Cat Financial Financing Activities (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Impaired loans and finance leases
Period after which collection of future income is considered as not probable (in days)	120 days
Finance Receivables
Impaired loans and finance leases
Period after which collection of future income is considered as not probable (in days)	120 days
Finance Receivables \| Customer
Impaired loans and finance leases
Recorded Investment With No Allowance Recorded	$ 251	$ 446	$ 378
Unpaid Principal Balance With No Allowance Recorded	249	443	377
Related Allowance With No Allowance Recorded	0	0	0
Recorded Investment With An Allowance Recorded	362	182	215
Unpaid Principal Balance With An Allowance Recorded	360	177	207
Related Allowance	75	70	54
Recorded Investment, Total	613	628	593
Unpaid Principal Balance, Total	609	620	584
Related Allowance, Total	75	70	54
Average Recorded Investment With No Allowance Recorded	333	421	332
Interest Income Recognized With No Allowance Recorded	11	12	6
Average Recorded Investment With An Allowance Recorded	274	238	188
Interest Income Recognized With An Allowance Recorded	12	6	5
Average Recorded Investment, Total	607	659	520
Interest Income Recognized, Total	23	18	11
Finance Receivables \| Customer \| North America
Impaired loans and finance leases
Recorded Investment With No Allowance Recorded	14	23	28
Unpaid Principal Balance With No Allowance Recorded	14	22	27
Related Allowance With No Allowance Recorded	0	0	0
Recorded Investment With An Allowance Recorded	6	13	25
Unpaid Principal Balance With An Allowance Recorded	6	13	23
Related Allowance	1	4	7
Recorded Investment, Total	20	36	53
Unpaid Principal Balance, Total	20	35	50
Related Allowance, Total	1	4	7
Average Recorded Investment With No Allowance Recorded	20	25	50
Interest Income Recognized With No Allowance Recorded	1	3	3
Average Recorded Investment With An Allowance Recorded	9	18	25
Interest Income Recognized With An Allowance Recorded	0	1	1
Average Recorded Investment, Total	29	43	75
Interest Income Recognized, Total	1	4	4
Finance Receivables \| Customer \| Europe
Impaired loans and finance leases
Recorded Investment With No Allowance Recorded	44	48	45
Unpaid Principal Balance With No Allowance Recorded	43	47	45
Related Allowance With No Allowance Recorded	0	0	0
Recorded Investment With An Allowance Recorded	12	20	28
Unpaid Principal Balance With An Allowance Recorded	12	19	26
Related Allowance	4	7	11
Recorded Investment, Total	56	68	73
Unpaid Principal Balance, Total	55	66	71
Related Allowance, Total	4	7	11
Average Recorded Investment With No Allowance Recorded	47	49	45
Interest Income Recognized With No Allowance Recorded	1	1	1
Average Recorded Investment With An Allowance Recorded	21	22	27
Interest Income Recognized With An Allowance Recorded	1	1	1
Average Recorded Investment, Total	68	71	72
Interest Income Recognized, Total	2	2	2
Finance Receivables \| Customer \| Asia Pacific
Impaired loans and finance leases
Recorded Investment With No Allowance Recorded	1	7	2
Unpaid Principal Balance With No Allowance Recorded	1	7	2
Related Allowance With No Allowance Recorded	0	0	0
Recorded Investment With An Allowance Recorded	29	16	19
Unpaid Principal Balance With An Allowance Recorded	29	16	19
Related Allowance	8	2	4
Recorded Investment, Total	30	23	21
Unpaid Principal Balance, Total	30	23	21
Related Allowance, Total	8	2	4
Average Recorded Investment With No Allowance Recorded	3	4	3
Interest Income Recognized With No Allowance Recorded	0	0	0
Average Recorded Investment With An Allowance Recorded	22	18	15
Interest Income Recognized With An Allowance Recorded	1	1	1
Average Recorded Investment, Total	25	22	18
Interest Income Recognized, Total	1	1	1
Finance Receivables \| Customer \| Mining
Impaired loans and finance leases
Recorded Investment With No Allowance Recorded	29	134	1
Unpaid Principal Balance With No Allowance Recorded	29	134	1
Related Allowance With No Allowance Recorded	0	0	0
Recorded Investment With An Allowance Recorded	138	0	0
Unpaid Principal Balance With An Allowance Recorded	137	0	0
Related Allowance	9	0	0
Recorded Investment, Total	167	134	1
Unpaid Principal Balance, Total	166	134	1
Related Allowance, Total	9	0	0
Average Recorded Investment With No Allowance Recorded	69	61	8
Interest Income Recognized With No Allowance Recorded	3	3	0
Average Recorded Investment With An Allowance Recorded	90	1	0
Interest Income Recognized With An Allowance Recorded	7	0	0
Average Recorded Investment, Total	159	62	8
Interest Income Recognized, Total	10	3	0
Finance Receivables \| Customer \| Latin America
Impaired loans and finance leases
Recorded Investment With No Allowance Recorded	34	11	7
Unpaid Principal Balance With No Allowance Recorded	34	11	7
Related Allowance With No Allowance Recorded	0	0	0
Recorded Investment With An Allowance Recorded	42	23	30
Unpaid Principal Balance With An Allowance Recorded	42	23	30
Related Allowance	12	6	8
Recorded Investment, Total	76	34	37
Unpaid Principal Balance, Total	76	34	37
Related Allowance, Total	12	6	8
Average Recorded Investment With No Allowance Recorded	30	11	6
Interest Income Recognized With No Allowance Recorded	0	0	0
Average Recorded Investment With An Allowance Recorded	36	44	27
Interest Income Recognized With An Allowance Recorded	1	2	2
Average Recorded Investment, Total	66	55	33
Interest Income Recognized, Total	1	2	2
Finance Receivables \| Customer \| Caterpillar Power Finance
Impaired loans and finance leases
Recorded Investment With No Allowance Recorded	129	223	295
Unpaid Principal Balance With No Allowance Recorded	128	222	295
Related Allowance With No Allowance Recorded	0	0	0
Recorded Investment With An Allowance Recorded	135	110	113
Unpaid Principal Balance With An Allowance Recorded	134	106	109
Related Allowance	41	51	24
Recorded Investment, Total	264	333	408
Unpaid Principal Balance, Total	262	328	404
Related Allowance, Total	41	51	24
Average Recorded Investment With No Allowance Recorded	164	271	220
Interest Income Recognized With No Allowance Recorded	6	5	2
Average Recorded Investment With An Allowance Recorded	96	135	94
Interest Income Recognized With An Allowance Recorded	2	1	0
Average Recorded Investment, Total	260	406	314
Interest Income Recognized, Total	8	6	2
Finance Receivables \| Dealer
Impaired loans and finance leases
Recorded Investment, Total	0	0	0
Average Recorded Investment, Total	$ 0	$ 0	$ 0

Amount of allowance for credit losses related to recorded investment

No definition available.

Name:	cat_ImpairedFinancingReceivableNoRelatedAllowance
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the period after which collection of future income is considered as not probable.

+ References

No definition available.

+ Details

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

- Details

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

- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5258-111524

+ Details

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

- Definition

Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

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

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524

+ Details

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

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of average investment of impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of interest income, recognized on cash basis, on financing receivables, for which there is no related allowance for credit losses and are recognized as impaired.

+ References

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of interest income on financing receivables, for which there is a related allowance for credit losses, recognized on a cash-basis method of accounting that the financing receivables were impaired.

+ References

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
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: