Segment Information (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) group_presidents segments dealers	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information
Number of group presidents \| group_presidents			5
Number of operating segments \| segments			6
Useful life to amortize goodwill for segment assets			20 years
Reportable Segments
Sales and revenues	$ 9,160	$ 10,962	$ 28,963	$ 35,981
Depreciation and amortization	761	758	2,255	2,272
Consolidated profit before taxes	383	783	1,487	3,686
Segment assets	76,402		76,402		$ 78,342
Capital expenditures	595	726	$ 2,200	2,197
All Other operating segments
Segment Reporting Information
Number of group presidents \| group_presidents			1
Number of smaller operating segments led by Group President \| group_presidents			2
Number of wholly-owned dealers involved in segment reallocation \| dealers			1
Reportable Segments
Sales and revenues	28	39	$ 107	166
Depreciation and amortization	53	51	158	151
Consolidated profit before taxes	(22)	(11)	(43)	(36)
Segment assets	1,368		1,368		1,405
Capital expenditures	35	33	102	86
Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	9,939	11,828	$ 31,282	38,638
Reportable Segments
Segment Reporting Information
Number of operating segments led by Group Presidents \| segments			3
Number of operating segments led by Group President responsible for corporate services \| segments			1
Reportable Segments
Number of reportable segments \| segments			4
Sales and revenues	9,214	11,021	$ 29,119	36,060
Depreciation and amortization	652	665	1,942	2,008
Consolidated profit before taxes	1,004	1,202	3,117	5,035
Segment assets	57,986		57,986		59,605
Capital expenditures	568	673	1,882	1,868
Intersegment Eliminations
Reportable Segments
Sales and revenues	725	807	2,163	2,578
Machinery, Energy & Transportation \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	9,190	11,076	29,031	36,306
Machinery, Energy & Transportation \| Reportable Segments
Reportable Segments
Sales and revenues	8,465	10,269	26,868	33,728
Depreciation and amortization	437	455	1,309	1,370
Consolidated profit before taxes	821	995	2,564	4,417
Segment assets	21,656		21,656		23,876
Capital expenditures	211	314	616	873
Machinery, Energy & Transportation \| Intersegment Eliminations
Reportable Segments
Sales and revenues	725	807	2,163	2,578
Construction Industries \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	3,581	4,092	12,070	13,958
Construction Industries \| Reportable Segments
Reportable Segments
Sales and revenues	3,554	4,075	12,023	13,892
Depreciation and amortization	117	139	346	419
Consolidated profit before taxes	326	354	1,316	1,687
Segment assets	5,521		5,521		6,176
Capital expenditures	46	62	114	156
Construction Industries \| Intersegment Eliminations
Reportable Segments
Sales and revenues	27	17	47	66
Resource Industries \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	1,446	1,930	4,480	6,111
Resource Industries \| Reportable Segments
Reportable Segments
Sales and revenues	1,377	1,842	4,283	5,861
Depreciation and amortization	150	144	458	441
Consolidated profit before taxes	(77)	(42)	(336)	81
Segment assets	8,017		8,017		8,931
Capital expenditures	68	73	162	152
Resource Industries \| Intersegment Eliminations
Reportable Segments
Sales and revenues	69	88	197	250
Energy & Transportation \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	4,163	5,054	12,481	16,237
Energy & Transportation \| Reportable Segments
Reportable Segments
Sales and revenues	3,534	4,352	10,562	13,975
Depreciation and amortization	170	172	505	510
Consolidated profit before taxes	572	683	1,584	2,649
Segment assets	8,118		8,118		8,769
Capital expenditures	97	179	340	565
Energy & Transportation \| Intersegment Eliminations
Reportable Segments
Sales and revenues	629	702	1,919	2,262
Financial Products Segment \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	749	752	2,251	2,332
Financial Products Segment \| Reportable Segments
Reportable Segments
Sales and revenues	749	752	2,251	2,332
Depreciation and amortization	215	210	633	638
Consolidated profit before taxes	183	207	553	618
Segment assets	36,330		36,330		$ 35,729
Capital expenditures	357	359	1,266	995
Financial Products Segment \| Intersegment Eliminations
Reportable Segments
Sales and revenues	$ 0	$ 0	$ 0	$ 0

The number of group presidents that comprise the reporting entity's executive office.

No definition available.

Name:	cat_NumberOfGroupPresidents
Namespace Prefix:	cat_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of operating segments that are led by the group president who is responsible for corporate services.

+ References

No definition available.

+ Details

Name:	cat_NumberOfOperatingSegmentsLedByGroupPresidentResponsibleForCorporateServices
Namespace Prefix:	cat_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of operating segments which are led by group presidents.

+ References

No definition available.

+ Details

Name:	cat_NumberOfOperatingSegmentsLedByGroupPresidents
Namespace Prefix:	cat_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of smaller operating segments that are led by the group president.

+ References

No definition available.

+ Details

Name:	cat_NumberOfSmallerOperatingSegmentsLedByGroupPresident
Namespace Prefix:	cat_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of wholly-owned dealers moved from one operating segment to different operating segment.

+ References

No definition available.

+ Details

Name:	cat_Numberofwhollyowneddealers
Namespace Prefix:	cat_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	cat_ScheduleOfSegmentReportingInformationBySegmentAbstract
Namespace Prefix:	cat_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of total capital expenditures attributable to the reportable segments.

+ References

No definition available.

+ Details

Name:	cat_SegmentReportingInformationExpenditureForAdditionsLongLivedAssets
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the useful life used to amortize goodwill to allocate to segments assets.

+ References

No definition available.

+ Details

Name:	cat_UsefulLifeToAmortizeGoodwillToSegmentAssets
Namespace Prefix:	cat_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_Assets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

+ Details

Name:	us-gaap_DepreciationDepletionAndAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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

- Details

Name:	us-gaap_SubsegmentsConsolidationItemsAxis=cat_NonreportableSubsegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsegmentsConsolidationItemsAxis=cat_ReportableSubsegmentsIncludingIntersegmentEliminationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsegmentsConsolidationItemsAxis=us-gaap_ReportableSubsegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsegmentsConsolidationItemsAxis=us-gaap_IntersubsegmentEliminationsMember
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_StatementBusinessSegmentsAxis=cat_ConstructionIndustriesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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