Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2021

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)	2021		2020
Land	$	26,627	$	5,686
Buildings	173,907		165,144
Machinery and equipment	687,502		645,195
Software	45,445		43,652
Construction in progress	130,838		69,297
Allowances for depreciation	(690,166)		(662,724)
Subtotal	374,153		266,250
Finance leases	32,865		34,301
Allowances for depreciation	(6,193)		(4,914)
Subtotal	26,672		29,387
Mineral resources	4,980		4,979
Mine development	30,059		30,058
Allowances for amortization and depletion	(26,889)		(20,988)
Subtotal	8,150		14,049
Property, plant, and equipment — net	$	408,975	$	309,686