Century Aluminum (CENX) 10-Q 9 Aug 17 2017 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 28, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	CENTURY ALUMINUM CO
Entity Central Index Key	949,157
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Amendment Flag	false
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		87,317,237

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
NET SALES:
Related parties	$ 296,271	$ 290,283	$ 576,844	$ 570,660
Other customers	92,531	36,471	177,744	74,948
Total net sales	388,802	326,754	754,588	645,608
Cost of goods sold	366,342	321,172	715,277	643,078
Gross profit	22,460	5,582	39,311	2,530
Selling, general and administrative expenses	9,352	9,945	20,054	19,570
Other operating expense - net	180	578	1,153	1,459
Operating income (loss)	12,928	(4,941)	18,104	(18,499)
Interest expense	(5,461)	(5,497)	(11,032)	(10,990)
Interest income	283	171	513	285
Net gain (loss) on forward and derivative contracts	2,957	353	(13,180)	706
Other (expense) - net	(1,876)	(299)	(1,492)	(305)
Income (loss) before income taxes and equity in earnings of joint ventures	8,831	(10,213)	(7,087)	(28,803)
Income tax (expense) benefit	(1,452)	319	(1,144)	2,389
Income (loss) before equity in earnings of joint ventures	7,379	(9,894)	(8,231)	(26,414)
Equity in (loss) earnings of joint ventures	(248)	379	223	736
Net income (loss)	7,131	(9,515)	(8,008)	(25,678)
Net income (loss) allocated to common stockholders	$ 6,563	$ (9,515)	$ (8,008)	$ (25,678)
INCOME (LOSS) PER COMMON SHARE:
Basic (in USD per share)	$ 0.08	$ (0.11)	$ (0.09)	$ (0.29)
Diluted (in USD per share)	$ 0.07	$ (0.11)	$ (0.09)	$ (0.29)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic (shares)	87,272	87,060	87,263	87,050
Diluted (shares)	88,057	87,060	87,263	87,050

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Comprehensive income (loss):
Net income (loss)	$ 7,131	$ (9,515)	$ (8,008)	$ (25,678)
Other comprehensive income (loss) before income tax effect:
Net loss on foreign currency cash flow hedges reclassified as income	(48)	(47)	(94)	(93)
Defined benefit plans and other postretirement benefits:
Amortization of prior service benefit during the period	(671)	(667)	(982)	(1,334)
Amortization of net loss during the period	577	1,920	2,720	3,839
Other comprehensive income (loss) before income tax effect	(142)	1,206	1,644	2,412
Income tax effect	311	(382)	(763)	(765)
Other comprehensive income	169	824	881	1,647
Total comprehensive income (loss)	$ 7,300	$ (8,691)	$ (7,127)	$ (24,031)

CONSOLIDATED BALANCE SHEETS (Un

CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 130,673	$ 132,403
Restricted cash	855	1,050
Accounts receivable - net	42,473	12,432
Due from affiliates	10,495	16,651
Inventories	254,611	233,563
Prepaid and other current assets	18,624	22,210
Assets held for sale	0	22,313
Total current assets	457,731	440,622
Property, plant and equipment - net	1,000,503	1,026,285
Other assets	67,395	73,420
TOTAL	1,525,629	1,540,327
LIABILITIES:
Accounts payable, trade	92,131	94,960
Due to affiliates	19,092	15,368
Accrued and other current liabilities	45,679	50,100
Accrued employee benefits costs	10,767	10,917
Industrial revenue bonds	7,815	7,815
Total current liabilities	175,484	179,160
Senior notes payable	247,922	247,699
Accrued pension benefits costs - less current portion	47,601	49,493
Accrued postretirement benefits costs - less current portion	128,033	126,355
Other liabilities	66,840	72,026
Deferred taxes	108,988	108,939
Total noncurrent liabilities	599,384	604,512
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY:
Preferred stock	1	1
Common stock	945	944
Additional paid-in capital	2,516,363	2,515,131
Treasury stock, at cost	(86,276)	(86,276)
Accumulated other comprehensive loss	(113,012)	(113,893)
Accumulated deficit	(1,567,260)	(1,559,252)
Total shareholders’ equity	750,761	756,655
TOTAL	$ 1,525,629	$ 1,540,327

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (8,008)	$ (25,678)
Adjustments to reconcile net loss to net cash provided by operating activities:
Unrealized loss on forward and derivative contracts	7,857	0
Unrealized gain on E.ON contingent obligation	(706)	(706)
Lower of cost or NRV inventory adjustment	(4,102)	(871)
Depreciation and amortization	42,222	42,504
Pension and other postretirement benefits	1,524	1,345
Deferred income taxes	(757)	(6,513)
Equity in earnings of joint ventures, net of dividends	(145)	(736)
Change in operating assets and liabilities:
Accounts receivable - net	(30,040)	(4,829)
Due from affiliates	6,156	2,906
Inventories	(16,946)	2,471
Prepaid and other current assets	3,834	12,516
Accounts payable, trade	(947)	(1,019)
Due to affiliates	3,604	1,560
Accrued and other current liabilities	(4,447)	(485)
Other - net	3,994	1,138
Net cash provided by operating activities	3,093	23,603
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(18,843)	(7,734)
Proceeds from sale of Ravenswood	13,585	0
Restricted and other cash deposits	195	(1,878)
Net cash used in investing activities	(5,063)	(9,612)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under revolving credit facilities	720	595
Repayments under revolving credit facilities	(720)	(595)
Issuance of common stock	240	0
Net cash provided by financing activities	240	0
CHANGE IN CASH AND CASH EQUIVALENTS	(1,730)	13,991
Cash and cash equivalents, beginning of period	132,403	115,393
Cash and cash equivalents, end of period	$ 130,673	$ 129,384

General

General	6 Months Ended
	Jun. 30, 2017
General [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, 2016 . 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 six months of 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 . 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. In May 2014, the Financial Accounting Standards Board ("FASB") and International Accounting Standards Board ("IASB") issued their final standard on revenue from contracts with customers. The standard, issued as ASU 2014-09 "Revenue From Contracts with Customers (Topic 606)" by the FASB, outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. Compared with current GAAP, the ASU requires significantly expanded disclosures about revenue recognition. The ASU is effective for Century beginning January 1, 2018. Based on our assessment completed to date and historical terms of our most significant revenue contract with customers, we anticipate identifying similar performance obligations under ASU 2014-09, as compared with deliverables and separate units of accounts previously. Accordingly, we do not expect a material difference in the timing and amount of revenues recognized today and those upon the adoption of ASU 2014-09, and we expect to adopt the standard on a modified retrospective basis. We continue to assess the impact of adopting this standard as our revenue contracts for 2018 are executed. Our preliminary conclusion may differ from that reached on the adoption date, based on actual terms of our revenue contracts with customers, industry clarifications and additional guidance from the FASB and the Securities and Exchange Commission, in effect as of the adoption date.

Related party transactions

Related party transactions	6 Months Ended
	Jun. 30, 2017
Related Party Transactions [Abstract]
Related party transactions	Related party transactions Our significant related party transactions occurring during the six months ended June 30, 2017 and 2016 are described below. We believe that all of the transactions with our related parties were on terms that approximate market. Glencore ownership As of June 30, 2017 , Glencore plc and its affiliates (together "Glencore") owned 42.9% of Century’s outstanding common stock ( 47.5% on a fully-diluted basis assuming the conversion of all of the Series A Convertible Preferred Stock) and all of our outstanding Series A Convertible Preferred Stock. From time to time Century and Glencore enter into various transactions for the purchase and sale of primary aluminum, purchase and sale of alumina, tolling agreements and certain forward financial contracts. Sales to Glencore For the three months ended June 30, 2017 and 2016 we derived approximately 76% and 89% , respectively, of our consolidated sales from Glencore, while for the six months ended June 30, 2017 and 2016, approximately 76% and 88% , respectively, of our consolidated sales were derived from Glencore. We have entered into agreements with Glencore pursuant to which Glencore has agreed to purchase aluminum produced from our U.S. and Icelandic operations through 2017. Glencore purchases aluminum produced at our North American smelters at prices based on the London Metal Exchange (the "LME") price for primary aluminum plus the Midwest regional delivery premium and any additional negotiated product premiums. Glencore purchases aluminum produced at our Grundartangi, Iceland smelter at prices based on the LME plus the European Duty Paid premium and any applicable product premiums. Glencore purchases the aluminum we produce for resale. Purchases from Glencore We purchase alumina from Glencore under a long-term supply agreement and on a spot basis. Pursuant to our current agreement, Glencore has agreed to supply us with alumina through 2017 at prices indexed to the LME price of primary aluminum. In 2016 and 2017, upon mutual agreement, all of our purchases from Glencore under this agreement were priced based on a published alumina index. Financial contracts with Glencore During 2017, we entered into certain financial contracts with Glencore. Refer to Note 13 Derivatives to the consolidated financial statements included herein. Transactions with Baise Haohai Carbon Co., Ltd. ("BHH") We own a 40% stake in BHH, a joint venture that owns a carbon anode and cathode facility located in the Guangxi Zhuang Autonomous Region of south China. We have an agreement with BHH to provide carbon anodes to Grundartangi through December 31, 2017. Summary A summary of the aforementioned significant related party transactions for the three and six months ended June 30, 2017 and 2016 is as follows: Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Net sales to Glencore $ 296,271 $ 290,283 $ 576,844 $ 570,660 Purchases from Glencore 41,587 50,177 113,168 94,190 Purchases from BHH 3,109 2,715 5,889 5,098

Fair value measurements

Fair value measurements	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements The following section describes the valuation methodology used to measure our financial assets and liabilities that were accounted for at fair value and are categorized based on the fair value hierarchy described in Accounting Standards Codification ("ASC") 820, "Fair Value Measurements and Disclosures." Overview of Century’s valuation methodology Level Significant inputs Cash equivalents 1 Quoted market prices Trust assets (1) 1 Quoted market prices Surety bonds 1 Quoted market prices Forward financial sales 2 Quoted market prices Fixed for floating swaps 3 Quoted market prices, management's estimates of future U.S. Midwest premium E.ON contingent obligation 3 Quoted market prices, management’s estimates of the LME forward market prices for periods beyond the quoted periods and management’s estimate of future level of operations (1) Trust assets are currently invested in money market funds. These trust assets are held to fund the non-qualified supplemental executive pension benefit obligations for certain of our officers. The trust has sole authority to invest the funds in secure interest producing investments consisting of short-term securities issued or guaranteed by the United States government or cash and cash equivalents. Our fair value measurements include the consideration of market risks that other market participants might consider in pricing the particular asset or liability, specifically non-performance risk and counterparty credit risk. Considerations of the non-performance risk and counterparty credit risk are used to establish the appropriate risk-adjusted discount rates used in our fair value measurements. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment, and may affect the valuation of fair value assets and liabilities and the placement within the fair value hierarchy levels. There were no transfers between Level 1 and 2 during the periods presented. There were no transfers into or out of Level 3 during the periods presented. It is our policy to recognize transfers into and transfers out of Level 3 as of the date of the event or change in circumstances that caused the transfer. The following table sets forth our financial assets and liabilities that were accounted for at fair value on a recurring basis by the level of input within the ASC 820 fair value hierarchy. Recurring Fair Value Measurements As of June 30, 2017 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 82,567 $ — $ — $ 82,567 Trust assets 2,703 — — 2,703 Surety bonds 1,625 — — 1,625 Derivatives — — 354 354 TOTAL $ 86,895 $ — $ 354 $ 87,249 LIABILITIES: E.ON contingent obligation - net $ — $ — $ — $ — Derivatives — 7,208 331 7,539 TOTAL $ — $ 7,208 $ 331 $ 7,539 Recurring Fair Value Measurements As of December 31, 2016 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 79,014 $ — $ — $ 79,014 Trust assets 3,147 — — 3,147 Surety bonds 1,874 — — 1,874 Derivatives — — 925 925 TOTAL $ 84,035 $ — $ 925 $ 84,960 LIABILITIES: E.ON contingent obligation – net $ — $ — $ — $ — Derivatives — — 253 253 TOTAL $ — $ — $ 253 $ 253

Earnings (loss) per share

Earnings (loss) per share	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Earnings (loss) per share	Earnings (loss) per share Basic earnings (loss) per share ("EPS") amounts are calculated by dividing net income (loss) allocated to common stockholders by the weighted average number of common shares outstanding. Diluted EPS amounts assume the issuance of common stock for all dilutive securities. The following table shows the basic and diluted earnings (loss) per share for the three and six months ended June 30, 2017 and 2016 : For the three months ended June 30, 2017 2016 Income Shares (000) Per Share Loss Shares (000) Per Share Net income (loss) $ 7,131 $ (9,515 ) Amount allocated to common stockholders 92.03 % 100.00 % Basic EPS: Net income (loss) allocated to common stockholders $ 6,563 87,272 $ 0.08 $ (9,515 ) 87,060 $ (0.11 ) Effect of Dilutive Securities: Share-based compensation — 785 — — Diluted EPS: Net income (loss) allocated to common stockholders with assumed conversion $ 6,563 88,057 $ 0.07 $ (9,515 ) 87,060 $ (0.11 ) For the six months ended June 30, 2017 2016 Loss Shares (000) Per Share Loss Shares (000) Per Share Net loss $ (8,008 ) $ (25,678 ) Amount allocated to common stockholders 100.00 % 100 % Basic and diluted EPS: Net loss allocated to common stockholders $ (8,008 ) 87,263 $ (0.09 ) $ (25,678 ) 87,050 $ (0.29 ) Securities excluded from the calculation of diluted EPS: Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Share-based compensation 432,506 1,800,096 462,506 1,288,473

