Century Aluminum (CENX) 10-K 7 Mar 16 2015 Q4 Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Feb. 29, 2016	Jun. 30, 2015
Document Information [Line Items]
Entity Registrant Name	CENTURY ALUMINUM CO
Entity Central Index Key	949,157
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 423
Entity Common Stock, Shares Outstanding		87,038,050
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q4
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
NET SALES:
Related parties	$ 1,867,711	$ 1,262,101	$ 511,051
Third-party customers	82,146	668,941	943,262
Sales Revenue – net	1,949,857	1,931,042	1,454,313
Cost of goods sold	1,908,544	1,729,243	1,414,790
Gross profit	41,313	201,799	39,523
Selling, general and administrative expenses	42,115	49,195	67,477
Ravenswood impairment	30,850	0	0
Other operating expense – net	7,436	12,481	8,602
Operating income (loss)	(39,088)	140,123	(36,556)
Interest expense	(21,954)	(22,015)	(23,091)
Interest income	339	301	728
Net gain on forward and derivative contracts	1,600	179	16,598
Gain on bargain purchase	0	0	5,253
Unrealized gain on fair value of contingent consideration	18,337	7,943	0
Gain on remeasurement of equity investment	0	15,955	0
Loss on early extinguishment of debt	0	0	(3,272)
Other income (expense) – net	(356)	991	496
Income (loss) before income taxes and equity in earnings of joint ventures	(41,122)	143,477	(39,844)
Income tax expense	(9,276)	(18,308)	(3,131)
Income (loss) before equity in earnings of joint ventures	(50,398)	125,169	(42,975)
BHH impairment	(11,584)	0	0
Equity in earnings of joint ventures	2,672	1,305	2,662
Net income (loss)	$ (59,310)	$ 126,474	$ (40,313)
EARNINGS (LOSS) PER COMMON SHARE:
Basic (in dollars per share)	$ (0.68)	$ 1.31	$ (0.45)
Diluted (in dollars per share)	$ (0.68)	$ 1.30	$ (0.45)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (59,310)	$ 126,474	$ (40,313)
Other comprehensive income (loss) before income tax effect:
Net gain on foreign currency cash flow hedges reclassified as income	(186)	(186)	(186)
Defined benefit plans and other postretirement benefits:
Net gain (loss) arising during the period	5,553	(41,995)	56,795
Prior service benefit (cost) arising during the period	1,758	(1,299)	0
Amortization of prior service benefit during the period	(8,351)	(3,504)	(3,920)
Amortization of actuarial net loss during the period	7,794	10,312	8,174
Change in equity in investee other comprehensive income	0	0	61
Other comprehensive income (loss) before income tax effect	6,568	(36,672)	60,924
Income tax effect	(1,536)	(1,829)	(1,564)
Other comprehensive income (loss)	5,032	(38,501)	59,360
Total comprehensive income (loss)	$ (54,278)	$ 87,973	$ 19,047

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
ASSETS
Cash and cash equivalents	$ 115,393	$ 163,242
Restricted cash	791	801
Accounts receivable — net	9,475	77,667
Due from affiliates	17,417	31,503
Inventories	231,872	283,480
Prepaid and other current assets	42,412	29,768
Deferred taxes	0	14,281
Assets held for sale	30,697	0
Total current assets	448,057	600,742
Property, plant and equipment — net	1,232,256	1,305,543
Other assets	72,155	118,773
TOTAL	1,752,468	2,025,058
LIABILITIES:
Accounts payable, trade	90,489	151,443
Due to affiliates	10,045	22,261
Accrued and other current liabilities	48,822	103,807
Accrued employee benefits costs	10,148	10,159
Industrial revenue bonds	7,815	7,815
Total current liabilities	167,319	295,485
Senior notes payable	247,278	246,888
Accrued pension benefits costs — less current portion	43,999	59,906
Accrued postretirement benefits costs — less current portion	125,999	152,894
Other liabilities	53,009	53,272
Deferred taxes	96,994	111,486
Total noncurrent liabilities	$ 567,279	$ 624,446
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY:
Series A Preferred stock	$ 1	$ 1
Common stock	942	939
Additional paid-in capital	2,513,631	2,510,261
Treasury stock, at cost	(86,276)	(49,924)
Accumulated other comprehensive loss	(112,650)	(117,682)
Accumulated deficit	(1,297,778)	(1,238,468)
Total shareholders’ equity	1,017,870	1,105,127
TOTAL	$ 1,752,468	$ 2,025,058

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred stock [Member]	Common stock [Member]	Additional paid-in capital [Member]	Treasury stock, at cost [Member]	Accumulated other comprehensive loss [Member]	Accumulated deficit [Member]
Balance at Dec. 31, 2012	$ 982,643	$ 1	$ 933	$ 2,507,454	$ (49,924)	$ (151,192)	$ (1,324,629)
Net income (loss)	(40,313)						(40,313)
Other comprehensive income (loss)	59,360					59,360
Issuance of common stock – compensation plans	44		1	43
Share-based compensation expense	1,078			1,078
Conversion of preferred stock to common stock	0		1	(1)
Balance at Dec. 31, 2013	1,002,812	1	935	2,508,574	(49,924)	(91,832)	(1,364,942)
Net income (loss)	126,474						126,474
Other comprehensive income (loss)	(38,501)					(38,501)
Elimination of equity in investee resulting from acquisition	12,651					12,651
Issuance of common stock – compensation plans	304		2	302
Share-based compensation expense	1,387			1,387
Conversion of preferred stock to common stock	0		2	(2)
Balance at Dec. 31, 2014	1,105,127	1	939	2,510,261	(49,924)	(117,682)	(1,238,468)
Net income (loss)	(59,310)						(59,310)
Other comprehensive income (loss)	5,032					5,032
Issuance of common stock – compensation plans	1,529		1	1,528
Repurchase of common stock	(36,352)				(36,352)
Share-based compensation expense	1,844			1,844
Conversion of preferred stock to common stock	0		2	(2)
Balance at Dec. 31, 2015	$ 1,017,870	$ 1	$ 942	$ 2,513,631	$ (86,276)	$ (112,650)	$ (1,297,778)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (59,310)	$ 126,474	$ (40,313)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Gain on bargain purchase	0	0	(5,253)
Unrealized gain on fair value of contingent consideration	(18,337)	(7,943)	0
Gain on remeasurement of equity investment	0	(15,955)	0
Unrealized gain on E.ON contingent obligation	(1,411)	(1,412)	(16,781)
Lower of cost or market inventory adjustment	7,539	(1,247)	1,247
Depreciation	80,117	70,827	66,570
Ravenswood impairment	30,850	0	0
BHH impairment	11,584	0	0
Sebree power contract amortization	0	(5,534)	(31,031)
Pension and other postretirement benefits	(4,991)	6,939	1,740
Deferred income taxes	(178)	2,633	(1,493)
Stock-based compensation	1,844	1,334	1,078
Loss on early extinguishment of debt	0	0	3,272
Equity in earnings of joint ventures, net of dividends	(806)	425	871
Change in operating assets and liabilities:
Accounts receivable — net	68,192	(8,712)	(6,001)
Due from affiliates	14,086	12,084	(5,717)
Inventories	44,896	(16,513)	(21,740)
Prepaid and other current assets	(144)	3,392	5,318
Accounts payable, trade	(60,583)	11,797	25,224
Due to affiliates	(12,216)	3,058	13,845
Accrued and other current liabilities	(31,540)	18,071	5,834
Pension contribution - Mt. Holly	(34,595)	0	0
Other — net	(3,131)	7,962	23,048
Net cash provided by operating activities	31,866	207,680	19,718
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(54,700)	(55,126)	(68,077)
Purchase of Sebree smelter	0	(1,042)	(48,058)
Investments in and advances to joint ventures	0	0	(125)
Purchase of remaining interest in Mt. Holly smelter	11,313	(65,100)	0
Proceeds from sale of property, plant and equipment	14	46	525
Restricted and other cash deposits	10	896	(1,439)
Net cash used in investing activities	(43,363)	(120,326)	(117,174)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of debt	0	(2,603)	(249,604)
Proceeds from issuance of debt	0	0	246,330
Borrowings under revolving credit facilities	1,737	92,423	22,725
Repayments under revolving credit facilities	(1,737)	(98,423)	(16,725)
Debt issuance costs	0	0	(3,994)
Debt retirement costs	0	0	(1,208)
Repurchase of common stock	(36,352)	0	0
Issuance of common stock	0	403	44
Net cash used in financing activities	(36,352)	(8,200)	(2,432)
CHANGE IN CASH AND CASH EQUIVALENTS	(47,849)	79,154	(99,888)
Cash and cash equivalents, beginning of year	163,242	84,088	183,976
Cash and cash equivalents, end of year	$ 115,393	$ 163,242	$ 84,088

Summary of significant accounti

Summary of significant accounting policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of significant accounting policies Organization and Basis of Presentation — Century Aluminum Company ("Century Aluminum," "Century," the "Company", "we", "us", "our" or "ours") is a holding company, whose principal subsidiaries are Century Kentucky, Inc. (together with its subsidiaries, "CAKY"), Nordural ehf ("Nordural"), Century Aluminum Sebree LLC ("Century Sebree"), Century Aluminum of South Carolina ("CASC"), and Century Aluminum of West Virginia, Inc. ("Century of West Virginia"). Century Kentucky, Inc. operates a primary aluminum reduction facility in Hawesville, Kentucky ("Hawesville"). Nordural Grundartangi ehf, a subsidiary of Nordural, operates a primary aluminum reduction facility in Grundartangi, Iceland ("Grundartangi"). Century Sebree operates a primary aluminum reduction facility in Robards, Kentucky ("Sebree"). CASC operates a primary aluminum reduction facility in Mt. Holly, South Carolina ("Mt. Holly"). Nordural Helguvik ehf, a subsidiary of Nordural, owns a greenfield primary aluminum project in Helguvik, Iceland ("Helguvik" or the "Helguvik project"), construction of which is currently curtailed. In July 2015, we announced the permanent closure of our Ravenswood facility, located adjacent to the Ohio River near Ravenswood, West Virginia ("Ravenswood"). Ravenswood is owned by our wholly-owned subsidiary, Century of West Virginia. In addition to our primary aluminum assets, our subsidiary, Century Vlissingen, owns and operates a carbon anode production facility owned located in Vlissingen, the Netherlands ("Vlissingen"). We also own a 40% stake in Baise Haohai Carbon Co., Ltd. ("BHH"), a joint venture that owns and operates a carbon anode and cathode facility located in the Guangxi Zhuang Autonomous Region of south China. Carbon anodes are used in the production of primary aluminum and both BHH and Vlissingen currently supply carbon anodes to Grundartangi. As of December 31, 2015 , Glencore owns 42.9% of Century’s outstanding common stock and all of our outstanding Series A Convertible Preferred stock. Through its ownership of our common and preferred stock, Glencore has an overall 47.5% economic ownership of Century. Century and Glencore enter into various transactions such as the purchase and sale of primary aluminum, purchase and sale of alumina, tolling agreements and certain forward financial contracts. See Note 2 Related party transactions Principles of Consolidation — The consolidated financial statements include the accounts of Century Aluminum Company and our subsidiaries, after elimination of all intercompany transactions and accounts. Our interest in the BHH joint venture is accounted for under the equity method. For BHH, we report our investment in its results of operations on a one-quarter lag. Prior to the acquisition of Mt. Holly, we accounted for our interest in Mt. Holly using the equity method of accounting. Revenue recognition — In connection with our sales agreement with Glencore, we invoice Glencore prior to physical shipment of goods for substantially all production generated from each of our US domestic smelters. For those sales, revenue is recognized only when Glencore has specifically requested such treatment and has made a commitment to purchase the product. The goods must be complete, ready for shipment and separated from other inventory with title and risk of ownership passing to Glencore. We must retain no performance obligations. For all other shipments, including sales to Glencore from our smelter in Iceland, our tolling agreement with Glencore, revenue is recognized when title and risk of loss pass to the customer which is upon shipment. Cash and Cash Equivalents — Cash and cash equivalents are comprised of cash, money market funds and short-term investments having original maturities of three months or less. The carrying amount of cash equivalents approximates fair value. Accounts Receivable and Due from Affiliates — These amounts are net of an allowance for uncollectible accounts and credit memos of $ 1,000 and $ 1,000 at December 31, 2015 and 2014 , respectively. Inventories — Our inventories are stated at the lower of cost or Net Realizable Value ("NRV"), using the first-in, first-out ("FIFO") method. Property, Plant and Equipment — Property, plant and equipment is stated at cost. Additions, renewals and improvements are capitalized. Asset and accumulated depreciation accounts are relieved for dispositions with resulting gains or losses included in other income – net . Maintenance and repairs are expensed as incurred. We capitalize interest for the construction of qualifying assets. Depreciation of plant and equipment is provided for by the straight-line method over the following estimated useful lives: Building and improvements 10 to 45 years Machinery and equipment 5 to 35 years Technology and software 3 to 7 years Impairment of long-lived assets — We evaluate our property, plant and equipment for potential impairment whenever events or circumstances indicate that the carrying amount of these assets may not be recoverable. If deemed unrecoverable, an impairment loss would be recognized for the amount by which the carrying amount exceeds the fair value of the assets. Impairment evaluation and fair value is based on estimates and assumptions that take into account our business plans and a long-term investment horizon. In June 2015, we recognized an impairment charge of $30,850 based on our decision to immediately and permanently close our Ravenswood facility. In establishing the Ravenswood impairment we evaluated the recoverability of the remaining inventory and fixed assets. The resulting fair value is classified as Assets held for sale and was determined using management’s assumptions based on a pending plan of sale. Such assumptions include an estimated future sale price based on scrap value or based on the market price of scrap components or similar assets. These non-recurring fair value adjustments and the inputs used in the measurement are classified as Level 3 fair value measurements. In the fourth quarter of 2015 , we completed the construction of a second furnace at our carbon anode facility in Vlissingen, Netherlands which increased our capacity to produce carbon anodes and reduced our need to source carbon anodes from BHH. As a result, in the fourth quarter of 2015, we made the decision to pursue an exit from our investment in BHH. In connection with our exit plan, we concluded that our investment in BHH was other than temporarily impaired and recorded a charge of $11,584 . Fair value for the investment was based on a proposed sale transaction for a portion of the investment and we classified the fair value within Level 3 of the fair value hierarchy as its fair value was determined with inputs that are not readily observable in the market. We did not recognize any impairment losses on our long-lived fixed assets during 2014 or 2013. Business Acquisitions — We allocate the purchase price to the assets acquired and liabilities assumed based on their estimated fair values on the date of the acquisition. The difference between the fair value of the net assets acquired and the purchase price is recorded as either goodwill or a bargain purchase gain. We record the operating results of our acquired businesses in our consolidated statements of operations from the date of acquisition. Income Taxes — We account for income taxes using the asset and liability method, whereby deferred income taxes reflect the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. In evaluating our ability to realize deferred tax assets, we use judgment to determine if it is more likely than not that some portion or all of a deferred tax asset will not be realized, and if a corresponding valuation allowance is required. Accordingly, we have a valuation allowance against all of our net U.S. federal and state deferred tax assets, a portion of our Icelandic and all of our Hong Kong and Netherlands net operating loss ("NOL") deferred tax assets. Additionally, we have provided for deferred taxes on unremitted foreign earnings. Defined Benefit Pension and Other Postretirement Benefits — We sponsor defined benefit pension and other postretirement benefit ("OPEB") plans for certain of our domestic hourly and salaried employees and a SERB plan for certain current and former executive officers. We recognize expenses, assets and liabilities based on actuarial assumptions. We contribute to our defined benefit pension plans based upon actuarial and economic assumptions designed to achieve adequate funding of the projected benefit obligations and to meet the minimum funding requirements. Postemployment Benefits — We provide certain postemployment benefits to certain former and inactive employees and their dependents during the period following employment, but before retirement. These benefits include salary continuance, supplemental unemployment and disability healthcare. We recognize the estimated future cost of providing postemployment benefits on an accrual basis over the active service life of the employee. Foreign Currency – We are exposed to foreign currency risk due to fluctuations in the value of the U.S. dollar as compared to the euro, the Icelandic krona ("ISK") and the Chinese renminbi. Grundartangi and Vlissingen use the U.S. dollar as their functional currency, however a portion of the operating expenses of their respective facilities are denominated and payable in currencies other than the U.S. dollar. In addition, our joint venture, BHH, uses the Chinese renminbi as its functional currency. Grundartangi’s labor costs, part of its maintenance costs and other local services are denominated in ISK and a portion of its anode costs are denominated in euros. Labor costs, maintenance costs and other local services at Vlissingen are denominated in euros. Transactions denominated in currencies other than the functional currency are recorded based on exchange rates at the time such transactions arise and any transaction gains and losses are reflected in other income – net in the consolidated statements of operations. For our joint venture investments we record gains and losses associated with foreign currency exchange rates in equity in earnings of joint ventures . Financial Instruments — Receivables, certain life insurance policies, payables, borrowings under revolving credit facilities and debt related to industrial revenue bonds ("IRBs") are carried at amounts that approximate fair value. Earnings per share — Basic earnings (loss) per share ("EPS") amounts are calculated by dividing earnings (loss) available to common stockholders by the weighted average number of common shares outstanding. Diluted EPS amounts assume the issuance of common stock for all potentially dilutive common shares outstanding. We calculate the amount of net income (loss) allocated to common stockholders and basic EPS using the Two-Class Method earnings allocation formula, allocating undistributed income to our Series A Convertible Preferred Stock shareholder consistent with their participation rights, and diluted EPS using the If-Converted Method when applicable. Our Series A Convertible Preferred Stock is a non-cumulative perpetual participating convertible preferred stock with no set dividend preferences. In periods where we report net losses, we do not allocate these losses to the convertible preferred stock for the computation of basic or diluted EPS. Asset Retirement Obligations — We are subject to environmental regulations which create certain legal obligations related to the normal operations of our domestic primary aluminum smelter operations. Our asset retirement obligations ("AROs") consist primarily of costs associated with the disposal of spent pot liner used in the reduction cells of our domestic facilities. AROs are recorded on a discounted basis at the time the obligation is incurred (when the pot liner is put in service) and accreted over time for the change in the present value of the liability. We capitalize the asset retirement costs by increasing the carrying amount of the related long-lived assets and depreciating these assets over their remaining useful lives. Certain conditional asset retirement obligations ("CAROs") relate to the remediation of our primary aluminum facilities for hazardous material, such as landfill materials and asbestos which have not been recorded because they have an indeterminate settlement date. CAROs are a legal obligation to perform an asset retirement activity in which the timing and (or) method of settlement are conditional on a future event that may or may not be within our control. Concentrations of Credit Risk — Financial instruments, which potentially expose us to concentrations of credit risk, consist principally of trade receivables. Our limited customer base increases our concentrations of credit risk with respect to trade receivables. We routinely assess the financial strength of our customers and collectability of our trade receivables. Use of Estimates — The preparation of financial statements in conformity with generally accepted accounting principles in the United States ("GAAP") requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Share-Based Compensation — We measure the cost of employee services received in exchange for an award of equity instruments based on the fair value of the award on the grant date. We recognize the cost over the period during which an employee is required to provide service in exchange for the award. We issue shares to satisfy the requirements of our share-based compensation plans. At this time, we do not plan to issue treasury shares to support our share-based compensation plans, but we may in the future. We award performance units to certain officers and employees. The performance units may be settled in cash or common stock at the discretion of the Board. These awards have historically been settled in cash, although a portion of these awards were settled in common stock in 2015. We have not issued any stock options since 2009. Recently Issued Accounting Standards On November 20, 2015, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes, requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as non-current on the balance sheet. The classification change for all deferred taxes as non-current simplifies entities’ processes as it eliminates the need to separately identify the net current and net non-current deferred tax asset or liability in each jurisdiction and allocate valuation allowances. We elected to prospectively adopt the accounting standard in the beginning of our fourth quarter of fiscal 2015. Prior periods in our Consolidated Financial Statements were not retrospectively adjusted. In May 2014, the 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" 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 for our fiscal year 2018 and thereafter. We are currently evaluating the impact of adoption on our consolidated financial position, results of operations and cash flows.

Related party transactions

Related party transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related party transactions	Related party transactions The significant related party transactions occurring during the years ended December 31, 2015 , 2014 and 2013 are described below. Glencore ownership Through its ownership of our common and preferred stock, Glencore plc and its subsidiaries (together, "Glencore") has an overall 47.5% economic ownership in Century Aluminum. Sales to Glencore Pursuant to several agreements with Glencore, we sell substantially all of our production to Glencore. Glencore purchases the aluminum we produce for resale to end users. Glencore purchases substantially all of the aluminum produced at our North American smelters pursuant to that certain sales agreement, effective as of December 31, 2014 (the "U.S. Sales Agreement"). Under the U.S. Sales Agreement, Glencore purchases our aluminum on a take or pay basis at prices determined by reference to the Midwest Transaction Price plus additional negotiated product premiums. The current term of the U.S. Sales Agreement continues through December 31, 2016. Glencore has also agreed to purchase substantially all primary aluminum produced at Grundartangi from 2014 through 2017 at market prices, less commitments under existing tolling contracts (the "Glencore Grundartangi Metal Agreement"). The price for aluminum delivered to Glencore under the Glencore Grundartangi Metal Agreement is determined by reference to the LME price for primary aluminum, plus the European Duty Paid premium and any applicable product premiums. We have also entered into a tolling agreement with Glencore for 90,000 tpy through July 2016. Under this agreement, Glencore provides Grundartangi alumina for processing and receives primary aluminum in return for tolling fees that are based on the price of primary aluminum. We had a long-term contract to sell Glencore primary aluminum, at a variable price based on the LME, adjusted by a negotiated U.S. Midwest market premium with a cap and floor as applied to the current U.S. Midwest premium, which expired at the end of 2013. In addition, we had a contract to sell Glencore all U.S. produced primary aluminum, less existing sales agreements and high-purity metal sales, which expired at the end of 2013. We sold high-purity metal in 2013 on a spot basis at variable prices based on the LME, plus U.S. Midwest premium and product premiums. We believe that all of the transactions with Glencore were at prices that approximate market. Purchases from Glencore We purchase alumina from Glencore on both a spot and long-term contract basis. We are party to a long-term alumina supply agreement with Glencore, in which Glencore has agreed to supply us with alumina through 2017 at prices indexed to the LME price of primary aluminum. In 2014, upon mutual agreement, approximately half of the purchases under this agreement were priced based on a published alumina index. For 2015, we priced all of the purchases under this agreement based on a published alumina index. We had additional agreements to buy alumina from Glencore, which expired at the end of 2014 and 2013. In 2014 and 2013, the pricing on these alumina purchase agreements for Grundartangi was indexed to the LME price for primary aluminum. We believe that the alumina purchased from Glencore under these contracts were purchased at prices that approximate market. Transactions with BHH We own a 40% stake in BHH, a carbon anode and cathode facility located in the Guangxi Zhuang Autonomous Region of south China. We purchase carbon anodes from BHH. In the fourth quarter of 2015, we completed the construction of a second furnace at our carbon anode facility in Vlissingen, Netherlands. This investment increases our capacity to produce carbon anodes and reduces our need to source carbon anodes from BHH. As a result, in the fourth quarter of 2015, we made the decision to pursue an exit from our investment in BHH. In connection with our exit plan, we concluded that our investment in BHH was other than temporarily impaired and recorded a charge of $11,584 . Fair value for the investment was based on a proposed sale transaction for a portion of the investment. Summary A summary of the aforementioned related party transactions for the years ended December 31, 2015 , 2014 and 2013 is as follows: Year Ended December 31, 2015 2014 2013 Net sales to Glencore $ 1,867,711 $ 1,262,101 $ 511,051 Purchases from Glencore 393,158 285,167 173,693 Purchases from BHH 46,592 47,804 86,678

Business acquisitions

Business acquisitions	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Business acquisitions	Business acquisitions Acquisition of Mt. Holly aluminum smelter On October 23, 2014, our wholly-owned subsidiary, Berkeley Aluminum Inc. ("Berkeley"), entered into a stock purchase agreement (the "Stock Purchase Agreement") with Alumax Inc. ("Alumax"), a wholly-owned subsidiary of Alcoa, pursuant to which Berkeley acquired all of the issued and outstanding shares of Alumax of South Carolina, Inc. ("Alumax of SC") and, thereby, acquired Alcoa's 50.3% stake in Mt. Holly. Immediately following the consummation of the transaction, Berkeley merged with and into Alumax of SC with Alumax of SC surviving and changed its name to "Century Aluminum of South Carolina, Inc." CASC now owns 100% of Mt. Holly. Mt. Holly, located in Goose Creek, South Carolina, employed approximately 600 people and had an annual production capacity of 231,000 tonnes of primary aluminum as of the acquisition date. Pursuant to the terms of the Stock Purchase Agreement, Berkeley acquired all of the issued and outstanding shares of capital stock of Alumax of SC for $67,500 in cash subject to working capital and other similar adjustments. The acquisition was funded with available cash on hand. We incurred $1,087 of acquisition related costs during 2014 and $452 of acquisition-related costs during 2015. All acquisition-related costs were expensed to selling, general and administrative expenses in the period they were incurred. The following table summarizes all of the elements of consideration for the transaction. December 1, 2014 Purchase price $ 67,500 Contingent consideration 13,780 Economic, working capital and other closing adjustments (13,513 ) Total consideration $ 67,767 Contingent Consideration - Earn-out provision The Stock Purchase Agreement provides for a post-closing cash payment to be made following December 31, 2015 based on (i) changes in the Midwest Transaction Price for aluminum between July 2, 2014 and December 31, 2015 and (ii) the aggregate cast house production of Mt. Holly from October 1, 2014 through December 31, 2015. The maximum amount of this post-closing cash payment by (i) CASC to Alcoa is $22,500 and (ii) Alcoa to CASC is $12,500 . We measured the fair value of the contingent consideration and recognized a $13,780 liability at December 1, 2014. Each period, until the end of the measurement period on December 31, 2015, we remeasured the fair value of the contingent consideration and the change in the fair value was recognized in earnings. We classified the contingent consideration within Level 3 of the fair value hierarchy as its fair value was determined with inputs that are not readily observable in the market. During 2015, we recognized $18,337 in gain on fair value of contingent consideration, primarily related to decreases in the forward curve of the LME price of primary aluminum. Pursuant to the earn-out provision, we currently expect Alcoa to pay us $12,500 in the first quarter of 2016. Economic Adjustment, working capital and other adjustments The Stock Purchase Agreement provides for an economic adjustment that was established to put the parties in the same economic position as if the closing date for the acquisition had occurred on September 30, 2014. The related adjustments include metal off-take and aluminum sales agreements, cash funding and management fee adjustments, as well adjustments for inventory and transition services. We received $11,189 from Alcoa for the economic adjustment in April 2015. The Stock Purchase Agreement also contained provisions for working capital adjustments. The working capital adjustment was based on actual working capital at closing compared to established working capital targets. We received $124 from Alcoa for the working capital adjustments in April 2015. Other adjustments include amounts due to CASC for expected future post-employment benefit payments and certain other items. The amounts were negotiated as part of the Stock Purchase Agreement and we received $2,400 from Alcoa for these adjustments at closing. Step Acquisition We accounted for this transaction as a step acquisition which required that we remeasure our prior 49.7% ownership interest, which was previously accounted for as an equity method investment, to fair value. The fair value of our interest in Mt. Holly was $47,855 at closing, resulting in a non-cash pre-tax gain of $15,955 . $14,637 of that gain was recorded retroactively to the closing date resulting in an adjustment to Accumulated Deficit in the Consolidated Balance Sheets as of December 31, 2014. Our previously recorded equity method investment in Mt. Holly and the proportionally consolidated property, plant and equipment was derecognized from our Consolidated Balance Sheets. Since the date of the step acquisition, the financial results of Mt. Holly and all of its operating assets have been included within our consolidated financial statements. Below is the final purchase price allocation for Mt. Holly. Preliminary estimate of the acquisition date fair value as of December 1, 2014 Measurement period adjustments Final acquisition date fair value as of December 1, 2014 Assets Acquired: Inventories $ 26,105 $ (2,126 ) $ 23,979 Due from Alumax 20,786 (9,517 ) 11,269 Prepaid and other current assets 2,527 — 2,527 Intangible asset 2,580 — 2,580 Pension asset 30,842 — 30,842 Property, plant and equipment – net 127,089 15,748 142,837 Total assets acquired $ 209,929 $ 4,105 $ 214,034 Liabilities Assumed: Accounts payable, trade $ 41,471 $ — $ 41,471 Accrued and other current liabilities 8,335 255 8,590 Accrued pension benefit costs — 34,595 34,595 Accrued postretirement benefit costs 2,857 — 2,857 Asset retirement obligations 8,213 — 8,213 Deferred taxes 4,804 (2,118 ) 2,686 Total liabilities assumed $ 65,680 $ 32,732 $ 98,412 Goodwill $ 4,804 $ (4,804 ) $ — We have adjusted the purchase price allocation to appropriately reflect the liability for the pension funding obligations that we assumed as of the acquisition date, pursuant to the Stock Purchase Agreement. Additionally, we have revised the Consolidated Statements of Cash Flows for 2014 to classify $11,269 of accounts receivable collected from Alcoa at the closing out of investing activities and into operating activities. Pension funding obligations Pursuant to the Stock Purchase Agreement, Alcoa spun-off the pension plan assets for the current and former Mt. Holly employees into a qualified defined benefit plan that we established. Alcoa and Berkeley agreed to fund their proportionate share of the underfunded Mt. Holly pension plan benefit obligations, measured in accordance with generally accepted accounting principles in the United States ("GAAP") using agreed upon assumptions as of the transaction date. In addition, Berkeley agreed to fund any additional amount needed to bring the Mt. Holly pension benefit obligations to fully funded status on a termination basis under IRS Code Section 414(l) (the "414(l) liability"). In April 2015, CASC, as successor in interest to Berkeley, contributed a total of $34,595 to satisfy its pension plan funding obligations under the Stock Purchase Agreement. The Pension Benefit Guaranty Corporation (the "PBGC") assumptions used for termination basis funding are more conservative than those used for GAAP purposes and resulted in the recognition of a pension asset for the over funded plan. Settlement of amounts due from Alumax Prior to the closing date, the Mt. Holly partnership had amounts due from Alumax of SC for metal off-take, capital, plant administrative and various other costs. These amounts totaling $11,269 were received at closing. From the acquisition date of December 1, 2014 through December 31, 2014, the revenue and earnings that were attributable to the acquired Alcoa’s 50.3% stake in Mt. Holly included in the Consolidated Statements of Operations is as follows: Year ended December 31, 2014 Mt. Holly revenue $ 25,911 Mt. Holly income from continuing operations (1) $ 3,024 (1) The income attributable to the acquired Alcoa’s 50.3% stake in Mt. Holly excludes the gain on the fair value of the contingent consideration and the gain on remeasurement of the equity investment. The following unaudited pro forma financial information for the years ended December 31, 2014 and December 31, 2013 reflects our results of continuing operations as if the acquisition of the remaining interest in Mt. Holly had been completed on January 1, 2013. This unaudited pro forma financial information is provided for informational purposes only and is not necessarily indicative of what the actual results of operations would have been had the transactions taken place on January 1, 2013, nor is it indicative of the future consolidated results of operations or financial position of the combined companies. Year ended December 31, 2014 2013 Pro forma revenues $ 2,176,552 $ 1,707,838 Pro forma earnings from continuing operations 125,847 (38,819 ) Pro forma earnings per common share, basic 1.30 (0.44 ) Pro forma earnings per common share, diluted 1.29 (0.44 ) Acquisition of Sebree aluminum smelter On June 1, 2013, Century Sebree acquired the Sebree aluminum smelter from a subsidiary of Rio Tinto Alcan ("RTA"). Sebree, located in Robards, Kentucky, has an annual hot metal production capacity of 218,000 tonnes of primary aluminum and employs approximately 500 people. The purchase price for the acquisition was $61,000 (subject to customary working capital adjustments). As part of the transaction, RTA retained all historical environmental liabilities of the Sebree smelter and funded the pension plan assumed by Century in accordance with the purchase agreement. In July 2014, we reached the final determination of the working capital adjustments for the Sebree acquisition, resulting in a final purchase price of $49,035 . As the final determination was subsequent to the expiration of measurement period, we recognized a gain of approximately $965 in the second quarter of 2014 (these adjustments were not included as part of the gain on bargain purchase recorded in 2013). The gain was recorded in other income – net, from the release of accrued amounts related to the acquisition. In 2013, we allocated the purchase price using the estimated fair values at the date of acquisition and recorded a gain on bargain purchase of $5,253 in 2013. The following table summarizes the fair value of the assets acquired and the liabilities assumed as of the acquisition date: Acquisition Date Fair Value Consideration: Cash $ 48,083 Deferred purchase price 1,910 Assets Acquired: Inventories $ 59,018 Prepaid and other current assets 2,273 Property, plant and equipment – net 55,520 Total assets acquired $ 116,811 Liabilities Assumed: Accrued and other current liabilities $ 43,316 Accrued pension benefit costs 996 Accrued postretirement benefit costs 6,544 Other liabilities 7,476 Deferred taxes 3,233 Total liabilities assumed $ 61,565 Gain on bargain purchase: $ 5,253 From the acquisition date of June 1, 2013 through December 31, 2013, the revenue and earnings that were attributable to Sebree included in the consolidated statement of operations is as follows: Year ended December 31, 2013 Sebree revenue $ 247,178 Sebree income from continuing operations 8,705 Our net income for the years ended December 31, 2014 and 2013, includes a non-recurring credit for the amortization of the deferred power contract liability of $5,534 and $31,031 , respectively, related to the amortization of an unfavorable power contract assumed as part of the Sebree acquisition resulting in a credit to our depreciation and amortization expense within cost of goods sold on the consolidated statement of operations for the first quarter of 2014. The power contract terminated on January 31, 2014. The following unaudited pro forma financial information for the year ended December 31, 2013 reflects our results of continuing operations as if the acquisition of Sebree had been completed on January 1, 2013. This unaudited pro forma financial information is provided for informational purposes only and is not necessarily indicative of what the actual results of operations would have been had the transactions taken place on January 1, 2013, nor is it indicative of the future consolidated results of operations or financial position of the combined companies. Year ended December 31, 2013 Pro forma revenues $ 1,662,707 Pro forma loss from continuing operations (83,035 ) Pro forma loss per common share, basic (0.94 ) Pro forma loss per common share, diluted (0.94 )

Fair value measurements

Fair value measurements	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements ASC 820 defines fair value as "the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date." Valuation techniques used for fair value measurements are based upon observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect our internal market assumptions. These two types of inputs create the following fair value hierarchy: • Level 1 – Valuations are based on quoted prices for identical assets or liabilities in an active market. • Level 2 – Valuations are based on quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; and model-derived valuations for which all significant inputs are observable or can be corroborated by observable market data. • Level 3 – Assets or liabilities whose significant inputs are unobservable. Valuations are determined using pricing models and discounted cash flow models and include management judgment and estimation which may be significant. The following section describes the valuation methodology used to measure our financial assets and liabilities that were accounted for at fair value. 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 E.ON contingent obligation 3 Quoted LME forward market, 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. 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. 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 actual date of the event or change in circumstances that caused the transfer. Recurring Fair Value Measurements As of December 31, 2015 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 102,675 $ — $ — $ 102,675 Trust assets 5,226 — — 5,226 Surety bonds 1,870 — — 1,870 TOTAL $ 109,771 $ — $ — $ 109,771 LIABILITIES: E.ON contingent obligation – net (1) $ — $ — $ — $ — TOTAL $ — $ — $ — $ — Recurring Fair Value Measurements As of December 31, 2014 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 137,712 $ — $ — $ 137,712 Trust assets 8,067 — — 8,067 Surety bonds 1,987 — — 1,987 TOTAL $ 147,766 $ — $ — $ 147,766 LIABILITIES: E.ON contingent obligation – net (1) $ — $ — $ — $ — TOTAL $ — $ — $ — $ — (1) See Note 5 Debt for additional information about the E.ON contingent obligation.

