Cat Financial Financing Activities (Details) - Finance Receivables - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Allowance for Credit Loss Activity
Balance at beginning of year	$ 507	$ 362
Receivables written off	(38)	(235)
Recoveries on receivables previously written off	8	46
Provision for credit losses	52	349
Other		(15)
Balance at end of period	529	507
Allowance for Credit Losses
Individually evaluated for impairment			$ 329	$ 302
Collectively evaluated for impairment			200	205
Ending Balance	507	362	529	507
Recorded Investment in Finance Receivables
Individually evaluated for impairment			891	936
Collectively evaluated for impairment			21,228	21,490
Ending balance-recorded investment in finance receivables			22,119	22,426
Customer
Allowance for Credit Loss Activity
Balance at beginning of year	486	353
Receivables written off	(38)	(235)
Recoveries on receivables previously written off	8	46
Provision for credit losses	39	337
Other		(15)
Balance at end of period	495	486
Allowance for Credit Losses
Individually evaluated for impairment			302	288
Collectively evaluated for impairment			193	198
Ending Balance	486	353	495	486
Recorded Investment in Finance Receivables
Individually evaluated for impairment			813	858
Collectively evaluated for impairment			17,881	18,152
Ending balance-recorded investment in finance receivables			18,694	19,010
Dealer
Allowance for Credit Loss Activity
Balance at beginning of year	21	9
Receivables written off	0	0
Recoveries on receivables previously written off	0	0
Provision for credit losses	13	12
Other		0
Balance at end of period	34	21
Allowance for Credit Losses
Individually evaluated for impairment			27	14
Collectively evaluated for impairment			7	7
Ending Balance	$ 21	$ 9	34	21
Recorded Investment in Finance Receivables
Individually evaluated for impairment			78	78
Collectively evaluated for impairment			3,347	3,338
Ending balance-recorded investment in finance receivables			$ 3,425	$ 3,416

No definition available.

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Balance Type:	na
Period Type:	duration

- Definition

This element represents the other activity, net, in the allowance for credit loss during the period not otherwise defined in the taxonomy.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
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- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

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Balance Type:	credit
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- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

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

- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

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Data Type:	xbrli:monetaryItemType
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- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- 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

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-Publisher FASB
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-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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

- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

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-Publisher FASB
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-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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Balance Type:	debit
Period Type:	duration

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