Restructuring Costs (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Restructuring and Related Cost [Abstract]
Restructuring costs total	$ 36us-gaap_RestructuringCharges	$ 149us-gaap_RestructuringCharges	$ 441us-gaap_RestructuringCharges
Employee separation costs	34us-gaap_SeveranceCosts1	142us-gaap_SeveranceCosts1	382us-gaap_SeveranceCosts1
Restructuring fixed asset impairments and other restructuring costs	2
Restructuring fixed asset impairments		7us-gaap_TangibleAssetImpairmentCharges	33us-gaap_TangibleAssetImpairmentCharges
Other restructuring costs			26us-gaap_OtherRestructuringCosts
Employee Separation Charges [Roll Forward]
Liability balance at beginning of period	182cat_AccruedSeparationCharges	89cat_AccruedSeparationCharges	89cat_AccruedSeparationCharges
Increase in liability (separation charges)	34us-gaap_SeveranceCosts1	142us-gaap_SeveranceCosts1	382us-gaap_SeveranceCosts1
Reduction in liability (payments and other adjustments)	(87)cat_BenefitPaymentsSeparationCharges		(289)cat_BenefitPaymentsSeparationCharges
Liability balance at end of period	129cat_AccruedSeparationCharges		182cat_AccruedSeparationCharges
Gosselies, Belgium facility
Restructuring and Related Cost [Abstract]
Employee separation costs	7		273
Estimated cash separation costs	300
Employee Separation Charges [Roll Forward]
Increase in liability (separation charges)	$ 7		$ 273

As of the balance sheet date, the liability for employee separation charges.

No definition available.

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- Definition

Benefit payments made during the period in connection with employee separation programs.

+ References

No definition available.

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- Definition

The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value and the amount of other expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses associated with a discontinued operation or an asset retirement obligation.

+ References

No definition available.

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- Definition

Amount of other expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses associated with a discontinued operation or an asset retirement obligation.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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Amount expected to be recognized in earnings for the specified restructuring cost.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

+ References

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- Definition

Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

+ References

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- Definition

The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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