Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (75,444)	$ 48,259	$ 24,842
Unrealized foreign currency translation adjustment (net of tax benefit of $897 in 2020, net of tax benefit of $623 in 2019 and net of tax of $281 in 2018)	(8,781)	(3,723)	(10,762)
Reclassification of foreign currency translation loss realized on the sale of Personal Care Films	25,295	0	0
Other comprehensive income (loss):
Other comprehensive income (loss)	19,247	(17,664)	(3,318)
Comprehensive income (loss)	(56,197)	30,595	21,524
Net gains (losses) and prior service costs (net of tax benefit of $4,228 in 2020, net of tax benefit of $6,417 in 2019 and net of tax benefit of $319 in 2018)	(12,197)	(22,508)	(1,118)
Amortization of prior service costs and net gains or losses (net of tax of $3,937 in 2020, net of tax of $2,359 in 2019 and net of tax of $3,028 in 2018)	11,359	8,273	10,622
Other Comprehensive Income (Loss), Net of Tax	19,247	(17,664)	(3,318)
Derivative financial instruments adjustment	$ 3,571	$ 294	$ (2,060)