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt	Debt December 31, 2015 2014 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 $2,722 and $3,112, respectively, interest payable semiannually 247,278 246,888 Total $ 255,093 $ 254,703 (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 December 31, 2015 was 0.21% . U.S. Revolving Credit Facility General . We and certain of our direct and indirect domestic subsidiaries (together with Century, the "Borrowers") and Wells Fargo Capital Finance, LLC, as lender and agent, and Credit Suisse AG, BNP Paribas and Morgan Stanley Senior Funding Inc., as lenders, are parties to the Amended and Restated Loan and Security Agreement, dated May 24, 2013 (as amended from time to time, the "U.S. revolving credit facility"). The U.S. revolving credit facility has a term through June 26, 2020 and provides for borrowings of up to $150,000 in the aggregate, including up to $ 110,000 under a letter of credit sub-facility. Any letters of credit issued and outstanding under the U.S. revolving credit facility reduce our borrowing availability on a dollar-for-dollar basis. Status of our U.S. revolving credit facility: December 31, 2015 Credit facility maximum amount $ 150,000 Borrowing availability 81,292 Outstanding letters of credit issued 46,346 Outstanding borrowings — Borrowing availability, net of outstanding letters of credit and borrowings 34,946 Borrowing Base . The availability of funds under the U.S. revolving credit facility is limited by a specified borrowing base consisting of accounts receivable and inventory of the Borrowers which meet the eligibility criteria. Guaranty . The Borrowers' obligations under the U.S. revolving credit facility are guaranteed by certain of our domestic subsidiaries and secured by a continuing lien upon and a security interest in all of the Borrowers' accounts receivable, inventory and certain bank accounts. Each Borrower is liable for any and all obligations under the U.S. revolving credit facility on a joint and several basis. Interest Rates and Fees . Any amounts outstanding under the U.S. revolving credit facility will bear interest, at our option, at LIBOR or a base rate, plus, in each case, an applicable interest margin. The applicable interest margin is determined based on the average daily availability for the immediately preceding quarter. In addition, we pay an unused line fee on undrawn amounts, less the amount of our letters of credit exposure. For standby letters of credit, we are required to pay a fee on the face amount of such letters of credit that varies depending on whether the letter of credit exposure is cash collateralized. Prepayments . We can make prepayments of amounts outstanding under the U.S. revolving credit facility, in whole or in part, without premium or penalty, subject to standard LIBOR breakage costs, if applicable. We may be required to apply the proceeds from sales of collateral accounts, other than sales of inventory in the ordinary course of business, to repay amounts outstanding under the revolving credit facility and correspondingly reduce the commitments there under. Covenants . The U.S. revolving credit facility contains customary covenants, including restrictions on mergers and acquisitions, indebtedness, affiliate transactions, liens, dividends and distributions, dispositions of collateral, investments and prepayments of indebtedness, as well as a covenant that requires the Borrowers to maintain certain minimum liquidity or availability requirements. Events of Default . The U.S. revolving credit facility also includes customary events of default, including nonpayment, misrepresentation, breach of covenant, bankruptcy, change of ownership, certain judgments and certain cross defaults. Upon the occurrence of an event of default, commitments under the U.S. revolving credit facility may be terminated and amounts outstanding may be accelerated and declared immediately due and payable. Iceland Revolving Credit Facility General . Our wholly-owned subsidiary, Nordural Grundartangi ehf ("Grundartangi"), has entered into a $50,000 Committed Revolving Credit Facility agreement with Landsbankinn hf., dated November 27, 2013 (the "Iceland revolving credit facility"). Under the terms of the Iceland revolving credit facility, when Grundartangi borrows funds it will designate a repayment date, which may be any date prior to the maturity of the Iceland revolving credit facility. The Iceland revolving credit facility has a term through November 27, 2016. Status of our Iceland revolving credit facility: December 31, 2015 Credit Facility maximum amount $ 50,000 Borrowing availability 49,294 Outstanding letters of credit issued — Outstanding borrowings — Borrowing availability, net of outstanding letters of credit and borrowings 49,294 Borrowing Base . 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. Security . Grundartangi's obligations under the Iceland revolving credit facility are secured by a general bond under which Grundartangi's inventory and accounts receivable are pledged to secure full payment of the loan. Interest Rates and Fees . Any amounts outstanding under the Iceland revolving credit facility will bear interest at LIBOR plus a margin per annum. Prepayments . Any outstanding borrowings may be prepaid without penalty or premium (except incurred breakage costs) in whole or in part. Covenants . The Iceland revolving credit facility contains customary covenants, including restrictions on mergers and acquisitions, dispositions of assets, compliance with permits, laws and payment of taxes, as well as a covenant that requires Grundartangi to maintain a certain minimum equity ratio. Events of Default . The Iceland revolving credit facility also includes customary events of default, including nonpayment, loss of license, cessation of operations, unlawfulness, breach of covenant, bankruptcy, change of ownership, certain judgments and certain cross defaults. Upon the occurrence of an event of default, commitments under the Iceland revolving credit facility may be terminated and amounts outstanding may be accelerated and declared immediately due and payable. 2021 Notes 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. The 2021 Notes were issued at a discount and we received proceeds of $246,330 , prior to payment of financing fees and related expenses. The interest rate at 7.5% per annum on the principal amount, payable semi-annually in arrears in cash on June 1st and December 1st of each year. The Notes are senior secured obligations of Century, ranking equally in right of payment with all existing and future senior indebtedness of Century, but effectively senior to unsecured debt to the extent of the value of the collateral. Fair Value. Fair value for our 7.5% Notes due 2021 was based on the latest trading data available and was $169,220 and $256,408 , as of December 31, 2015 and 2014, 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. Guaranty. Our obligations under the 2021 Notes are guaranteed by all of our existing and future domestic restricted subsidiaries (the "Guarantor Subsidiaries"), except for foreign owned holding companies and any domestic restricted subsidiary that owns no assets other than equity interests or other investments in foreign subsidiaries, which guaranty shall in each case be a senior secured obligation of such Guarantor Subsidiaries, ranking equally in right of payment with all existing and future senior indebtedness of such Guarantor Subsidiaries but effectively senior to unsecured debt. Collateral. Our obligations under the 2021 Notes due and the Guarantor Subsidiaries' obligations under the guarantees are secured by a pledge of and lien on (subject to certain exceptions): (i) all of our and the Guarantor Subsidiaries' property, plant and equipment; (ii) all equity interests in domestic subsidiaries directly owned by us and the Guarantor Subsidiaries and 65% of equity interests in foreign subsidiaries or foreign holding companies directly owned by us and the Guarantor Subsidiaries; (iii) intercompany notes owed by any non-guarantor to us or any Guarantor Subsidiary to us; and (iv) proceeds of the foregoing. Under certain circumstances, we may incur additional debt that also may be secured by liens on the collateral that are equal to or have priority over the liens securing the 2021 Notes. Redemption Rights. Prior to June 1, 2016, we may redeem the 2021 Notes, in whole or in part, at a redemption price equal to 100% of the principal amount plus a make-whole premium, and if redeemed during the twelve-month period beginning on June 1 of the years indicated below, at the following redemption prices plus accrued and unpaid interest: Year Percentage 2016 105.625% 2017 103.750% 2018 101.875% 2019 and thereafter 100.000% Upon a change of control (as defined in the indenture governing the 2021 Notes), we will be required to make an offer to purchase the 2021 Notes at a purchase price equal to 101% of the outstanding principal amount of the 2021 Notes on the date of the purchase, plus accrued interest to the date of purchase. Covenants. The indenture governing the 2021 Notes contains customary covenants which may limit our ability, and the ability of certain of our subsidiaries, to: (i) incur additional debt; (ii) incur additional liens; (iii) pay dividends or make distributions in respect of capital stock; (iv) purchase or redeem capital stock; (v) make investments or certain other restricted payments; (vi) sell assets; (vii) issue or sell stock of certain subsidiaries; (viii) enter into transactions with shareholders or affiliates; and (ix) effect a consolidation or merger. 7.5% Notes due 2014 In August 2004, we sold $ 250,000 of our 7.5% Notes due 2014 in a private offering exempt from the registration requirements of the Securities Act. The 7.5% Notes due 2014 were subsequently registered with the SEC in December 2004. The 7.5% Notes due 2014 matured on August 15, 2014 and were repaid upon maturity. E.ON contingent obligation General. The E.ON contingent obligation consists of the aggregate E.ON payments made to Big Rivers Electric Corporation ("Big Rivers") on CAKY’s behalf in excess of the agreed upon base amount under the long-term cost-based power contract with Kenergy, a member cooperative of Big Rivers (the "Big Rivers Agreement"). Our obligation to make repayments is contingent upon certain operating criteria for Hawesville and the LME price of primary aluminum. When the conditions for repayment are met, and for so long as those conditions continue to be met, we will be obligated to make principal and interest payments, in up to 72 monthly payments . Interest accrues at an annual rate equal to 10.94% and the term of the agreement is through December 31, 2028. Based on the LME forward market prices for primary aluminum at December 31, 2015 and management's estimate of the LME forward market for periods beyond the quoted periods, we recognized a derivative asset which offsets our contingent obligation. As a result, our net liability decreased and we recorded a gain of $1,411 and $1,412 in net gain (loss) on forward and derivative contracts for the years ended December 31, 2015 and 2014 . These amounts are exactly offset by interest expense on the E.On contingent obligation which is recorded as part of interest expense. In addition, we believe that we will not have any payment obligations for the E.ON contingent obligation through the term of the agreement, which expires in 2028. However, future increases in the LME forward market may result in a partial or full derecognition of the derivative asset and a corresponding recognition of a loss. The following table provides information about the balance sheet location and gross amounts offset: Offsetting of financial instruments and derivatives Balance sheet location December 31, 2015 December 31, 2014 E.ON contingent obligation – principal Other liabilities $ (12,902 ) $ (12,902 ) E.ON contingent obligation – accrued interest Other liabilities (6,702 ) (5,291 ) E.ON contingent obligation – derivative asset Other liabilities 19,604 18,193 $ — $ — Industrial Revenue Bonds General. As part of the purchase price for our acquisition of the Hawesville facility, we assumed industrial revenue bonds ("IRB's") which were issued in connection with the financing of certain solid waste disposal facilities constructed at the Hawesville facility. The IRBs bear interest at a variable rate not to exceed 12% per annum determined weekly based upon prevailing rates for similar bonds in the industrial revenue bond market and interest on the IRB's is paid quarterly. The IRB's are secured by a letter of credit issued under our revolving credit facility and mature on April 1, 2028. Principal Payments on Long Term Debt We have no principal payments due in the next five years for our long-term borrowings.

Shareholders' equity

Shareholders' equity	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
Shareholders' equity	Shareholders' equity Common Stock As of December 31, 2015 and 2014, we had 195,000,000 shares of common stock, $0.01 cent par value, authorized under our Restated Certificate of Incorporation, of which 94,224,571 shares were issued and 87,038,050 shares were outstanding at December 31, 2015; 93,851,103 shares were issued and 89,064,582 shares were outstanding at December 31, 2014. 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. Preferred Stock As of December 31, 2015 and 2014, we had 5,000,000 shares of preferred stock, $0.01 cent par value per share, authorized under our Restated Certificate of Incorporation. 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. Series A Convertible Preferred Stock Shares Authorized and Outstanding. In 2008, we issued 160,000 shares of our Series A Convertible Preferred Stock. Glencore holds all of the issued and outstanding Series A Convertible Preferred Stock. At December 31, 2015 and December 31, 2014, 76,539 shares and 78,141 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. The Common and Preferred Stock Activity table below contains additional information about preferred stock conversions during 2015 , 2014 and 2013 : Common and Preferred Stock Activity: Preferred stock Common stock (in shares) Series A Convertible Treasury Outstanding Balance as of December 31, 2012 80,283 4,786,521 88,548,637 Conversion of convertible preferred stock (663 ) — 66,244 Issuance for share-based compensation plans — — 95,396 Balance as of December 31, 2013 79,620 4,786,521 88,710,277 Conversion of convertible preferred stock (1,479 ) — 147,952 Issuance for share-based compensation plans — — 206,353 Balance as of December 31, 2014 78,141 4,786,521 89,064,582 Repurchase of common stock — 2,400,000 (2,400,000 ) Conversion of convertible preferred stock (1,602 ) — 160,162 Issuance for share-based compensation plans — — 213,306 Balance as of December 31, 2015 76,539 7,186,521 87,038,050 Dividend Rights. So long as any shares of our Series A Convertible Preferred Stock are outstanding, we may not pay or declare any dividend or make any distribution upon or in respect of our common stock or any other capital stock ranking on a parity with or junior to the Series A Convertible Preferred Stock in respect of dividends or liquidation preference, unless we, at the same time, declare and pay a dividend or distribution on the shares of Series A Convertible Preferred Stock (a) in an amount equal to the amount such holders would receive if they were the holders of the number of shares of our common stock into which their shares of Series A Convertible Preferred Stock are convertible as of the record date fixed for such dividend or distribution, or (b) in the case of a dividend or distribution on other capital stock ranking on a parity with or junior to the Series A Convertible Preferred Stock in such amount and in such form as (based on the determination of holders of a majority of the Series A Convertible Preferred Stock) will preserve, without dilution, the economic position of the Series A Convertible Preferred Stock relative to such other capital stock. Voting Rights. The Series A Convertible Preferred Stock has no voting rights for the election of directors or on other matters where the shares of common stock have voting rights. However, we may not change the powers, preferences, or rights given to the Series A Convertible Preferred Stock, or authorize, create or issue any additional shares of Series A Convertible Preferred Stock without the affirmative vote of the holders of a majority of the shares of Series A Convertible Preferred Stock then outstanding (voting separately as a class). Liquidation Rights. Upon any liquidation, dissolution, or winding-up of Century, the holders of shares of Series A Convertible Preferred Stock are entitled to receive a preferential distribution of $ 0.01 per share out of the assets available for distribution. In addition, upon any liquidation, dissolution or winding-up of Century, if our assets are sufficient to make any distribution to the holders of the common stock, then the holders of shares of Series A Convertible Preferred Stock are also entitled to share ratably with the holders of common stock in the distribution of Century’s assets (as though the holders of Series A Convertible Preferred Stock were holders of that number of shares of common stock into which their shares of Series A Convertible Preferred Stock are convertible). However, the amount of any such distribution will be reduced by the amount of the preferential distribution received by the holders of the Series A Convertible Preferred Stock. Transfer Restrictions. Glencore is prohibited from transferring shares of Series A Convertible Preferred Stock to any party other than an affiliate who agrees to become bound by certain agreements associated with these shares. Automatic Conversion. The Series A Convertible Preferred Stock automatically converts, without any further act of Century or any holders of Series A Convertible Preferred Stock, into shares of common stock, at a conversion ratio of 100 shares of common stock for each share of Series A Convertible Preferred Stock, upon the occurrence of any of the following automatic conversion events: • If we sell or issue shares of common stock or any other stock that votes generally with our common stock, or the occurrence of any other event, including a sale, transfer or other disposition of common stock by Glencore, as a result of which the percentage of voting stock held by Glencore decreases, an amount of Series A Convertible Preferred Stock will convert to common stock to restore Glencore to its previous ownership percentage; • If shares of Series A Convertible Preferred Stock are transferred to an entity that is not an affiliate of Glencore, such shares of Series A Convertible Preferred Stock will convert to shares of our common stock, provided that such transfers may only be made pursuant to an effective registration statement; • Upon a sale of Series A Convertible Preferred Stock by Glencore in a Rule 144 transaction in which the shares of Series A Convertible Preferred Stock and our common stock issuable upon the conversion thereof are not directed to any purchaser, such shares of Series A Convertible Preferred Stock sold will convert to shares of our common stock; and • Immediately prior to and conditioned upon the consummation of a merger, reorganization or consolidation to which we are a party or a sale, abandonment, transfer, lease, license, mortgage, exchange or other disposition of all or substantially all of our property or assets, in one or a series of transactions where, in any such case, all of our common stock would be converted into the right to receive, or exchanged for, cash and/or securities, other than any transaction in which the Series A Convertible Preferred Stock will be redeemed. Optional Conversion. Glencore has the option to convert the Series A Convertible Preferred Stock in a tender offer or exchange offer, at the same conversion ratio as above, in which a majority of the outstanding shares of our common stock have been tendered by the holders thereof and not duly withdrawn at the expiration time of such tender or exchange offer, so long as the Series A Convertible Preferred Stock is tendered or exchanged in such offer. Stock Combinations – Adjustments. If, at any time while the Series A Convertible Preferred Stock is outstanding, Century combines outstanding common stock into a smaller number of shares, then the number of shares of common stock issuable on conversion of each share of Series A Convertible Preferred Stock will be decreased in proportion to such decrease in the aggregate number of shares of common stock outstanding. Redemptions or Repurchases of Common Stock. We may not redeem or repurchase our common stock unless we redeem or repurchase, or otherwise make a payment on, a pro rata number of shares of the Series A Convertible Preferred Stock. These restrictions do not apply to our open market repurchases or our repurchases pursuant to our employee benefit plans. Right of Redemption. The Series A Convertible Preferred Stock will be redeemed by Century if any of the following events occur (at a redemption price based on the trading price of our common stock prior to the announcement of such event) and Glencore votes its shares of our common stock in opposition to such events: • We propose a merger, reorganization or consolidation, sale, abandonment, transfer, lease, license, mortgage, exchange or other disposition of all or substantially all of our property or assets where any of our common stock would be converted into the right to receive, or exchanged for, assets other than cash and/or securities traded on a national stock exchange or that are otherwise readily marketable, or • We propose to dissolve and wind up operations and any assets, other than cash and/or securities traded on a national stock exchange or that are otherwise readily marketable, are to be distributed to the holders of our common stock. Stock Repurchase Program In 2011, our Board of Directors authorized a $60 million stock repurchase program and during the first quarter of 2015, our Board of Directors increased the size of the program by $70 million . Under the program, Century is authorized to repurchase up to $130 million of our outstanding shares of common stock, from time to time, on the open market at prevailing market prices, in block trades or otherwise. The timing and amount of any shares repurchased will be determined by our management based on its evaluation of market conditions, the trading price of our common stock and other factors. The stock repurchase program may be suspended or discontinued 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 as contributions to our employee benefit plans and for the conversion of convertible preferred stock. When shares are reissued, we use an average cost method for determining cost. The difference between the cost of the shares and the reissuance price is added to or deducted from additional paid-in capital. Through December 31, 2015 , we repurchased 7,186,521 shares of common stock for an aggregate purchase price of $86,276 . We have made no repurchases since April 2015 and have approximately $43,724 remaining under the repurchase program authorization as of December 31, 2015 .

Inventories

Inventories	12 Months Ended
	Dec. 31, 2015
Inventory, Net [Abstract]
Inventories	Inventories Inventories, at December 31, consist of the following: 2015 2014 Raw materials $ 52,121 $ 76,655 Work-in-process 34,025 43,248 Finished goods 15,988 19,969 Operating and other supplies 129,738 143,608 Inventories $ 231,872 $ 283,480

Property, plant and equipment

Property, plant and equipment	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, plant and equipment	Property, plant and equipment Property, plant and equipment, at December 31, consist of the following: 2015 2014 Land and improvements $ 42,654 $ 43,385 Buildings and improvements 325,580 345,271 Machinery and equipment 1,349,731 1,476,518 Construction in progress 173,418 182,393 1,891,383 2,047,567 Less accumulated depreciation (659,127 ) (742,024 ) Property, plant and equipment - net $ 1,232,256 $ 1,305,543 For the years ended December 31, 2015 , 2014 and 2013 , we recorded depreciation expense of $80,117 , $70,827 and $66,570 , respectively.

Supplemental financial statemen

Supplemental financial statement information	12 Months Ended
	Dec. 31, 2015
Additional financial information disclosures [Abstract]
Supplemental financial statement information	Supplemental financial statement information Components of Accumulated Other Comprehensive Loss: 2015 2014 Defined benefit plan liabilities $ (121,910 ) $ (128,664 ) Unrealized loss on financial instruments (1,435 ) (1,249 ) Other comprehensive loss before income tax effect (123,345 ) (129,913 ) Income tax effect (1) 10,695 12,231 Accumulated other comprehensive loss $ (112,650 ) $ (117,682 ) (1) The allocation of the income tax effect to the components of other comprehensive income is as follows: 2015 2014 Defined benefit plan liabilities $ 11,243 $ 12,812 Unrealized loss on financial instruments (548 ) (581 ) The following table summarizes the changes in the accumulated balances for each component of accumulated other comprehensive loss ("AOCI"): Defined benefit plan and other postretirement liabilities Equity in investee other comprehensive income Unrealized loss on financial instruments Total, net of tax Balance, December 31, 2012 $ (137,441 ) $ (12,224 ) $ (1,527 ) $ (151,192 ) Other comprehensive income (loss) before reclassifications 56,795 (8 ) — 56,787 Net amount reclassified to net income 2,725 — (152 ) 2,573 Balance, December 31, 2013 (77,921 ) (12,232 ) (1,679 ) (91,832 ) Other comprehensive income (loss) before reclassifications (42,926 ) (419 ) — (43,345 ) Net amount reclassified to net income 4,995 — (151 ) 4,844 Elimination of equity in investee resulting from acquisition — 12,651 — 12,651 Balance, December 31, 2014 (115,852 ) — (1,830 ) (117,682 ) Other comprehensive income before reclassifications 7,311 — — 7,311 Net amount reclassified to net income (2,126 ) — (153 ) (2,279 ) Balance, December 31, 2015 $ (110,667 ) $ — $ (1,983 ) $ (112,650 ) Reclassifications out of AOCI were included in the consolidated statements of operations as follows: Gains (Losses) Reclassified from AOCI to the Consolidated Statements of Operations AOCI Components Location 2015 2014 2013 Defined benefit plan and other postretirement liabilities Cost of goods sold $ (1,696 ) $ 6,237 $ 3,264 Selling, general and administrative expenses 235 569 990 Other operating expense, net 904 — — Income tax expense (1,569 ) (1,811 ) (1,529 ) Net of tax $ (2,126 ) $ 4,995 $ 2,725 Equity in investee other comprehensive income Cost of goods sold $ — $ — $ — Income tax expense — (419 ) (70 ) Net of tax $ — $ (419 ) $ (70 ) Unrealized loss on financial instruments Cost of goods sold $ (186 ) $ (185 ) $ (186 ) Income tax expense 33 34 34 Net of tax $ (153 ) $ (151 ) $ (152 )

Pension and other postretiremen

Pension and other postretirement benefits	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Pension and other postretirement benefits	Pension and other postretirement benefits Pension Benefits We maintain noncontributory defined benefit pension plans for certain domestic hourly and salaried employees. For the eligible domestic salaried employees, plan benefits are based primarily on years of service and average compensation during the later years of employment. For hourly employees, plan benefits are based primarily on a formula that provides a specific benefit for each year of service. Our funding policy is to contribute amounts based upon actuarial and economic assumptions designed to achieve adequate funding of the projected benefit obligations and to meet the minimum funding requirements of the Employee Retirement Income Security Act 1974 ("ERISA"). In addition, we maintain the SERB plan for certain current and former executive officers. Partial Freeze In 2014, the Salaried Pension Plan was amended to eliminate future accruals for participants who are under age 50 as of January 1, 2015. The plan was also closed to new entrants. The amendment decreased the plans' projected benefit obligations by approximately $6,600 and a curtailment charge of $263 was recorded in 2014. Pension Settlement - Lump Sum Payout In 2014, we offered certain former employees with vested pension benefits a lump sum payout in an effort to reduce our long-term pension obligations. As a result, net periodic benefit cost for our pension plans increased by a non-cash settlement charge of $4,701 for 2014 and the projected benefit obligation decreased by $19,573 . PBGC settlement In April 2013, we entered into a settlement agreement with the Pension Benefit Guaranty Corporation ("PBGC") regarding an alleged "cessation of operations" at our Ravenswood facility as a result of the curtailment of operations at the facility and, pursuant to the agreement, we agreed to make additional contributions (above any minimum required contributions) to our defined benefit pension plans totaling approximately $17,400 over the term of the agreement, which runs through 2016. Under certain circumstances, in periods of lower primary aluminum prices relative to our cost of operations, we may defer one or more of these payments, but we would be required to provide the PBGC with acceptable security for any deferred payments. We made the contributions pursuant to this agreement of $1,100 in 2015 and $6,700 in 2013. We did not make any contribution during 2014. The remaining contributions under this agreement are approximately $9,600 . Other Postretirement Benefits (OPEB) In addition to providing pension benefits, we provide certain healthcare and life insurance benefits for certain domestic retired employees. We accrue the estimated cost of providing postretirement benefits during the working careers of those employees who could become eligible for such benefits when they retire. We fund these benefits as the retirees submit claims. Retiree medical benefits changes Under the current Hawesville labor agreement, employees who retire during the term of the labor agreement have been divided into sub-groups based on attributes such as Medicare eligibility, hire date, age and years of service. Levels of benefits are defined for the sub-groups and range from no substantive change from the benefits provided under the previous labor agreement to replacement of the defined retiree medical benefit program with individual health reimbursement accounts for each eligible participant. The health reimbursement accounts will be funded by CAKY based on established rates per hour worked by each eligible participant. Eligible participants will be able to withdraw from their health reimbursement accounts to fund their own retiree medical coverage. Obligations and Funded Status The change in benefit obligations and change in plan assets as of December 31 are as follows: Pension OPEB 2015 2014 2015 2014 Change in benefit obligation: Benefit obligation at beginning of year $ 336,292 $ 238,319 $ 158,781 $ 134,652 Service cost 6,346 5,605 1,970 1,591 Interest cost 13,388 11,629 5,985 6,420 Plan amendments — (5,308 ) (1,758 ) — Medicare Part D — — — 273 Actuarial loss (gain) (11,429 ) 32,772 (18,150 ) 17,669 Acquisition — 84,743 — 2,857 Benefits paid (19,247 ) (11,895 ) (5,878 ) (4,681 ) Curtailment 1,221 — (8,400 ) — Settlements — (19,573 ) — — Benefit obligation at end of year $ 326,571 $ 336,292 $ 132,550 $ 158,781 Pension OPEB 2015 2014 2015 2014 Change in plan assets: Fair value of plan assets at beginning of year $ 305,520 $ 199,304 $ — $ — Actual return on plan assets (11,321 ) 16,118 — — Acquisition — 115,982 — — Employer contributions 5,910 5,584 5,878 4,681 Benefits paid (19,247 ) (11,895 ) (5,878 ) (4,681 ) Settlements — (19,573 ) — — Fair value of assets at end of year $ 280,862 $ 305,520 $ — $ — Pension OPEB 2015 2014 2015 2014 Funded status of plans: Funded status $ (45,709 ) $ (30,772 ) $ (132,550 ) $ (158,781 ) Amounts recognized in the Consolidated Balance Sheets: Non-current assets $ — $ 30,842 $ — $ — Current liabilities (1,743 ) (1,744 ) (6,551 ) (6,118 ) Non-current liabilities (43,966 ) (59,870 ) (125,999 ) (152,663 ) Net amount recognized $ (45,709 ) $ (30,772 ) $ (132,550 ) $ (158,781 ) Amounts recognized in accumulated other comprehensive loss (pre-tax): Net loss $ 80,514 $ 63,360 $ 49,562 $ 79,720 Prior service cost (benefit) 1,211 1,335 (9,377 ) (15,751 ) Total $ 81,725 $ 64,695 $ 40,185 $ 63,969 Pension Plans That Are Not Fully Funded At December 31, 2015, the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets were $326,571 , $319,873 and $280,862 , respectively. At December 31, 2014, the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets were $336,292 , $328,963 and $305,520 , respectively. Components of net periodic benefit cost and other amounts recognized in other comprehensive loss: Net Periodic Benefit Cost: Year Ended December 31, Pension OPEB 2015 2014 2013 2015 2014 2013 Service cost $ 6,346 $ 5,605 $ 4,735 $ 1,970 $ 1,591 $ 2,527 Interest cost 13,388 11,629 8,908 5,985 6,420 5,681 Expected return on plan assets (21,241 ) (14,694 ) (10,592 ) — — — Amortization of prior service costs 110 77 113 (3,728 ) (3,844 ) (3,995 ) Amortization of net loss 3,980 1,907 3,152 3,814 3,704 5,022 Settlements — 4,701 — — — — Curtailment cost (benefit) 1,235 263 (18 ) (4,266 ) — (20 ) Net periodic benefit cost $ 3,818 $ 9,488 $ 6,298 $ 3,775 $ 7,871 $ 9,215 Other changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Loss (pre-tax): Year Ended December 31, Pension OPEB 2015 2014 2015 2014 Net loss (gain) $ 21,133 $ 24,326 $ (26,686 ) $ 17,669 Prior service cost (benefit) — 1,299 (1,758 ) — Amortization of net loss, including recognition due to settlement (3,980 ) (6,608 ) (3,814 ) (3,704 ) Amortization of prior service benefit (cost), including recognition due to curtailment (124 ) (340 ) 8,475 3,844 Total amount recognized in other comprehensive loss 17,029 18,677 (23,783 ) 17,809 Net periodic benefit cost 3,818 9,488 3,775 7,871 Total recognized in net periodic benefit cost and other comprehensive loss $ 20,847 $ 28,165 $ (20,008 ) $ 25,680 Amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2016: Pension OPEB Amortization of net loss $ 4,161 $ 3,518 Amortization of prior service cost (benefit) 106 (2,781 ) Weighted average assumptions used to determine benefit obligations at December 31: Pension OPEB 2015 2014 2015 2014 Discount rate (1) 4.44% 4.05% 4.50% 4.00% Rate of compensation increase (2) 3%/4% 3%/4% 3%/4% 3%/4% Measurement date 12/31/2015 12/31/2014 12/31/2015 12/31/2014 Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31: Pension OPEB 2015 2014 2013 2015 2014 2013 Measurement date 12/31/2014 12/31/2013 12/31/2012 12/31/2014 12/31/2013 12/31/2012 Fiscal year end 12/31/2015 12/31/2014 12/31/2013 12/31/2015 12/31/2014 12/31/2013 Discount rate (1) 4.05% 4.89% 4.00% 4.00% 4.99% 4.01% Rate of compensation increase (2) 3%/4% 3%/4% 3%/4% 3%/4% 3%/4% 3%/4% Expected return on plan assets (3) 7.16% 7.25% 7.25% — — — (1) We use the Ryan Discount Rate Curve ("Ryan Curve") to determine the discount rate. (2) For 2015, the rate of compensation increase is 3% per year for the first three years and 4% per year for year four and thereafter. For 2014, the rate of compensation increase is 3% per year for the first four years and 4% per year for year five and thereafter. For 2013, the rate of compensation increase is 3% per year for the first five years and 4% per year for year six and thereafter. (3) The rate for each of our defined benefit plans was selected by taking into account our expected asset mix and is based on historical performance as well as expected future rates of return on plan assets. For measurement purposes, medical cost inflation is initially estimated to be 8% , declining to 5% over six years and thereafter. Assumed health care cost trend rates have a significant effect on the amounts reported for the health care benefit obligations. A one-percentage-point change in the assumed health care cost trend rate would have had the following effects in 2015 : 1% Increase 1% Decrease Effect on total of service and interest cost $ 1,403 $ (1,108 ) Effect on accumulated postretirement benefit obligation 18,170 (15,086 ) Benefit Plan Assets Pension Plan Investment Strategy and Policy The Pension Plans’ assets are invested in a prudent manner for the exclusive purpose of providing benefits to participants. Other objectives are to: • Provide a total return that, over the long term, provides sufficient assets to fund the pension plan liabilities subject to a level of risk, contributions and pension expense deemed appropriate by the company. • Minimize, where possible, pension expense volatility, and inclusion of liability driven investing as an investment strategy when appropriate. As the funding ratio improves, the objectives will evolve to minimize the funded status volatility. • Diversify investments within asset classes to reduce the impact of losses in single investments. The assets of the Pension Plans are invested in compliance with ERISA, as amended, and any subsequent applicable regulations and laws. Performance Our performance objective is to outperform the return of weighing passive investment alternatives by the policy target allocations after fees at a comparable level of risk. This investment objective is expected to be achieved over the long term and is measured over rolling multi-year periods. Peer-relative performance comparisons will also be considered especially when performance deviates meaningfully from market indexes. Investment objectives for each asset class are included below. Policy Portfolio Asset allocation policy is the principal method for achieving the Pension Plans' investment objectives stated above. The Pension Plans’ weighted average long-term strategic asset allocation policy targets are as follows: Pension Plan Asset Allocation 2015 Target December 31, 2015 December 31, 2014 Equities: U.S. equities 31% 30% 42% International equities 21% 20% 18% Fixed income 48% 50% 40% 100% 100% U.S. and international equities are held for their long-term expected return premium over fixed income investments and inflation. Fixed income is held for diversification relative to equities. The strategic role of U.S. and international equities is to: • Provide higher expected returns of the major asset classes. • Maintain a diversified exposure within the U.S. and international stock markets through the use of multi-manager portfolio strategies. • Achieve returns in excess of passive indexes through the use of active investment managers and strategies. The strategic role of fixed income is to: • Diversify the Pension Plans’ equity exposure by investing in fixed income securities that exhibit a low correlation to equities, thereby lowering the overall return volatility of the entire investment portfolio. • Maintain a diversified exposure within the U.S. fixed income market through the use of multi-manager portfolio strategies. • Achieve returns in excess of passive indexes through the use of active investment managers and strategies. The long-term strategic asset allocation policy is reviewed regularly or whenever significant changes occur to Century’s or the Pension Plans' financial position and liabilities. Fair Value Measurements of Pension Plan assets The following table sets forth by level the fair value hierarchy our Pension Plans' assets. These assets 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. Fair Value of Pension Plans’ assets included under the fair value hierarchy: As of December 31, 2015 Level 1 Level 2 Level 3 Total Equities: U.S. equities $ 86,723 $ — $ — $ 86,723 International equities 54,769 — — 54,769 Fixed income 139,370 — — 139,370 Total $ 280,862 $ — $ — $ 280,862 As of December 31, 2014 Equities: U.S. equities $ 79,148 $ — $ — $ 79,148 International equities 33,720 — — 33,720 Fixed income 76,204 — — 76,204 Plan Receivable (1) — — 116,448 116,448 Total $ 189,072 $ — $ 116,448 $ 305,520 (1) Represents the receivable to the Century Aluminum of South Carolina defined benefit plan related to pension funding obligations under the Stock Purchase Agreement which was received in 2015. The plan receivable was considered a Level 3 asset because determining the fair value requires significant unobservable inputs, including census data and various actuarial assumptions. Our Pension Plans’ assets are held in certain mutual funds. The fair value of the mutual funds is based on the Net Asset Value ("NAV") which is calculated every business day. The value of the underlying securities within the mutual funds are determined as follows: • U.S. listed equities; equity and fixed income options: Last sale price; last bid price if no last sale price; • U.S. over-the-counter equities: Official closing price; last bid price if no closing price; • Foreign equities: Official closing price, where available, or last sale price; last bid price if no official closing price; and • Municipal bonds, US bonds, Eurobonds/foreign bonds: Evaluated bid price; broker quote if no evaluated bid price. Our other postretirement benefit plans are unfunded. We fund these benefits as the retirees submit claims. Pension and OPEB Cash Flows During 2015 and 2014, we made contributions of approximately $5,910 and $5,584 , respectively, to the qualified defined benefit and SERB plans we sponsor. We expect to make the following contributions for 2016 : 2016 Expected pension plan contributions $ 1,769 Expected OPEB benefits payments 6,551 Estimated Future Benefit Payments The following table provides the estimated future benefit payments for the pension and other postretirement benefit plans: Pension Benefits OPEB Benefits 2016 $ 26,438 $ 6,551 2017 19,755 6,789 2018 20,228 7,099 2019 21,229 7,388 2020 21,655 7,508 2021 – 2025 105,301 39,031 Participation in Multiemployer Pension Plans We contribute to one multiemployer defined benefit pension plan under the terms of a collective-bargaining agreement that covers our union-represented employees at Hawesville. Our contributions to the plan are determined at a fixed rate per hour worked. Currently, we do not have any plans to withdraw from or curtail participation in this plan. The risks of participating in a multiemployer plan are different from single-employer plans in the following aspects: • Assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. • If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers. • If a participating employer chooses to stop participating in a multiemployer plan, the employer may be required to pay the plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability. The union-represented employees at Hawesville are part of a United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union ("USWA") sponsored multiemployer plan. Our contributions to the plan are determined at a fixed rate per hour worked. Century’s participation in the plan for the year ended December 31, 2015 , is outlined in the table below. Fund Steelworkers Pension Trust EIN / PN 23-6648508/499 Pension Protection Act Zone Status 2015 (1) Green Pension Protection Act Zone Status 2014 (1) Green Subject to Financial Improvement/Rehabilitation Plan No Contributions of Century Aluminum 2015 $1,618 Contributions of Century Aluminum 2014 $2,164 Contributions of Century Aluminum 2013 $2,171 Withdrawal from Plan Probable No Surcharge Imposed No Expiration Date of Collective Bargaining Agreement April 1, 2020 (1) The most recent Pension Protection Act zone status available in 2015 and 2014 is for the plan's year-end December 31, 2014 and December 31, 2013 , respectively. The zone status is based on information that Century received from the plan as well as publicly available information per the Department of Labor and is certified by the plan’s actuary. Among other factors, plans in the green zone are at least 80 percent funded. Century 401(k) Plans We sponsor a tax-deferred savings plan under which eligible domestic employees may elect to contribute specified percentages of their compensation with Century. We match a portion of participants' contributions to the savings plan. Employee and matching contributions are considered fully vested immediately upon participation in the plan. Concurrent with the 2014 amendment to the Salaried Pension Plan that eliminated future accruals for participants who are under age 50 as of January 1, 2015 and closed the plan to new entrants, the Company increased the proportional match of contributions made by those affected by the amendment. The expense related to the plan was $5,446 , $1,547 and $1,138 for 2015, 2014 and 2013, respectively.

