Cat Financial Financing Activities (Details 2) - Finance Receivables - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Contractual maturities of outstanding finance receivables
2019	$ 8,750
2020	5,768
2021	3,633
2022	2,203
2023	999
Thereafter	739
Total Amounts Due	22,092
Guaranteed residual value	392
Unguaranteed residual value	822
Less: Unearned Income	(880)
Total	22,426	$ 22,632
Retail loans
Contractual maturities of outstanding finance receivables
2019	5,769
2020	3,742
2021	2,560
2022	1,750
2023	833
Thereafter	683
Total Amounts Due	15,337
Guaranteed residual value	0
Unguaranteed residual value	0
Less: Unearned Income	(252)
Total	15,085
Retail leases
Contractual maturities of outstanding finance receivables
2019	2,981
2020	2,026
2021	1,073
2022	453
2023	166
Thereafter	56
Total Amounts Due	6,755
Guaranteed residual value	392
Unguaranteed residual value	822
Less: Unearned Income	(628)
Total	$ 7,341

No definition available.

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

- Definition

This element represents the aggregate amount of finance receivables due as of the latest balance sheet presented in the financial statements.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesAggregateAmountsReceivable
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of finance receivables due after year five following the date of the latest balance sheet presented in the financial statements.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesDueAfterYearFive
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of finance receivables due within the next twelve months following the date of the latest balance sheet presented in the financial statements.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesDueInNextTwelveMonths
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of finance receivables due in year five following the date of the latest balance sheet presented in the financial statements.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesDueInYearFive
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of finance receivables due in year four following the date of the latest balance sheet presented in the financial statements.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesDueInYearFour
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of finance receivables due in year three following the date of the latest balance sheet presented in the financial statements.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesDueInYearThree
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of finance receivables due in year two following the date of the latest balance sheet presented in the financial statements.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesDueInYearTwo
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the guaranteed residual value of finance receivables.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesGuaranteedResidualValue
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the unguaranteed residual value of finance receivables.

+ References

No definition available.

+ Details

Name:	cat_FinanceReceivablesUnguaranteedResidualValue
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=84165051&loc=d3e45377-112738

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159169&loc=d3e10152-111534

+ Details

Name:	us-gaap_LoansAndLeasesReceivableDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

+ Details

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

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=cat_FinanceReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cat_FinanceReceivablesAxis=cat_RetailloansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cat_FinanceReceivablesAxis=cat_RetailLeasesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: