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Segmented Information - Schedule of Aggregates External Revenues by Customer (Detail) - USD ($) $ in Millions | 12 Months Ended
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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. + Details
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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 + Details
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