Equity, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in Accumulated Other Comprehensive Loss by Component, Net of Tax
Beginning balance, accumulated other comprehensive loss, net of tax	$ 21,803
Other comprehensive income (loss) before reclassifications	69	$ 147	$ (508)
Amounts reclassified from accumulated other comprehensive  loss	28	9	32
Other comprehensive income (loss)	97	156	(476)
Reclassification of stranded income tax effects			0
Ending balance, accumulated other comprehensive loss, net of tax	18,801	21,803
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	(1,351)	(1,507)	(940)
Reclassification of stranded income tax effects			(91)
Ending balance, accumulated other comprehensive loss, net of tax	(1,254)	(1,351)	(1,507)
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	(676)	(1,022)	(507)
Other comprehensive income (loss) before reclassifications	161	346	(515)
Amounts reclassified from accumulated other comprehensive  loss	0	0	0
Other comprehensive income (loss)	161	346	(515)
Reclassification of stranded income tax effects			0
Ending balance, accumulated other comprehensive loss, net of tax	(515)	(676)	(1,022)
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	(672)	(485)	(433)
Other comprehensive income (loss) before reclassifications	(106)	(197)	7
Amounts reclassified from accumulated other comprehensive  loss	41	10	32
Other comprehensive income (loss)	(65)	(187)	39
Reclassification of stranded income tax effects			(91)
Ending balance, accumulated other comprehensive loss, net of tax	(737)	(672)	(485)
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		0	0
Other comprehensive income (loss) before reclassifications			0
Amounts reclassified from accumulated other comprehensive  loss			0
Other comprehensive income (loss)			0
Reclassification of stranded income tax effects			0
Ending balance, accumulated other comprehensive loss, net of tax			$ 0
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	(3)
Other comprehensive income (loss) before reclassifications	14	(2)
Amounts reclassified from accumulated other comprehensive  loss	(13)	(1)
Other comprehensive income (loss)	1	(3)
Ending balance, accumulated other comprehensive loss, net of tax	$ (2)	$ (3)