Derivative financial instruments and risk management (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Designated derivatives \| Fair Value Hedges
Derivative Instruments Gain (Loss)
Gains (Losses) on Derivatives	$ (41)	$ (107)	$ (20)
Gains (Losses) on Borrowings	23	114	36
Designated derivatives \| Fair Value Hedges \| Interest rate contracts \| Financial Products \| Other Income (Expense)
Derivative Instruments Gain (Loss)
Gains (Losses) on Derivatives	(41)	(107)	(20)
Gains (Losses) on Borrowings	23	114	36
Designated derivatives \| Cash Flow Hedges
Derivative Instruments Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	(187)	(6)	(77)
Amount of Gains (Losses) Reclassified from AOCI to Earnings	(6)	(66)	(26)
Recognized in Earnings (Ineffective Portion)	0	1	(1)
Designated derivatives \| Cash Flow Hedges \| Foreign exchange contracts \| Machinery, Energy & Transportation
Derivative Instruments Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	(118)	(4)	(78)
Designated derivatives \| Cash Flow Hedges \| Foreign exchange contracts \| Machinery, Energy & Transportation \| Other Income (Expense)
Derivative Instruments Gain (Loss)
Amount of Gains (Losses) Reclassified from AOCI to Earnings	5	(57)	(30)
Recognized in Earnings (Ineffective Portion)	0	0	0
Gains (Losses) reclassified from AOCI to earnings for derivatives dedesignated as related transactions are no longer probable to occur		(3)	(7)
Designated derivatives \| Cash Flow Hedges \| Interest rate contracts \| Machinery, Energy & Transportation
Derivative Instruments Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	(63)	0
Designated derivatives \| Cash Flow Hedges \| Interest rate contracts \| Machinery, Energy & Transportation \| Other Income (Expense)
Derivative Instruments Gain (Loss)
Amount of Gains (Losses) Reclassified from AOCI to Earnings		(3)
Recognized in Earnings (Ineffective Portion)		0
Designated derivatives \| Cash Flow Hedges \| Interest rate contracts \| Machinery, Energy & Transportation \| Interest expense
Derivative Instruments Gain (Loss)
Amount of Gains (Losses) Reclassified from AOCI to Earnings	(5)
Recognized in Earnings (Ineffective Portion)	0
Designated derivatives \| Cash Flow Hedges \| Interest rate contracts \| Financial Products
Derivative Instruments Gain (Loss)
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	(6)	(2)	1
Designated derivatives \| Cash Flow Hedges \| Interest rate contracts \| Financial Products \| Interest expense
Derivative Instruments Gain (Loss)
Amount of Gains (Losses) Reclassified from AOCI to Earnings	(6)	(6)	4
Recognized in Earnings (Ineffective Portion)	0	1	(1)
Undesignated derivatives
Derivative Instruments Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	(120)	18	72
Undesignated derivatives \| Foreign exchange contracts \| Machinery, Energy & Transportation \| Other Income (Expense)
Derivative Instruments Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	(60)	17	62
Undesignated derivatives \| Foreign exchange contracts \| Financial Products \| Other Income (Expense)
Derivative Instruments Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	(47)	8	6
Undesignated derivatives \| Interest rate contracts \| Machinery, Energy & Transportation \| Other Income (Expense)
Derivative Instruments Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	2	(1)	2
Undesignated derivatives \| Interest rate contracts \| Financial Products \| Other Income (Expense)
Derivative Instruments Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	0	(3)	0
Undesignated derivatives \| Commodity contracts \| Machinery, Energy & Transportation \| Other Income (Expense)
Derivative Instruments Gain (Loss)
Gains (Losses) on Derivatives Not Designated as Hedging Instruments	$ (15)	$ (3)	$ 2

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 25

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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

-Publisher FASB

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

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

-Publisher FASB

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The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

+ References

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

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The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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The amount of net gain (loss) reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

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