Shareholders' equity

Shareholders' equity	6 Months Ended
	Jun. 30, 2017
Stockholders' Equity Note [Abstract]
Shareholders' equity	Shareholders’ equity Common Stock As of June 30, 2017 and December 31, 2016 , we had 195,000,000 shares of common stock, $0.01 cent par value per share, authorized under our Restated Certificate of Incorporation, of which 94,502,486 shares were issued and 87,315,965 shares were outstanding at June 30, 2017 ; 94,437,418 shares were issued and 87,250,897 shares were outstanding at December 31, 2016 . The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock which are currently outstanding, including our Series A Convertible Preferred Stock, or which we may designate and issue in the future. Stock Repurchase Program In 2011, our Board of Directors approved a $60,000 common stock repurchase program which was expanded in 2015 to $130,000 . Through June 30, 2017 we had repurchased 7,186,521 shares of common stock for an aggregate purchase price of $86,276 . We have made no share repurchases since April 2015 and we have $43,724 remaining under the repurchase program authorization. The repurchase program may be expanded, suspended or discontinued by our Board, in its sole discretion, at any time. Shares of common stock repurchased are recorded at cost as treasury stock and result in a reduction of shareholders’ equity in the consolidated balance sheets. From time to time, treasury shares may be reissued and we use an average cost method for determining the cost for reissued treasury shares. The difference between the cost of the shares and the reissuance price is added to or deducted from additional paid-in capital. Preferred Stock As of June 30, 2017 and December 31, 2016 we had 5,000,000 shares of preferred stock, $0.01 cent par value per share, authorized under our Restated Certificate of Incorporation. In 2008, we issued 160,000 shares of our Series A Convertible Preferred Stock, all of which are held by Glencore, and at June 30, 2017 and December 31, 2016 , 75,346 and 75,625 shares were outstanding, respectively. The issuance of common stock under our stock incentive programs, debt exchange transactions and any stock offering that excludes Glencore participation triggers anti-dilution provisions of the preferred stock agreement and results in the automatic conversion of Series A Convertible Preferred Stock shares into shares of common stock. The conversion of preferred to common shares is 100 shares of common for each share of preferred stock. Our Series A Convertible Preferred Stock has a par value of $0.01 per share. Our Board of Directors may issue preferred stock in one or more series and determine for each series the dividend rights, conversion rights, voting rights, redemption rights, liquidation preferences, sinking fund terms and the number of shares constituting that series, as well as the designation thereof. Depending upon the terms of preferred stock established by our Board of Directors, any or all of the preferred stock could have preference over the common stock with respect to dividends and other distributions and upon the liquidation of Century. In addition, issuance of any shares of preferred stock with voting powers may dilute the voting power of the outstanding common stock. The Common and Preferred Stock Activity table below contains additional information about preferred stock conversions during the six months ended June 30, 2017 and 2016 . Common and Preferred Stock Activity: Preferred stock Common stock (in shares) Series A convertible Treasury Outstanding Beginning balance as of December 31, 2016 75,625 7,186,521 87,250,897 Conversion of convertible preferred stock (279 ) — 27,904 Issuance for share-based compensation plans — — 37,164 Ending balance as of June 30, 2017 75,346 7,186,521 87,315,965 Beginning balance as of December 31, 2015 76,539 7,186,521 87,038,050 Conversion of convertible preferred stock (161 ) — 16,109 Issuance for share-based compensation plans — — 21,428 Ending balance as of June 30, 2016 76,378 7,186,521 87,075,587

Income taxes

Income taxes	6 Months Ended
	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income taxes	Income taxes We recorded income tax expense of $1,452 for the three months ended June 30, 2017 and an income tax benefit of $319 for the three months ended June 30, 2016 which primarily consisted of foreign income taxes. For the six months ended June 30, 2017 we recorded income tax expense of $1,144 and for the six months ended June 30, 2016 we recorded an income tax benefit of $2,389 . Our income tax benefit or expense is based on an annual effective tax rate forecast, including estimates and assumptions that could change during the year. The application of the accounting requirements for income taxes in interim periods, after consideration of our valuation allowance, causes a significant variation in the typical relationship between income tax expense and pretax accounting income. As of June 30, 2017 , all of Century's U.S. and certain foreign deferred tax assets, net of deferred tax liabilities, continue to be subject to a valuation allowance.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2017
Inventory, Net [Abstract]
Inventories	Inventories Inventories consist of the following: June 30, 2017 December 31, 2016 Raw materials $ 80,134 $ 59,415 Work-in-process 43,931 35,539 Finished goods 23,169 26,613 Operating and other supplies 107,377 111,996 Total inventories $ 254,611 $ 233,563 Inventories are stated at the lower of cost or Net Realizable Value ("NRV") using the first-in, first-out ("FIFO") or the weighted average cost method.

Debt

Debt	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Debt	Debt June 30, 2017 December 31, 2016 Debt classified as current liabilities: Hancock County industrial revenue bonds ("IRBs") due 2028, interest payable quarterly (variable interest rates (not to exceed 12%)) (1) $ 7,815 $ 7,815 Debt classified as non-current liabilities: 7.5% senior secured notes due June 1, 2021, net of debt discount of $2,078 and $2,301, respectively, interest payable semiannually 247,922 247,699 Total $ 255,737 $ 255,514 (1) The IRBs are classified as current liabilities because they are remarketed weekly and could be required to be repaid upon demand if there is a failed remarketing. The IRB interest rate at June 30, 2017 was 1.11% . U.S. Revolving Credit Facility We and certain of our direct and indirect domestic subsidiaries are party to a senior secured revolving credit facility, dated May 24, 2013, as amended, with a syndicate of lenders which provides for borrowings of up to $150,000 in the aggregate, including up to $110,000 under a letter of credit sub-facility (the "U.S. revolving credit facility"). Our U.S. revolving credit facility matures in June 2020. Any letters of credit issued and outstanding under the U.S. revolving credit facility reduce our borrowing availability on a dollar-for-dollar basis. The availability of funds under the U.S. revolving credit facility is limited by a specified borrowing base consisting of accounts receivable, inventory and qualified cash deposits of the borrowers which meet the eligibility criteria. Status of our U.S. revolving credit facility: June 30, 2017 Credit facility maximum amount $ 150,000 Borrowing availability 123,921 Outstanding letters of credit issued 38,242 Outstanding borrowings — Borrowing availability, net of outstanding letters of credit and borrowings 85,679 Iceland Revolving Credit Facility We have also entered into, through our wholly-owned subsidiary Nordural Grundartangi ehf, a $50,000 revolving credit facility, dated November 27, 2013 (the "Iceland revolving credit facility"). The Iceland revolving credit facility expires on November 27, 2018. The availability of funds under the Iceland revolving credit facility is limited by a specified borrowing base consisting of inventory and accounts receivable of Grundartangi. Status of our Iceland revolving credit facility: June 30, 2017 Credit facility maximum amount $ 50,000 Borrowing availability 50,000 Outstanding borrowings — Borrowing availability, net of borrowings 50,000 7.5% Notes due 2021 General. On June 4, 2013, we issued $250,000 of our 7.5% Notes due June 1, 2021 (the "2021 Notes") in a private offering exempt from the registration requirements of the Securities Act of 1933, as amended. The 2021 Notes were issued at a discount and bear interest at the rate of 7.5% per annum on the principal amount, payable semi-annually in arrears in cash on June 1st and December 1st of each year. Fair Value. Fair value for our 2021 Notes was based on the latest trading data available and was $257,625 and $234,220 , as of June 30, 2017 and December 31, 2016 , respectively. Although we use quoted market prices for identical debt instruments, the markets on which they trade are not considered to be active and are therefore considered Level 2 fair value measurements.

Commitments and contingencies

Commitments and contingencies	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies Environmental Contingencies Based upon all available information, we believe our current environmental liabilities do not have, and are not likely to have, a material adverse effect on our financial condition, results of operations or liquidity. However, because of the inherent uncertainties in estimating environmental liabilities primarily due to unknown facts and circumstances and changing governmental regulations and legal standards regarding liability, there can be no assurance that future capital expenditures and costs for environmental compliance at currently or formerly owned or operated properties will not result in liabilities that may have a material adverse effect on our financial condition, results of operations or liquidity. It is our policy to accrue for costs associated with environmental assessments and remedial efforts when it becomes probable that a liability has been incurred and the costs can be reasonably estimated. The aggregate environmental-related accrued liabilities were $ 1,222 and $ 998 at June 30, 2017 and December 31, 2016 , respectively. All accrued amounts have been recorded without giving effect to any possible future recoveries. Costs for ongoing environmental compliance, including maintenance and monitoring are expensed as incurred. Vernon In July 2006, we were named as a defendant, together with certain affiliates of Alcan Inc., in a lawsuit brought by Alcoa Inc. seeking to determine responsibility for certain environmental indemnity obligations related to the sale of a cast aluminum plate manufacturing facility located in Vernon, California, which we purchased from Alcoa Inc. in December 1998, and sold to Alcan Rolled Products-Ravenswood LLC in July 1999. The complaint also seeks costs and attorney fees. The matter was stayed by the court in 2008 to allow for the remediation of environmental areas at the site. On June 30, 2016 the court ordered the stay lifted and reopened the case. The matter is in a preliminary stage in the U.S. District Court for the District of Delaware, and we cannot predict the ultimate outcome of this action or estimate a range of possible losses related to this matter at this time. Matters relating to the St. Croix Alumina Refining Facility We are a party to a United States Environmental Protection Agency Administrative Order on Consent (the "Order") pursuant to which certain past and present owners of an alumina refining facility at St. Croix, Virgin Islands (the "St. Croix Alumina Refinery") have agreed to carry out a Hydrocarbon Recovery Plan to remove and manage hydrocarbons floating on groundwater underlying the facility. Pursuant to the Hydrocarbon Recovery Plan, recovered hydrocarbons and groundwater are delivered to the adjacent petroleum refinery where they are received and managed. Through June 30, 2017 , our affiliate, Virgin Islands Alumina Corporation LLC, has expended approximately $ 1,085 on the Hydrocarbon Recovery Plan. At this time, we are not able to estimate the amount of any future potential payments under this indemnification to comply with the Order, but we do not anticipate that any such amounts will have a material adverse effect on our financial condition, results of operations or liquidity, regardless of the final outcome. In December 2010, Century was among several defendants named in a lawsuit filed by plaintiffs who either worked, resided or owned property in the area downwind from the St. Croix Alumina Refinery. In March 2011, Century was also named a defendant in a nearly identical suit brought by certain additional plaintiffs. The plaintiffs in both suits allege damages caused by the presence of red mud and other particulates coming from the alumina facility and are seeking unspecified monetary damages, costs and attorney fees as well as certain injunctive relief. We tendered indemnity and defense to St. Croix Alumina LLC and Alcoa Alumina & Chemical LLC under the terms of an acquisition agreement relating to the facility and have filed motions to dismiss plaintiffs’ claims. In August 2015, the Superior Court of the Virgin Islands, Division of St. Croix denied the motions to dismiss but ordered all plaintiffs to refile individual complaints. At this time, it is not possible to predict the ultimate outcome of or to estimate a range of possible losses for any of the foregoing actions relating to the St. Croix Alumina Refinery. Legal Contingencies In addition to the foregoing matters, we have pending against us or may be subject to various lawsuits, claims and proceedings related primarily to employment, commercial, stockholder, safety and health matters. While the results of such litigation matters and claims cannot be predicted with certainty, we believe that the final outcome of such matters will not have a material adverse impact on our financial condition, results of operations or liquidity. However, because of the nature and inherent uncertainties of litigation, should the outcome of these actions be unfavorable, our business, financial condition, results of operations and liquidity could be materially and adversely affected. In evaluating whether to accrue for losses associated with legal contingencies, it is our policy to take into consideration factors such as the facts and circumstances asserted, our historical experience with contingencies of a similar nature, the likelihood of our prevailing and the severity of any potential loss. For some matters, no accrual is established because we have assessed our risk of loss to be remote. Where the risk of loss is probable and the amount of the loss can be reasonably estimated, we record an accrual, either on an individual basis or with respect to a group of matters involving similar claims, based on the factors set forth above. When we have assessed that a loss associated with legal contingencies is reasonably possible, we determine if estimates of possible losses or ranges of possible losses are in excess of related accrued liabilities, if any. Based on current knowledge, management has ascertained estimates for losses that are reasonably possible and management does not believe that any reasonably possible outcomes in excess of our accruals, if any, either individually or in aggregate, would be material to our financial condition, results of operations or liquidity. We reevaluate and update our assessments and accruals as matters progress over time. Ravenswood Retiree Medical Benefits changes In November 2009, Century Aluminum of West Virginia ("CAWV") filed a class action complaint for declaratory judgment against the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union ("USW"), the USW’s local and certain CAWV retirees, individually and as class representatives ("CAWV Retirees"), seeking a declaration of CAWV’s rights to modify/terminate retiree medical benefits. Later in November 2009, the USW and representatives of a retiree class filed a separate suit against CAWV, Century Aluminum Company, Century Aluminum Master Welfare Benefit Plan, and various John Does with respect to the foregoing. On February 9, 2017, CAWV entered into a settlement agreement in potential settlement of these actions. Under the terms of the settlement agreement, CAWV has agreed to make payments into a trust for the benefit of the CAWV Retirees in the aggregate amount of $23,000 over the course of 10 years, with $5,000 payable upon final approval by the court of the settlement agreement and $2,000 payable annually thereafter for nine years. We recognized a $23,000 liability in the consolidated balance sheets with a corresponding expense included in Ravenswood charges in the consolidated statements of operations in the third quarter of 2016. The settlement agreement is subject to final court approval which is expected in the third or fourth quarter of 2017. PBGC Settlement In 2013, we entered into a settlement agreement with the Pension Benefit Guarantee Corporation ("PBGC") regarding an alleged "cessation of operations" at our Ravenswood facility. Pursuant to the terms of the agreement, we agreed to make additional contributions (above any minimum required contributions) to our defined benefit pension plans totaling approximately $17,400 . Under certain circumstances, in periods of lower primary aluminum prices relative to our cost of operations, we are able to defer one or more of these payments provided that we provide the PBGC with acceptable security for such deferred payments. We made contributions pursuant to this agreement of $1,100 in 2015 and $6,700 in 2013. We did not make any contributions in 2014, 2016 or the six months ended June 30, 2017 . We have elected to defer certain payments under the PBGC agreement and have provided the PBGC with the appropriate security. The remaining contributions under this agreement are approximately $9,600 . Power Commitments and Contingencies Hawesville Hawesville has a power supply arrangement with Kenergy and EDF Trading North America, LLC (“EDF") which provides market-based power to the Hawesville smelter. Under this arrangement, the power companies purchase power on the open market and pass it through to Hawesville at Midcontinent Independent System Operator ("MISO") pricing plus transmission and other costs. The power supply arrangement with Kenergy has an effective term through December 2023. The arrangement with EDF to act as our market participant with MISO has an effective term through May 2019, extending year to year thereafter unless a one year notice is given. Sebree Sebree has a power supply arrangement with Kenergy and EDF which provides market-based power to the Sebree smelter. Similar to the arrangement at Hawesville, the power companies purchase power on the open market and pass it through to Sebree at MISO pricing plus transmission and other costs. The power supply arrangement with Kenergy has an effective term through December 2023. The arrangement with EDF to act as our market participant with MISO has an effective term through May 2019, extending year to year thereafter unless a one year notice is given. Mt. Holly Mt. Holly has a power supply arrangement pursuant to which 25% of the Mt. Holly load is served from the South Carolina Public Service Authority’s ("Santee Cooper") generation at a cost-based industrial rate and 75% of the Mt. Holly load is sourced from a supplier that is outside Santee Cooper’s service territory at market prices that are tied to natural gas prices. The agreement with Santee Cooper has a term through December 31, 2018. The agreement with the other power supplier has a term through December 31, 2017. Both of these agreements may be terminated by Mt. Holly on 60 days' notice. Grundartangi Grundartangi has power purchase agreements for approximately 525 MW with HS Orka hf ("HS"), Landsvirkjun and Orkuveita Reykjavikur ("OR") to provide power to its Grundartangi smelter. These power purchase agreements expire on various dates from 2023 through 2036 (subject to extension). The power purchase agreements with HS and OR both provide power at LME-based variable rates for the duration of these agreements. The power purchase agreement with Landsvirkjun for 161 MW provides power at LME-based variable rates through October 2019 and at rates linked to the Nord Pool power market from November 2019 through the expiration of the agreement on December 31, 2023. Helguvik Nordural Helguvik ehf ("Helguvik") has a power purchase agreement with OR to provide a portion of the power requirements to the Helguvik project. The agreement would provide power at LME-based variable rates and contain take-or-pay obligations with respect to a significant percentage of the total committed and available power under such agreements. The first stage of power under the OR purchase agreement (approximately 47.5 MW) became available in the fourth quarter of 2011 and is currently being utilized at Grundartangi. The agreement contains certain conditions to OR’s obligations with respect to the remaining phases and OR has alleged that certain of these conditions have not been satisfied. We are in discussions with OR with respect to such conditions and other matters pertaining to this agreement. Other Commitments and Contingencies Labor Commitments The bargaining unit employees at our Grundartangi, Vlissingen, Hawesville and Sebree facilities are represented by labor unions, representing 66% of our total workforce. Approximately 86% of Grundartangi’s work force is represented by five labor unions, governed by a labor agreement which is effective through December 31, 2019 that establishes wages and work rules for covered employees. 100% of Vlissingen's work force is represented by the Federation for the Metal and Electrical Industry ("FME") by a labor agreement that is effective to June 1, 2018. The FME negotiates working conditions with trade unions on behalf of its members. Approximately 53% of our U.S. based work force is represented by the USW. The labor agreement for Hawesville employees is effective through April 1, 2020. Century Sebree's labor agreement with the USW for its employees is effective through October 28, 2019. Mt. Holly employees are not represented by a labor union.

Components of accumulated other

Components of accumulated other comprehensive loss	6 Months Ended
	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Components of accumulated other comprehensive loss	Components of accumulated other comprehensive loss June 30, 2017 December 31, 2016 Defined benefit plan liabilities $ (124,180 ) $ (125,917 ) Unrealized loss on financial instruments 2,766 2,860 Other comprehensive loss before income tax effect (121,414 ) (123,057 ) Income tax effect (1) 8,402 9,164 Accumulated other comprehensive loss $ (113,012 ) $ (113,893 ) (1) The allocation of the income tax effect to the components of other comprehensive loss is as follows: June 30, 2017 December 31, 2016 Defined benefit plan liabilities $ 8,955 $ 9,736 Unrealized loss on financial instruments (553 ) (572 ) The following table summarizes the changes in the accumulated balances for each component of accumulated other comprehensive loss ("AOCL"): Defined benefit plan and other postretirement liabilities Unrealized gain (loss) on financial instruments Total, net of tax Balance, April 1, 2017 $ (115,431 ) $ 2,250 $ (113,181 ) Net amount reclassified to net income 206 (37 ) 169 Balance, June 30, 2017 $ (115,225 ) $ 2,213 $ (113,012 ) Balance, April 1, 2016 $ (109,806 ) $ (2,021 ) $ (111,827 ) Net amount reclassified to net loss 862 (38 ) 824 Balance, June 30, 2016 $ (108,944 ) $ (2,059 ) $ (111,003 ) Balance, December 31, 2016 $ (116,181 ) $ 2,288 $ (113,893 ) Net amount reclassified to net loss 956 (75 ) 881 Balance, June 30, 2017 $ (115,225 ) $ 2,213 $ (113,012 ) Balance, December 31, 2015 $ (110,667 ) $ (1,983 ) $ (112,650 ) Net amount reclassified to net loss 1,723 (76 ) 1,647 Balance, June 30, 2016 $ (108,944 ) $ (2,059 ) $ (111,003 ) Reclassifications out of AOCL were included in the consolidated statements of operations as follows: For the three months ended June 30, For the six months ended June 30, AOCL Components Location 2017 2016 2017 2016 Defined benefit plan and other postretirement liabilities Cost of goods sold $ (1,468 ) $ 778 $ (161 ) $ 1,555 Selling, general and administrative expenses 845 125 977 250 Other operating expense, net 528 350 922 700 Income tax effect 301 (391 ) (782 ) (782 ) Net of tax $ 206 $ 862 $ 956 $ 1,723 Unrealized loss on financial instruments Cost of goods sold $ (47 ) $ (47 ) $ (94 ) $ (93 ) Income tax effect 10 9 19 17 Net of tax $ (37 ) $ (38 ) $ (75 ) $ (76 )

Components of net periodic bene

Components of net periodic benefit cost	6 Months Ended
	Jun. 30, 2017
Components of net periodic benefit cost [Abstract]
Components of net periodic benefit cost	Components of net periodic benefit cost Pension Benefits Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Service cost $ 968 $ 1,270 $ 2,192 $ 2,540 Interest cost 3,323 3,482 6,655 6,962 Expected return on plan assets (5,116 ) (4,816 ) (9,865 ) (9,632 ) Amortization of prior service costs 26 28 53 56 Amortization of net loss 1,506 1,041 2,738 2,084 Net periodic benefit cost $ 707 $ 1,005 $ 1,773 $ 2,010 Other Postretirement Benefits ("OPEB") Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Service cost $ 191 $ 330 $ 438 $ 660 Interest cost 2,978 1,439 4,344 2,895 Amortization of prior service cost (698 ) (695 ) (1,036 ) (1,390 ) Amortization of net loss (929 ) 879 (18 ) 1,755 Net periodic benefit cost $ 1,542 $ 1,953 $ 3,728 $ 3,920 Employer contributions During the six months ended June 30, 2017 , we made contributions of $874 to the qualified defined benefit and unqualified supplemental executive retirement benefit ("SERB") plans that we sponsor.

Supplemental cash flow informat

Supplemental cash flow information	6 Months Ended
	Jun. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental cash flow information	Supplemental cash flow information Six months ended June 30, 2017 2016 Cash paid for: Interest $ 9,903 $ 9,701 Income taxes, net 1,796 6,316

Derivatives

Derivatives	6 Months Ended
	Jun. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives As of June 30, 2017, we had an open position of 36,090 tonnes related to LME forward financial sales contracts, 33,390 tonnes of which are with Glencore, to fix the forward LME price (the “Forward Financial Sales Contracts”). Of these Forward Financial Sales Contracts, 33,000 tonnes settle monthly, on a ratable basis, through December 31, 2017, with the remainder expected to settle between November 1, 2019 and December 31, 2020. We also have financial contracts with Glencore to offset fixed price sales arrangements with certain of our customers (the “fixed for floating swaps”) to remain exposed to the LME price. As of June 30, 2017, we had an open position related to such arrangements of 7,386 tonnes settling at various dates through August 2018. We have also entered into financial contracts to fix the forward price of approximately 4% of power purchases at Grundartangi for the period November 1, 2019 through December 31, 2020 (the “power price swaps”). The power price swaps are not designated as cash flow hedges. As of June 30, 2017, we had an open position of 256,200 MWh related to the power price swaps. As of June 30, 2017, we had a derivative asset and liability of $354 and $7,539 , respectively, in the consolidated balance sheets. We recognized a gain of $2,957 and a loss of $13,180 related to our derivative instruments during the three and six months ended June 30, 2017, respectively, in the consolidated statements of operations, substantially all of which related to transactions with Glencore. The impact of the derivative instruments on the consolidated balance sheets and consolidated statements of operations was not material for the corresponding prior periods presented.