Share-based compensation

Share-based compensation	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based compensation	Share-based compensation Amended and Restated Stock Incentive Plan — We award restricted share awards and grant qualified incentive and nonqualified stock options to our salaried officers, non-employee directors, and other key employees from our Amended and Restated Stock Incentive Plan (the "Stock Incentive Plan"). The Stock Incentive Plan has 10,000,000 shares authorized for issuance with approximately 6,832,000 shares remaining at December 31, 2015 . Our share-based compensation consists of service-based (time vested) and performance share awards that typically vest over a period of three years from the date of grant, provided that the recipient is still our employee at the time of vesting. Our independent non-employee directors receive annual grants of service-based share awards that vest following 12 months of service. In the past, we have granted stock options that have a term of 10 years and typically vest one-third on the grant date and an additional one-third on the first and second anniversary dates of the grant. Our most recent grant of stock options was in 2009. As of December 31, 2015 , options to purchase 443,737 shares of common stock and 541,304 service-based share awards were outstanding. A summary of activity under our Stock Incentive Plan during the year ended December 31, 2015 is presented below: Options Number Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2015 544,171 $ 26.85 Exercised — — Forfeited/expired (100,434 ) 25.95 Outstanding, fully vested and exercisable at December 31, 2015 (1) 443,737 $ 27.06 2.19 $ — (1) As the result of actions in 2011 that were determined to be a "change of control" under the Stock Incentive Plan, all options will remain exercisable for their respective remaining term, regardless of whether the awardees remain employees of Century. Long-Term Incentive Plan — We also grant annual long-term incentive awards under our Amended and Restated Long-Term Incentive Plan (the "LTIP"). The LTIP is designed to provide senior-level employees the opportunity to earn long-term incentive awards through the achievement of performance goals and to align compensation with the interests of our stockholders by linking compensation to share price appreciation and total stockholder return over a multi-year period. Awards made under the LTIP are granted subject to the Stock Incentive Plan to the extent the award is deliverable in stock. We provide two types of LTIP awards: time-vested performance share units and performance units. Time-vested share units are stock-settled awards (which do not contain any performance-based vesting requirements) that are granted at the beginning of the performance period. Performance units are generally cash-settled awards (although the Board of Directors retains the discretion to settle these awards in stock) and vest based on the achievement of pre-determined performance metrics, subject to the discretion of the Board. We recorded a performance unit liability for approximately $4,853 and $6,251 as of December 31, 2015 and 2014, respectively. Both the performance units and time-vested share units vest, in their entirety, after three years. Service-based share awards Outstanding at January 1, 2015 464,485 Granted 478,798 Vested (354,688 ) Forfeited (47,291 ) Outstanding at December 31, 2015 541,304 Year ended December 31, 2015 2014 2013 Weighted average per share fair value of service-based share grants $ 4.21 $ 15.31 $ 8.19 Total intrinsic value of option exercises — 1,011 13 Fair Value Measurement of Share-Based Compensation Awards – We estimate the fair value of each stock option award using the Black-Scholes model on the date of grant. We have not granted any stock options since 2009. For our service-based awards, fair value is equal to the closing stock price on the date of grant. For our performance-based awards, fair value is equal to the closing stock price at each reporting period end. The following table summarizes the compensation cost recognized for the years ended December 31, 2015 , 2014 and 2013 for all options, service-based share and performance-based share awards. This expense is included as part of selling, general and administrative expenses in our Consolidated Statements of Operations. Year ended December 31, 2015 2014 2013 Share-based compensation expense reported: Performance-based share expense $ 1,587 $ 1,090 $ 475 Service-based share expense 257 244 603 Stock option expense — — — Total share-based compensation expense before income tax 1,844 1,334 1,078 Income tax — — — Total share-based compensation expense, net of income tax $ 1,844 $ 1,334 $ 1,078 No share-based compensation cost was capitalized during these periods and there were no significant modifications of any share-based awards in 2015, 2014 and 2013. As of December 31, 2015 , we had unrecognized compensation expense of $2,334 before taxes. This expense will be recognized over a weighted average period of one year .

Earnings (loss) per share

Earnings (loss) per share	12 Months Ended
	Dec. 31, 2015
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 potentially dilutive common shares outstanding. The following table shows the basic and diluted earnings (loss) per share for 2015 , 2014 , and 2013 : For the year ended December 31, 2015 Net loss Shares (000) Per-Share Net loss $ (59,310 ) Amount allocated to common stockholders 100.00 % Basic and Diluted EPS: Net loss allocated to common stockholders (59,310 ) 87,375 $ (0.68 ) For the year ended December 31, 2014 Net income Shares (000) Per-Share Net income $ 126,474 Amount allocated to common stockholders 91.81 % Basic EPS: Net income allocated to common stockholders 116,118 88,823 $ 1.31 Effect of Dilutive Securities: Share-based compensation plans 605 Diluted EPS: $ 116,118 89,428 $ 1.30 For the year ended December 31, 2013 Net loss Shares (000) Per-Share Net loss $ (40,313 ) Amount allocated to common stockholders 100.00 % Basic and Diluted EPS: Net loss allocated to common stockholders $ (40,313 ) 88,612 $ (0.45 ) Securities excluded from the calculation of diluted EPS: 2015 2014 2013 Stock options (1) 356,634 320,553 619,833 Service-based share awards (1) 608,914 — 442,737 (1) In periods when we report a net loss, all share awards are excluded from the calculation of diluted weighted average shares outstanding because of their antidilutive effect on earnings (loss) per share.

