Contingencies and Legal Matters (Details)	9 Months Ended
	Sep. 30, 2020 employee
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year
Concentrations
Number of employees	0
IG BCE | Germany | Workforce Subject to Collective Bargaining Arrangements
Concentrations
Percentage of salaried employees eligible to be represented by Mining, Chemicals and Energy Trade Union (IG BCE)	50.00%
Percentage of hourly employees eligible to be represented by Mining, Chemicals and Energy Trade Union (IG BCE)	80.00%
USW | Lowville, NY | November 2021 | Workforce Subject to Collective Bargaining Arrangements
Concentrations
Number of employees	85
USW | Whiting, WI | January 2022 | Workforce Subject to Collective Bargaining Arrangements
Concentrations
Number of employees	198
USW | Appleton, WI | May 2022 | Workforce Subject to Collective Bargaining Arrangements
Concentrations
Number of employees	83
USW | Neenah, WI | June 2022 | Workforce Subject to Collective Bargaining Arrangements
Concentrations
Number of employees	173
USW | Munising, MI | July 2022 | Workforce Subject to Collective Bargaining Arrangements
Concentrations
Number of employees	172