Pensions Benefit Plans and Other Postretirement Benefits - Projected and Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets (Details) - Pension Benefit Plans - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
U.S.
Projected Benefit Obligation Exceeds the Fair Value of Plan Assets
Projected benefit obligations	$ 1,413	$ 1,650
Accumulated benefit obligation	1,412	1,650
Fair value of plan assets	1,094	1,394
Accumulated Benefit Obligations Exceeds the Fair Value of Plan Assets
Projected benefit obligations	1,413	1,650
Accumulated benefit obligation	1,412	1,650
Fair value of plan assets	1,094	1,394
Non-U.S.
Projected Benefit Obligation Exceeds the Fair Value of Plan Assets
Projected benefit obligations	815	905
Accumulated benefit obligation	793	878
Fair value of plan assets	591	682
Accumulated Benefit Obligations Exceeds the Fair Value of Plan Assets
Projected benefit obligations	815	261
Accumulated benefit obligation	793	241
Fair value of plan assets	$ 591	$ 39