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Accounting Principles and Practices - Schedule of Changes in Accounting Principle (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Operating income | $ 799 | $ 335
Other income (expense) | $ (15) | (2)
As Reported |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Operating income |  | 343
Other income (expense) |  | (10)
Accounting Standards Update 2017-07 | Adjustments |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Operating income |  | (8)
Other income (expense) |  | $ 8

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- Definition Amount of income (expense) related to nonoperating activities, classified as other. + 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 210.5-03.9) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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