| **Transactions with Related Parties (Tables)** | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
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| **Related Party Transactions [Abstract]**      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| Transactions with Related Parties              | We have variable amount lending agreements and other notes receivable with Caterpillar.  Under these agreements, we may borrow up to $2.28 billion from Caterpillar, and Caterpillar may borrow up to $1.29 billion from us.  The agreements are in effect for indefinite periods of time and may be changed or terminated by either party with 30 days notice.  We extended a $2 billion committed credit facility to Caterpillar, which expires in February 2019.  Under this agreement, we receive a fee from Caterpillar based on amounts drawn under the credit facility and a commitment fee for the undrawn amounts under the credit facility.  Information concerning these agreements was as follows: (Millions of dollars)        2015 2014 2013Notes payable as of December 31, $1,096 $1,108 $1,118Notes receivable as of December 31, $490 $414 $345Interest expense $6 $7 $7Interest income on Notes Receivable with Caterpillar(1) $21 $18 $19Fees on committed credit facility extended to Caterpillar(1) $40 $41 $41       (1) Included in Other revenues, net in the Consolidated Statements of Profit. We have agreements with Caterpillar to purchase certain trade receivables at a discount.  Information pertaining to these purchases was as follows: (Millions of dollars)        2015 2014 2013Purchases made $33,154 $36,816 $33,018Discounts earned $222 $243 $233Balance as of December 31, $2,601 $3,238 $3,092        |

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| - Definition
Tabular disclosure of related party transactions. Examples of related party transactions include, but are not limited to, transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners and (d) affiliates.
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