Cat Financial Financing Activities (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Dec. 31, 2012
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	$ 222	$ 188
61-90 Days Past Due	113	70
91+ Days Past Due	421	418
Total Past Due	756	676
Current	22,817	22,632
Total Finance Receivables	23,573	23,308
91+ Still Accruing	39	28
North America
Aging related to loans and finance leases
Total Finance Receivables	8,072	8,030
Europe
Aging related to loans and finance leases
Total Finance Receivables	2,679	2,740
Asia Pacific
Aging related to loans and finance leases
Total Finance Receivables	3,773	3,789
Mining
Aging related to loans and finance leases
Total Finance Receivables	2,120	1,974
Latin America
Aging related to loans and finance leases
Total Finance Receivables	3,716	3,603
Caterpillar Power Finance
Aging related to loans and finance leases
Total Finance Receivables	3,213	3,172
Customer
Aging related to loans and finance leases
Total Finance Receivables	19,694	19,424
Investment in loans and finance leases on non-accrual status	517	513
Customer \| North America
Aging related to loans and finance leases
31-60 Days Past Due	27	35
61-90 Days Past Due	7	8
91+ Days Past Due	43	52
Total Past Due	77	95
Current	5,906	5,872
Total Finance Receivables	5,983	5,967
91+ Still Accruing	1	0
Investment in loans and finance leases on non-accrual status	48	59
Customer \| Europe
Aging related to loans and finance leases
31-60 Days Past Due	33	23
61-90 Days Past Due	16	9
91+ Days Past Due	41	36
Total Past Due	90	68
Current	2,411	2,487
Total Finance Receivables	2,501	2,555
91+ Still Accruing	6	6
Investment in loans and finance leases on non-accrual status	41	38
Customer \| Asia Pacific
Aging related to loans and finance leases
31-60 Days Past Due	62	53
61-90 Days Past Due	33	19
91+ Days Past Due	81	54
Total Past Due	176	126
Current	2,845	2,912
Total Finance Receivables	3,021	3,038
91+ Still Accruing	30	18
Investment in loans and finance leases on non-accrual status	53	36
Customer \| Mining
Aging related to loans and finance leases
31-60 Days Past Due	5	0
61-90 Days Past Due	0	1
91+ Days Past Due	12	12
Total Past Due	17	13
Current	2,102	1,960
Total Finance Receivables	2,119	1,973
91+ Still Accruing	0	0
Investment in loans and finance leases on non-accrual status	12	12
Customer \| Latin America
Aging related to loans and finance leases
31-60 Days Past Due	87	62
61-90 Days Past Due	26	19
91+ Days Past Due	152	138
Total Past Due	265	219
Current	2,592	2,500
Total Finance Receivables	2,857	2,719
91+ Still Accruing	0	0
Investment in loans and finance leases on non-accrual status	167	148
Customer \| Caterpillar Power Finance
Aging related to loans and finance leases
31-60 Days Past Due	8	15
61-90 Days Past Due	31	14
91+ Days Past Due	92	126
Total Past Due	131	155
Current	3,082	3,017
Total Finance Receivables	3,213	3,172
91+ Still Accruing	2	4
Investment in loans and finance leases on non-accrual status	196	220
Dealer
Aging related to loans and finance leases
Total Finance Receivables	3,879	3,884
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
61-90 Days Past Due
91+ Days Past Due
Total Past Due	0	0
Current	2,089	2,063
Total Finance Receivables	2,089	2,063
91+ Still Accruing
Dealer \| Europe
Aging related to loans and finance leases
31-60 Days Past Due
61-90 Days Past Due
91+ Days Past Due
Total Past Due	0	0
Current	178	185
Total Finance Receivables	178	185
91+ Still Accruing
Dealer \| Asia Pacific
Aging related to loans and finance leases
31-60 Days Past Due
61-90 Days Past Due
91+ Days Past Due
Total Past Due	0	0
Current	752	751
Total Finance Receivables	752	751
91+ Still Accruing
Dealer \| Mining
Aging related to loans and finance leases
31-60 Days Past Due
61-90 Days Past Due
91+ Days Past Due
Total Past Due	0	0
Current	1	1
Total Finance Receivables	1	1
91+ Still Accruing
Dealer \| Latin America
Aging related to loans and finance leases
31-60 Days Past Due
61-90 Days Past Due
91+ Days Past Due
Total Past Due	0	0
Current	859	884
Total Finance Receivables	859	884
91+ Still Accruing
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=7512638&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=7512638&loc=d3e5111-111524

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph g

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ 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 OTS

-Name Federal Regulation (FR)

-Number Title 12

-Section 563c.102

-Paragraph 8

-Subparagraph e

-Chapter V

-Subsection I

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Paragraph 116

-IssueDate 2006-05-01

-Chapter 8

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: 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=7512638&loc=d3e5074-111524

Reference 4: 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=6375948&loc=d3e4428-111522

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ 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