Summary Of Significant Accounting Policies (Narrative) (Details). - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Summary Of Significant Accounting Policies [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax	$ 200	$ (400)	$ (500)
Cash	13,500	19,200
Cash and cash equivalents	9,660	19,232
Goodwill	35,717	70,608	70,608
Goodwill impairment	$ 34,891	$ 0	$ 0
Incremental shares excluded from the calculation of incremental shares attributable to stock options and restricted stock	2,925,091	2,760,983	1,582,222
Business Exit Costs	$ 1,300
Impairment of Richmond, Virginia Technical Center assets	3,500
Restructuring and Related Cost, Accelerated Depreciation	300
Gain (Loss) on Termination of Lease	100
Restructuring Reserve	513	$ 0
Charges	4,977
Payments for Restructuring	822
Restructuring Reserve, Charges Against Assets	3,642
Aluminum Extrusions
Summary Of Significant Accounting Policies [Line Items]
Goodwill	13,270	13,270	$ 13,270
Goodwill impairment	0
Closure of PE Films Technical Center
Summary Of Significant Accounting Policies [Line Items]
Restructuring Reserve		4,977
Employee Severance [Member]
Summary Of Significant Accounting Policies [Line Items]
Restructuring Reserve	385	0
Charges	895
Payments for Restructuring	510
Restructuring Reserve, Charges Against Assets	0
Employee Severance [Member] | Closure of PE Films Technical Center
Summary Of Significant Accounting Policies [Line Items]
Restructuring Reserve		895
Asset Impairment
Summary Of Significant Accounting Policies [Line Items]
Restructuring Reserve	0	0
Charges	3,454
Payments for Restructuring	0
Restructuring Reserve, Charges Against Assets	3,454
Asset Impairment | Closure of PE Films Technical Center
Summary Of Significant Accounting Policies [Line Items]
Restructuring Reserve		3,454
Other Restructuring [Member]
Summary Of Significant Accounting Policies [Line Items]
Restructuring Reserve	128	0
Charges	628
Payments for Restructuring	312
Restructuring Reserve, Charges Against Assets	188
Other Restructuring [Member] | Closure of PE Films Technical Center
Summary Of Significant Accounting Policies [Line Items]
Restructuring Reserve		628
Employee Severance [Member]
Summary Of Significant Accounting Policies [Line Items]
Business Exit Costs	900
Other Expense
Summary Of Significant Accounting Policies [Line Items]
Business Exit Costs	400
Surface protection films
Summary Of Significant Accounting Policies [Line Items]
Goodwill impairment	34,900
Goodwill, Impairment Loss, Net of Tax	27,000
Surface protection films
Summary Of Significant Accounting Policies [Line Items]
Goodwill	$ 22,400
Minimum | Buildings And Land Improvements
Summary Of Significant Accounting Policies [Line Items]
Average useful life	5 years
Minimum | Machinery and Equipment
Summary Of Significant Accounting Policies [Line Items]
Average useful life	2 years
Maximum | Buildings And Land Improvements
Summary Of Significant Accounting Policies [Line Items]
Average useful life	40 years
Maximum | Machinery and Equipment
Summary Of Significant Accounting Policies [Line Items]
Average useful life	20 years
Foreign Country
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 9,800	$ 10,300