Business Segments (Schedule Of Net Sales By Geographic Area) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1],[2]	$ 1,029,444	$ 927,647	$ 799,272
United States
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	691,232	584,066	475,734
Exports From The United States | Asia
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	75,904	84,846	73,220
Exports From The United States | Canada
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	51,984	46,505	45,683
Exports From The United States | Europe
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	6,203	8,505	7,348
Exports From The United States | Latin America
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	12,106	15,199	5,561
Operations Outside The United States | Brazil
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	101,217	87,155	90,571
Operations Outside The United States | The Netherlands
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	45,667	54,380	54,352
Operations Outside The United States | Hungary
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	33,512	24,727	24,207
Operations Outside The United States | China
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	7,814	12,199	14,390
Operations Outside The United States | India
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	$ 3,805	$ 10,065	$ 8,206

[1] Information on exports and foreign operations are provided on the previous page. Cash and cash equivalents includes funds held in locations outside the U.S. of $31.1 million and $32.7 million at December 31, 2018 and 2017, respectively. Export sales relate almost entirely to PE Films. Operations outside the U.S. in The Netherlands, Hungary, China and India also relate to PE Films. Operations in Brazil are primarily related to Flexible Packaging Films, but also include PE Films operations. Sales from locations in The Netherlands and Hungary are primarily to customers located in Europe. Sales from locations in China (Guangzhou and Shanghai) are primarily to customers located in China, but also include other customers in Asia.

[2] The difference between total consolidated sales as reported in the consolidated statements of income and segment, geographic and product group net sales reported in this note is freight of $36.0 million in 2018, $33.7 million in 2017 and $29.1 million in 2016.