Accumulated Other Comprehensive Loss - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassifications out of accumulated other comprehensive income loss by component
Other income (expense), net	$ 25	$ 14	$ 63	$ 6
Total before tax	329	139	802	486
Income tax expense	(57)	(47)	(123)	(214)
NET INCOME	272	92	679	272
Reclassification out of Accumulated Other Comprehensive Income | Net actuarial loss
Reclassifications out of accumulated other comprehensive income loss by component
Other income (expense), net	45	51	135	154
Reclassification out of Accumulated Other Comprehensive Income | Prior service cost
Reclassifications out of accumulated other comprehensive income loss by component
Other income (expense), net	3	3	9	9
Reclassification out of Accumulated Other Comprehensive Income | Defined benefit plan
Reclassifications out of accumulated other comprehensive income loss by component
Total before tax	48	54	144	163
Income tax expense	(11)	(16)	(35)	(60)
NET INCOME	$ 37	$ 38	$ 109	$ 103