Pension, Post-Retirement and Post-Employment Plans - Key Assumptions Used to Determine Net Periodic Benefit Expense (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Domestic | Pension and SERP Benefits
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	3.30%	4.40%	3.70%
Rate of compensation increase	3.50%	3.50%	3.50%
Interest crediting rate	5.30%	5.20%	5.20%
Long-term rate of return on assets	5.10%	5.40%	5.40%
Domestic | Post-retirement Medical Benefits
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	3.20%	4.30%	3.70%
Foreign | Pension and SERP Benefits
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	1.00%	1.50%	1.40%
Rate of compensation increase	3.10%	3.40%	3.40%
Interest crediting rate	2.60%	2.60%	2.60%
Long-term rate of return on assets	1.70%	1.40%	1.80%
Foreign | Post-retirement Medical Benefits
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	7.30%	9.20%	9.90%