General	9 Months Ended
Sep. 30, 2018
Accounting Policies [Abstract]
General	General The accompanying unaudited interim consolidated financial statements of Century Aluminum Company should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2017. In management’s opinion, the unaudited interim consolidated financial statements reflect all adjustments, which are of a normal and recurring nature, that are necessary for a fair presentation of financial results for the interim periods presented. Operating results for the first nine months of 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. Throughout this Form 10-Q, and unless expressly stated otherwise or as the context otherwise requires, "Century Aluminum," "Century," the "Company", "we," "us," "our" and "ours" refer to Century Aluminum Company and its consolidated subsidiaries. Hawesville Restart Project During 2018, we began restarting the curtailed capacity at our Hawesville facility, which may ultimately involve rebuilding all five potlines. The nature, size and scope of this effort represents a discrete construction project. All associated costs that meet the capitalization criteria will be capitalized as a component of property, plant and equipment. Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-02, "Leases (Topic 842)". The objective of ASU 2016-02 is to provide enhanced transparency and comparability among organizations by, among other things, recognizing right-of-use assets and lease liabilities on the balance sheet for all leases other than those that meet the definition of short-term leases and disclosing qualitative and quantitative information about lease arrangements. The new standard continues to classify leases as either finance or operating, with classification affecting the pattern of expense recognition in the statement of operations. ASU 2016-02 is effective for Century beginning January 1, 2019. Through September 30, 2018, we have determined the scope of arrangements impacted by the standard, and are evaluating the impact of adopting this standard to such arrangements. We are also in the process of determining the applicable key assumptions in applying the standard. In conjunction with the aforementioned implementation activities, we continue enhancing our internal processes and controls to capture arrangements that are likely to be in scope of the standard upon and post adoption. We anticipate the adoption of ASU 2016-02 to result in the recognition of right-of-use assets and lease liabilities for most leases currently accounted for as operating leases. We do not anticipate the adoption of this standard to have any impact to our cash flows. We continue to monitor modifications, clarifications or interpretations undertaken by the FASB and Securities and Exchange Commission ("SEC") and changes in our business and new arrangements, which may impact our current conclusions. We expect to adopt the standard on a modified retrospective basis.

General

The accompanying unaudited interim consolidated financial statements of Century Aluminum Company should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2017. In management’s opinion, the unaudited interim consolidated financial statements reflect all adjustments, which are of a normal and recurring nature, that are necessary for a fair presentation of financial results for the interim periods presented. Operating results for the first nine months of 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. Throughout this Form 10-Q, and unless expressly stated otherwise or as the context otherwise requires, "Century Aluminum," "Century," the "Company", "we," "us," "our" and "ours" refer to Century Aluminum Company and its consolidated subsidiaries.

Hawesville Restart Project

During 2018, we began restarting the curtailed capacity at our Hawesville facility, which may ultimately involve rebuilding all five potlines. The nature, size and scope of this effort represents a discrete construction project. All associated costs that meet the capitalization criteria will be capitalized as a component of property, plant and equipment.

Recently Issued Accounting Standards

In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-02, "Leases (Topic 842)". The objective of ASU 2016-02 is to provide enhanced transparency and comparability among organizations by, among other things, recognizing right-of-use assets and lease liabilities on the balance sheet for all leases other than those that meet the definition of short-term leases and disclosing qualitative and quantitative information about lease arrangements. The new standard continues to classify leases as either finance or operating, with classification affecting the pattern of expense recognition in the statement of operations. ASU 2016-02 is effective for Century beginning January 1, 2019.

Through September 30, 2018, we have determined the scope of arrangements impacted by the standard, and are evaluating the impact of adopting this standard to such arrangements. We are also in the process of determining the applicable key assumptions in applying the standard. In conjunction with the aforementioned implementation activities, we continue enhancing our internal processes and controls to capture arrangements that are likely to be in scope of the standard upon and post adoption. We anticipate the adoption of ASU 2016-02 to result in the recognition of right-of-use assets and lease liabilities for most leases currently accounted for as operating leases. We do not anticipate the adoption of this standard to have any impact to our cash flows. We continue to monitor modifications, clarifications or interpretations undertaken by the FASB and Securities and Exchange Commission ("SEC") and changes in our business and new arrangements, which may impact our current conclusions. We expect to adopt the standard on a modified retrospective basis.