Retirement Plans and Other Retiree Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension Benefits, United States
Components of net periodic benefit cost
Service cost	$ 1	$ 1	$ 1	$ 1
Interest cost	23	26	47	53
ESOP offset	0	0	0	0
Expected return on plan assets	(28)	(28)	(55)	(55)
Amortization of transition and prior service costs (credits)	0	0	0	0
Amortization of actuarial loss (gain)	12	10	24	20
Net periodic benefit cost	8	9	17	19
Voluntary benefit plan contribution			57	50
Pension Benefits, International
Components of net periodic benefit cost
Service cost	3	4	7	8
Interest cost	5	6	10	12
ESOP offset	0	0	0	0
Expected return on plan assets	(5)	(6)	(10)	(11)
Amortization of transition and prior service costs (credits)	0	0	0	0
Amortization of actuarial loss (gain)	3	2	5	4
Net periodic benefit cost	6	6	12	13
Other Retiree Benefits
Components of net periodic benefit cost
Service cost	4	3	8	6
Interest cost	10	11	21	22
ESOP offset	0	(1)	0	(1)
Expected return on plan assets	0	0	0	0
Amortization of transition and prior service costs (credits)	0	0	0	0
Amortization of actuarial loss (gain)	4	4	8	8
Net periodic benefit cost	$ 18	$ 17	$ 37	$ 35