|**Other Assets**                                    | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                              
|--------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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|**Other Assets [Abstract]**                         |                                                                                                                                                                                                                                                                                                                                                                                              
|Other Assets                                        | OTHER ASSETSThe components of other assets as of December 31, were as follows:(Millions of dollars)20172016Customer and other miscellaneous receivables$457$417Collateral held for resale, at net realizable value432654Other(1)136180Total other assets$1,025$1,251(1)Includes$31 millionand$21 millionof other receivables from Caterpillar as of December 31, 2017 and 2016, respectively.
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|(Millions of dollars)                               |                                                                                                                                                                                                                                                                                                                                                                                              
|                                                    |                                                                                                                                                                                                                                                                                                                                                                                              
|Customer and other miscellaneous receivables        |                                                                                                                                                                                                                                                                                                                                                                                              
|Collateral held for resale, at net realizable value |                                                                                                                                                                                                                                                                                                                                                                                              
|Other(1)                                            |                                                                                                                                                                                                                                                                                                                                                                                              
|Total other assets                                  |                                                                                                                                                                                                                                                                                                                                                                                              
|                                                    |                                                                                                                                                                                                                                                                                                                                                                                              

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