Postretirement Benefits (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension and Other Postretirement Benefits
Pension and other postretirement benefit contributions
Contributions to pension and other postretirement benefit plans		$ 1,573		$ 1,771
Expected full year contributions to pension and other postretirement benefit plans during the year	$ 1,830	1,830		1,830
UNITED STATES
Components of net periodic benefit cost:
Service cost		29	$ 31	86	$ 94
Interest cost		150	134	450	401
Expected return on plan assets		(180)	(202)	(540)	(607)
Amortization of prior service cost / (credit)		0	0	0	0
Net periodic benefit cost (benefit)		(1)	(37)	(4)	(112)
Foreign Plan
Components of net periodic benefit cost:
Service cost		20	22	61	67
Interest cost		23	25	70	74
Expected return on plan assets		(37)	(55)	(112)	(167)
Amortization of prior service cost / (credit)		0	0	0	0
Net periodic benefit cost (benefit)		6	(8)	19	(26)
Discretionary contribution
Pension and other postretirement benefit contributions
Contributions to pension and other postretirement benefit plans	$ 1,500				1,000
Other Postretirement Benefits Plan
Components of net periodic benefit cost:
Service cost		19	22	60	64
Interest cost		34	31	102	93
Expected return on plan assets		(4)	(9)	(14)	(25)
Amortization of prior service cost / (credit)		(10)	(9)	(30)	(26)
Net periodic benefit cost (benefit)		$ 39	$ 35	$ 118	$ 106