Operations and summary of significant accounting policies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Operations and summary of significant accounting policies
Ownership percentage of investments in companies accounted for under the equity method, low end of range (as a percent)	20.00%
Ownership percentage of investments in companies accounted for under the equity method, high end of range (as a percent)	50.00%
Ownership percentage of investments in companies below which the entity must exercise significant influence in order to be accounted for under the equity method (as a percent)	20.00%
Security deposit related to a deposit obligation			$ 232
Standard invoice terms, maximum extension period (in years)	1
Standard invoice terms, amount of extension allowed to receivables	221	312	544
Percentage of consolidated sales representing extension to standard invoice terms not more than one year (as a percent)	1.00%	1.00%	1.00%
Percentage of value of inventories on the LIFO basis to total inventories (as a percent)	70.00%	70.00%	70.00%
Incremental value of inventory if FIFO method had been in use	2,575	3,022	3,216
Depreciation on equipment leased to others	690	713	724
Consolidated depreciation expense	$ 2,202	$ 2,254	$ 1,907
Maximum amortizable period of purchased intangibles	20

The maximun ownership percentage of investments in companies accounted for under the equity method.

Name:	cat_EquityMethodInvestmentOwnershipPrecentageHighEndOfRange
Namespace Prefix:	cat
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum ownership percentage of investments in companies, except where significant influence is exercised, to be accounted for under the equity method.

+ Details

Name:	cat_EquityMethodInvestmentOwnershipPrecentageLowEndOfRange
Namespace Prefix:	cat
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The ownership percentage of investments in companies below which the entity must exercise significant influence in order to be accounted for under the equity method.

+ Details

Name:	cat_EquityMethodInvestmentOwnershipPrecentageSignificantInfluence
Namespace Prefix:	cat
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	cat_OperationsAndSummaryOfSignificantAccountingPoliciesDisclosureAbstract
Namespace Prefix:	cat
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the percentage of consolidated sales representing extension to standard invoice terms not more than one year.

+ Details

Name:	cat_PercentageOfConsolidatedSalesRepresentingExtensionToStandardInvoiceTermsNotMoreThanOneYear
Namespace Prefix:	cat
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the amount of extension allowed during the period to receivables under the standard invoice terms.

+ Details

Name:	cat_StandardInvoiceTermsAmountOfExtensionAllowedToReceivables
Namespace Prefix:	cat
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the maximum extension given to the standard invoice period terms.

+ Details

Name:	cat_StandardInvoiceTermsMaximumExtensionPeriod
Namespace Prefix:	cat
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 5

+ Details

Name:	us-gaap_Depreciation
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The maximum useful life of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar either by their nature or by their use in the operations of a company.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsUsefulLifeMaximum
Namespace Prefix:	us-gaap
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the difference between (a) inventory at the lower of LIFO cost or market and (b) inventory at replacement cost or at the lower of some acceptable inventory accounting method (such as FIFO or average cost), or market. If material, reflects an excess of replacement or current cost over stated LIFO value parenthetically on the balance sheet or in a note to the financial statements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 6
-Subparagraph c
-Article 5

+ Details

Name:	us-gaap_InventoryLIFOReserve
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total depreciation charge recorded for property subject to or held for lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 5

+ Details

Name:	us-gaap_OperatingLeasesIncomeStatementDepreciationExpenseOnPropertySubjectToOrHeldForLease
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

+ Details

Name:	us-gaap_PercentageOfLIFOInventory
Namespace Prefix:	us-gaap
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of an asset, typically cash, provided to a counterparty to provide certain assurance of performance by the entity pursuant to the terms of a written or oral agreement, such as a lease.

+ Details

Name:	us-gaap_SecurityDeposit
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant