Losses Associated With Plant Shutdowns, Asset Impairments And Restructurings, Unusual Items, Gains From Sale Of Assets And Other Items Restructuring Tables (Details) - USD ($) $ in Thousands	12 Months Ended			18 Months Ended	19 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2016
Other Accrued Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 1,380	$ 776	$ 1,103		$ 1,380	$ 2,408
Other Restructuring Costs	4,125	3,005
Restructuring and Related Cost, Incurred Cost			102,488
Payments for Restructuring	(2,639)	(3,099)	(2,198)
Restructuring Reserve Charged Against Assets	(882)	(141)	(101,595)
Restructuring Reserve Reversed to Income		(92)
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	1,294	616	627		1,294	1,854
Other Restructuring Costs	2,417
Severance Costs		2,654	589
Payments for Restructuring	(1,739)	(2,665)	(1,816)
Restructuring Reserve Charged Against Assets	0	0	0
Restructuring Reserve Reversed to Income		0
Long Lived Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	0	0		0	0
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items		233	101,595
Other Restructuring Costs	882
Payments for Restructuring	0	0	0
Restructuring Reserve Charged Against Assets	(882)	(141)	(101,595)
Restructuring Reserve Reversed to Income		(92)
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	86	160	476		86	$ 554
Other Restructuring Costs	826	118
Restructuring and Related Cost, Incurred Cost			304
Payments for Restructuring	(900)		(382)
Restructuring Reserve Charged Against Assets	0	0	0
Restructuring Reserve Reversed to Income		0
PE Films [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	800
PE Films [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	800	700	200
Terphane Ltda [Member] | Other Accrued Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items			101,254
Terphane Ltda [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items			0
Terphane Ltda [Member] | Long Lived Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items			101,254
Terphane Ltda [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items			0
PE Films [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	52
PE Films [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	842	822	589
PE Films [Member] | Long Lived Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	595	0	341
PE Films [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs		20
Aluminum Extrusions [Member] | Other Accrued Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	1,489	842	1,234
Aluminum Extrusions [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs			$ 304
Film Products Manufacturing Facility In Shanghai, China [Member] | PE Films [Member] | Other Accrued Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	829	2,163
Film Products Manufacturing Facility In Shanghai, China [Member] | PE Films [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	113	1,832
Film Products Manufacturing Facility In Shanghai, China [Member] | PE Films [Member] | Long Lived Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	0	200
Film Products Manufacturing Facility In Shanghai, China [Member] | PE Films [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	716	98
Payments for Restructuring	800	$ (434)			$ 3,300
Personal Care Materials [Member] | FilmProductsManufacturingFacilityInLakeZurichIllinois [Member] | PE Films [Member] | Other Accrued Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	1,123
Personal Care Materials [Member] | FilmProductsManufacturingFacilityInLakeZurichIllinois [Member] | PE Films [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	874
Personal Care Materials [Member] | FilmProductsManufacturingFacilityInLakeZurichIllinois [Member] | PE Films [Member] | Long Lived Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	200
Personal Care Materials [Member] | FilmProductsManufacturingFacilityInLakeZurichIllinois [Member] | PE Films [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	58
Other Restructuring Costs				$ 5,100
Severance Costs				$ 1,800
Payments for Restructuring	500
Personal Care Materials [Member] | PE Films Personal Care European Operations [Member] | PE Films [Member] | Other Accrued Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	684
Personal Care Materials [Member] | PE Films Personal Care European Operations [Member] | PE Films [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	588
Personal Care Materials [Member] | PE Films Personal Care European Operations [Member] | PE Films [Member] | Long Lived Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	100
Personal Care Materials [Member] | PE Films Personal Care European Operations [Member] | PE Films [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Losses Associated With Plant Shutdowns Asset Impairments Restructurings Unusual Items Gains Losses From Sale Of Assets Other Items	0
Payments for Restructuring	$ 500