Equity, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Changes in Accumulated Other Comprehensive Loss, By Component, Net of Tax
Beginning balance, accumulated other comprehensive loss, net of tax	$ 21,991
Other comprehensive income (loss) before reclassifications	(244)	$ 282
Amounts reclassified from accumulated other comprehensive loss	13	5
Other comprehensive income (loss)	(231)	287
Reclassification of stranded income tax effects of Tax Reform to retained earnings per ASU 2018-02	(91)	0
Ending balance, accumulated other comprehensive loss, net of tax	21,769
Accumulated Other Comprehensive Loss [Member]
Changes in Accumulated Other Comprehensive Loss, By Component, Net of Tax
Beginning balance, accumulated other comprehensive loss, net of tax	(940)	(1,410)
Ending balance, accumulated other comprehensive loss, net of tax	(1,262)	(1,123)
Foreign Currency Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive Loss, By Component, Net of Tax
Beginning balance, accumulated other comprehensive loss, net of tax	(507)	(1,021)
Other comprehensive income (loss) before reclassifications	(244)	282
Amounts reclassified from accumulated other comprehensive loss	0	0
Other comprehensive income (loss)	(244)	282
Reclassification of stranded income tax effects of Tax Reform to retained earnings per ASU 2018-02	0	0
Ending balance, accumulated other comprehensive loss, net of tax	(751)	(739)
Defined Benefit Plans Items [Member]
Changes in Accumulated Other Comprehensive Loss, By Component, Net of Tax
Beginning balance, accumulated other comprehensive loss, net of tax	(433)	(389)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	13	5
Other comprehensive income (loss)	13	5
Reclassification of stranded income tax effects of Tax Reform to retained earnings per ASU 2018-02	(91)	0
Ending balance, accumulated other comprehensive loss, net of tax	$ (511)	$ (384)

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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