Condensed consolidating financi

Condensed consolidating financial information	6 Months Ended
	Jun. 30, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed consolidating financial information	Condensed consolidating financial information Our 2021 Notes are guaranteed by each of our material existing and future domestic subsidiaries (The "Guarantor Subsidiaries"), except for Nordural US LLC, Century Aluminum Development LLC and Century Aluminum of West Virginia, Inc. The Guarantor Subsidiaries are 100% owned by Century. All guarantees are full and unconditional; all guarantees are joint and several. These notes are not guaranteed by our foreign subsidiaries (such foreign subsidiaries, Nordural US LLC, Century Aluminum Development LLC and Century Aluminum of West Virginia, Inc., collectively the “Non-Guarantor Subsidiaries”). We allocate corporate expenses or income to our subsidiaries and charge interest on certain intercompany balances. The following summarized condensed consolidating statements of comprehensive income (loss) for three and six months ended June 30, 2017 and 2016 , condensed consolidating balance sheets as of June 30, 2017 and December 31, 2016 and the condensed consolidating statements of cash flows for the six months ended June 30, 2017 and 2016 present separate results for Century, the Guarantor Subsidiaries, the Non-Guarantor Subsidiaries, consolidating adjustments and total consolidated amounts. Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended June 30, 2017 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 134,850 $ 161,421 $ — $ 296,271 Other customers — 92,496 35 — 92,531 Total net sales — 227,346 161,456 — 388,802 Cost of goods sold — 220,553 145,789 — 366,342 Gross profit — 6,793 15,667 — 22,460 Selling, general and administrative expenses 8,914 — 438 — 9,352 Other operating expense - net — — 180 — 180 Operating income (loss) (8,914 ) 6,793 15,049 — 12,928 Interest expense (5,035 ) (382 ) (44 ) — (5,461 ) Intercompany interest 9,213 2,147 (11,360 ) — — Interest income 49 (1 ) 235 — 283 Net gain on forward and derivative contracts — 2,644 313 — 2,957 Other income (expense) - net (110 ) 114 (1,880 ) — (1,876 ) Income (loss) before income taxes and equity in earnings of joint ventures (4,797 ) 11,315 2,313 — 8,831 Income tax (expense) benefit 529 (493 ) (1,488 ) — (1,452 ) Income (loss) before equity in earnings of joint ventures (4,268 ) 10,822 825 — 7,379 Equity in earnings (loss) of joint ventures 11,399 1,667 (248 ) (13,066 ) (248 ) Net income $ 7,131 $ 12,489 $ 577 $ (13,066 ) $ 7,131 Other comprehensive income (loss) before income tax effect (142 ) (1,467 ) 481 986 (142 ) Income tax effect 311 — 11 (11 ) 311 Other comprehensive income (loss) 169 (1,467 ) 492 975 169 Total comprehensive income (loss) $ 7,300 $ 11,022 $ 1,069 $ (12,091 ) $ 7,300 Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended June 30, 2016 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 169,640 $ 144,557 $ (23,914 ) $ 290,283 Other customers — 36,462 9 — 36,471 Total net sales — 206,102 144,566 (23,914 ) 326,754 Cost of goods sold — 211,586 133,390 (23,804 ) 321,172 Gross profit (loss) — (5,484 ) 11,176 (110 ) 5,582 Selling, general and administrative expenses 8,261 — 1,684 — 9,945 Other operating expense - net — — 578 — 578 Operating income (loss) (8,261 ) (5,484 ) 8,914 (110 ) (4,941 ) Interest expense (5,070 ) (383 ) (44 ) — (5,497 ) Intercompany interest 9,727 1,997 (11,724 ) — — Interest income 38 9 124 — 171 Net gain on forward and derivative contracts — 353 — — 353 Other income (expense) - net (137 ) 21 (183 ) — (299 ) Loss before income taxes and equity in earnings of joint ventures (3,703 ) (3,487 ) (2,913 ) (110 ) (10,213 ) Income tax (expense) benefit 848 — (529 ) — 319 Loss before equity in earnings of joint ventures (2,855 ) (3,487 ) (3,442 ) (110 ) (9,894 ) Equity in earnings (loss) of joint ventures (6,660 ) — 379 6,660 379 Net loss $ (9,515 ) $ (3,487 ) $ (3,063 ) $ 6,550 $ (9,515 ) Other comprehensive income (loss) before income tax effect 1,206 777 304 (1,081 ) 1,206 Income tax effect (382 ) — 9 (9 ) (382 ) Other comprehensive income (loss) 824 777 313 (1,090 ) 824 Total comprehensive income (loss) $ (8,691 ) $ (2,710 ) $ (2,750 ) $ 5,460 $ (8,691 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the six months ended June 30, 2017 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 265,918 $ 310,926 $ — $ 576,844 Other customers — 177,679 65 — 177,744 Total net sales — 443,597 310,991 — 754,588 Cost of goods sold — 434,304 280,973 — 715,277 Gross profit — 9,293 30,018 — 39,311 Selling, general and administrative expenses 19,114 — 940 — 20,054 Other operating expense - net — — 1,153 — 1,153 Operating income (loss) (19,114 ) 9,293 27,925 — 18,104 Interest expense (10,183 ) (761 ) (88 ) — (11,032 ) Intercompany interest 18,195 4,228 (22,423 ) — Interest income 129 (1 ) 385 — 513 Net gain (loss) on forward and derivative contracts — (13,203 ) 23 — (13,180 ) Other income (expense) - net 677 161 (2,330 ) — (1,492 ) Income (loss) before income taxes and equity in earnings of joint ventures (10,296 ) (283 ) 3,492 — (7,087 ) Income tax (expense) benefit 1,100 — (2,244 ) — (1,144 ) Income (loss) before equity in earnings of joint ventures (9,196 ) (283 ) 1,248 — (8,231 ) Equity in earnings of joint ventures 1,188 2,520 223 (3,708 ) 223 Net income (loss) $ (8,008 ) $ 2,237 $ 1,471 $ (3,708 ) $ (8,008 ) Other comprehensive income (loss) before income tax effect 1,644 (161 ) 829 (668 ) 1,644 Income tax effect (763 ) — 19 (19 ) (763 ) Other comprehensive income (loss) 881 (161 ) 848 (687 ) 881 Total comprehensive income (loss) $ (7,127 ) $ 2,076 $ 2,319 $ (4,395 ) $ (7,127 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the six months ended June 30, 2016 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 331,760 $ 286,211 $ (47,311 ) $ 570,660 Other customers — 74,930 18 — 74,948 Total net sales — 406,690 286,229 (47,311 ) 645,608 Cost of goods sold — 421,159 269,694 (47,775 ) 643,078 Gross profit (loss) — (14,469 ) 16,535 464 2,530 Selling, general and administrative expenses 16,560 — 3,010 — 19,570 Other operating expense - net — — 1,459 — 1,459 Operating income (loss) (16,560 ) (14,469 ) 12,066 464 (18,499 ) Interest expense (10,135 ) (765 ) (90 ) — (10,990 ) Intercompany interest 19,275 3,954 (23,229 ) — — Interest income 75 9 201 — 285 Net gain on forward and derivative contracts — 706 — — 706 Other income (expense) - net 634 15 (954 ) — (305 ) Loss before income taxes and equity in earnings of joint ventures (6,711 ) (10,550 ) (12,006 ) 464 (28,803 ) Income tax benefit 1,468 — 921 — 2,389 Loss before equity in earnings of joint ventures (5,243 ) (10,550 ) (11,085 ) 464 (26,414 ) Equity in earnings (loss) of joint ventures (20,435 ) — 736 20,435 736 Net loss $ (25,678 ) $ (10,550 ) $ (10,349 ) $ 20,899 $ (25,678 ) Other comprehensive income before income tax effect 2,412 1,555 607 (2,162 ) 2,412 Income tax effect (765 ) — 17 (17 ) (765 ) Other comprehensive income 1,647 1,555 624 (2,179 ) 1,647 Total comprehensive income (loss) $ (24,031 ) $ (8,995 ) $ (9,725 ) $ 18,720 $ (24,031 ) Condensed Consolidating Balance Sheet As of June 30, 2017 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 29,305 $ (270 ) $ 101,638 $ — $ 130,673 Restricted cash — 800 55 — 855 Accounts receivable - net — 42,252 221 — 42,473 Due from affiliates 42 10,453 — — 10,495 Inventories 180 159,857 94,574 — 254,611 Prepaid and other current assets 6,269 2,669 9,686 — 18,624 Total current assets 35,796 215,761 206,174 — 457,731 Property, plant and equipment - net 17,015 313,307 670,181 — 1,000,503 Investment in subsidiaries 704,533 53,760 — (758,293 ) — Due from affiliates - long term 528,232 389,099 13,854 (931,185 ) — Other assets 28,175 44,012 27,059 (31,851 ) 67,395 TOTAL $ 1,313,751 $ 1,015,939 $ 917,268 $ (1,721,329 ) $ 1,525,629 Accounts payable, trade $ 2,823 $ 52,886 $ 36,422 $ — $ 92,131 Due to affiliates 133 8,409 10,550 — 19,092 Accrued and other current liabilities 10,569 14,557 20,553 — 45,679 Accrued employee benefits costs 1,932 8,256 579 — 10,767 Industrial revenue bonds — 7,815 — — 7,815 Total current liabilities 15,457 91,923 68,104 — 175,484 Senior notes payable 247,922 — — — 247,922 Accrued pension benefits costs - less current portion 45,857 19,746 13,849 (31,851 ) 47,601 Accrued postretirement benefits costs - less current portion 3,805 122,556 1,672 — 128,033 Due to affiliates - long term 243,668 101,441 586,076 (931,185 ) — Other liabilities 6,281 31,640 28,919 — 66,840 Deferred taxes — 2,720 106,268 — 108,988 Total noncurrent liabilities 547,533 278,103 736,784 (963,036 ) 599,384 Preferred stock 1 — — — 1 Common stock 945 1 59 (60 ) 945 Other shareholders' equity 749,815 645,912 112,321 (758,233 ) 749,815 Total shareholders' equity 750,761 645,913 112,380 (758,293 ) 750,761 TOTAL $ 1,313,751 $ 1,015,939 $ 917,268 $ (1,721,329 ) $ 1,525,629 Condensed Consolidating Balance Sheet As of December 31, 2016 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 36,670 $ (255 ) $ 95,988 $ — $ 132,403 Restricted cash — 794 256 — 1,050 Accounts receivable - net 167 11,883 382 — 12,432 Due from affiliates 42 16,606 3 — 16,651 Inventories 180 146,689 86,694 — 233,563 Prepaid and other current assets 6,838 5,699 9,673 — 22,210 Assets held for sale — — 22,313 — 22,313 Total current assets 43,897 181,416 215,309 — 440,622 Property, plant and equipment - net 12,311 328,069 685,905 — 1,026,285 Investment in subsidiaries 702,659 51,240 — (753,899 ) — Due from affiliates - long term 529,873 346,893 1,792 (878,558 ) — Other assets 28,215 49,331 27,596 (31,722 ) 73,420 TOTAL $ 1,316,955 $ 956,949 $ 930,602 $ (1,664,179 ) $ 1,540,327 Accounts payable, trade $ 6,125 $ 52,921 $ 35,914 $ — $ 94,960 Due to affiliates 417 9,641 5,310 — 15,368 Accrued and other current liabilities 11,950 17,744 20,406 — 50,100 Accrued employee benefits costs 1,932 8,317 668 — 10,917 Industrial revenue bonds — 7,815 — — 7,815 Total current liabilities 20,424 96,438 62,298 — 179,160 Senior notes payable 247,699 — — — 247,699 Accrued pension benefits costs - less current portion 46,390 20,167 14,658 (31,722 ) 49,493 Accrued postretirement benefits costs - less current portion 4,380 120,242 1,733 — 126,355 Other liabilities 4,160 30,920 36,946 — 72,026 Due to affiliates - long term 237,247 42,609 598,702 (878,558 ) — Deferred taxes — 2,735 106,204 — 108,939 Total noncurrent liabilities 539,876 216,673 758,243 (910,280 ) 604,512 Preferred stock 1 — — — 1 Common stock 944 1 59 (60 ) 944 Other shareholders' equity 755,710 643,837 110,002 (753,839 ) 755,710 Total shareholders' equity 756,655 643,838 110,061 (753,899 ) 756,655 TOTAL $ 1,316,955 $ 956,949 $ 930,602 $ (1,664,179 ) $ 1,540,327 Condensed Consolidating Statement of Cash Flows For the six months ended June 30, 2017 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (7,988 ) $ (25,946 ) $ 37,027 $ — $ 3,093 Purchase of property, plant and equipment (7,811 ) (4,963 ) (6,069 ) — (18,843 ) Proceeds from sale of property, plant and equipment — — 13,585 — 13,585 Restricted and other cash deposits — (6 ) 201 — 195 Intercompany transactions 11,784 (27,931 ) (12,061 ) 28,208 — Net cash provided by (used in) investing activities 3,973 (32,900 ) (4,344 ) 28,208 (5,063 ) Borrowings under revolving credit facilities 720 — — — 720 Repayments under revolving credit facilities (720 ) — — — (720 ) Issuance of common stock 240 — — — 240 Intercompany transactions (3,590 ) 58,831 (27,033 ) (28,208 ) — Net cash provided by (used in) financing activities (3,350 ) 58,831 (27,033 ) (28,208 ) 240 CHANGE IN CASH AND CASH EQUIVALENTS (7,365 ) (15 ) 5,650 — (1,730 ) Cash and cash equivalents, beginning of period 36,670 (255 ) 95,988 — 132,403 Cash and cash equivalents, end of period $ 29,305 $ (270 ) $ 101,638 $ — $ 130,673 Condensed Consolidating Statement of Cash Flows For the six months ended June 30, 2016 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (11,105 ) $ 18,847 $ 11,268 $ 4,593 $ 23,603 Purchase of property, plant and equipment — (2,697 ) (5,037 ) — (7,734 ) Restricted and other cash deposits — (4 ) (1,874 ) — (1,878 ) Net cash used in investing activities — (2,701 ) (6,911 ) — (9,612 ) Borrowings under revolving credit facilities 595 — — — 595 Repayments under revolving credit facilities (595 ) — — — (595 ) Intercompany transactions — (12,777 ) 17,370 (4,593 ) — Net cash provided by (used in) financing activities — (12,777 ) 17,370 (4,593 ) — CHANGE IN CASH AND CASH EQUIVALENTS (11,105 ) 3,369 21,727 — 13,991 Cash and cash equivalents, beginning of period 58,421 (3,647 ) 60,619 — 115,393 Cash and cash equivalents, end of period $ 47,316 $ (278 ) $ 82,346 $ — $ 129,384

Fair value measurements (Polici

Fair value measurements (Policies)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Transfer, Policy	It is our policy to recognize transfers into and transfers out of Level 3 as of the date of the event or change in circumstances that caused the transfer.

Related party transactions (Tab

Related party transactions (Tables)	6 Months Ended
	Jun. 30, 2017
Related Party Transactions [Abstract]
Schedule of related party transactions	A summary of the aforementioned significant related party transactions for the three and six months ended June 30, 2017 and 2016 is as follows: Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Net sales to Glencore $ 296,271 $ 290,283 $ 576,844 $ 570,660 Purchases from Glencore 41,587 50,177 113,168 94,190 Purchases from BHH 3,109 2,715 5,889 5,098

Fair value measurements (Tables

Fair value measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of valuation methodology for assets and liabilities at fair value	The following section describes the valuation methodology used to measure our financial assets and liabilities that were accounted for at fair value and are categorized based on the fair value hierarchy described in Accounting Standards Codification ("ASC") 820, "Fair Value Measurements and Disclosures." Overview of Century’s valuation methodology Level Significant inputs Cash equivalents 1 Quoted market prices Trust assets (1) 1 Quoted market prices Surety bonds 1 Quoted market prices Forward financial sales 2 Quoted market prices Fixed for floating swaps 3 Quoted market prices, management's estimates of future U.S. Midwest premium E.ON contingent obligation 3 Quoted market prices, management’s estimates of the LME forward market prices for periods beyond the quoted periods and management’s estimate of future level of operations (1) Trust assets are currently invested in money market funds. These trust assets are held to fund the non-qualified supplemental executive pension benefit obligations for certain of our officers. The trust has sole authority to invest the funds in secure interest producing investments consisting of short-term securities issued or guaranteed by the United States government or cash and cash equivalents.
Financial assets and liabilities at fair value on a recurring basis	The following table sets forth our financial assets and liabilities that were accounted for at fair value on a recurring basis by the level of input within the ASC 820 fair value hierarchy. Recurring Fair Value Measurements As of June 30, 2017 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 82,567 $ — $ — $ 82,567 Trust assets 2,703 — — 2,703 Surety bonds 1,625 — — 1,625 Derivatives — — 354 354 TOTAL $ 86,895 $ — $ 354 $ 87,249 LIABILITIES: E.ON contingent obligation - net $ — $ — $ — $ — Derivatives — 7,208 331 7,539 TOTAL $ — $ 7,208 $ 331 $ 7,539 Recurring Fair Value Measurements As of December 31, 2016 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 79,014 $ — $ — $ 79,014 Trust assets 3,147 — — 3,147 Surety bonds 1,874 — — 1,874 Derivatives — — 925 925 TOTAL $ 84,035 $ — $ 925 $ 84,960 LIABILITIES: E.ON contingent obligation – net $ — $ — $ — $ — Derivatives — — 253 253 TOTAL $ — $ — $ 253 $ 253

