Equity, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Changes in Accumulated Other Comprehensive Loss, By Component, Net of Tax
Beginning balance, accumulated other comprehensive loss, net of tax	$ 21,667
Other comprehensive income before reclassifications	153	$ 42
Amounts reclassified from accumulated other comprehensive loss	2	6
Other comprehensive income	155	48
Reclassification of stranded income tax effects of Tax Reform to retained earnings		0
Ending balance, accumulated other comprehensive loss, net of tax	21,309
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	(1,507)	(940)
Reclassification of stranded income tax effects of Tax Reform to retained earnings	0	(91)
Ending balance, accumulated other comprehensive loss, net of tax	(1,352)	(983)
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	(1,022)	(507)
Other comprehensive income before reclassifications	153	42
Amounts reclassified from accumulated other comprehensive loss	0	0
Other comprehensive income	153	42
Reclassification of stranded income tax effects of Tax Reform to retained earnings	0	0
Ending balance, accumulated other comprehensive loss, net of tax	(869)	(465)
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	(485)	(433)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	2	6
Other comprehensive income	2	6
Reclassification of stranded income tax effects of Tax Reform to retained earnings	0	(91)
Ending balance, accumulated other comprehensive loss, net of tax	$ (483)	$ (518)