Property, Plant and Equipment - Additional Information (Detail) £ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2024 GBP (£)
Property Plant And Equipment [Line Items]
Remaining lease term		20 years
Estimated cost on upgrading existing equipment			$ 26,000
Finance lease assets gross value	$ 2,964	$ 4,223
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Long-Term Debt and Lease Obligation, Current	Long-Term Debt and Lease Obligation, Current		Long-Term Debt and Lease Obligation, Current
Finance lease, lease related accumulated amortization	$ 1,498	$ 1,959
Depreciation expense	18,264	17,317
Depreciation on assets under finance leases	318	333
Interest capitalized on strategic capital projects	251	1,522
Union Electric Steel UK Limited [Member]
Property Plant And Equipment [Line Items]
Land and buildings held as collateral	2,660			£ 2,122
UES Domestic [Member] | Construction-in-Process, Machinery and Equipment or Buildings [Member]
Property Plant And Equipment [Line Items]
Machinery and equipment purchased	$ 24,239
Capital Expenditures [Member]
Property Plant And Equipment [Line Items]
Proceeds from disbursement agreement		$ 2,500