Segment information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Segment Reporting Information
Segment profit (loss)			$ 2,204
Machinery and Power Systems \| Reportable segments
Segment Reporting Information
External sales and revenues		37,776	27,753	45,645
Inter-segment sales and revenues		3,252	1,785	3,087
Total sales and revenues		41,028	29,538	48,732
Depreciation and amortization		1,298	1,307	998
Segment profit (loss)		4,860	1,180	5,026
Segment assets		19,140	17,038	18,124
Capital expenditures		1,482	1,177	2,069
Construction Industries \| Reportable segments
Segment Reporting Information
External sales and revenues		13,572	8,507	16,763
Inter-segment sales and revenues		674	516	838
Total sales and revenues		14,246	9,023	17,601
Depreciation and amortization		515	555	305
Segment profit (loss)		783	(768)	1,246
Segment assets		6,927	6,600	6,979
Capital expenditures		576	403	762
Resource Industries \| Reportable segments
Segment Reporting Information
External sales and revenues		8,667	5,857	10,254
Inter-segment sales and revenues		894	414	696
Total sales and revenues		9,561	6,271	10,950
Depreciation and amortization		281	313	284
Segment profit (loss)		1,789	288	1,258
Segment assets		3,892	3,773	4,100
Capital expenditures		339	243	468
Power Systems \| Reportable segments
Segment Reporting Information
External sales and revenues		15,537	13,389	18,628
Inter-segment sales and revenues		1,684	855	1,553
Total sales and revenues		17,221	14,244	20,181
Depreciation and amortization		502	439	409
Segment profit (loss)		2,288	1,660	2,522
Segment assets		8,321	6,665	7,045
Capital expenditures		567	531	839
Financial Products Segment \| Reportable segments
Segment Reporting Information
External sales and revenues		2,946	3,139	3,561
Total sales and revenues		2,946	3,139	3,561
Depreciation and amortization		715	742	755
Segment profit (loss)		429	399	548
Segment assets		30,346	32,230	34,578
Capital expenditures		960	976	1,608
Reportable segments
Segment Reporting Information
Operating segments (in number of segments)	7	25
Reportable segments (in number of segments)	4	12
Number of operating segments led by Group Presidents	3
Number of operating segments led by Group president responsible for corporate services	1
Number of smaller operating segments led by Group President	3
Useful life of goodwill (in years)	20
External sales and revenues		40,722	30,892	49,206
Inter-segment sales and revenues		3,252	1,785	3,087
Total sales and revenues		43,974	32,677	52,293
Depreciation and amortization		2,013	2,049	1,753
Segment profit (loss)		5,289	1,579	5,574
Segment assets		49,486	49,268	52,702
Capital expenditures		$ 2,442	$ 2,153	$ 3,677

The overall number of the entity's operating segments for its business activity.

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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 operating segments which are led by group presidents.

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The number of the entity's reportable segments, which are operating segments that meet the segment reporting criteria set forth in the related guidance and thus need to report separate information.

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

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- Definition

Amount of total capital expenditures attributable to the reportable segments.

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The useful life of all finite-lived intangible assets. This may be stated as a fixed number (for example, 10 years) if all assets have the same useful life, or it can be stated in a range (for example, six to eight years) if there is a range of useful lives in the asset group.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 12, 13, 14

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Amount of total assets attributed to the reportable segment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 27

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Amount of depreciation, depletion, and amortization expense for the reportable segment. Must be disclosed if the amount (a) is included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) is otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 27
-Subparagraph e

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Amount of revenue from transactions with other operating segments of the same entity. Must be disclosed if the amount (a) is included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) is otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 27
-Subparagraph b

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of income or loss for the reportable segment before unusual Items, equity method income or loss, income taxes, and extraordinary items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 27

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Amount of total revenue for the reportable segment, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 27
-Subparagraph a, b, c

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Amount of revenue from external customers for the reportable segment. Must be disclosed if the amounts (a) is included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) is otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 27
-Subparagraph a

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