Cat Financial Financing Activities (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Period after which Unpaid Installments are Considered as Past Due (in days)	30 days
Period after which collection of future income is considered as not probable (in days)	120 days
Aging related to loans and finance leases
31-60 Days Past Due	$ 274	$ 175
61-90 Days Past Due	119	80
91+ Days Past Due	495	396
Total Past Due	888	651
Current	22,234	23,415
Total Finance Receivables	23,122	24,066
91+ Still Accruing	90	35
North America
Aging related to loans and finance leases
Total Finance Receivables	9,531	9,462
Europe
Aging related to loans and finance leases
Total Finance Receivables	2,554	2,828
Asia Pacific
Aging related to loans and finance leases
Total Finance Receivables	2,771	3,002
Mining
Aging related to loans and finance leases
Total Finance Receivables	1,989	2,123
Latin America
Aging related to loans and finance leases
Total Finance Receivables	3,117	3,503
Caterpillar Power Finance
Aging related to loans and finance leases
Total Finance Receivables	3,160	3,148
Customer
Aging related to loans and finance leases
Total Finance Receivables	19,584	20,512
Investment in loans and finance leases on non-accrual status	598	468
Customer \| North America
Aging related to loans and finance leases
31-60 Days Past Due	37	46
61-90 Days Past Due	14	8
91+ Days Past Due	35	27
Total Past Due	86	81
Current	7,170	7,192
Total Finance Receivables	7,256	7,273
91+ Still Accruing	9	4
Investment in loans and finance leases on non-accrual status	31	27
Customer \| Europe
Aging related to loans and finance leases
31-60 Days Past Due	26	16
61-90 Days Past Due	15	23
91+ Days Past Due	43	29
Total Past Due	84	68
Current	2,335	2,607
Total Finance Receivables	2,419	2,675
91+ Still Accruing	6	6
Investment in loans and finance leases on non-accrual status	43	28
Customer \| Asia Pacific
Aging related to loans and finance leases
31-60 Days Past Due	73	29
61-90 Days Past Due	32	22
91+ Days Past Due	64	69
Total Past Due	169	120
Current	2,073	2,316
Total Finance Receivables	2,242	2,436
91+ Still Accruing	24	16
Investment in loans and finance leases on non-accrual status	44	54
Customer \| Mining
Aging related to loans and finance leases
31-60 Days Past Due	20	28
61-90 Days Past Due	10	0
91+ Days Past Due	76	11
Total Past Due	106	39
Current	1,883	2,084
Total Finance Receivables	1,989	2,123
91+ Still Accruing	50	0
Investment in loans and finance leases on non-accrual status	124	62
Customer \| Latin America
Aging related to loans and finance leases
31-60 Days Past Due	100	55
61-90 Days Past Due	47	23
91+ Days Past Due	190	196
Total Past Due	337	274
Current	2,181	2,583
Total Finance Receivables	2,518	2,857
91+ Still Accruing	0	8
Investment in loans and finance leases on non-accrual status	213	201
Customer \| Caterpillar Power Finance
Aging related to loans and finance leases
31-60 Days Past Due	17	1
61-90 Days Past Due	1	4
91+ Days Past Due	87	64
Total Past Due	105	69
Current	3,055	3,079
Total Finance Receivables	3,160	3,148
91+ Still Accruing	1	1
Investment in loans and finance leases on non-accrual status	143	96
Dealer
Aging related to loans and finance leases
Total Finance Receivables	3,538	3,554
Investment in loans and finance leases on non-accrual status	0	0
Dealer \| North America
Aging related to loans and finance leases
31-60 Days Past Due	0	0
61-90 Days Past Due	0	0
91+ Days Past Due	0	0
Total Past Due	0	0
Current	2,275	2,189
Total Finance Receivables	2,275	2,189
91+ Still Accruing	0	0
Dealer \| Europe
Aging related to loans and finance leases
31-60 Days Past Due	0	0
61-90 Days Past Due	0	0
91+ Days Past Due	0	0
Total Past Due	0	0
Current	135	153
Total Finance Receivables	135	153
91+ Still Accruing	0	0
Dealer \| Asia Pacific
Aging related to loans and finance leases
31-60 Days Past Due	1	0
61-90 Days Past Due	0	0
91+ Days Past Due	0	0
Total Past Due	1	0
Current	528	566
Total Finance Receivables	529	566
91+ Still Accruing	0	0
Dealer \| Mining
Aging related to loans and finance leases
31-60 Days Past Due	0	0
61-90 Days Past Due	0	0
91+ Days Past Due	0	0
Total Past Due	0	0
Current	0	0
Total Finance Receivables	0	0
91+ Still Accruing	0	0
Dealer \| Latin America
Aging related to loans and finance leases
31-60 Days Past Due	0	0
61-90 Days Past Due	0	0
91+ Days Past Due	0	0
Total Past Due	0	0
Current	599	646
Total Finance Receivables	599	646
91+ Still Accruing	0	0
Dealer \| Caterpillar Power Finance
Aging related to loans and finance leases
Total Finance Receivables	$ 0	$ 0

Financing receivables that are less than 61 days past due but more than 30 days past due.

No definition available.

Name:	cat_FinancingReceivableRecordedInvestment31To60DaysPastDue
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are less than 91 days past due but more than 60 days past due.

+ References

No definition available.

+ Details

Name:	cat_FinancingReceivableRecordedInvestment61To90DaysPastDue
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment in financing receivables that are 91 days or more past due and still accruing.

+ References

No definition available.

+ Details

Name:	cat_FinancingReceivableRecordedInvestment91DaysPastDueAndStillAccruing
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are more than 91 days past due.

+ References

No definition available.

+ Details

Name:	cat_FinancingReceivableRecordedInvestmentGreaterThan91DaysPastDue
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

- Definition

This element represents the period after which the unpaid contractual payments are considered as past due.

+ References

No definition available.

+ Details

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

- Definition

Financing receivables that are current.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7A

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524

+ Details

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

- Definition

Recorded Investment in financing receivables that are past due at the balance sheet date.

+ References

+ Details

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

- Details

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

- Definition

Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524

+ Details

Name:	us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5074-111524

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

+ Details

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

- Details

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

- Details

Name:	cat_ImpairedFinancingReceivableAxis=cat_CaterpillarPowerFinanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cat_ImpairedFinancingReceivableAxis=cat_MiningMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cat_ImpairedFinancingReceivableAxis=us-gaap_AsiaPacificMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cat_ImpairedFinancingReceivableAxis=us-gaap_EMEAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cat_ImpairedFinancingReceivableAxis=us-gaap_LatinAmericaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cat_ImpairedFinancingReceivableAxis=us-gaap_NorthAmericaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cat_CustomerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cat_DealerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: