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Derivative financial instruments and risk management (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivatives Fair Value
Asset Fair Value	$ 74	$ 95
Liability Fair Value	(93)	(167)
Machinery, Energy & Transportation
Derivatives Fair Value
Asset Fair Value	52	23
Liability Fair Value	(25)	(159)
Financial Products
Derivatives Fair Value
Asset Fair Value	22	72
Liability Fair Value	(68)	(8)
Designated derivatives
Derivatives Fair Value
Asset (Liability) Fair Value	(53)	(87)
Undesignated derivatives
Derivatives Fair Value
Asset (Liability) Fair Value	34	15
Foreign exchange contracts \| Designated derivatives \| Receivables - trade and other \| Machinery, Energy & Transportation
Derivatives Fair Value
Asset Fair Value	8	13
Foreign exchange contracts \| Designated derivatives \| Long-term receivables - trade and other \| Machinery, Energy & Transportation
Derivatives Fair Value
Asset Fair Value	4	0
Foreign exchange contracts \| Designated derivatives \| Long-term receivables - trade and other \| Financial Products
Derivatives Fair Value
Asset Fair Value	7	29
Foreign exchange contracts \| Designated derivatives \| Accrued expenses \| Machinery, Energy & Transportation
Derivatives Fair Value
Liability Fair Value	(14)	(93)
Foreign exchange contracts \| Designated derivatives \| Accrued expenses \| Financial Products
Derivatives Fair Value
Liability Fair Value	(57)	(3)
Foreign exchange contracts \| Designated derivatives \| Other liabilities \| Machinery, Energy & Transportation
Derivatives Fair Value
Liability Fair Value	(2)	(36)
Foreign exchange contracts \| Undesignated derivatives \| Receivables - trade and other \| Machinery, Energy & Transportation
Derivatives Fair Value
Asset Fair Value	19	0
Foreign exchange contracts \| Undesignated derivatives \| Receivables - trade and other \| Financial Products
Derivatives Fair Value
Asset Fair Value	12	39
Foreign exchange contracts \| Undesignated derivatives \| Accrued expenses \| Machinery, Energy & Transportation
Derivatives Fair Value
Liability Fair Value	(9)	(30)
Foreign exchange contracts \| Undesignated derivatives \| Accrued expenses \| Financial Products
Derivatives Fair Value
Liability Fair Value	(9)	(4)
Interest rate contracts \| Designated derivatives \| Long-term receivables - trade and other \| Financial Products
Derivatives Fair Value
Asset Fair Value	3	4
Interest rate contracts \| Designated derivatives \| Accrued expenses \| Financial Products
Derivatives Fair Value
Liability Fair Value	(2)	(1)
Commodity contracts \| Undesignated derivatives \| Receivables - trade and other \| Machinery, Energy & Transportation
Derivatives Fair Value
Asset Fair Value	21	10
Cash Flow Hedges \| Designated derivatives
Derivatives Fair Value
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	(5)	(95)	$ (30)
Cash Flow Hedges \| Foreign exchange contracts \| Designated derivatives \| Machinery, Energy & Transportation
Derivatives Fair Value
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	72	(118)	(33)
Cash Flow Hedges \| Foreign exchange contracts \| Designated derivatives \| Financial Products
Derivatives Fair Value
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)		15	0
Cash Flow Hedges \| Interest rate contracts \| Designated derivatives \| Machinery, Energy & Transportation
Derivatives Fair Value
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	0	0	0
Cash Flow Hedges \| Interest rate contracts \| Designated derivatives \| Financial Products
Derivatives Fair Value
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	0	$ 8	$ 3
Other Income (Expense) \| Cash Flow Hedges \| Foreign exchange contracts \| Designated derivatives \| Financial Products
Derivatives Fair Value
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	(77)
Interest expense \| Cash Flow Hedges \| Foreign exchange contracts \| Designated derivatives \| Financial Products
Derivatives Fair Value
Amount of Gains (Losses) Recognized in AOCI (Effective Portion)	$ 0