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income taxes	Income taxes The components of pre-tax book income (loss) consist of the following: Year Ended December 31, 2015 2014 2013 U.S. $ (62,203 ) $ 91,026 $ (47,080 ) Foreign 21,081 52,451 7,236 Total $ (41,122 ) $ 143,477 $ (39,844 ) Significant components of the income tax expense consist of the following: Year Ended December 31, 2015 2014 2013 Current: U.S. federal current expense (benefit) $ — $ (112 ) $ 532 State current expense (benefit) (706 ) 2,252 (445 ) Foreign current expense 13,473 15,098 6,198 Total current expense 12,767 17,238 6,285 Deferred: U.S. federal deferred benefit (1,564 ) (1,696 ) (3,905 ) State deferred benefit — (12 ) (207 ) Foreign deferred tax expense (1,927 ) 2,778 958 Total deferred benefit (3,491 ) 1,070 (3,154 ) Total income tax expense $ 9,276 $ 18,308 $ 3,131 A reconciliation of the statutory U.S. Federal income tax rate to the effective income tax rate on income (loss) is as follows: 2015 2014 2013 Federal Statutory Rate 35.0 % 35.0 % 35.0 % Permanent differences 1.9 4.3 54.5 State taxes, net of Federal benefit (16.0 ) (6.2 ) 97.2 Foreign earnings taxed at different rates than U.S. 3.0 (1.3 ) 17.4 Valuation allowance (56.6 ) (26.0 ) (265.9 ) Changes in uncertain tax reserves (4.2 ) 0.6 40.5 Other 14.3 6.4 13.4 Effective tax rate (22.6 )% 12.8 % (7.9 )% The effect of earnings of foreign subsidiaries includes the difference between the U.S. statutory rate and local jurisdiction tax rates, as well as the provision (benefit) for incremental U.S. taxes on unremitted earnings of foreign subsidiaries due to the removal of the election to permanently reinvest the related earnings during 2012. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our deferred tax assets and liabilities as of December 31 are as follows: 2015 2014 Deferred tax assets: Accrued postretirement benefit cost $ 14,825 $ 15,683 Accrued liabilities 1,080 4,494 Share-based compensation 6,421 7,350 Derivative and hedging contracts — 58,687 Goodwill 7,949 10,521 Pension and post-retirement obligations in other comprehensive income 78,753 81,567 Net operating losses and tax credits 700,819 646,158 Foreign basis differences 2,083 668 Other 10,676 8,748 Total deferred tax assets 822,606 833,876 Valuation allowance (768,764 ) (748,283 ) Net deferred tax assets $ 53,842 $ 85,593 Deferred tax liabilities: Tax over financial statement depreciation $ (116,327 ) $ (142,627 ) Pension (15,608 ) (14,222 ) Unremitted foreign earnings (18,901 ) (30,308 ) Total deferred tax liabilities (150,836 ) (187,157 ) Net deferred tax liability $ (96,994 ) $ (101,564 ) We establish a valuation allowance when it is more likely than not that all or a portion of a deferred tax asset will not be realized. The amount of valuation allowance is based upon our best estimate of our ability to realize the net deferred tax assets. A valuation allowance can subsequently be reversed when we believe that the assets are realizable on a more likely than not basis. The changes in the valuation allowance are as follows: 2015 2014 Beginning balance, valuation allowance $ 748,283 $ 765,023 Change in valuation allowance 20,481 (16,740 ) Ending balance, valuation allowance $ 768,764 $ 748,283 As a result of certain realization requirements of ASC Topic 718 "Compensation - Stock Compensation", the table of deferred tax assets and liabilities shown above does not include net operating loss deferred tax assets at December 31, 2015 and 2014 that arose directly from tax deductions related to equity compensation in excess of compensation recognized for financial reporting. Net operating losses of $7,746 will increase equity if and when such deferred tax assets are ultimately realized. The significant components of our NOL carryforwards are as follows: 2015 2014 Federal (1) $ 1,470,251 $ 1,306,482 State (2) 2,094,687 2,078,105 Foreign (3) 466,743 446,234 (1) The federal NOL begins to expire in 2028 . (2) The state NOLs begin to expire in 2027 . (3) The Icelandic NOL begins to expire in 2017 ; Dutch NOL begins to expire in 2022 . A reconciliation of the beginning and ending amounts of gross unrecognized tax benefits (excluding interest) is as follows: 2015 2014 2013 Balance as of January 1, $ 2,000 $ 1,200 $ 17,600 Additions based on tax positions related to the current year 1,800 1,100 700 Decreases due to lapse of applicable statute of limitations — (300 ) (2,800 ) Settlements — — (14,300 ) Balance as of December 31, $ 3,800 $ 2,000 $ 1,200 Included in the above balances are tax positions whose tax characterization is highly certain but for which there is uncertainty about the timing of tax return inclusion. Because of the impact of deferred tax accounting, other than interest and penalties, the timing would not impact the annual effective tax rate but could accelerate the payment of cash to the taxing authority to an earlier period. The remaining amounts of unrecognized tax benefits would affect our effective tax rate if recognized. It is our policy to recognize potential accrued interest and penalties related to unrecognized tax benefits in income tax expense. The components of our unrecognized tax positions are as follows: 2015 2014 2013 Highly certain tax positions $ 3,700 $ 1,900 $ 1,100 Other unrecognized tax benefits 100 100 100 Gross unrecognized tax benefits $ 3,800 $ 2,000 $ 1,200 Accrued interest and penalties related to unrecognized tax benefits $ — $ — $ 100 Century and its subsidiaries file income tax returns in the U.S. federal jurisdiction, various state and local jurisdictions, and several foreign jurisdictions. In April 2013, we received notice from the Internal Revenue Service ("IRS") that the Congressional Joint Committee on Taxation finalized their review of the US Federal examinations for the income tax years 2008, 2009, and 2010 and refund years of 2004, 2005, 2006, and 2007 without exception to the conclusions reached by the IRS. This Joint Committee is a special nonpartisan Congressional committee involved with the analysis and drafting of federal tax legislation and, as part of its mandate, reviews all federal tax refund claims over a certain amount. As a result of this determination, we have reduced the reserve for the unrecognized tax benefits related to prior years by approximately $14,300 . The reduction did not result in an impact to the effective tax rate since the reduction was offset by an increase in our valuation allowance. During the second quarter of 2013, we received refunds from the IRS of $5,009 following the Joint Committee review. Our federal income tax returns have been reviewed by the IRS through 2010. However, we have NOL's beginning in 2008 that are available for carryforward to future years. Under U.S. tax law, NOL's may be adjusted by the IRS until the statute of limitations expires for the year in which the NOL is used. Accordingly, our 2008 and later NOL's may be reviewed until they are used or expire. Material state and local income tax matters have been concluded for years through 2006. The majority of our state returns beginning in 2008 are subject to examination. As of December 31, 2015 , we had federal net operating loss carryforwards of $1,470,251 . Our ability to utilize our deferred tax assets to offset future federal taxable income may be significantly limited if we experience an "ownership change" as defined in Section 382 of the Internal Revenue Code of 1986, as amended (the "Code"). In general, an ownership change would occur if our "five-percent shareholders," as defined under the Code, collectively increase their ownership in us by more than 50 percentage points over a rolling three-year period. Future transactions in our stock that may not be in our control may cause us to experience such an ownership change and thus limit our ability to utilize net operating losses, tax credits and other tax assets to offset future taxable income. Our Icelandic tax returns are subject to examination beginning with the 2009 tax year. A review of our 2010 through 2012 tax years was recently completed by the Directorate of Internal Revenue of Iceland and no further action is expected for this matter. As of December 31, 2015 and 2014 we had income taxes payable of $13,092 and $14,302 , respectively. The income taxes payable are included within accrued and other current liabilities in our Consolidated Balance Sheets. We do not expect a significant change in the balance of unrecognized tax benefits within the next twelve months.

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2015
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. Because of the issues and uncertainties described below and the inability to predict the requirements of future environmental laws, 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. We 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 $1,112 and $1,101 at December 31, 2015 and 2014 , respectively. All accrued amounts have been recorded without giving effect to any possible future recoveries. With respect to costs for ongoing environmental compliance, including maintenance and monitoring, such costs are expensed as incurred. 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 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. In connection with the sale of the facility by Lockheed Martin Corporation ("Lockheed") to one of our affiliates, Virgin Islands Alumina Corporation ("Vialco"), in 1989, Lockheed, Vialco and Century entered into the Lockheed-Vialco Asset Purchase Agreement. The indemnity provisions contained in the Lockheed-Vialco Asset Purchase Agreement allocate responsibility for certain environmental matters. Lockheed has tendered indemnity to Vialco. We have likewise tendered indemnity to Lockheed. Through December 31, 2015 , we have 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. Vialco sold the St. Croix Alumina Refinery to St. Croix Alumina, LLC, a subsidiary of Alcoa, in 1995. 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 have 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, we are not able 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. 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, 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 (the "USW"), the USW’s local and certain CAWV retirees, individually and as class representatives, 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. These actions, entitled Dewhurst, et al. v. Century Aluminum Co., et al., and Century Aluminum of West Virginia, Inc. v. United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union, AFL-CIO/CLC, et al., have been consolidated and venue has been set in the District Court for the Southern District of West Virginia. In September 2015, the trial court granted CAWV's motion for summary judgment of these actions. The trial court decision is currently being appealed by the USW to the Court of Appeals for the 4th Circuit. PBGC Settlement In April 2013, we entered into a settlement agreement with the Pension Benefit Guaranty Corporation ("PBGC") regarding an alleged "cessation of operations" at our Ravenswood facility as a result of the curtailment of operations at the facility and, pursuant to the agreement, we agreed to make additional contributions (above any minimum required contributions) to our defined benefit pension plans totaling approximately $17,400 over the term of the agreement, which runs through 2016. Under certain circumstances, in periods of lower primary aluminum prices relative to our cost of operations, we may defer one or more of these payments, but we would be required to provide the PBGC with acceptable security for any deferred payments. We made the contributions pursuant to this agreement of $1,100 in 2015 and $6,700 in 2013. We did not make any contribution during 2014. The remaining contributions under this agreement are approximately $9,600 . Power Commitments and Contingencies Hawesville CAKY is party to a power supply arrangement with Kenergy and Big Rivers which provides market-based power to the Hawesville smelter. The power supply arrangement has an effective term through December 2023. 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 incurred by Kenergy. Effective January 1, 2015, new agreements were approved by the Kentucky Public Service Commission pursuant to which EDF Trading North America, LLC ("EDF") replaced Big Rivers as the market participant with MISO under this arrangement. Sebree Century Sebree is party to a power supply arrangement with Kenergy and Big Rivers which provides market-based power to the Sebree smelter. The power supply arrangement has an effective term through December 2023. 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 incurred by Kenergy. Effective January 1, 2015, new agreements were approved by the Kentucky Public Service Commission pursuant to which EDF replaced Big Rivers as our market participant with MISO under this arrangement. Mt. Holly CASC's power agreement with the South Carolina Public Service Authority ("Santee Cooper") for power to the Mt. Holly smelter expired on December 31, 2015. On December 18, 2015, CASC reached an agreement with Santee Cooper that would allow Mt. Holly to operate at 50% capacity while CASC worked on a long-term solution that would allow Mt. Holly to access market power for all our its power supply requirements. This agreement with Santee Cooper provides for the supply of power to Mt. Holly from two sources: (1) 25% of the Mt. Holly load is served from Santee Cooper’s generation at a standard cost-based industrial rate and (2) 75% of the power to serve Mt. Holly is sourced from a third party supplier from generation that is outside Santee Cooper’s service territory at market prices plus transmission that are tied to natural gas prices. The agreement with Santee Cooper has a term through December 31, 2018 but can be terminated by Mt. Holly on 60 days' notice; the current third party supply contract has a term through May 31, 2016. Grundartangi Nordural Grundartangi ehf has power purchase agreements with HS Orka hf ("HS"), Landsvirkjun and Orkuveita Reykjavikur ("OR") to provide power to its Grundartangi smelter. These power purchase agreements, which will expire on various dates from 2019 through 2036 (subject to extension), provide power at LME-based variable rates. Each power purchase agreement contains take-or-pay obligations with respect to a significant percentage of the total committed and available power under such agreement. In June 2012, Nordural Grundartangi ehf entered into a supplemental power contract with Landsvirkjun. The supplemental power contract, which will expire in October 2029 (or upon the occurrence of certain earlier events), will provide Nordural Grundartangi ehf with supplemental power, as Nordural Grundartangi ehf may request from time to time, at LME-based variable rates. Nordural Grundartangi ehf made certain prepayments to Landsvirkjun for power expected to be used at a later date in connection with the contract, which will reduce the price paid for power at the time of consumption. As of December 31, 2015 , these power prepayments totaled approximately $1,477 . Helguvik Nordural Helguvik ehf has power purchase agreements with HS and OR to provide power to the Helguvik project. These power purchase agreements 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 power purchase agreements with HS and OR to provide power to Helguvik contain certain conditions to HS’s and OR’s obligations. HS (with respect to all phases) and OR (with respect to all phases other than the first phase) have alleged that certain of these conditions have not been satisfied. The first stage of power under the OR power purchase agreement (approximately 47.5 MW) became available in the fourth quarter of 2011 and is currently being utilized at Grundartangi. In July 2014, HS commenced arbitration proceedings against Nordural Helguvik ehf seeking, among other things, an order declaring, (i) that the conditions to the power contract have not been fulfilled and, (ii) that the power contract is therefore no longer valid. Nordural Helguvik ehf believes HS' claims are without merit and intends to defend itself against them. Nordural Helguvik ehf is in discussions with both HS and OR with respect to such conditions and other matters pertaining to these agreements. In June 2014, Nordural Helguvik ehf entered into a supplemental power contract with OR which will expire in October 2036 (or upon the occurrence of certain earlier events) and will provide Grundartangi or Helguvik with supplemental power at LME-based rates, as may be requested from Grundartangi or Helguvik from time to time. Other Commitments and Contingencies Labor Commitments The bargaining unit employees at our Grundartangi, Vlissingen, Hawesville, Sebree and Ravenswood facilities are represented by labor unions, representing 63% of our total workforce. 84% of Grundartangi’s work force is represented by five labor unions, governed by a labor agreement that establishes wages and work rules for covered employees. A new labor agreement was reached in 2015 which is effective through December 31, 2019. 100% of Vlissingen's work force is represented by the FME, governed by a labor agreement that expired on May 1, 2015 and contract negotiations are in process. The FME negotiates working conditions with trade unions on behalf of its members. 53% of our U.S. based work force is represented by USW. In June 2015, CAKY entered into a new collective bargaining agreement with the USW for its employees at the Hawesville smelter. The agreement is effective through April 1, 2020. Century Sebree has a collective bargaining agreement with the USW for its employees at the Sebree smelter that is effective through October 28, 2019. The labor agreement for CAWV’s Ravenswood plant employees represented by the USW expired on August 31, 2010.

