Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Segments - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2026	Jun. 28, 2025	Jun. 27, 2026	Jun. 28, 2025
Segment Reporting [Line Items]
Net sales	$ 376,142	$ 340,048	$ 695,207	$ 696,015
Operating Segments
Segment Reporting [Line Items]
Net sales	376,126	339,979	695,120	695,886
Operating Segments \| Total High Purity Cellulose
Segment Reporting [Line Items]
Net sales	301,462	271,960	564,363	553,982
Operating Segments \| Cellulose Specialties
Segment Reporting [Line Items]
Net sales	188,508	200,126	336,580	394,678
Operating Segments \| Cellulose Commodities
Segment Reporting [Line Items]
Net sales	100,980	58,484	203,191	131,326
Operating Segments \| Biomaterials and other
Segment Reporting [Line Items]
Net sales	11,974	13,350	24,592	27,978
Operating Segments \| Total Paperboard & High Yield Pulp
Segment Reporting [Line Items]
Net sales	74,664	68,019	130,757	141,904
Operating Segments \| Paperboard
Segment Reporting [Line Items]
Net sales	48,381	46,451	90,107	95,644
Operating Segments \| High Yield Pulp
Segment Reporting [Line Items]
Net sales	26,283	21,568	40,650	46,260
Corporate & Other
Segment Reporting [Line Items]
Net sales	$ 16	$ 69	$ 87	$ 129