Commitments and Contingencies (Details)	1 Months Ended	12 Months Ended
	Aug. 31, 2005 USD ($)	Dec. 31, 2019 USD ($) claim defendant case	Dec. 31, 2015	Dec. 31, 2014	Nov. 01, 2019 USD ($)	Nov. 01, 2019 BRL (R$)	Mar. 19, 2019 USD ($)	Mar. 19, 2019 BRL (R$)	Dec. 31, 2018 USD ($)
Commitments and Contingencies
Litigation Settlement, Amount Awarded to Other Party		$ 195,000,000
Accrual for Environmental Loss Contingencies		$ 7,000,000.0
Penalties per day					$ 6,000	R$ 25,000	$ 1,300	R$ 5,000
Penalties					2,500,000	10,000,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		35.00%
Loss contingency, Brazilian labor claims
Commitments and Contingencies
Liabilities for asserted and unasserted claims		$ 6,500,000							$ 7,100,000
Other
Commitments and Contingencies
Number of pending claims | claim		17,142
Loss provision		$ 0
Loss Contingency, Number of Defendants | defendant		90
Loss Contingency, Claims Dismissed, Number | case		28,227
Other | Minimum
Commitments and Contingencies
Loss Contingency, Damages Sought, Value		$ 20,000,000
Other | Maximum
Commitments and Contingencies
Loss Contingency, Damages Sought, Value		$ 25,000,000
Pending Litigation, Active Or In Extremis Docket | Other
Commitments and Contingencies
Number of pending claims | claim		45
Sao Paulo State Revenue Authority | Value-Added Tax Assessments January 2004 To May 2005
Commitments and Contingencies
Loss Contingency, Damages Sought, Principal Amount		$ 2,000,000
Estimated claims or assessment, additional amount		21,000,000
Loss Contingency, Reduced Penalty		2,000,000
Loss Contingency, Reduced Penalty, Including Interest		9,000,000
Sao Paulo State Revenue Authority | Value-Added Tax Assessments January 2002 To December 2003
Commitments and Contingencies
Loss Contingency, Damages Sought, Principal Amount	$ 1,500,000
Estimated claims or assessment, additional amount	4,800,000
Loss Contingency, Reduced Penalty		1,200,000
Loss Contingency, Damages Sought, Value	$ 6,300,000	12,000,000
Loss provision		$ 0
New York County as managed by the New York Supreme Court | Other
Commitments and Contingencies
Number of pending claims | case		16,595
New York County as managed by the New York Supreme Court | Pending And Future Litigation, Deferred Or Inactive Docket | Other
Commitments and Contingencies
Number of pending claims | claim		16,550
New York State Supreme Court, Counties Excluding New York County [Member] | Other
Commitments and Contingencies
Number of pending claims | case		117
Courts Located In States Other Than New York | Other
Commitments and Contingencies
Number of pending claims | case		430
NETHERLANDS
Commitments and Contingencies
Estimated claims or assessment, additional amount		$ 500,000
Allegheny County Health Department [Member]
Commitments and Contingencies
Estimated claims or assessment, additional amount		107,020
Pennsylvania Department Of Environmental Protection, Processed Slag [Member]
Commitments and Contingencies
Liabilities for asserted and unasserted claims		$ 400,000
Consolidated Revenue, Net [Member] | Subsidiary Concentration Risk [Member]
Commitments and Contingencies
Concentration risk			2.00%	2.00%
CSN [Member]
Commitments and Contingencies
Penalties per day					$ 25,000	R$ 100,000		R$ 20,000