and liabilities measured at fair value using Level 3 inputs for the three months ended March 31, 2013 and 2012.  These instruments were valued using pricing models that, in management’s judgment, reflect the assumptions of a marketplace participant.(Millions of dollars)GuaranteesBalance as of December 31, 2012$2Issuance of guarantees1Expiration of guarantees(1)Balance as of March 31, 2013$2  (Millions of dollars)GuaranteesBalance as of December 31, 2011$2Issuance of guarantees—Expiration of guarantees—Balance as of March 31, 2012$2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| Fair values of financial instruments                                                | Please refer to the table below for the fair values of our financial instruments.(Millions of dollars)March 31, 2013 December 31, 2012     CarryingAmount FairValue CarryingAmount FairValue Fair ValueLevels ReferenceCash and cash equivalents$2,256 $2,256 $2,080 $2,080 1  Foreign currency contracts:           In a receivable position$9 $9 $10 $10 2 Note 5In a payable position$(16) $(16) $(5) $(5) 2 Note 5Cross currency contracts$(4) $(4) $(1) $(1) 2 Note 5Finance receivables, net (excluding finance leases(1))$20,343 $20,184 $20,189 $20,079 2 Note 4Restricted cash and cash equivalents(2)$39 $39 $19 $19 1  Short-term borrowings$(4,315) $(4,315) $(4,651) $(4,651) 1  Long-term debt$(25,725) $(26,675) $(25,077) $(26,063) 2  Interest rate swaps:           In a net receivable position$199 $199 $228 $228 2 Note 5In a net payable position$(9) $(9) $(9) $(9) 2 Note 5Guarantees$(2) $(2) $(2) $(2) 3 Note 7            (1)As of March 31, 2013 and December 31, 2012, represents finance leases with a net carrying value of $8,008 million and $7,968 million, respectively.(2) Included in Other assets in the Consolidated Statements of Financial Position. |

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| - Definition
Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.
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| - Definition
Tabular disclosure of the fair value measurement of liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and gains or losses recognized in other comprehensive income (loss) and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs) by class of liability.
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| - Definition
Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).
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