This element represents the percentage of total goodwill as of the balance sheet date.

No definition available.

Name:	cmi_PercentageofGoodwillAccountedbyaSingleoraggregatedReportingUnit
Namespace Prefix:	cmi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Carrying amount of items included in each line item in the statement of financial position that are not eligible for the fair value option.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

+ Details

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

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

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

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

- Definition

Percentage of fair value of reporting unit in excess of carrying amount.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_ReportingUnitAxis=cmi_EatonAutomatedTransmissionTechnologiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ReportingUnitAxis=cmi_AggregatedEmissionSolutionandFiltrationReportingUnitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ReportingUnitAxis=cmi_NewPowerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ReportingUnitAxis=cmi_DistributionMember
Namespace Prefix:
Data Type:	na
Balance Type:
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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 4) Goodwill - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill
Goodwill	$ 1,286	$ 1,126	$ 1,082
Automated Transmission
Goodwill
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	34.00%
Goodwill	$ 544
Reporting Unit Carrying Value	$ 1,200
Percentage of Goodwill Accounted by a Single or aggregated Reporting Unit	42.00%
Aggregated Emission Solution and Filtration Reporting Unit
Goodwill
Percentage of Goodwill Accounted by a Single or aggregated Reporting Unit	30.00%
New Power
Goodwill
Percentage of Goodwill Accounted by a Single or aggregated Reporting Unit	20.00%
Distribution
Goodwill
Percentage of Goodwill Accounted by a Single or aggregated Reporting Unit	6.00%