Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance	$ 363	$ 279
Other comprehensive income	194	50
Balance	616	416
Net Effect of Exchange Rate Fluctuations
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance	(788)	(568)
Change before reclassifications	186	90
Other comprehensive income	186	90
Balance	(602)	(478)
Change in Certain Derivative Instruments
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance	(4)	(17)
Amounts reclassified from accumulated other comprehensive income	(6)	(2)
Other comprehensive income	(6)	(2)
Balance	(10)	(19)
Employee Benefit Plans
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance	(1,380)	(1,432)
Change before reclassifications	(12)
Amounts reclassified from accumulated other comprehensive income	19	(43)
Translation effect	4	1
Other comprehensive income	11	(42)
Balance	(1,369)	(1,474)
Accumulated Other Comprehensive Loss
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance	(2,172)	(2,017)
Change before reclassifications	174	90
Amounts reclassified from accumulated other comprehensive income	13	(45)
Translation effect	4	1
Other comprehensive income	191	46
Balance	$ (1,981)	$ (1,971)