Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Summary of Property, Plant and Equipment

Property, plant, and equipment on the Consolidated Balance Sheets is summarized as follows:

	December 31,
(Thousands)	2022		2021
Land	$	26,579	$	26,627
Buildings	200,223		173,907
Machinery and equipment	770,628		687,502
Software	44,886		45,445
Construction in progress	100,188		130,838
Allowances for depreciation	(720,455)		(690,166)
Subtotal	422,049		374,153
Finance leases	31,662		32,865
Allowances for depreciation	(7,395)		(6,193)
Subtotal	24,267		26,672
Mineral resources	4,980		4,980
Mine development	30,059		30,059
Allowances for amortization and depletion	(32,590)		(26,889)
Subtotal	2,449		8,150
Property, plant, and equipment — net	$	448,765	$	408,975