Derivative Financial Instruments and Risk Management (Details 4) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Designated Derivatives \| Fair Value Hedges
Derivative Instruments, Gain (Loss)
Gains (Losses) on Derivatives	$ (1)	$ 3
Gains (Losses) on Borrowings	1	(4)
Designated Derivatives \| Fair Value Hedges \| Interest rate contracts \| Financial Products \| Other Income (Expense)
Derivative Instruments, Gain (Loss)
Gains (Losses) on Derivatives	(1)	3
Gains (Losses) on Borrowings	1	(4)
Designated Derivatives \| Cash Flow Hedges
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	15	15
Amount of Gains (Losses) Reclassified from AOCI to Earnings	(62)	(14)
Recognized in Earnings (Ineffective Portion)	0	0
Designated Derivatives \| Cash Flow Hedges \| Foreign exchange contracts \| Machinery, Energy & Transportation
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	33	16
Designated Derivatives \| Cash Flow Hedges \| Foreign exchange contracts \| Machinery, Energy & Transportation \| Other Income (Expense)
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Reclassified from AOCI to Earnings	(39)	(10)
Recognized in Earnings (Ineffective Portion)	0	0
Designated Derivatives \| Cash Flow Hedges \| Foreign exchange contracts \| Financial Products
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	(18)
Designated Derivatives \| Cash Flow Hedges \| Foreign exchange contracts \| Financial Products \| Other Income (Expense)
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Reclassified from AOCI to Earnings	(22)
Recognized in Earnings (Ineffective Portion)	0
Designated Derivatives \| Cash Flow Hedges \| Interest rate contracts \| Machinery, Energy & Transportation
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	0	0
Designated Derivatives \| Cash Flow Hedges \| Interest rate contracts \| Machinery, Energy & Transportation \| Interest Expense
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Reclassified from AOCI to Earnings	(2)	(2)
Recognized in Earnings (Ineffective Portion)	0	0
Designated Derivatives \| Cash Flow Hedges \| Interest rate contracts \| Financial Products
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	0	(1)
Designated Derivatives \| Cash Flow Hedges \| Interest rate contracts \| Financial Products \| Interest Expense
Derivative Instruments, Gain (Loss)
Amount of Gains (Losses) Reclassified from AOCI to Earnings	1	(2)
Recognized in Earnings (Ineffective Portion)	0	0
Undesignated Derivatives
Derivative Instruments, Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	7	18
Undesignated Derivatives \| Foreign exchange contracts \| Machinery, Energy & Transportation \| Other Income (Expense)
Derivative Instruments, Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	13	22
Undesignated Derivatives \| Foreign exchange contracts \| Financial Products \| Other Income (Expense)
Derivative Instruments, Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	(7)	(4)
Undesignated Derivatives \| Commodity contracts \| Machinery, Energy & Transportation \| Other Income (Expense)
Derivative Instruments, Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	$ 1	$ 0

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

+ Details

Name:	us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

+ References

+ Details

Name:	us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: 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=64837297&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624177-113959

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1),(2)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_FairValueHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=cat_FinancialProductsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=cat_OtherIncomeExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=cat_MachineryEnergyTransportationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_InterestExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: