Energy & Transportation sales (Details) - Energy & Transportation - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Reportable Subsegments
Energy and transportation sales
Sales and revenues by geographic region	$ 3,618	$ 4,233
Oil and Gas
Energy and transportation sales
Sales and revenues by geographic region	861	1,131
Power generation
Energy and transportation sales
Sales and revenues by geographic region	854	1,036
Industrial
Energy and transportation sales
Sales and revenues by geographic region	801	904
Transportation
Energy and transportation sales
Sales and revenues by geographic region	1,102	1,162
Operating Segments \| Reportable Subsegments
Energy and transportation sales
Sales and revenues by geographic region	$ 3,618	$ 4,233

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration