Equity, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Changes in Accumulated Other Comprehensive Loss, By Component, Net of Tax
Beginning balance, accumulated other comprehensive loss, net of tax	$ 18,801
Other comprehensive income (loss) before reclassifications	72	$ (585)
Amounts reclassified from accumulated other comprehensive loss	17	(1)
Other comprehensive income (loss)	89	(586)
Ending balance, accumulated other comprehensive loss, net of tax	17,801
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	(1,254)	(1,351)
Ending balance, accumulated other comprehensive loss, net of tax	(1,165)	(1,937)
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	(515)	(676)
Other comprehensive income (loss) before reclassifications	76	(606)
Amounts reclassified from accumulated other comprehensive loss	0	0
Other comprehensive income (loss)	76	(606)
Ending balance, accumulated other comprehensive loss, net of tax	(439)	(1,282)
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	(737)	(672)
Other comprehensive income (loss) before reclassifications	1	0
Amounts reclassified from accumulated other comprehensive loss	8	9
Other comprehensive income (loss)	9	9
Ending balance, accumulated other comprehensive loss, net of tax	(728)	(663)
Gains (Losses) on Cash Flow Hedges [Member]
Changes in Accumulated Other Comprehensive Loss, By Component, Net of Tax
Beginning balance, accumulated other comprehensive loss, net of tax	(2)	(3)
Other comprehensive income (loss) before reclassifications	(5)	21
Amounts reclassified from accumulated other comprehensive loss	9	(10)
Other comprehensive income (loss)	4	11
Ending balance, accumulated other comprehensive loss, net of tax	$ 2	$ 8

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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