| **Derivative Financial Instruments and Risk Management (Tables)**                                                       | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
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| **Derivative Instruments and Hedging Activities Disclosure [Abstract]**                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| Location and fair value of derivative instruments reported in the Consolidated Statements of Financial Position         | The location and fair value of derivative instruments reported in the Consolidated Statements of Financial Position were as follows:(Millions of dollars)        Asset (Liability) Fair Value Consolidated Statements ofFinancial Position Location June 30, 2013 December 31, 2012Designated derivatives     Interest rate contractsOther assets $153 $226Interest rate contractsAccrued expenses (6) (8)   $147 $218Undesignated derivatives     Foreign exchange contractsOther assets $10 $10Foreign exchange contractsAccrued expenses (3) (5)Cross currency contractsOther assets 6 —Cross currency contractsAccrued expenses — (1)Interest rate contractsOther assets 1 2Interest rate contractsAccrued expenses — (1)   $14 $5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Deferred gains (losses) recorded in AOCI on the Consolidated Statements of Changes in Stockholder's Equity              | For the six months ended June 30, 2013 and 2012, the deferred gains (losses) recorded in AOCI on the Consolidated Statements of Changes in Stockholder’s Equity associated with our cash flow interest rate contract hedges were as follows:(Millions of dollars) Balance as of December 31, 2012, net of tax of $4$(8)Gains (losses) deferred during the period, net of tax of $(1)2(Gains) losses reclassified to earnings, net of tax of $12Balance as of June 30, 2013, net of tax of $2$(4)  (Millions of dollars) Balance as of December 31, 2011, net of tax of $3$(6)Gains (losses) deferred during the period, net of tax of $1(1)(Gains) losses reclassified to earnings, net of tax of $11Balance as of June 30, 2012, net of tax of $3$(6)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Schedule of effect of derivatives designated as fair value hedging instruments in the Consolidated Statements of Profit | The effect of derivatives designated as hedging instruments on the Consolidated Statements of Profit was as follows:Fair Value Hedges(Millions of dollars)   Three Months EndedJune 30, 2013 Three Months EndedJune 30, 2012 Classification Gains(Losses)onDerivatives Gains(Losses)onBorrowings Gains(Losses)onDerivatives Gains (Losses)onBorrowingsInterest rate contractsOther income (expense) $(49) $50 $6 $(5)             Six Months EndedJune 30, 2013 Six Months EndedJune 30, 2012 Classification Gains(Losses)onDerivatives Gains(Losses)onBorrowings Gains(Losses)onDerivatives Gains (Losses)onBorrowingsInterest rate contractsOther income (expense) $(78) $80 $(3) $10                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Schedule of effect of derivatives designated as cash flow hedging instruments in the Consolidated Statements of Profit  | Cash Flow Hedges(Millions of dollars)   Three Months Ended June 30, 2013 Classification Reclassified from AOCIto Earnings(Effective Portion) Recognized in Earnings(Ineffective Portion)Interest rate contractsInterest expense $(2) $—Interest rate contractsOther income (expense) — —   $(2) $—         Three Months Ended June 30, 2012 Classification Reclassified from AOCIto Earnings(Effective Portion) Recognized in Earnings(Ineffective Portion)Interest rate contractsInterest expense $(1) $—Interest rate contractsOther income (expense) — (1)   $(1) $(1)         Six Months Ended June 30, 2013 Classification Reclassified from AOCIto Earnings(Effective Portion) Recognized in Earnings(Ineffective Portion)Interest rate contractsInterest expense $(3) $—Interest rate contractsOther income (expense) — —   $(3) $—         Six Months Ended June 30, 2012 Classification Reclassified from AOCIto Earnings(Effective Portion) Recognized in Earnings(Ineffective Portion)Interest rate contractsInterest expense $(2) $—Interest rate contractsOther income (expense) — (1)   $(2) $(1)       |
| Schedule of effect of derivatives not designated as hedging instruments on the Consolidated Statements of Profit        | The effect of derivatives not designated as hedging instruments on the Consolidated Statements of Profit was as follows:Undesignated Derivatives     (Millions of dollars)  Three Months Ended June 30, Classification 2013 2012Foreign exchange contractsOther income (expense) $5 $(5)Cross currency contractsOther income (expense) 11 —Interest rate contractsOther income (expense) — —   $16 $(5)         Six Months Ended June 30, Classification 2013 2012Foreign exchange contractsOther income (expense) $(6) $2Cross currency contractsOther income (expense) 7 —Interest rate contractsOther income (expense) — —   $1 $2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Schedule of offsetting of derivative assets and liabilities                                                             | The effect of the net settlement provisions of the master netting agreements on our derivative balances upon an event of default or a termination event is as follows: Offsetting of Derivative Assets and Liabilities    (Millions of dollars)      June 30, 2013 December 31, 2012Derivative Assets    Gross Amount of Recognized Assets $170 $238Gross Amounts Offset — —Net Amount of Assets(1) 170 238Gross Amounts Not Offset    Financial Instruments (8) (12)Cash Collateral Received — —Net Amount $162 $226     Derivative Liabilities    Gross Amount of Recognized Liabilities $(9) $(15)Gross Amounts Offset — —Net Amount of Liabilities(1) (9) (15)Gross Amounts Not Offset    Financial Instruments 8 12Cash Collateral Received — —Net Amount $(1) $(3)     (1) As presented in the Consolidated Statements of Financial Position.                                                                                                                                                                                                                                                                                                                                                                                |

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| - Definition
Tabular disclosure of derivative and other financial assets and liabilities that are subject to offsetting, including master netting arrangements.
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No definition available.
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| - Definition
Tabular disclosure of the effective portion of gains and losses on derivative instruments (and nonderivative instruments) designated and qualifying in cash flow hedges recorded in accumulated other comprehensive income (loss) during the term of the hedging relationship and reclassified into earnings during the current period.
+ References
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| - Definition
Tabular disclosure for cash flow hedging instruments of (a) the location and amount of gains and losses reported in the statement of financial performance and (b) the location and fair value amounts of the instruments reported in the statement of financial position.
+ References
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| - Definition
Tabular disclosure of the location and amount of gains and losses reported in the statement of financial performance, or when applicable, the statement of financial position. For example,  (a) gains and losses recognized in the income statement on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges and (b) gains and losses initially recognized in other comprehensive income on derivative instruments designated and qualifying as cash flow hedges.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 205G -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44C -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5618551-113959
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| - Definition
Tabular disclosure of the location and fair value amounts of derivative instruments (and nonderivative instruments that are designated and qualify as hedging instruments) reported in the statement of financial position.
+ References
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| - Definition
Tabular disclosure for other derivative instruments not designated as hedging instruments of (a) the location and amount of gains and losses reported in the statement of financial performance and (b) the location and fair value amounts of the instruments reported in the statement of financial position.
+ References
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