Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015 segments group_presidents	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information
Number of group presidents	5cat_NumberOfGroupPresidents
Number of operating segments	7us-gaap_NumberOfOperatingSegments
Useful life to amortize goodwill for segment assets	20 years
Reportable Segments
Sales and revenues	$ 12,702us-gaap_Revenues	$ 13,241us-gaap_Revenues
Depreciation and amortization	753	781
Consolidated profit before taxes	1,555	1,342
Segment assets	82,490us-gaap_Assets		84,681us-gaap_Assets
Capital expenditures	826	739
All Other operating segments
Segment Reporting Information
Number of group presidents	1
Number of smaller operating segments led by Group President	3
Number of wholly-owned dealers involved in segment reallocation	1
Reportable Segments
Sales and revenues	586	554
Depreciation and amortization	66	66
Consolidated profit before taxes	225	235
Segment assets	2,614		2,810
Capital expenditures	46	38
Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	12,838	13,507
Reportable Segments
Segment Reporting Information
Number of operating segments led by Group Presidents	3
Number of operating segments led by Group President responsible for corporate services	1
Reportable Segments
Number of reportable segments	4
Sales and revenues	12,180	12,780
Depreciation and amortization	651	682
Consolidated profit before taxes	2,038	1,904
Segment assets	60,110		61,574
Capital expenditures	509	433
Intersegment Eliminations
Reportable Segments
Sales and revenues	658	727
Machinery, Energy & Transportation \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	12,043	12,690
Machinery, Energy & Transportation \| Reportable Segments
Reportable Segments
Sales and revenues	11,385	11,963
Depreciation and amortization	436	463
Consolidated profit before taxes	1,811	1,664
Segment assets	23,938		24,563
Capital expenditures	215	164
Machinery, Energy & Transportation \| Intersegment Eliminations
Reportable Segments
Sales and revenues	658	727
Construction Industries \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	4,746	5,139
Construction Industries \| Reportable Segments
Reportable Segments
Sales and revenues	4,695	5,064
Depreciation and amortization	119	134
Consolidated profit before taxes	740	688
Segment assets	6,252		6,596
Capital expenditures	36	64
Construction Industries \| Intersegment Eliminations
Reportable Segments
Sales and revenues	51	75
Resource Industries \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	2,021	2,225
Resource Industries \| Reportable Segments
Reportable Segments
Sales and revenues	1,928	2,123
Depreciation and amortization	161	171
Consolidated profit before taxes	85	143
Segment assets	9,301		9,497
Capital expenditures	30	24
Resource Industries \| Intersegment Eliminations
Reportable Segments
Sales and revenues	93	102
Energy & Transportation \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	5,276	5,326
Energy & Transportation \| Reportable Segments
Reportable Segments
Sales and revenues	4,762	4,776
Depreciation and amortization	156	158
Consolidated profit before taxes	986	833
Segment assets	8,385		8,470
Capital expenditures	149	76
Energy & Transportation \| Intersegment Eliminations
Reportable Segments
Sales and revenues	514	550
Financial Products Segment \| Reportable Segments Including Intersegment Eliminations
Reportable Segments
Sales and revenues	795	817
Financial Products Segment \| Reportable Segments
Reportable Segments
Sales and revenues	795	817
Depreciation and amortization	215	219
Consolidated profit before taxes	227	240
Segment assets	36,172		37,011
Capital expenditures	294	269
Financial Products Segment \| Intersegment Eliminations
Reportable Segments
Sales and revenues	$ 0	$ 0

The number of group presidents that comprise the reporting entity's executive office.

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Represents the number of operating segments that are led by the group president who is responsible for corporate services.

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Represents the number of smaller operating segments that are led by the group president.

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Number of wholly-owned dealers moved from one operating segment to different operating segment.

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Amount of total capital expenditures attributable to the reportable segments.

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Represents the useful life used to amortize goodwill to allocate to segments assets.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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