Commitments and Contingencies (Details) € in Thousands			3 Months Ended	6 Months Ended
	Jun. 30, 2025 USD ($) claim	Jun. 30, 2025 BRL (R$)	Jun. 30, 2025 USD ($) claim	Jun. 30, 2025 USD ($) claim case	Jun. 30, 2025 BRL (R$) claim	Jan. 17, 2025 company	Dec. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)	Jul. 19, 2024 EUR (€)	Nov. 30, 2022 USD ($)	Feb. 25, 2022 EUR (€)	Oct. 14, 2021 EUR (€)	Dec. 30, 2020 USD ($)	Jan. 27, 2020 party
Commitments and Contingencies
Number Of Potentially Related Parties						30
Reserve for loss contingencies	$ 29,000,000.0		$ 29,000,000.0	$ 29,000,000.0
Penalties	6,000,000		6,000,000	6,000,000	R$ 32,000,000
Current Portion of Environmental Liabilities	10,934,000		10,934,000	10,934,000			$ 11,815,000
Environmental liabilities	43,157,000		43,157,000	43,157,000			46,585,000
Total environmental liabilities	54,091,000		54,091,000	54,091,000			$ 58,400,000
BRAZIL
Commitments and Contingencies
Loss Contingencies, Unpaid Service Taxes													$ 1,900,000
Loss Contingencies, Overall Liability	$ 6,500,000		$ 6,500,000	6,500,000
Loss Contingency Accrual, Provision				$ 0
Kentucky Department of Environmental Protection
Commitments and Contingencies
Current Portion of Environmental Liabilities								$ 200,000
Proposed civil penalty								$ 800,000		$ 800,000
Other
Commitments and Contingencies
Number of pending claims | claim	17,000		17,000	17,000	17,000
Number of claims dismissed to date by stipulation or summary judgment prior to trial | case				28,500
Loss Contingency Accrual, Provision				$ 0
Alleged Violation of Environmental Permit in Ijmuiden, Netherland | Amsterdam Public Prosecutor’s Office
Commitments and Contingencies
Loss Contingency, Amount Seeking From Other Party | €												€ 100
Loss Contingency, Fine Issued By Court | €									€ 25		€ 5
Unfavorable Regulatory Action
Commitments and Contingencies
Loss Contingency Accrual, Provision			$ 27,200,000
Limit and Reduce the Accumulation of Customer-Owned Slag
Commitments and Contingencies
Loss contingency, damages sought, value	$ 12,000,000	R$ 66,000,000
Limit and Reduce the Accumulation of Customer-Owned Slag | CSN
Commitments and Contingencies
Loss contingency, damages sought, value	$ 48,000,000	R$ 264,000,000