Retirement Plans and Postretirement Medical Benefits (Weighted-Average Actuarial Assumptions) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits | United States
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.54%	3.34%	4.34%
Discount rate	3.34%	4.34%	3.69%
Expected return on plan assets	6.25%	6.75%	7.00%
Pension Benefits | Foreign | Minimum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	0.70%	0.65%	0.75%
Discount rate	0.65%	0.75%	0.65%
Expected return on plan assets	4.25%	4.25%	3.75%
Rate of compensation increase	1.50%	1.50%	1.50%
Rate of compensation increase	1.50%	1.50%	1.50%
Pension Benefits | Foreign | Maximum
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.40%	2.95%	3.55%
Discount rate	2.95%	3.55%	3.35%
Expected return on plan assets	6.00%	6.25%	6.25%
Rate of compensation increase	2.50%	2.50%	2.50%
Rate of compensation increase	2.50%	2.50%	3.25%
Nonpension postretirement benefit plans | United States
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.35%	3.20%	4.20%
Discount rate	3.20%	4.20%	3.55%
Nonpension postretirement benefit plans | Canada
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.50%	3.00%	3.60%
Discount rate	3.00%	3.60%	3.35%