Earnings (loss) per share (Tabl

Earnings (loss) per share (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Basic and diluted earnings (loss) per share	The following table shows the basic and diluted earnings (loss) per share for the three and six months ended June 30, 2017 and 2016 : For the three months ended June 30, 2017 2016 Income Shares (000) Per Share Loss Shares (000) Per Share Net income (loss) $ 7,131 $ (9,515 ) Amount allocated to common stockholders 92.03 % 100.00 % Basic EPS: Net income (loss) allocated to common stockholders $ 6,563 87,272 $ 0.08 $ (9,515 ) 87,060 $ (0.11 ) Effect of Dilutive Securities: Share-based compensation — 785 — — Diluted EPS: Net income (loss) allocated to common stockholders with assumed conversion $ 6,563 88,057 $ 0.07 $ (9,515 ) 87,060 $ (0.11 ) For the six months ended June 30, 2017 2016 Loss Shares (000) Per Share Loss Shares (000) Per Share Net loss $ (8,008 ) $ (25,678 ) Amount allocated to common stockholders 100.00 % 100 % Basic and diluted EPS: Net loss allocated to common stockholders $ (8,008 ) 87,263 $ (0.09 ) $ (25,678 ) 87,050 $ (0.29 )
Securities excluded from the calculation of diluted EPS	Securities excluded from the calculation of diluted EPS: Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Share-based compensation 432,506 1,800,096 462,506 1,288,473

Shareholders' equity (Tables)

Shareholders' equity (Tables)	6 Months Ended
	Jun. 30, 2017
Stockholders' Equity Note [Abstract]
Common and Preferred Stock Activity	The Common and Preferred Stock Activity table below contains additional information about preferred stock conversions during the six months ended June 30, 2017 and 2016 . Common and Preferred Stock Activity: Preferred stock Common stock (in shares) Series A convertible Treasury Outstanding Beginning balance as of December 31, 2016 75,625 7,186,521 87,250,897 Conversion of convertible preferred stock (279 ) — 27,904 Issuance for share-based compensation plans — — 37,164 Ending balance as of June 30, 2017 75,346 7,186,521 87,315,965 Beginning balance as of December 31, 2015 76,539 7,186,521 87,038,050 Conversion of convertible preferred stock (161 ) — 16,109 Issuance for share-based compensation plans — — 21,428 Ending balance as of June 30, 2016 76,378 7,186,521 87,075,587

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2017
Inventory, Net [Abstract]
Schedule of Inventories	Inventories consist of the following: June 30, 2017 December 31, 2016 Raw materials $ 80,134 $ 59,415 Work-in-process 43,931 35,539 Finished goods 23,169 26,613 Operating and other supplies 107,377 111,996 Total inventories $ 254,611 $ 233,563

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Schedule of Debt	June 30, 2017 December 31, 2016 Debt classified as current liabilities: Hancock County industrial revenue bonds ("IRBs") due 2028, interest payable quarterly (variable interest rates (not to exceed 12%)) (1) $ 7,815 $ 7,815 Debt classified as non-current liabilities: 7.5% senior secured notes due June 1, 2021, net of debt discount of $2,078 and $2,301, respectively, interest payable semiannually 247,922 247,699 Total $ 255,737 $ 255,514 (1) The IRBs are classified as current liabilities because they are remarketed weekly and could be required to be repaid upon demand if there is a failed remarketing. The IRB interest rate at June 30, 2017 was 1.11% .
Schedule of Line of Credit Facilities	Status of our Iceland revolving credit facility: June 30, 2017 Credit facility maximum amount $ 50,000 Borrowing availability 50,000 Outstanding borrowings — Borrowing availability, net of borrowings 50,000 Status of our U.S. revolving credit facility: June 30, 2017 Credit facility maximum amount $ 150,000 Borrowing availability 123,921 Outstanding letters of credit issued 38,242 Outstanding borrowings — Borrowing availability, net of outstanding letters of credit and borrowings 85,679

Components of accumulated oth27

Components of accumulated other comprehensive loss (Tables)	6 Months Ended
	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated balances for each component of AOCI	June 30, 2017 December 31, 2016 Defined benefit plan liabilities $ (124,180 ) $ (125,917 ) Unrealized loss on financial instruments 2,766 2,860 Other comprehensive loss before income tax effect (121,414 ) (123,057 ) Income tax effect (1) 8,402 9,164 Accumulated other comprehensive loss $ (113,012 ) $ (113,893 ) (1) The allocation of the income tax effect to the components of other comprehensive loss is as follows: June 30, 2017 December 31, 2016 Defined benefit plan liabilities $ 8,955 $ 9,736 Unrealized loss on financial instruments (553 ) (572 ) The following table summarizes the changes in the accumulated balances for each component of accumulated other comprehensive loss ("AOCL"): Defined benefit plan and other postretirement liabilities Unrealized gain (loss) on financial instruments Total, net of tax Balance, April 1, 2017 $ (115,431 ) $ 2,250 $ (113,181 ) Net amount reclassified to net income 206 (37 ) 169 Balance, June 30, 2017 $ (115,225 ) $ 2,213 $ (113,012 ) Balance, April 1, 2016 $ (109,806 ) $ (2,021 ) $ (111,827 ) Net amount reclassified to net loss 862 (38 ) 824 Balance, June 30, 2016 $ (108,944 ) $ (2,059 ) $ (111,003 ) Balance, December 31, 2016 $ (116,181 ) $ 2,288 $ (113,893 ) Net amount reclassified to net loss 956 (75 ) 881 Balance, June 30, 2017 $ (115,225 ) $ 2,213 $ (113,012 ) Balance, December 31, 2015 $ (110,667 ) $ (1,983 ) $ (112,650 ) Net amount reclassified to net loss 1,723 (76 ) 1,647 Balance, June 30, 2016 $ (108,944 ) $ (2,059 ) $ (111,003 )
Reclassification out of AOCI	Reclassifications out of AOCL were included in the consolidated statements of operations as follows: For the three months ended June 30, For the six months ended June 30, AOCL Components Location 2017 2016 2017 2016 Defined benefit plan and other postretirement liabilities Cost of goods sold $ (1,468 ) $ 778 $ (161 ) $ 1,555 Selling, general and administrative expenses 845 125 977 250 Other operating expense, net 528 350 922 700 Income tax effect 301 (391 ) (782 ) (782 ) Net of tax $ 206 $ 862 $ 956 $ 1,723 Unrealized loss on financial instruments Cost of goods sold $ (47 ) $ (47 ) $ (94 ) $ (93 ) Income tax effect 10 9 19 17 Net of tax $ (37 ) $ (38 ) $ (75 ) $ (76 )

Components of net periodic be28

Components of net periodic benefit cost (Tables)	6 Months Ended
	Jun. 30, 2017
Components of net periodic benefit cost [Abstract]
Schedule of net periodic benefit cost	Pension Benefits Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Service cost $ 968 $ 1,270 $ 2,192 $ 2,540 Interest cost 3,323 3,482 6,655 6,962 Expected return on plan assets (5,116 ) (4,816 ) (9,865 ) (9,632 ) Amortization of prior service costs 26 28 53 56 Amortization of net loss 1,506 1,041 2,738 2,084 Net periodic benefit cost $ 707 $ 1,005 $ 1,773 $ 2,010 Other Postretirement Benefits ("OPEB") Three months ended June 30, Six months ended June 30, 2017 2016 2017 2016 Service cost $ 191 $ 330 $ 438 $ 660 Interest cost 2,978 1,439 4,344 2,895 Amortization of prior service cost (698 ) (695 ) (1,036 ) (1,390 ) Amortization of net loss (929 ) 879 (18 ) 1,755 Net periodic benefit cost $ 1,542 $ 1,953 $ 3,728 $ 3,920

Supplemental cash flow inform29

Supplemental cash flow information (Tables)	6 Months Ended
	Jun. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental cash flow information	Six months ended June 30, 2017 2016 Cash paid for: Interest $ 9,903 $ 9,701 Income taxes, net 1,796 6,316

