Goodwill (Schedule of Goodwill) (Details) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)
Goodwill [Line Items]
Goodwill, Acquired During Period	$ 27
Goodwill, Written off Related to Sale of Business Unit	8
Goodwill, Reclassification to Assets Held for Sale	60
Goodwill [Roll Forward]
Balance at December 31, 2017	2,727
Foreign currency translation adjustments	(54)
Balance at September 30, 2018	2,632
Western Hemisphere
Goodwill [Line Items]
Goodwill, Written off Related to Sale of Business Unit	8
Goodwill, Reclassification to Assets Held for Sale	44
Goodwill [Roll Forward]
Balance at December 31, 2017	1,958
Foreign currency translation adjustments	(35)
Eastern Hemisphere
Goodwill [Line Items]
Goodwill, Acquired During Period	27
Goodwill, Written off Related to Sale of Business Unit	0
Goodwill, Reclassification to Assets Held for Sale	16
Goodwill [Roll Forward]
Balance at December 31, 2017	769
Foreign currency translation adjustments	(19)
Balance at September 30, 2018	761
Western Hemisphere
Goodwill [Line Items]
Goodwill, Acquired During Period	0
Goodwill [Roll Forward]
Balance at September 30, 2018	$ 1,871

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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-Topic 350
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-Section 45
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