Derivative Financial Instruments (Narrative) (Details) R$ in Thousands, $ in Thousands, lbs in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2020 BRL (R$)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($) lbs	Jun. 30, 2020 BRL (R$) lbs	Dec. 31, 2019 USD ($) lbs
Derivative [Line Items]
Amounts of unrealized after tax gains (losses) to be Reclassified within Twelve Months		$ 1,400
Aluminum Futures Contracts
Derivative [Line Items]
Derivative, Notional Amount			$ 20,100		$ 20,200
Net asset (liability), Fair Value			$ (1,857)		$ (1,253)
Commitment Under Cash Flow Hedges, Mass | lbs			21.7	21.7	19.6
Terphane Ltda [Member]
Derivative [Line Items]
Derivative, Notional Amount			$ 13,050	R$ 51,573
Accrued Expenses [Member] | Derivatives Designated As Hedging Instruments [Member] | Aluminum Futures Contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset			172		$ 6
Derivative Liability, Fair Value, Gross Liability			2,029		$ 1,259
Cash Flow Hedging [Member] | Foreign Currency Forwwards And Options [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax			$ 3,500
Oct-2018 [Member] | Terphane Ltda [Member]
Derivative [Line Items]
Annual Net Costs Mismatch Translation Exposure - Real vs US Dollar | R$	R$ 136,000