Business Segments (Schedule Of Net Sales By Geographic Area) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	$ 729,604	$ 797,344	$ 824,664
United States
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	530,243	593,599	636,968
Exports From The United States | Asia
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	80,217	82,342	74,499
Revenues		35,100	32,100	28,900
Exports From The United States | Canada
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	18,024	15,022	16,467
Exports From The United States | Europe
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	5,440	5,752	3,909
Exports From The United States | Latin America
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	2,169	4,135	991
Operations Outside The United States | Brazil
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	93,511	96,274	85,868
Operations Outside The United States | China
Segment Reporting Information [Line Items]
Net Sales by Geographic Area, Total	[1]	$ 0	$ 220	$ 5,962

[1] Cash and cash equivalents includes funds held in locations outside the U.S. of $9.4 million and $8.9 million at December 31, 2020 and 2019, respectively. (c)Information on exports and foreign operations are provided on the previous page. Export sales relate almost entirely to PE Films. Operations in China relate to PE Films. Operations in Brazil relate to Flexible Packaging Films.