Segments - Assets (Details) - USD ($) $ in Thousands	Mar. 28, 2026	Dec. 31, 2025
Segment Reporting Information [Line Items]
Total assets	$ 529,232	$ 568,383
Operating Segments \| High Purity Cellulose
Segment Reporting Information [Line Items]
Total assets	405,976	446,521
Operating Segments \| Paperboard & High Yield Pulp
Segment Reporting Information [Line Items]
Total assets	104,722	101,787
Corporate & Other
Segment Reporting Information [Line Items]
Total assets	$ 18,534	$ 20,075

Amount of asset recognized for present right to economic benefit, classified as current.

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+ Details