Condensed consolidating finan30

Condensed consolidating financial information (Tables)	6 Months Ended
	Jun. 30, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Statements of Comprehensive Income (Loss)	Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended June 30, 2017 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 134,850 $ 161,421 $ — $ 296,271 Other customers — 92,496 35 — 92,531 Total net sales — 227,346 161,456 — 388,802 Cost of goods sold — 220,553 145,789 — 366,342 Gross profit — 6,793 15,667 — 22,460 Selling, general and administrative expenses 8,914 — 438 — 9,352 Other operating expense - net — — 180 — 180 Operating income (loss) (8,914 ) 6,793 15,049 — 12,928 Interest expense (5,035 ) (382 ) (44 ) — (5,461 ) Intercompany interest 9,213 2,147 (11,360 ) — — Interest income 49 (1 ) 235 — 283 Net gain on forward and derivative contracts — 2,644 313 — 2,957 Other income (expense) - net (110 ) 114 (1,880 ) — (1,876 ) Income (loss) before income taxes and equity in earnings of joint ventures (4,797 ) 11,315 2,313 — 8,831 Income tax (expense) benefit 529 (493 ) (1,488 ) — (1,452 ) Income (loss) before equity in earnings of joint ventures (4,268 ) 10,822 825 — 7,379 Equity in earnings (loss) of joint ventures 11,399 1,667 (248 ) (13,066 ) (248 ) Net income $ 7,131 $ 12,489 $ 577 $ (13,066 ) $ 7,131 Other comprehensive income (loss) before income tax effect (142 ) (1,467 ) 481 986 (142 ) Income tax effect 311 — 11 (11 ) 311 Other comprehensive income (loss) 169 (1,467 ) 492 975 169 Total comprehensive income (loss) $ 7,300 $ 11,022 $ 1,069 $ (12,091 ) $ 7,300 Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended June 30, 2016 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 169,640 $ 144,557 $ (23,914 ) $ 290,283 Other customers — 36,462 9 — 36,471 Total net sales — 206,102 144,566 (23,914 ) 326,754 Cost of goods sold — 211,586 133,390 (23,804 ) 321,172 Gross profit (loss) — (5,484 ) 11,176 (110 ) 5,582 Selling, general and administrative expenses 8,261 — 1,684 — 9,945 Other operating expense - net — — 578 — 578 Operating income (loss) (8,261 ) (5,484 ) 8,914 (110 ) (4,941 ) Interest expense (5,070 ) (383 ) (44 ) — (5,497 ) Intercompany interest 9,727 1,997 (11,724 ) — — Interest income 38 9 124 — 171 Net gain on forward and derivative contracts — 353 — — 353 Other income (expense) - net (137 ) 21 (183 ) — (299 ) Loss before income taxes and equity in earnings of joint ventures (3,703 ) (3,487 ) (2,913 ) (110 ) (10,213 ) Income tax (expense) benefit 848 — (529 ) — 319 Loss before equity in earnings of joint ventures (2,855 ) (3,487 ) (3,442 ) (110 ) (9,894 ) Equity in earnings (loss) of joint ventures (6,660 ) — 379 6,660 379 Net loss $ (9,515 ) $ (3,487 ) $ (3,063 ) $ 6,550 $ (9,515 ) Other comprehensive income (loss) before income tax effect 1,206 777 304 (1,081 ) 1,206 Income tax effect (382 ) — 9 (9 ) (382 ) Other comprehensive income (loss) 824 777 313 (1,090 ) 824 Total comprehensive income (loss) $ (8,691 ) $ (2,710 ) $ (2,750 ) $ 5,460 $ (8,691 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the six months ended June 30, 2017 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 265,918 $ 310,926 $ — $ 576,844 Other customers — 177,679 65 — 177,744 Total net sales — 443,597 310,991 — 754,588 Cost of goods sold — 434,304 280,973 — 715,277 Gross profit — 9,293 30,018 — 39,311 Selling, general and administrative expenses 19,114 — 940 — 20,054 Other operating expense - net — — 1,153 — 1,153 Operating income (loss) (19,114 ) 9,293 27,925 — 18,104 Interest expense (10,183 ) (761 ) (88 ) — (11,032 ) Intercompany interest 18,195 4,228 (22,423 ) — Interest income 129 (1 ) 385 — 513 Net gain (loss) on forward and derivative contracts — (13,203 ) 23 — (13,180 ) Other income (expense) - net 677 161 (2,330 ) — (1,492 ) Income (loss) before income taxes and equity in earnings of joint ventures (10,296 ) (283 ) 3,492 — (7,087 ) Income tax (expense) benefit 1,100 — (2,244 ) — (1,144 ) Income (loss) before equity in earnings of joint ventures (9,196 ) (283 ) 1,248 — (8,231 ) Equity in earnings of joint ventures 1,188 2,520 223 (3,708 ) 223 Net income (loss) $ (8,008 ) $ 2,237 $ 1,471 $ (3,708 ) $ (8,008 ) Other comprehensive income (loss) before income tax effect 1,644 (161 ) 829 (668 ) 1,644 Income tax effect (763 ) — 19 (19 ) (763 ) Other comprehensive income (loss) 881 (161 ) 848 (687 ) 881 Total comprehensive income (loss) $ (7,127 ) $ 2,076 $ 2,319 $ (4,395 ) $ (7,127 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the six months ended June 30, 2016 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 331,760 $ 286,211 $ (47,311 ) $ 570,660 Other customers — 74,930 18 — 74,948 Total net sales — 406,690 286,229 (47,311 ) 645,608 Cost of goods sold — 421,159 269,694 (47,775 ) 643,078 Gross profit (loss) — (14,469 ) 16,535 464 2,530 Selling, general and administrative expenses 16,560 — 3,010 — 19,570 Other operating expense - net — — 1,459 — 1,459 Operating income (loss) (16,560 ) (14,469 ) 12,066 464 (18,499 ) Interest expense (10,135 ) (765 ) (90 ) — (10,990 ) Intercompany interest 19,275 3,954 (23,229 ) — — Interest income 75 9 201 — 285 Net gain on forward and derivative contracts — 706 — — 706 Other income (expense) - net 634 15 (954 ) — (305 ) Loss before income taxes and equity in earnings of joint ventures (6,711 ) (10,550 ) (12,006 ) 464 (28,803 ) Income tax benefit 1,468 — 921 — 2,389 Loss before equity in earnings of joint ventures (5,243 ) (10,550 ) (11,085 ) 464 (26,414 ) Equity in earnings (loss) of joint ventures (20,435 ) — 736 20,435 736 Net loss $ (25,678 ) $ (10,550 ) $ (10,349 ) $ 20,899 $ (25,678 ) Other comprehensive income before income tax effect 2,412 1,555 607 (2,162 ) 2,412 Income tax effect (765 ) — 17 (17 ) (765 ) Other comprehensive income 1,647 1,555 624 (2,179 ) 1,647 Total comprehensive income (loss) $ (24,031 ) $ (8,995 ) $ (9,725 ) $ 18,720 $ (24,031 )
Condensed Consolidating Balance Sheet	Condensed Consolidating Balance Sheet As of June 30, 2017 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 29,305 $ (270 ) $ 101,638 $ — $ 130,673 Restricted cash — 800 55 — 855 Accounts receivable - net — 42,252 221 — 42,473 Due from affiliates 42 10,453 — — 10,495 Inventories 180 159,857 94,574 — 254,611 Prepaid and other current assets 6,269 2,669 9,686 — 18,624 Total current assets 35,796 215,761 206,174 — 457,731 Property, plant and equipment - net 17,015 313,307 670,181 — 1,000,503 Investment in subsidiaries 704,533 53,760 — (758,293 ) — Due from affiliates - long term 528,232 389,099 13,854 (931,185 ) — Other assets 28,175 44,012 27,059 (31,851 ) 67,395 TOTAL $ 1,313,751 $ 1,015,939 $ 917,268 $ (1,721,329 ) $ 1,525,629 Accounts payable, trade $ 2,823 $ 52,886 $ 36,422 $ — $ 92,131 Due to affiliates 133 8,409 10,550 — 19,092 Accrued and other current liabilities 10,569 14,557 20,553 — 45,679 Accrued employee benefits costs 1,932 8,256 579 — 10,767 Industrial revenue bonds — 7,815 — — 7,815 Total current liabilities 15,457 91,923 68,104 — 175,484 Senior notes payable 247,922 — — — 247,922 Accrued pension benefits costs - less current portion 45,857 19,746 13,849 (31,851 ) 47,601 Accrued postretirement benefits costs - less current portion 3,805 122,556 1,672 — 128,033 Due to affiliates - long term 243,668 101,441 586,076 (931,185 ) — Other liabilities 6,281 31,640 28,919 — 66,840 Deferred taxes — 2,720 106,268 — 108,988 Total noncurrent liabilities 547,533 278,103 736,784 (963,036 ) 599,384 Preferred stock 1 — — — 1 Common stock 945 1 59 (60 ) 945 Other shareholders' equity 749,815 645,912 112,321 (758,233 ) 749,815 Total shareholders' equity 750,761 645,913 112,380 (758,293 ) 750,761 TOTAL $ 1,313,751 $ 1,015,939 $ 917,268 $ (1,721,329 ) $ 1,525,629 Condensed Consolidating Balance Sheet As of December 31, 2016 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 36,670 $ (255 ) $ 95,988 $ — $ 132,403 Restricted cash — 794 256 — 1,050 Accounts receivable - net 167 11,883 382 — 12,432 Due from affiliates 42 16,606 3 — 16,651 Inventories 180 146,689 86,694 — 233,563 Prepaid and other current assets 6,838 5,699 9,673 — 22,210 Assets held for sale — — 22,313 — 22,313 Total current assets 43,897 181,416 215,309 — 440,622 Property, plant and equipment - net 12,311 328,069 685,905 — 1,026,285 Investment in subsidiaries 702,659 51,240 — (753,899 ) — Due from affiliates - long term 529,873 346,893 1,792 (878,558 ) — Other assets 28,215 49,331 27,596 (31,722 ) 73,420 TOTAL $ 1,316,955 $ 956,949 $ 930,602 $ (1,664,179 ) $ 1,540,327 Accounts payable, trade $ 6,125 $ 52,921 $ 35,914 $ — $ 94,960 Due to affiliates 417 9,641 5,310 — 15,368 Accrued and other current liabilities 11,950 17,744 20,406 — 50,100 Accrued employee benefits costs 1,932 8,317 668 — 10,917 Industrial revenue bonds — 7,815 — — 7,815 Total current liabilities 20,424 96,438 62,298 — 179,160 Senior notes payable 247,699 — — — 247,699 Accrued pension benefits costs - less current portion 46,390 20,167 14,658 (31,722 ) 49,493 Accrued postretirement benefits costs - less current portion 4,380 120,242 1,733 — 126,355 Other liabilities 4,160 30,920 36,946 — 72,026 Due to affiliates - long term 237,247 42,609 598,702 (878,558 ) — Deferred taxes — 2,735 106,204 — 108,939 Total noncurrent liabilities 539,876 216,673 758,243 (910,280 ) 604,512 Preferred stock 1 — — — 1 Common stock 944 1 59 (60 ) 944 Other shareholders' equity 755,710 643,837 110,002 (753,839 ) 755,710 Total shareholders' equity 756,655 643,838 110,061 (753,899 ) 756,655 TOTAL $ 1,316,955 $ 956,949 $ 930,602 $ (1,664,179 ) $ 1,540,327
Condensed Consolidating Statement of Cash Flows	Condensed Consolidating Statement of Cash Flows For the six months ended June 30, 2017 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (7,988 ) $ (25,946 ) $ 37,027 $ — $ 3,093 Purchase of property, plant and equipment (7,811 ) (4,963 ) (6,069 ) — (18,843 ) Proceeds from sale of property, plant and equipment — — 13,585 — 13,585 Restricted and other cash deposits — (6 ) 201 — 195 Intercompany transactions 11,784 (27,931 ) (12,061 ) 28,208 — Net cash provided by (used in) investing activities 3,973 (32,900 ) (4,344 ) 28,208 (5,063 ) Borrowings under revolving credit facilities 720 — — — 720 Repayments under revolving credit facilities (720 ) — — — (720 ) Issuance of common stock 240 — — — 240 Intercompany transactions (3,590 ) 58,831 (27,033 ) (28,208 ) — Net cash provided by (used in) financing activities (3,350 ) 58,831 (27,033 ) (28,208 ) 240 CHANGE IN CASH AND CASH EQUIVALENTS (7,365 ) (15 ) 5,650 — (1,730 ) Cash and cash equivalents, beginning of period 36,670 (255 ) 95,988 — 132,403 Cash and cash equivalents, end of period $ 29,305 $ (270 ) $ 101,638 $ — $ 130,673 Condensed Consolidating Statement of Cash Flows For the six months ended June 30, 2016 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (11,105 ) $ 18,847 $ 11,268 $ 4,593 $ 23,603 Purchase of property, plant and equipment — (2,697 ) (5,037 ) — (7,734 ) Restricted and other cash deposits — (4 ) (1,874 ) — (1,878 ) Net cash used in investing activities — (2,701 ) (6,911 ) — (9,612 ) Borrowings under revolving credit facilities 595 — — — 595 Repayments under revolving credit facilities (595 ) — — — (595 ) Intercompany transactions — (12,777 ) 17,370 (4,593 ) — Net cash provided by (used in) financing activities — (12,777 ) 17,370 (4,593 ) — CHANGE IN CASH AND CASH EQUIVALENTS (11,105 ) 3,369 21,727 — 13,991 Cash and cash equivalents, beginning of period 58,421 (3,647 ) 60,619 — 115,393 Cash and cash equivalents, end of period $ 47,316 $ (278 ) $ 82,346 $ — $ 129,384

Related party transactions - Na

Related party transactions - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
BHH [Member]
Related Party Transaction [Line Items]
Ownership percentage	40.00%		40.00%
Consolidated Sales [Member] | Customer Concentration Risk [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Major customer, percentage of revenue, net (percent)	76.00%	89.00%	76.00%	88.00%
Glencore [Member]
Related Party Transaction [Line Items]
Ownership percentage by majority shareholder	47.50%		47.50%
Common Stock [Member] | Glencore [Member]
Related Party Transaction [Line Items]
Ownership percentage by majority shareholder	42.90%		42.90%

Related party transactions - Su

Related party transactions - Summary of related party transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Related Party Transaction [Line Items]
Net sales to Glencore	$ 296,271	$ 290,283	$ 576,844	$ 570,660
Glencore [Member]
Related Party Transaction [Line Items]
Net sales to Glencore	296,271	290,283	576,844	570,660
Purchases from Glencore	41,587	50,177	113,168	94,190
BHH [Member]
Related Party Transaction [Line Items]
Purchases from BHH	$ 3,109	$ 2,715	$ 5,889	$ 5,098

Fair value measurements (Detail

Fair value measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
ASSETS:
Derivatives	$ 354
Fair Value, Measurements, Recurring [Member]
ASSETS:
Cash equivalents	82,567	$ 79,014
Trust assets	2,703	3,147
Surety bonds	1,625	1,874
Derivatives	354	925
TOTAL	87,249	84,960
LIABILITIES:
E.ON contingent obligation - net	0	0
Derivatives	7,539	253
TOTAL	7,539	253
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
ASSETS:
Cash equivalents	82,567	79,014
Trust assets	2,703	3,147
Surety bonds	1,625	1,874
Derivatives	0	0
TOTAL	86,895	84,035
LIABILITIES:
E.ON contingent obligation - net	0	0
Derivatives	0	0
TOTAL	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
ASSETS:
Cash equivalents	0	0
Trust assets	0	0
Surety bonds	0	0
Derivatives	0	0
TOTAL	0	0
LIABILITIES:
E.ON contingent obligation - net	0	0
Derivatives	7,208	0
TOTAL	7,208	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
ASSETS:
Cash equivalents	0	0
Trust assets	0	0
Surety bonds	0	0
Derivatives	354	925
TOTAL	354	925
LIABILITIES:
E.ON contingent obligation - net	0	0
Derivatives	331	253
TOTAL	$ 331	$ 253

Earnings (loss) per share (Deta

Earnings (loss) per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income (loss)	$ 7,131	$ (9,515)	$ (8,008)	$ (25,678)
Amount allocated to common stockholders (in hundredths)	92.03%	100.00%	100.00%	100.00%
Basic EPS:
Net income (loss) allocated to common stockholders	$ 6,563	$ (9,515)	$ (8,008)	$ (25,678)
Net income (loss) allocated to common stockholders (shares)	87,272,000	87,060,000	87,263,000	87,050,000
Net income (loss) allocated to common stockholders, per share (in USD per share)	$ 0.08	$ (0.11)	$ (0.09)	$ (0.29)
Effect of Dilutive Securities:
Share-based compensation	$ 0	$ 0
Share-based compensation (shares)	785,000	0
Diluted EPS:
Net income (loss) allocated to common stockholders with assumed conversion	$ 6,563	$ (9,515)	$ (8,008)	$ (25,678)
Net income (loss) allocated to common stockholders with assumed conversion (shares)	88,057,000	87,060,000	87,263,000	87,050,000
Net income (loss) allocated to common stockholders with assumed conversion, per share (in USD per share)	$ 0.07	$ (0.11)	$ (0.09)	$ (0.29)
Securities excluded from calculation of diluted EPS (shares)	432,506	1,800,096	462,506	1,288,473

Shareholders' equity (Details)

Shareholders' equity (Details) - USD ($)	6 Months Ended		24 Months Ended	75 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2011	Dec. 31, 2008
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	195,000,000				195,000,000
Common stock, par value (in dollars per share)	$ 0.01				$ 0.01
Common stock, shares issued (in shares)	94,502,486				94,437,418
Common stock, shares outstanding (in shares)	87,315,965				87,250,897
Stock repurchase program, authorized amount						$ 130,000,000	$ 60,000,000
Repurchase of common stock (in shares)			0	7,186,521
Repurchase of common stock, aggregate purchase price				$ 86,276,000
Stock repurchase program, remaining authorized repurchase amount	$ 43,724,000
Preferred stock, shares authorized (in shares)	5,000,000				5,000,000
Preferred stock par value (in dollars per share)	$ 0.01				$ 0.01
Preferred shares issued (in shares)								160,000
Number of shares issued for each share of preferred stock (in shares)	100
Series A Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock par value (in dollars per share)	$ 0.01
Preferred shares outstanding (in shares)	75,346				75,625
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance (in shares)	75,625	76,539
Conversion of convertible preferred stock (in shares)	(279)	(161)
Issuance for stock compensation plans (in shares)	0	0
Shares, Ending balance (in shares)	75,346	76,378
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance (in shares)	7,186,521	7,186,521
Conversion of convertible preferred stock (in shares)	0	0
Issuance for stock compensation plans (in shares)	0	0
Shares, Ending balance (in shares)	7,186,521	7,186,521
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance (in shares)	87,250,897	87,038,050
Conversion of convertible preferred stock (in shares)	27,904	16,109
Issuance for stock compensation plans (in shares)	37,164	21,428
Shares, Ending balance (in shares)	87,315,965	87,075,587

