Employee Benefits - Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension Benefits
Net Periodic Benefit Cost
Net Periodic Other Benefit Costs	$ 245	$ 221	$ 487	$ 437
Pension Benefits | United States
Net Periodic Benefit Cost
Service cost	125	102	249	203
Interest cost	88	99	176	198
Expected return on plan assets	(163)	(141)	(325)	(282)
Amortization of prior service costs (credits)	0	1	1	1
Amortization of actuarial losses (gains)	96	59	192	119
Settlement losses	60	60	120	120
Net Periodic Other Benefit Costs	206	180	413	359
Pension Benefits | International
Net Periodic Benefit Cost
Service cost	32	36	64	71
Interest cost	44	53	87	104
Expected return on plan assets	(51)	(57)	(103)	(115)
Amortization of prior service costs (credits)	3	3	5	6
Amortization of actuarial losses (gains)	11	6	21	11
Settlement losses	0	0	0	1
Net Periodic Other Benefit Costs	39	41	74	78
Other Benefits
Net Periodic Benefit Cost
Service cost	10	9	19	18
Interest cost	17	24	35	48
Amortization of prior service costs (credits)	(8)	(7)	(14)	(14)
Amortization of actuarial losses (gains)	2	0	2	(1)
Net Periodic Other Benefit Costs	$ 21	$ 26	$ 42	$ 51