Helguvik and Ravenswood Gains and (Losses)	12 Months Ended
Dec. 31, 2018
Asset Impairment Charges [Abstract]
Helguvik and Ravenswood Gains and (Losses)	Helguvik and Ravenswood Gains and (Losses) Helguvik In November 2016, the arbitration panel in the proceedings between Nordural Helguvik ehf and HS concluded that our agreement with HS was no longer in force. We determined that the lack of a power agreement for the entirety of the project requirements represented an indicator of impairment associated with the Helguvik project. Our analysis of the project indicated the undiscounted cash flows did not exceed the carrying value of the Helguvik project. Discounted cash flows were utilized to reduce the carrying value of the Helguvik project to fair value. We considered future development plans for the project, the lack of a power agreement for the entirety of the project requirements and long-term forward prices of LME and European Duty Paid premium along with alumina and power costs. As a result, we recorded an impairment loss of $152.2 million representing the net book value of the Helguvik project as of December 31, 2016. During 2018 and 2017, we extinguished our contractual commitments associated with the construction of the Helguvik project. Such extinguishment resulted in gains of $4.5 million and $7.3 million recognized in Helguvik (gains) losses in the consolidated statements of operations for the years ended December 31, 2018 and 2017, respectively. Ravenswood In July 2015, we announced the permanent closure of our Ravenswood, West Virginia aluminum smelter ("Ravenswood"). Ravenswood had been idled since February 2009. The decision to permanently close Ravenswood was based on the inability to secure a competitive power contract for the smelter, compounded by challenging aluminum market conditions largely driven by increased exports of aluminum from China. In June 2015, we recorded an impairment charge of $30.9 million to write down the asset values related to Ravenswood. Based on an asset purchase agreement for the sale of assets entered into in 2016, we recorded an additional impairment charge of $3.8 million, included in Ravenswood (gains) losses in the consolidated statements of operations for the year ended December 31, 2016. In January 2017, we completed our sale of the Ravenswood facility for $13.6 million in net proceeds from the buyer.

Helguvik and Ravenswood Gains and (Losses)

Helguvik

In November 2016, the arbitration panel in the proceedings between Nordural Helguvik ehf and HS concluded that our agreement with HS was no longer in force. We determined that the lack of a power agreement for the entirety of the project requirements represented an indicator of impairment associated with the Helguvik project.

Our analysis of the project indicated the undiscounted cash flows did not exceed the carrying value of the Helguvik project. Discounted cash flows were utilized to reduce the carrying value of the Helguvik project to fair value. We considered future development plans for the project, the lack of a power agreement for the entirety of the project requirements and long-term forward prices of LME and European Duty Paid premium along with alumina and power costs. As a result, we recorded an impairment loss of $152.2 million representing the net book value of the Helguvik project as of December 31, 2016.

During 2018 and 2017, we extinguished our contractual commitments associated with the construction of the Helguvik project. Such extinguishment resulted in gains of $4.5 million and $7.3 million recognized in Helguvik (gains) losses in the consolidated statements of operations for the years ended December 31, 2018 and 2017, respectively.

Ravenswood

In July 2015, we announced the permanent closure of our Ravenswood, West Virginia aluminum smelter ("Ravenswood"). Ravenswood had been idled since February 2009. The decision to permanently close Ravenswood was based on the inability to secure a competitive power contract for the smelter, compounded by challenging aluminum market conditions largely driven by increased exports of aluminum from China.

In June 2015, we recorded an impairment charge of $30.9 million to write down the asset values related to Ravenswood. Based on an asset purchase agreement for the sale of assets entered into in 2016, we recorded an additional impairment charge of $3.8 million, included in Ravenswood (gains) losses in the consolidated statements of operations for the year ended December 31, 2016. In January 2017, we completed our sale of the Ravenswood facility for $13.6 million in net proceeds from the buyer.