Income taxes (Details)

Income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income tax (expense) benefit	$ (1,452)	$ 319	$ (1,144)	$ 2,389

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Inventory, Net [Abstract]
Raw materials	$ 80,134	$ 59,415
Work-in-process	43,931	35,539
Finished goods	23,169	26,613
Operating and other supplies	107,377	111,996
Total inventories	$ 254,611	$ 233,563

Debt (Details)

Debt (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Jun. 04, 2013
Debt Instrument [Line Items]
Hancock County industrial revenue bonds (IRBs) due 2028, interest payable quarterly (variable interest rates (not to exceed 12%)) (1)	$ 7,815	$ 7,815
Total debt	255,737	255,514
Long-term Debt [Member] | Senior secured notes due June 01, 2021 [Member]
Debt Instrument [Line Items]
7.5% senior secured notes due June 1, 2021, net of debt discount of $2,078 and $2,301, respectively, interest payable semiannually	$ 247,922	$ 247,699
Maturity date	Jun. 1, 2021	Jun. 1, 2021
Stated interest rate, percentage	7.50%	7.50%	7.50%
Debt discount	$ 2,078	$ 2,301
Short-term Debt [Member] | Industrial revenue bonds due 2028 [Member]
Debt Instrument [Line Items]
Hancock County industrial revenue bonds (IRBs) due 2028, interest payable quarterly (variable interest rates (not to exceed 12%)) (1)	$ 7,815	$ 7,815
Maturity date	Apr. 1, 2028	Apr. 1, 2028
Stated interest rate, percentage	1.11%
Maximum [Member] | Short-term Debt [Member] | Industrial revenue bonds due 2028 [Member]
Debt Instrument [Line Items]
Effective interest rate, maximum	12.00%	12.00%

Debt - Credit Facility (Details

Debt - Credit Facility (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016	Nov. 27, 2013	Jun. 04, 2013
Line of Credit Facility [Line Items]
Fair value of debt instrument	$ 257,625,000	$ 234,220,000
U.S. revolving credit facility [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Credit facility face amount	150,000,000
Credit facility maximum amount	150,000,000
Borrowing availability	123,921,000
Borrowing availability, net of outstanding letters of credit and borrowings	85,679,000
U.S. letter of credit [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Letter of credit sub-facility amount	110,000,000
Borrowing availability, net of outstanding letters of credit and borrowings	38,242,000
Outstanding borrowings	0
Iceland revolving line of credit [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Credit facility face amount			$ 50,000,000
Credit facility maximum amount	50,000,000
Borrowing availability	50,000,000
Outstanding borrowings	0
Borrowing availability, net of outstanding letters of credit and borrowings	$ 50,000,000
Senior secured notes due June 01, 2021 [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Face amount				$ 250,000,000
Stated interest rate, percentage	7.50%	7.50%		7.50%

Commitments and contingencies (

Commitments and contingencies (Details) $ in Thousands	Feb. 09, 2017USD ($)	Dec. 18, 2015	Mar. 31, 2015USD ($)	Apr. 30, 2013USD ($)	Jun. 30, 2017USD ($)MWLaborUnions	Dec. 31, 2013USD ($)	Jun. 30, 2017USD ($)MWLaborUnions	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)
Environmental Contingencies [Abstract]
Environmental-related accrued liabilities					$ 1,222		$ 1,222	$ 998
Environmental remediation expense for Hydrocarbon Recovery Plan							$ 1,085
Labor Commitments [Abstract]
Percentage of total work force in union					66.00%		66.00%
Percentage of Grundartangi work force represented by the labor unions (in hundredths)					86.00%		86.00%
Number of labor unions Grundartangi subsidiary entered into a new labor agreement with | LaborUnions					5		5
Percentage of Vlissingen work force represented by the labor union (in hundredths)					100.00%		100.00%
Percentage of U.S. based work force represented by a union (in hundredths)					53.00%		53.00%
PBGC Agreement [Member]
Environmental Contingencies [Abstract]
Required pension contributions above minimum				$ 17,400
Pension Contributions			$ 1,100			$ 6,700
Pension contributions above minimum remaining					$ 9,600
Hawesville [Member]
Legal Contingencies [Abstract]
Power supply agreement, termination notice period					1 year
Sebree [Member]
Legal Contingencies [Abstract]
Power supply agreement, termination notice period					1 year
South Carolina Public Service Authority [Member]
Legal Contingencies [Abstract]
Power supply agreement, termination notice period		60 days
Power agreement, power supply from source one, percentage		25.00%
Power agreement, power supply from source two, percentage		75.00%
Grundartangi - HS, Landsvirkjun and OR [Member]
OR Power Agreement [Abstract]
Power currently available under the power purchase agreement (in megawatts) | MW					525		525
Grundartangi - Landsvirkjun [Member]
OR Power Agreement [Abstract]
Power currently available under the power purchase agreement (in megawatts) | MW					161		161
Helguvik [Member]
OR Power Agreement [Abstract]
Power currently available under the power purchase agreement (in megawatts) | MW					47.5		47.5
Ravenswood Retiree Medical Benefits Changes [Member]
Environmental Contingencies [Abstract]
Ravenswood litigation settlement amount	$ 23,000
Ravenswood litigation settlement period	10 years
Ravenswood settlement payment to be made upon final approval from court	$ 5,000
Ravenswood settlement, annual payment amount	$ 2,000
Ravenswood litigation settlement installment period	9 years
Ravenswood retiree medical benefits settlement liability									$ 23,000

Components of accumulated oth41

Components of accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	$ (121,414)		$ (121,414)		$ (123,057)
Income tax effect	8,402		8,402		9,164
Accumulated other comprehensive loss	(113,012)		(113,012)		(113,893)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Equity, beginning balance			756,655
Equity, ending balance	750,761		750,761
Defined benefit plan and other postretirement liabilities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	(124,180)		(124,180)		(125,917)
Income tax effect	8,955		8,955		9,736
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Equity, beginning balance	(115,431)	$ (109,806)	(116,181)	$ (110,667)
Net amount reclassified to net loss	206	862	956	1,723
Equity, ending balance	(115,225)	(108,944)	(115,225)	(108,944)
Unrealized gain (loss) on financial instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	2,766		2,766		2,860
Income tax effect	(553)		(553)		$ (572)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Equity, beginning balance	2,250	(2,021)	2,288	(1,983)
Net amount reclassified to net loss	(37)	(38)	(75)	(76)
Equity, ending balance	2,213	(2,059)	2,213	(2,059)
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Equity, beginning balance	(113,181)	(111,827)	(113,893)	(112,650)
Net amount reclassified to net loss	169	824	881	1,647
Equity, ending balance	$ (113,012)	$ (111,003)	$ (113,012)	$ (111,003)

Components of accumulated oth42

Components of accumulated other comprehensive loss - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of goods sold	$ 366,342	$ 321,172	$ 715,277	$ 643,078
Selling, general and administrative expenses	9,352	9,945	20,054	19,570
Other operating expense, net	(180)	(578)	(1,153)	(1,459)
Income tax (expense) benefit	(1,452)	319	(1,144)	2,389
Net income (loss)	7,131	(9,515)	(8,008)	(25,678)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined benefit plan and other postretirement liabilities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of goods sold	(1,468)	778	(161)	1,555
Selling, general and administrative expenses	845	125	977	250
Other operating expense, net	528	350	922	700
Income tax (expense) benefit	301	(391)	(782)	(782)
Net income (loss)	206	862	956	1,723
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized gain (loss) on financial instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of goods sold	(47)	(47)	(94)	(93)
Income tax (expense) benefit	10	9	19	17
Net income (loss)	$ (37)	$ (38)	$ (75)	$ (76)

Components of net periodic be43

Components of net periodic benefit cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 968	$ 1,270	$ 2,192	$ 2,540
Interest cost	3,323	3,482	6,655	6,962
Expected return on plan assets	(5,116)	(4,816)	(9,865)	(9,632)
Amortization of prior service costs	26	28	53	56
Amortization of net loss	1,506	1,041	2,738	2,084
Net periodic benefit cost	707	1,005	1,773	2,010
Employer contributions			874
Other Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	191	330	438	660
Interest cost	2,978	1,439	4,344	2,895
Amortization of prior service costs	(698)	(695)	(1,036)	(1,390)
Amortization of net loss	(929)	879	(18)	1,755
Net periodic benefit cost	$ 1,542	$ 1,953	$ 3,728	$ 3,920

Supplemental cash flow inform44

Supplemental cash flow information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash paid for:
Interest	$ 9,903	$ 9,701
Income taxes, net	$ 1,796	$ 6,316

Derivatives (Details)

Derivatives (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)MWht	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)MWht	Jun. 30, 2016USD ($)
Derivative [Line Items]
Derivative asset | $	$ 354		$ 354
Derivative liability | $	7,539		7,539
Net gain (loss) on forward and derivative contracts | $	$ 2,957	$ 353	$ (13,180)	$ 706
LME Swap [Member]
Derivative [Line Items]
Other forward delivery contracts to sell primary aluminum (in tonnes)	36,090		36,090
Other forward delivery contracts to sell primary aluminum, settled monthly (in tonnes)	33,000		33,000
Price Swap [Member]
Derivative [Line Items]
Open position to offset fixed prices			7,386
Affiliated Entity [Member] | LME Swap [Member]
Derivative [Line Items]
Other forward delivery contracts to sell primary aluminum (in tonnes)	33,390		33,390
Grundartangi [Member] | Power Price Swap [Member]
Derivative [Line Items]
Percentage of power purchases included in forward price contract (percent)			4.00%
Power available | MWh	256,200		256,200

Condensed consolidating finan46

Condensed consolidating financial information - Statement of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue, Net [Abstract]
Related parties	$ 296,271	$ 290,283	$ 576,844	$ 570,660
Other customers	92,531	36,471	177,744	74,948
Total net sales	388,802	326,754	754,588	645,608
Cost of goods sold	366,342	321,172	715,277	643,078
Gross profit	22,460	5,582	39,311	2,530
Selling, general and administrative expenses	9,352	9,945	20,054	19,570
Other operating expense - net	180	578	1,153	1,459
Operating income (loss)	12,928	(4,941)	18,104	(18,499)
Interest expense	(5,461)	(5,497)	(11,032)	(10,990)
Intercompany interest	0	0	0	0
Interest income	283	171	513	285
Net gain on forward and derivative contracts	2,957	353	(13,180)	706
Other (expense) - net	(1,876)	(299)	(1,492)	(305)
Income (loss) before income taxes and equity in earnings of joint ventures	8,831	(10,213)	(7,087)	(28,803)
Income tax (expense) benefit	(1,452)	319	(1,144)	2,389
Income (loss) before equity in earnings of joint ventures	7,379	(9,894)	(8,231)	(26,414)
Equity in earnings (loss) of joint ventures	(248)	379	223	736
Net income (loss)	7,131	(9,515)	(8,008)	(25,678)
Other comprehensive income (loss) before income tax effect	(142)	1,206	1,644	2,412
Income tax effect	311	(382)	(763)	(765)
Other comprehensive income	169	824	881	1,647
Total comprehensive income (loss)	7,300	(8,691)	(7,127)	(24,031)
Consolidating Adjustments [Member]
Revenue, Net [Abstract]
Related parties	0	(23,914)	0	(47,311)
Other customers	0	0	0	0
Total net sales	0	(23,914)	0	(47,311)
Cost of goods sold	0	(23,804)	0	(47,775)
Gross profit	0	(110)	0	464
Selling, general and administrative expenses	0	0	0	0
Other operating expense - net	0	0	0	0
Operating income (loss)	0	(110)	0	464
Interest expense	0	0	0	0
Intercompany interest	0	0		0
Interest income	0	0	0	0
Net gain on forward and derivative contracts	0	0	0	0
Other (expense) - net	0	0	0	0
Income (loss) before income taxes and equity in earnings of joint ventures	0	(110)	0	464
Income tax (expense) benefit	0	0	0	0
Income (loss) before equity in earnings of joint ventures	0	(110)	0	464
Equity in earnings (loss) of joint ventures	(13,066)	6,660	(3,708)	20,435
Net income (loss)	(13,066)	6,550	(3,708)	20,899
Other comprehensive income (loss) before income tax effect	986	(1,081)	(668)	(2,162)
Income tax effect	(11)	(9)	(19)	(17)
Other comprehensive income	975	(1,090)	(687)	(2,179)
Total comprehensive income (loss)	(12,091)	5,460	(4,395)	18,720
The Company [Member]
Revenue, Net [Abstract]
Related parties	0	0	0	0
Other customers	0	0	0	0
Total net sales	0	0	0	0
Cost of goods sold	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	8,914	8,261	19,114	16,560
Other operating expense - net	0	0	0	0
Operating income (loss)	(8,914)	(8,261)	(19,114)	(16,560)
Interest expense	(5,035)	(5,070)	(10,183)	(10,135)
Intercompany interest	9,213	9,727	18,195	19,275
Interest income	49	38	129	75
Net gain on forward and derivative contracts	0	0	0	0
Other (expense) - net	(110)	(137)	677	634
Income (loss) before income taxes and equity in earnings of joint ventures	(4,797)	(3,703)	(10,296)	(6,711)
Income tax (expense) benefit	529	848	1,100	1,468
Income (loss) before equity in earnings of joint ventures	(4,268)	(2,855)	(9,196)	(5,243)
Equity in earnings (loss) of joint ventures	11,399	(6,660)	1,188	(20,435)
Net income (loss)	7,131	(9,515)	(8,008)	(25,678)
Other comprehensive income (loss) before income tax effect	(142)	1,206	1,644	2,412
Income tax effect	311	(382)	(763)	(765)
Other comprehensive income	169	824	881	1,647
Total comprehensive income (loss)	$ 7,300	(8,691)	$ (7,127)	(24,031)
Combined Guarantor Subsidiaries [Member]
Condensed Statement of Income Captions [Line Items]
Ownership percentage	100.00%		100.00%
Revenue, Net [Abstract]
Related parties	$ 134,850	169,640	$ 265,918	331,760
Other customers	92,496	36,462	177,679	74,930
Total net sales	227,346	206,102	443,597	406,690
Cost of goods sold	220,553	211,586	434,304	421,159
Gross profit	6,793	(5,484)	9,293	(14,469)
Selling, general and administrative expenses	0	0	0	0
Other operating expense - net	0	0	0	0
Operating income (loss)	6,793	(5,484)	9,293	(14,469)
Interest expense	(382)	(383)	(761)	(765)
Intercompany interest	2,147	1,997	4,228	3,954
Interest income	(1)	9	(1)	9
Net gain on forward and derivative contracts	2,644	353	(13,203)	706
Other (expense) - net	114	21	161	15
Income (loss) before income taxes and equity in earnings of joint ventures	11,315	(3,487)	(283)	(10,550)
Income tax (expense) benefit	(493)	0	0	0
Income (loss) before equity in earnings of joint ventures	10,822	(3,487)	(283)	(10,550)
Equity in earnings (loss) of joint ventures	1,667	0	2,520	0
Net income (loss)	12,489	(3,487)	2,237	(10,550)
Other comprehensive income (loss) before income tax effect	(1,467)	777	(161)	1,555
Income tax effect	0	0	0	0
Other comprehensive income	(1,467)	777	(161)	1,555
Total comprehensive income (loss)	11,022	(2,710)	2,076	(8,995)
Combined Non-Guarantor Subsidiaries [Member]
Revenue, Net [Abstract]
Related parties	161,421	144,557	310,926	286,211
Other customers	35	9	65	18
Total net sales	161,456	144,566	310,991	286,229
Cost of goods sold	145,789	133,390	280,973	269,694
Gross profit	15,667	11,176	30,018	16,535
Selling, general and administrative expenses	438	1,684	940	3,010
Other operating expense - net	180	578	1,153	1,459
Operating income (loss)	15,049	8,914	27,925	12,066
Interest expense	(44)	(44)	(88)	(90)
Intercompany interest	(11,360)	(11,724)	(22,423)	(23,229)
Interest income	235	124	385	201
Net gain on forward and derivative contracts	313	0	23	0
Other (expense) - net	(1,880)	(183)	(2,330)	(954)
Income (loss) before income taxes and equity in earnings of joint ventures	2,313	(2,913)	3,492	(12,006)
Income tax (expense) benefit	(1,488)	(529)	(2,244)	921
Income (loss) before equity in earnings of joint ventures	825	(3,442)	1,248	(11,085)
Equity in earnings (loss) of joint ventures	(248)	379	223	736
Net income (loss)	577	(3,063)	1,471	(10,349)
Other comprehensive income (loss) before income tax effect	481	304	829	607
Income tax effect	11	9	19	17
Other comprehensive income	492	313	848	624
Total comprehensive income (loss)	$ 1,069	$ (2,750)	$ 2,319	$ (9,725)

