Segment Reporting Schedule of Revenue by Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Sales	$ 219,722	$ 239,445
UNITED STATES
Disaggregation of Revenue [Line Items]
Sales	146,183	172,254
PE Films
Disaggregation of Revenue [Line Items]
Sales	71,261	66,779
PE Films \| Personal Care Materials [Member]
Disaggregation of Revenue [Line Items]
Sales	41,230	44,855
PE Films \| Surface Protection Films [Member]
Disaggregation of Revenue [Line Items]
Sales	28,353	19,888
PE Films \| Films For Other Markets [Member]
Disaggregation of Revenue [Line Items]
Sales	1,678	2,036
PE Films \| Film Products Subtotal [Member]
Disaggregation of Revenue [Line Items]
Sales	71,261	66,779
Flexible Packaging Films [Member] [Domain]
Disaggregation of Revenue [Line Items]
Sales	30,574	33,619
Aluminum Extrusions [Member]
Disaggregation of Revenue [Line Items]
Sales	117,887	139,047
Aluminum Extrusions [Member] \| Nonresidential Building And Construction [Member]
Disaggregation of Revenue [Line Items]
Sales	63,139	69,638
Aluminum Extrusions [Member] \| Consumer Durables [Member]
Disaggregation of Revenue [Line Items]
Sales	12,549	15,545
Aluminum Extrusions [Member] \| Distribution [Member]
Disaggregation of Revenue [Line Items]
Sales	7,738	8,573
Aluminum Extrusions [Member] \| Automotive [Member]
Disaggregation of Revenue [Line Items]
Sales	9,471	12,627
Aluminum Extrusions [Member] \| Residential Building And Construction [Member]
Disaggregation of Revenue [Line Items]
Sales	9,815	11,672
Aluminum Extrusions [Member] \| Aluminum Extrusions Subtotal [Member]
Disaggregation of Revenue [Line Items]
Sales	117,887	139,047
Aluminum Extrusions [Member] \| Machinery and Equipment BNL [Domain]
Disaggregation of Revenue [Line Items]
Sales	7,936	9,923
Aluminum Extrusions [Member] \| Electrical [Member]
Disaggregation of Revenue [Line Items]
Sales	7,239	11,069
Exports From United States [Member] \| Asia [Member]
Disaggregation of Revenue [Line Items]
Sales	22,164	13,493
Exports From United States [Member] \| CANADA
Disaggregation of Revenue [Line Items]
Sales	4,898	3,605
Exports From United States [Member] \| Europe [Member]
Disaggregation of Revenue [Line Items]
Sales	1,501	1,360
Exports From United States [Member] \| Latin America [Member]
Disaggregation of Revenue [Line Items]
Sales	3,134	2,867
Operations Outside United States [Member] \| BRAZIL
Disaggregation of Revenue [Line Items]
Sales	25,948	28,138
Operations Outside United States [Member] \| NETHERLANDS
Disaggregation of Revenue [Line Items]
Sales	7,885	9,587
Operations Outside United States [Member] \| HUNGARY
Disaggregation of Revenue [Line Items]
Sales	6,604	6,834
Operations Outside United States [Member] \| CHINA
Disaggregation of Revenue [Line Items]
Sales	0	230
Operations Outside United States [Member] \| INDIA
Disaggregation of Revenue [Line Items]
Sales	$ 1,405	$ 1,077