Equity, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 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	$ (263)	$ 217	(132)	$ (232)
Amounts reclassified from accumulated other comprehensive loss	12	11	47	12
Effect of exchange rates	2	0	1	0
Other comprehensive income (loss)	(249)	228	(84)	(220)
Ending balance, accumulated other comprehensive loss, net of tax	17,476		17,476
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	(1,089)	(1,799)	(1,254)	(1,351)
Ending balance, accumulated other comprehensive loss, net of tax	(1,338)	(1,571)	(1,338)	(1,571)
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	(373)	(1,144)	(515)	(676)
Other comprehensive income (loss) before reclassifications	(255)	217	(113)	(251)
Amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Effect of exchange rates	0	0	0	0
Other comprehensive income (loss)	(255)	217	(113)	(251)
Ending balance, accumulated other comprehensive loss, net of tax	(628)	(927)	(628)	(927)
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	(715)	(653)	(737)	(672)
Other comprehensive income (loss) before reclassifications	0	0	1	0
Amounts reclassified from accumulated other comprehensive loss	10	9	32	28
Effect of exchange rates	2	0	1	0
Other comprehensive income (loss)	12	9	34	28
Ending balance, accumulated other comprehensive loss, net of tax	(703)	(644)	(703)	(644)
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	(1)	(2)	(2)	(3)
Other comprehensive income (loss) before reclassifications	(8)	0	(20)	19
Amounts reclassified from accumulated other comprehensive loss	2	2	15	(16)
Effect of exchange rates	0	0	0	0
Other comprehensive income (loss)	(6)	2	(5)	3
Ending balance, accumulated other comprehensive loss, net of tax	$ (7)	$ 0	$ (7)	$ 0