Condensed consolidating finan47

Condensed consolidating financial information - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	$ 130,673	$ 132,403	$ 129,384	$ 115,393
Restricted cash	855	1,050
Accounts receivable - net	42,473	12,432
Due from affiliates	10,495	16,651
Inventories	254,611	233,563
Prepaid and other current assets	18,624	22,210
Assets held for sale	0	22,313
Total current assets	457,731	440,622
Property, plant and equipment - net	1,000,503	1,026,285
Investment in subsidiaries	0	0
Due from affiliates - long term	0	0
Other assets	67,395	73,420
TOTAL	1,525,629	1,540,327
Accounts payable, trade	92,131	94,960
Due to affiliates	19,092	15,368
Accrued and other current liabilities	45,679	50,100
Accrued employee benefits costs	10,767	10,917
Industrial revenue bonds	7,815	7,815
Total current liabilities	175,484	179,160
Senior notes payable	247,922	247,699
Accrued pension benefits costs - less current portion	47,601	49,493
Accrued postretirement benefits costs - less current portion	128,033	126,355
Due to affiliates - long term	0
Other liabilities	66,840	72,026
Intercompany loan		0
Deferred taxes	108,988	108,939
Total noncurrent liabilities	599,384	604,512
Preferred stock	1	1
Common stock	945	944
Other shareholders' equity	749,815	755,710
Total shareholders’ equity	750,761	756,655
Liabilities and Equity	1,525,629	1,540,327
Consolidating Adjustments [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	0	0	0	0
Restricted cash	0	0
Accounts receivable - net	0	0
Due from affiliates	0	0
Inventories	0	0
Prepaid and other current assets	0	0
Assets held for sale		0
Total current assets	0	0
Property, plant and equipment - net	0	0
Investment in subsidiaries	(758,293)	(753,899)
Due from affiliates - long term	(931,185)	(878,558)
Other assets	(31,851)	(31,722)
TOTAL	(1,721,329)	(1,664,179)
Accounts payable, trade	0	0
Due to affiliates	0	0
Accrued and other current liabilities	0	0
Accrued employee benefits costs	0	0
Industrial revenue bonds	0	0
Total current liabilities	0	0
Senior notes payable	0	0
Accrued pension benefits costs - less current portion	(31,851)	(31,722)
Accrued postretirement benefits costs - less current portion	0	0
Due to affiliates - long term	(931,185)
Other liabilities	0	0
Intercompany loan		(878,558)
Deferred taxes	0	0
Total noncurrent liabilities	(963,036)	(910,280)
Preferred stock	0	0
Common stock	(60)	(60)
Other shareholders' equity	(758,233)	(753,839)
Total shareholders’ equity	(758,293)	(753,899)
Liabilities and Equity	(1,721,329)	(1,664,179)
The Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	29,305	36,670	47,316	58,421
Restricted cash	0	0
Accounts receivable - net	0	167
Due from affiliates	42	42
Inventories	180	180
Prepaid and other current assets	6,269	6,838
Assets held for sale		0
Total current assets	35,796	43,897
Property, plant and equipment - net	17,015	12,311
Investment in subsidiaries	704,533	702,659
Due from affiliates - long term	528,232	529,873
Other assets	28,175	28,215
TOTAL	1,313,751	1,316,955
Accounts payable, trade	2,823	6,125
Due to affiliates	133	417
Accrued and other current liabilities	10,569	11,950
Accrued employee benefits costs	1,932	1,932
Industrial revenue bonds	0	0
Total current liabilities	15,457	20,424
Senior notes payable	247,922	247,699
Accrued pension benefits costs - less current portion	45,857	46,390
Accrued postretirement benefits costs - less current portion	3,805	4,380
Due to affiliates - long term	243,668
Other liabilities	6,281	4,160
Intercompany loan		237,247
Deferred taxes	0	0
Total noncurrent liabilities	547,533	539,876
Preferred stock	1	1
Common stock	945	944
Other shareholders' equity	749,815	755,710
Total shareholders’ equity	750,761	756,655
Liabilities and Equity	1,313,751	1,316,955
Combined Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	(270)	(255)	(278)	(3,647)
Restricted cash	800	794
Accounts receivable - net	42,252	11,883
Due from affiliates	10,453	16,606
Inventories	159,857	146,689
Prepaid and other current assets	2,669	5,699
Assets held for sale		0
Total current assets	215,761	181,416
Property, plant and equipment - net	313,307	328,069
Investment in subsidiaries	53,760	51,240
Due from affiliates - long term	389,099	346,893
Other assets	44,012	49,331
TOTAL	1,015,939	956,949
Accounts payable, trade	52,886	52,921
Due to affiliates	8,409	9,641
Accrued and other current liabilities	14,557	17,744
Accrued employee benefits costs	8,256	8,317
Industrial revenue bonds	7,815	7,815
Total current liabilities	91,923	96,438
Senior notes payable	0	0
Accrued pension benefits costs - less current portion	19,746	20,167
Accrued postretirement benefits costs - less current portion	122,556	120,242
Due to affiliates - long term	101,441
Other liabilities	31,640	30,920
Intercompany loan		42,609
Deferred taxes	2,720	2,735
Total noncurrent liabilities	278,103	216,673
Preferred stock	0	0
Common stock	1	1
Other shareholders' equity	645,912	643,837
Total shareholders’ equity	645,913	643,838
Liabilities and Equity	1,015,939	956,949
Combined Non-Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	101,638	95,988	$ 82,346	$ 60,619
Restricted cash	55	256
Accounts receivable - net	221	382
Due from affiliates	0	3
Inventories	94,574	86,694
Prepaid and other current assets	9,686	9,673
Assets held for sale		22,313
Total current assets	206,174	215,309
Property, plant and equipment - net	670,181	685,905
Investment in subsidiaries	0	0
Due from affiliates - long term	13,854	1,792
Other assets	27,059	27,596
TOTAL	917,268	930,602
Accounts payable, trade	36,422	35,914
Due to affiliates	10,550	5,310
Accrued and other current liabilities	20,553	20,406
Accrued employee benefits costs	579	668
Industrial revenue bonds	0	0
Total current liabilities	68,104	62,298
Senior notes payable	0	0
Accrued pension benefits costs - less current portion	13,849	14,658
Accrued postretirement benefits costs - less current portion	1,672	1,733
Due to affiliates - long term	586,076
Other liabilities	28,919	36,946
Intercompany loan		598,702
Deferred taxes	106,268	106,204
Total noncurrent liabilities	736,784	758,243
Preferred stock	0	0
Common stock	59	59
Other shareholders' equity	112,321	110,002
Total shareholders’ equity	112,380	110,061
Liabilities and Equity	$ 917,268	$ 930,602

Condensed consolidating finan48

Condensed consolidating financial information - Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	$ 3,093	$ 23,603
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchase of property, plant and equipment	(18,843)	(7,734)
Proceeds from sale of property, plant and equipment	13,585	0
Restricted and other cash deposits	195	(1,878)
Intercompany transactions	0
Net cash used in investing activities	(5,063)	(9,612)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings under revolving credit facilities	720	595
Repayments under revolving credit facilities	(720)	(595)
Issuance of common stock	240	0
Intercompany transactions	0	0
Net cash provided by financing activities	240	0
CHANGE IN CASH AND CASH EQUIVALENTS	(1,730)	13,991
Cash and cash equivalents, beginning of period	132,403	115,393
Cash and cash equivalents, end of period	130,673	129,384
Consolidating Adjustments [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	0	4,593
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchase of property, plant and equipment	0	0
Proceeds from sale of property, plant and equipment	0
Restricted and other cash deposits	0	0
Intercompany transactions	28,208
Net cash used in investing activities	28,208	0
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings under revolving credit facilities	0	0
Repayments under revolving credit facilities	0	0
Issuance of common stock	0
Intercompany transactions	(28,208)	(4,593)
Net cash provided by financing activities	(28,208)	(4,593)
CHANGE IN CASH AND CASH EQUIVALENTS	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
The Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	(7,988)	(11,105)
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchase of property, plant and equipment	(7,811)	0
Proceeds from sale of property, plant and equipment	0
Restricted and other cash deposits	0	0
Intercompany transactions	11,784
Net cash used in investing activities	3,973	0
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings under revolving credit facilities	720	595
Repayments under revolving credit facilities	(720)	(595)
Issuance of common stock	240
Intercompany transactions	(3,590)	0
Net cash provided by financing activities	(3,350)	0
CHANGE IN CASH AND CASH EQUIVALENTS	(7,365)	(11,105)
Cash and cash equivalents, beginning of period	36,670	58,421
Cash and cash equivalents, end of period	29,305	47,316
Combined Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	(25,946)	18,847
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchase of property, plant and equipment	(4,963)	(2,697)
Proceeds from sale of property, plant and equipment	0
Restricted and other cash deposits	(6)	(4)
Intercompany transactions	(27,931)
Net cash used in investing activities	(32,900)	(2,701)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings under revolving credit facilities	0	0
Repayments under revolving credit facilities	0	0
Issuance of common stock	0
Intercompany transactions	58,831	(12,777)
Net cash provided by financing activities	58,831	(12,777)
CHANGE IN CASH AND CASH EQUIVALENTS	(15)	3,369
Cash and cash equivalents, beginning of period	(255)	(3,647)
Cash and cash equivalents, end of period	(270)	(278)
Combined Non-Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	37,027	11,268
Net Cash Provided by (Used in) Investing Activities [Abstract]
Purchase of property, plant and equipment	(6,069)	(5,037)
Proceeds from sale of property, plant and equipment	13,585
Restricted and other cash deposits	201	(1,874)
Intercompany transactions	(12,061)
Net cash used in investing activities	(4,344)	(6,911)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings under revolving credit facilities	0	0
Repayments under revolving credit facilities	0	0
Issuance of common stock	0
Intercompany transactions	(27,033)	17,370
Net cash provided by financing activities	(27,033)	17,370
CHANGE IN CASH AND CASH EQUIVALENTS	5,650	21,727
Cash and cash equivalents, beginning of period	95,988	60,619
Cash and cash equivalents, end of period	$ 101,638	$ 82,346