Pension and Postretirement Benefit Plans - Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2017 USD ($)
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
2018	$ 135
2019	1,072
2020	44
2021	43
2022	43
2023 to 2027	204
Total	1,541
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2018	17
2019	26
2020	17
2021	17
2022	19
2023 to 2027	105
Total	201
Other Postretirement Benefits Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2018	5
2019	5
2020	5
2021	5
2022	5
2023 to 2027	27
Total	$ 52