Postretirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension and Other Postretirement Benefits
Pension and other postretirement benefit contributions
Contributions to pension and other postretirement benefit plans	$ 72		$ 170
Expected full year contributions to pension and other postretirement benefit plans during the year	280		280
Other Postretirement Benefits Plan
Components of net periodic benefit cost:
Service cost	24	$ 21	47	$ 41
Interest cost	27	34	53	68
Expected return on plan assets	(3)	(5)	(6)	(10)
Amortization of prior service cost / (credit)	(10)	(10)	(19)	(20)
(Gain) loss on remeasurement of pension obligations	0	0	0	0
Curtailments, settlements and termination benefits	0	0	0	0
Net periodic benefit cost (benefit)	38	40	75	79
UNITED STATES
Components of net periodic benefit cost:
Service cost	0	28	0	57
Interest cost	121	150	242	300
Expected return on plan assets	(198)	(179)	(396)	(360)
Amortization of prior service cost / (credit)	0	0	0	0
(Gain) loss on remeasurement of pension obligations	2	0	2	0
Curtailments, settlements and termination benefits	0	0	0	0
Net periodic benefit cost (benefit)	(75)	(1)	(152)	(3)
Foreign Plan
Components of net periodic benefit cost:
Service cost	14	20	28	41
Interest cost	21	24	40	47
Expected return on plan assets	(38)	(38)	(73)	(75)
Amortization of prior service cost / (credit)	0	0	0	0
(Gain) loss on remeasurement of pension obligations	120	0	(134)	0
Curtailments, settlements and termination benefits	21	0	21	0
Net periodic benefit cost (benefit)	$ 138	$ 6	$ (118)	$ 13