Retirement Plans and Other Retiree Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Retiree Benefits
Components of net periodic benefit cost
Service cost	$ 3	$ 4	$ 7	$ 8
Interest cost	9	9	20	19
Expected return on plan assets	0	0	(1)	0
Amortization of actuarial loss (gain)	3	5	5	9
Net periodic benefit cost	15	18	31	36
United States | Pension Benefits
Components of net periodic benefit cost
Service cost	0	1	0	1
Interest cost	23	22	46	43
Expected return on plan assets	(24)	(29)	(49)	(58)
Amortization of actuarial loss (gain)	12	11	25	23
Net periodic benefit cost	11	5	22	9
Voluntary benefit plan contribution			102	0
International | Pension Benefits
Components of net periodic benefit cost
Service cost	3	3	7	7
Interest cost	5	5	10	11
Expected return on plan assets	(4)	(5)	(9)	(11)
Amortization of actuarial loss (gain)	3	2	5	4
Net periodic benefit cost	$ 7	$ 5	$ 13	$ 11