Pensions Benefit Plans and Other Postretirement Benefits - Components of Net Periodic Pension and Postretirement Cost (Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefit Plans
Amortization:
Accumulated benefit obligation	$ 2,379	$ 2,735
U.S. | Pension Benefit Plans
Components of net periodic pension cost
Service cost	14	14	$ 15
Interest cost	59	78	90
Expected asset return	(98)	(128)	(149)
Amortization:
Amortization of Actuarial loss	51	57	67
Net periodic pension cost	26	21	23
Settlement cost		176	98
Annuity contract purchase for settlement of pension obligation	94	369	200
U.S. | Other Postretirement Benefits
Components of net periodic pension cost
Interest cost	3	4	4
Amortization:
Amortization of Actuarial loss	2	2	2
Prior service cost	(7)	(8)	(8)
Net amortization	(5)	(6)	(6)
Net periodic pension cost	(2)	(2)	(2)
Non-U.S. | Pension Benefit Plans
Components of net periodic pension cost
Service cost	15	15	16
Interest cost	32	40	44
Expected asset return	(52)	(63)	(65)
Amortization:
Amortization of Actuarial loss	11	16	13
Net periodic pension cost	6	8	8
Non-U.S. | Other Postretirement Benefits
Components of net periodic pension cost
Service cost	1	1	1
Interest cost	3	3	3
Amortization:
Net periodic pension cost	$ 4	4	$ 4
Canadian Pension Plans | Pension Benefit Plans
Amortization:
Settlement cost		27
Annuity contract purchase for settlement of pension obligation		123
Pension Plan of the United Kingdom | Pension Benefit Plans
Amortization:
Settlement cost		$ 15