Retirement Plans and Other Retiree Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Other Retiree Benefits
Components of net periodic benefit cost
Service cost	$ 4	$ 4
Interest cost	11	10
Expected return on plan assets	(1)	0
Amortization of actuarial loss (gain)	2	4
Net periodic benefit cost	16	18
United States | Pension Benefits
Components of net periodic benefit cost
Service cost	0	0
Interest cost	23	21
Expected return on plan assets	(26)	(29)
Amortization of actuarial loss (gain)	13	12
Net periodic benefit cost	10	4
Voluntary benefit plan contribution	102	0
International | Pension Benefits
Components of net periodic benefit cost
Service cost	4	4
Interest cost	5	6
Expected return on plan assets	(5)	(6)
Amortization of actuarial loss (gain)	2	2
Net periodic benefit cost	$ 6	$ 6