Retirement Plans and Other Retiree Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Other Retiree Benefits
Components of net periodic benefit cost
Service cost	$ 3	$ 4	$ 14	$ 11
Interest cost	10	15	29	35
Expected return on plan assets	0	(2)	(1)	(3)
Amortization of actuarial loss (gain)	3	4	14	9
Net periodic benefit cost	16	21	56	52
United States | Pension Benefits
Components of net periodic benefit cost
Service cost	0	1	0	1
Interest cost	20	22	57	68
Expected return on plan assets	(29)	(29)	(83)	(78)
Amortization of actuarial loss (gain)	10	14	34	39
Net periodic benefit cost	1	8	8	30
Voluntary benefit plan contribution			0	113
International | Pension Benefits
Components of net periodic benefit cost
Service cost	4	3	11	10
Interest cost	5	6	14	16
Expected return on plan assets	(6)	(4)	(15)	(13)
Amortization of actuarial loss (gain)	2	1	7	6
Net periodic benefit cost	$ 5	$ 6	$ 17	$ 19