Equity, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 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	$ 59	$ 136	131	$ (449)
Amounts reclassified from accumulated other comprehensive loss	18	2	35	1
Effect of exchange rates	(1)	0	(1)	0
Other comprehensive income (loss)	76	138	165	(448)
Ending balance, accumulated other comprehensive loss, net of tax	17,651		17,651
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	(1,165)	(1,937)	(1,254)	(1,351)
Ending balance, accumulated other comprehensive loss, net of tax	(1,089)	(1,799)	(1,089)	(1,799)
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	(439)	(1,282)	(515)	(676)
Other comprehensive income (loss) before reclassifications	66	138	142	(468)
Amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Effect of exchange rates	0	0	0	0
Other comprehensive income (loss)	66	138	142	(468)
Ending balance, accumulated other comprehensive loss, net of tax	(373)	(1,144)	(373)	(1,144)
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	(728)	(663)	(737)	(672)
Other comprehensive income (loss) before reclassifications	0	0	1	0
Amounts reclassified from accumulated other comprehensive loss	14	10	22	19
Effect of exchange rates	(1)	0	(1)	0
Other comprehensive income (loss)	13	10	22	19
Ending balance, accumulated other comprehensive loss, net of tax	(715)	(653)	(715)	(653)
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	8	(2)	(3)
Other comprehensive income (loss) before reclassifications	(7)	(2)	(12)	19
Amounts reclassified from accumulated other comprehensive loss	4	(8)	13	(18)
Effect of exchange rates	0	0	0	0
Other comprehensive income (loss)	(3)	(10)	1	1
Ending balance, accumulated other comprehensive loss, net of tax	$ (1)	$ (2)	$ (1)	$ (2)