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Accumulated amortization of impaired intangible assets lacking physical substance with a finite life.

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Amount before amortization of impaired intangible assets lacking physical substance with a finite life.

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Tax benefit arisng from loss due to the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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The amount of identifiable intangible assets recognized as of the acquisition date.

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Amount recognized as of the acquisition date for the assets, including goodwill, in excess of (less than) the aggregate liabilities assumed, less the noncontrolling interest in the acquiree.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Intangible assets and goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 02, 2018	Oct. 01, 2016
Intangible assets
Goodwill impairment charge	$ 0	$ 0	$ 595
Goodwill	$ 6,217	$ 6,200	6,020
Tax benefit from goodwill impairment loss			17
Weighted Amortizable Life (in years)	14 years	14 years
Gross Carrying Amount	$ 4,219	$ 4,177
Accumulated Amortization	(2,322)	(2,066)
Net	1,897	2,111
Total intangible assets, net	1,897	2,111
Amortization expense	331	$ 323	326
2019	326
2020	311
2021	293
2022	274
2023	216
Thereafter	$ 477
ECM S.p.A.
Intangible assets
Goodwill				$ 109
Finite-lived intangible assets				112
Downer Freight Rail
Intangible assets
Goodwill				18
Finite-lived intangible assets				6
Customer relationships
Intangible assets
Weighted Amortizable Life (in years)	15 years	15 years
Gross Carrying Amount	$ 2,463	$ 2,441
Accumulated Amortization	(1,249)	(1,122)
Net	$ 1,214	$ 1,319
Intellectual property
Intangible assets
Weighted Amortizable Life (in years)	11 years	11 years
Gross Carrying Amount	$ 1,557	$ 1,538
Accumulated Amortization	(965)	(851)
Net	$ 592	$ 687
Other
Intangible assets
Weighted Amortizable Life (in years)	13 years	13 years
Gross Carrying Amount	$ 199	$ 198
Accumulated Amortization	(108)	(93)
Net	91	105
Resource Industries
Intangible assets
Goodwill	2,997	3,057	2,935
Impairment of Intangible Assets, Finite-lived			132
Resource Industries \| Customer relationships
Intangible assets
Impairment of Finite-lived Intangible Assets, Gross			96
Impairment of Finite-lived Intangible Assets, Accumulated Amortization			27
Resource Industries \| Intellectual property
Intangible assets
Impairment of Finite-lived Intangible Assets, Gross			111
Impairment of Finite-lived Intangible Assets, Accumulated Amortization			$ 48
Energy & Transportation
Intangible assets
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest				$ 127
Goodwill	$ 2,882	$ 2,806
Surface Mining & Technology
Intangible assets
Goodwill					$ 629