Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies [Line Items]
Purchase commitments for property, plant and equipment	$ 296,400,000
Asset retirement obligation depreciation and accretion	11,900,000	$ 14,500,000	$ 9,100,000
Liability reserve for insurance claims	42,000,000.0	37,700,000
Outstanding letters of credit	17,200,000
Surety bonds	419,700,000
Due from affiliate	4,800,000
Guarantee of affiliate's obligations	12,500,000
Capital expenditures	$ 99,000,000.0	77,000,000.0	$ 106,700,000
Percentage of employees represented in labor union	14.00%
Woodville
Commitments And Contingencies [Line Items]
Collective bargaining agreement expiration month year	2022-06
Magnesia Specialties
Commitments And Contingencies [Line Items]
Collective bargaining agreement expiration month year	2027-08
Interest-only loan
Commitments And Contingencies [Line Items]
Due from affiliate	$ 6,000,000.0	$ 6,000,000.0
Maturity date	Dec. 31, 2022	Dec. 31, 2022
Revolving Line Of Credit Expires In August 2015
Commitments And Contingencies [Line Items]
Line of credit maturity period	2022-03
Revolving Facility
Commitments And Contingencies [Line Items]
Outstanding letters of credit	$ 2,600,000	$ 2,600,000
Capital Addition Purchase Commitments
Commitments And Contingencies [Line Items]
Purchase commitments for property, plant and equipment	101,700,000
Energy And Service Contracts
Commitments And Contingencies [Line Items]
Purchase commitments for property, plant and equipment	$ 194,700,000