Equity, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Changes in Accumulated Other Comprehensive Loss, By Component
Beginning balance, accumulated other comprehensive loss, net of tax	$ 20,024
Ending balance, accumulated other comprehensive loss, net of tax	19,825
Accumulated Other Comprehensive Loss [Member]
Changes in Accumulated Other Comprehensive Loss, By Component
Beginning balance, accumulated other comprehensive loss, net of tax	(1,410)	$ (933)
Other comprehensive income before reclassifications	74	129
Amounts reclassified from accumulated other comprehensive loss	2	2
Net other comprehensive income	76	131
Ending balance, accumulated other comprehensive loss, net of tax	(1,334)	(802)
Foreign Currency Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive Loss, By Component
Beginning balance, accumulated other comprehensive loss, net of tax	(1,021)	(605)
Other comprehensive income before reclassifications	74	121
Amounts reclassified from accumulated other comprehensive loss	0	0
Net other comprehensive income	74	121
Ending balance, accumulated other comprehensive loss, net of tax	(947)	(484)
Defined Benefit Plans Items [Member]
Changes in Accumulated Other Comprehensive Loss, By Component
Beginning balance, accumulated other comprehensive loss, net of tax	(389)	(328)
Other comprehensive income before reclassifications	0	8
Amounts reclassified from accumulated other comprehensive loss	2	2
Net other comprehensive income	2	10
Ending balance, accumulated other comprehensive loss, net of tax	$ (387)	$ (318)