Significant Accounting Policies - Property, Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2020
Factory machinery and equipment | Minimum
Property, Plant and Equipment
Estimated useful lives	5 years
Factory machinery and equipment | Maximum
Property, Plant and Equipment
Estimated useful lives	25 years
Glass-melting furnaces and forming machines | Minimum
Property, Plant and Equipment
Estimated useful lives	7 years
Glass-melting furnaces and forming machines | Maximum
Property, Plant and Equipment
Estimated useful lives	15 years
Buildings and building equipment | Minimum
Property, Plant and Equipment
Estimated useful lives	10 years
Buildings and building equipment | Maximum
Property, Plant and Equipment
Estimated useful lives	50 years