Postemployment benefit plans (Details 7) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
U.S. pensions
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	$ 12,697	$ 13,416
Fair value of plan assets, end of year	$ 15,994	12,697
U.S. pensions \| Debt securities
Information about plan asset allocations
Target allocation of plan assets (as a percent)	70.00%
U.S. pensions \| Equities
Information about plan asset allocations
Target allocation of plan assets (as a percent)	30.00%
U.S. pensions \| Real estate
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	$ 10
Fair value of plan assets, end of year	10	10
Non-U.S. pensions
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	4,025	4,305
Fair value of plan assets, end of year	$ 4,525	4,025
Non-U.S. pensions \| Debt securities
Information about plan asset allocations
Target allocation of plan assets (as a percent)	79.00%
Non-U.S. pensions \| Equities
Information about plan asset allocations
Target allocation of plan assets (as a percent)	12.00%
Non-U.S. pensions \| Real estate
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	$ 185
Fair value of plan assets, end of year	$ 211	185
Information about plan asset allocations
Target allocation of plan assets (as a percent)	5.00%
Non-U.S. pensions \| Other plan assets
Information about plan asset allocations
Target allocation of plan assets (as a percent)	4.00%
Other postretirement benefits
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	$ 328	504
Fair value of plan assets, end of year	$ 255	328
Other postretirement benefits \| Debt securities
Information about plan asset allocations
Target allocation of plan assets (as a percent)	30.00%
Other postretirement benefits \| Equities
Information about plan asset allocations
Target allocation of plan assets (as a percent)	70.00%
Level 3 \| U.S. pensions
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	$ 107
Fair value of plan assets, end of year	90	107
Level 3 \| U.S. pensions \| Equities
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	36	20
Unrealized gains (losses)	(9)	(6)
Realized gains (losses)	7	0
Purchases, issuances and settlements	(10)	21
Transfers in and/or out of Level 3	(1)	1
Fair value of plan assets, end of year	23	36
Level 3 \| U.S. pensions \| Fixed income securities
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	61	60
Unrealized gains (losses)	0	(12)
Realized gains (losses)	0	0
Purchases, issuances and settlements	(4)	11
Transfers in and/or out of Level 3	0	2
Fair value of plan assets, end of year	57	61
Level 3 \| U.S. pensions \| Real estate
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	10	10
Unrealized gains (losses)	0	0
Realized gains (losses)	0	0
Purchases, issuances and settlements	0	0
Transfers in and/or out of Level 3	0	0
Fair value of plan assets, end of year	10	10
Level 3 \| Non-U.S. pensions
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	0
Fair value of plan assets, end of year	0	0
Level 3 \| Non-U.S. pensions \| Real estate
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	0
Fair value of plan assets, end of year	0	0
Level 3 \| Other postretirement benefits
Change in Fair Value of Plan Assets
Fair value of plan assets, beginning of year	0
Fair value of plan assets, end of year	$ 0	$ 0

This element represents the realized gains (losses) on level 3 plan assets of defined benefit plans for the period.

No definition available.

Name:	cat_DefinedBenefitPlanRealizedGainsLosses
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the unrealized gains (losses) on level 3 plan assets of defined benefit plans for the period.

+ References

No definition available.

+ Details

Name:	cat_DefinedBenefitPlanUnrealizedGainsLosses
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(01)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(01)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(ii)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(ii)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, measured using unobservable input, of increase (decrease) in plan asset of defined benefit plan from purchase, sale and settlement of trade associated with underlying investment.

+ References

+ Details

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

- Definition

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan, for assets transferred into (out of) Level 3 of fair value hierarchy. Includes, but is not limited to, transfer due to change in observability of significant inputs.

+ References

+ Details

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

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_RetirementPlanTypeAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_RealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_ForeignPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=cat_PlanAssetOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_FixedIncomeSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: