Employee Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Benefits
Net Periodic Benefit Cost
Net Periodic Other Benefit Costs	$ 292	$ 362	$ 755	$ 912
Pension Benefits | United States
Net Periodic Benefit Cost
Service cost	120	122	360	366
Interest cost	93	91	278	274
Expected return on plan assets	(159)	(149)	(477)	(447)
Amortization of prior service costs (credits)	0	(1)	1	(3)
Amortization of actuarial losses (gains)	76	85	228	255
Settlement losses	128	169	260	325
Net Periodic Other Benefit Costs	258	317	650	770
Pension Benefits | International
Net Periodic Benefit Cost
Service cost	36	38	109	114
Interest cost	49	54	155	164
Expected return on plan assets	(62)	(61)	(193)	(178)
Amortization of prior service costs (credits)	2	3	8	9
Amortization of actuarial losses (gains)	6	11	23	33
Curtailment losses	3	0	3	0
Net Periodic Other Benefit Costs	34	45	105	142
Other Benefits
Net Periodic Benefit Cost
Service cost	10	8	31	24
Interest cost	24	23	72	71
Amortization of prior service costs (credits)	(7)	(7)	(21)	(21)
Amortization of actuarial losses (gains)	4	(1)	11	(4)
Net Periodic Other Benefit Costs	$ 31	$ 23	$ 93	$ 70