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Segmented Information - Schedule of Aggregates External Revenues by Customer (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Revenue from External Customer [Line Items]
Sales	$ 38,946	$ 36,445
General Motors [Member]
Revenue from External Customer [Line Items]
Sales	6,854	7,207
Ford Motor Company [Member]
Revenue from External Customer [Line Items]
Sales	6,058	5,667
Fiat or Chrysler Group [Member]
Revenue from External Customer [Line Items]
Sales	5,502	5,349
Daimler AG [Member]
Revenue from External Customer [Line Items]
Sales	4,719	4,294
BMW [Member]
Revenue from External Customer [Line Items]
Sales	4,231	3,786
Volkswagen [Member]
Revenue from External Customer [Line Items]
Sales	4,025	3,758
Other Customers [Member]
Revenue from External Customer [Line Items]
Sales	$ 7,557	$ 6,384

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- Definition

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.

+ References

No definition available.

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- Definition

Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(a))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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