Asset retirement obligations ('

Asset retirement obligations ('ARO')	12 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligations (“ARO”)	Asset retirement obligations ("ARO") The reconciliation of the changes in the asset retirement obligations is presented below: Year ended December 31, 2015 2014 Beginning balance, ARO liability $ 36,950 $ 27,113 Additional ARO liability incurred 3,797 2,548 ARO liabilities settled (5,514 ) (4,731 ) Accretion expense 1,818 1,517 Adjustments (1,886 ) — ARO liability from Mt. Holly acquisition — 10,503 Ending balance, ARO liability $ 35,165 $ 36,950

Supplemental cash flow informat

Supplemental cash flow information	12 Months Ended
	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental cash flow information	Supplemental cash flow information Year Ended December 31, 2015 2014 2013 Cash paid for: Interest $ 18,781 $ 19,066 $ 20,539 Income/withholding taxes (1) 24,125 12,189 28,654 Non-cash investing activities: Accrued capital costs $ 777 $ 744 $ 9,409 (1) We paid withholding taxes in Iceland on intercompany dividends of $8,388 , $5,491 and $18,067 during the years ended December 31, 2015 , 2014 and 2013, respectively. Such withholding taxes are then refunded to us in the following year.

Quarterly information (Unaudite

Quarterly information (Unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Data [Abstract]
Quarterly information (Unaudited)	Quarterly information (Unaudited) Financial results by quarter for the years ended December 31, 2015 and 2014 are as follows: Net sales Gross profit (loss) Net income (loss) Net income (loss) allocated to common stockholders Basic earnings (loss) per share Diluted earnings (loss) per share 2015 4th Quarter (1) $ 383,915 $ (18,701 ) $ (43,080 ) $ (43,080 ) $ (0.50 ) $ (0.50 ) 3rd Quarter (2) 454,540 (42,423 ) (56,112 ) (56,112 ) (0.65 ) (0.65 ) 2nd Quarter (3) 523,491 8,342 (33,897 ) (33,897 ) (0.39 ) (0.39 ) 1st Quarter (4) 587,911 94,095 73,779 67,813 0.76 0.76 2014 4th Quarter (5) 551,239 89,339 75,829 69,669 0.78 0.78 3rd Quarter (6) 500,632 75,714 50,405 46,277 0.52 0.52 2nd Quarter (7) 458,324 38,504 20,344 18,675 0.21 0.21 1st Quarter (8) 420,847 (1,758 ) (20,104 ) (20,104 ) (0.23 ) (0.23 ) (1) The fourth quarter of 2015 was favorably impacted by a $23,474 lower of cost or market inventory adjustment, $3,400 related to non-cash, non-recurring post-retirement benefits. Results were negatively impacted by a $3,500 charge related to the partial curtailment of operations at Hawesville and Mt. Holly, a $5,000 charge for depreciation related to Mt. Holly purchase accounting and an $11,584 impairment charge at BHH. (2) The third quarter of 2015 was impacted by a $5,324 unfavorable lower of cost or market adjustment to cost of goods sold, $1,400 for labor disruption and $2,900 for partial curtailment expenses at Hawesville. (3) The second quarter of 2015 was impacted by a $25,689 unfavorable LCM adjustment to cost of goods sold and a $30,850 impairment reserve related to the permanent closure of our Ravenswood facility and $11,700 of labor disruption expenses associated with a new union contract at our Hawesville location in partially offset by a $10,287 gain on fair value of contingent consideration on our Mt. Holly acquisition. (4) The first quarter of 2015 included a $6,527 gain on fair value of contingent consideration partially offset by $1,570 of signing bonuses related to a new labor contract at Grundartangi and a $1,000 severance charge for a former executive. (5) The fourth quarter of 2014 net income included a benefit of $7,943 for the gain on remeasurement of contingent consideration and a benefit of $15,955 for gain on remeasurement of our equity investment in Mt. Holly. Results were negatively impacted by $4,964 in non-cash, non-recurring pension charges and by $2,616 related to the separation of former senior executives. (6) The third quarter of 2014 net income reflects higher aluminum prices and lower power prices in the Midwestern U.S. (7) The second quarter of 2014 net income reflects higher aluminum prices and lower power prices in the Midwestern U.S. Results were negatively impacted by a charge of $500 for the finalization of a legal settlement. (8) The first quarter of 2014 cost of sales included a benefit of $5,534 related to deferred power contract liability amortization. Results were negatively impacted by a $3,100 charge for increased legal reserves.

Business segments

Business segments	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Business segments	Business segments Century Aluminum is a producer of primary aluminum, which trades as a global commodity. We are organized as a holding company with each of our operating primary aluminum smelters managed and operated as a separate facility reporting to our corporate headquarters. Each of our operating primary aluminum smelters meets the definition of an operating segment. We evaluated the similar economic and other characteristics, including nearly identical products, production processes, customers and distribution and have aggregated our four operating segments into one reportable segment, primary aluminum, based on these factors. In addition, all of our primary aluminum smelters share several key economic factors inherent in their common products and production processes. For example, all of our facilities' revenue is based on the LME price for primary aluminum. A reconciliation of our consolidated assets to the total of primary aluminum segment assets is provided below. Segment assets (1) 2015 2014 2013 Primary $ 1,706,032 $ 1,987,727 $ 1,770,749 Corporate, unallocated 46,436 37,331 39,447 Total assets $ 1,752,468 $ 2,025,058 $ 1,810,196 (1) Segment assets include accounts receivable, due from affiliates, prepaid and other current assets, inventory, intangible assets and property, plant and equipment — net; the remaining assets are unallocated corporate assets. Geographic information Included in the consolidated financial statements are the following amounts related to geographic locations: 2015 2014 2013 Net sales: United States $ 1,373,714 $ 1,370,570 $ 1,022,081 Iceland 576,143 560,472 432,232 Long-lived assets: (1) United States $ 408,722 $ 497,057 $ 392,424 Iceland 801,268 831,507 853,636 Other 94,421 95,752 93,075 (1) Includes long-lived assets other than financial instruments. Major customer information The following table shows our major customers whose sales revenue exceeded 10% of our net sales. A loss of any of these customers could have a material adverse effect on our results of operations. The net sales revenue for these customers is as follows: Year Ended December 31, 2015 2014 2013 Glencore $ 1,867,711 $ 1,262,101 $ 511,051 Southwire — 226,740 312,102 RTA — — 223,353 BHP Billiton — — 191,445

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events We have evaluated all activity of the Company through the date the financial statements were issued and concluded that no subsequent events have occurred that would require recognition or disclosure in the consolidated financial statements.

Condensed consolidating financi

Condensed consolidating financial information	12 Months Ended
	Dec. 31, 2015
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, except for Nordural US LLC and Century Aluminum Development LLC. 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 and Century Aluminum Development LLC, 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 balance sheets as of December 31, 2015 and 2014, condensed consolidating statements of comprehensive income (loss) for the years ended December 31, 2015, 2014 and 2013 and the condensed consolidating statements of cash flows for the years ended December 31, 2015, 2014 and 2013 present separate results for Century, the Guarantor Subsidiaries, the Non-Guarantor Subsidiaries, consolidating adjustments and total consolidated amounts. Although Century Aluminum West Virginia (which owns our curtailed Ravenswood smelter) has guaranteed our Notes due 2021, because we are in the process of selling substantially all of its assets, we have included its assets and results of operations in the columns under the caption Non-Guarantor Subsidiaries. Condensed Consolidating Statements of Comprehensive Income (Loss) For the year ended December 31, 2015 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 1,277,474 $ 632,597 $ (42,360 ) $ 1,867,711 Third-party customers — 82,327 43 (224 ) 82,146 — 1,359,801 632,640 (42,584 ) 1,949,857 Cost of goods sold — 1,388,400 564,380 (44,236 ) 1,908,544 Gross profit (loss) — (28,599 ) 68,260 1,652 41,313 Selling, general and administrative expenses 28,000 8,798 5,317 — 42,115 Ravenswood impairment — — 30,850 — 30,850 Other operating expense - net — — 7,436 — 7,436 Operating income (loss) (28,000 ) (37,397 ) 24,657 1,652 (39,088 ) Interest expense - third parties (20,201 ) (1,567 ) (186 ) — (21,954 ) Interest income (expense) - affiliates 37,626 — (37,626 ) — — Interest income - third parties 65 4 270 — 339 Net gain on forward and derivative contracts — 1,411 189 — 1,600 Unrealized gain on fair value of contingent consideration — 18,337 — — 18,337 Other income (expense) - net 1,356 (658 ) 2,356 (3,410 ) (356 ) Loss before income taxes and equity in earnings (loss) of joint ventures (9,154 ) (19,870 ) (10,340 ) (1,758 ) (41,122 ) Income tax benefit (expense) 2,140 — (11,416 ) — (9,276 ) Loss before equity in earnings (loss) of joint ventures (7,014 ) (19,870 ) (21,756 ) (1,758 ) (50,398 ) BHH impairment — — (11,584 ) — (11,584 ) Equity in earnings (loss) of joint ventures (52,296 ) — 2,672 52,296 2,672 Net loss $ (59,310 ) $ (19,870 ) $ (30,668 ) $ 50,538 $ (59,310 ) Other comprehensive income (loss) before income tax effect 6,568 14,754 (1,114 ) (13,640 ) 6,568 Income tax effect (1,536 ) — 33 (33 ) (1,536 ) Other comprehensive income (loss) 5,032 14,754 (1,081 ) (13,673 ) 5,032 Total comprehensive loss $ (54,278 ) $ (5,116 ) $ (31,749 ) $ 36,865 $ (54,278 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the year ended December 31, 2014 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 715,796 $ 625,076 $ (78,771 ) $ 1,262,101 Third-party customers — 669,466 31 (556 ) 668,941 — 1,385,262 625,107 (79,327 ) 1,931,042 Cost of goods sold — 1,282,194 522,543 (75,494 ) 1,729,243 Gross profit — 103,068 102,564 (3,833 ) 201,799 Selling, general and administrative expenses 32,840 11,353 5,002 — 49,195 Other operating expense - net — — 12,481 — 12,481 Operating income (loss) (32,840 ) 91,715 85,081 (3,833 ) 140,123 Interest expense - third parties (20,228 ) (1,555 ) (232 ) — (22,015 ) Interest income (expense) - affiliates 43,688 — (43,688 ) — — Interest income - third parties 15 — 286 — 301 Net gain (loss) on forward and derivative contracts (1,080 ) 1,259 — — 179 Unrealized gain on fair value of contingent consideration — 7,943 — — 7,943 Gain on remeasurement of equity investment — 15,955 — — 15,955 Other income (expense) - net 518 (459 ) 4,564 (3,632 ) 991 Income (loss) before income taxes and equity in earnings of joint ventures (9,927 ) 114,858 46,011 (7,465 ) 143,477 Income tax expense (4,777 ) (493 ) (13,211 ) 173 (18,308 ) Income (loss) before equity in earnings of joint ventures (14,704 ) 114,365 32,800 (7,292 ) 125,169 Equity in earnings of joint ventures 141,178 — 1,305 (141,178 ) 1,305 Net income $ 126,474 $ 114,365 $ 34,105 $ (148,470 ) $ 126,474 Other comprehensive loss before income tax effect (24,022 ) (28,955 ) (2,662 ) 18,967 (36,672 ) Income tax effect (1,829 ) — 33 (33 ) (1,829 ) Other comprehensive loss (25,851 ) (28,955 ) (2,629 ) 18,934 (38,501 ) Total comprehensive income $ 100,623 $ 85,410 $ 31,476 $ (129,536 ) $ 87,973 Condensed Consolidating Statements of Comprehensive Income (Loss) For the year ended December 31, 2013 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 270,314 $ 244,680 $ (3,943 ) $ 511,051 Third-party customers — 752,808 191,495 (1,041 ) 943,262 — 1,023,122 436,175 (4,984 ) 1,454,313 Cost of goods sold — 1,061,597 358,124 (4,931 ) 1,414,790 Gross profit (loss) — (38,475 ) 78,051 (53 ) 39,523 Selling, general and administrative expenses 40,831 10,456 16,190 — 67,477 Other operating expense - net — — 8,602 — 8,602 Operating income (loss) (40,831 ) (48,931 ) 53,259 (53 ) (36,556 ) Interest expense - third parties (21,543 ) (1,510 ) (38 ) — (23,091 ) Interest income (expense) - affiliates 48,126 — (48,126 ) — — Interest income - third parties 27 6 695 — 728 Net gain on forward and derivative contracts 140 16,458 — — 16,598 Gain on bargain purchase — 5,253 — — 5,253 Loss on early extinguishment of debt (3,272 ) — — — (3,272 ) Other income (expense) - net 138,548 (113 ) 94 (138,033 ) 496 Income (loss) before income taxes and equity in earnings (loss) of joint ventures 121,195 (28,837 ) 5,884 (138,086 ) (39,844 ) Income tax benefit (expense) (3,386 ) — 255 — (3,131 ) Income (loss) before equity in earnings (loss) of joint ventures 117,809 (28,837 ) 6,139 (138,086 ) (42,975 ) Equity in earnings (loss) of joint ventures (158,122 ) — 2,662 158,122 2,662 Net income (loss) $ (40,313 ) $ (28,837 ) $ 8,801 $ 20,036 $ (40,313 ) Other comprehensive income before income tax effect 60,924 31,258 22,634 (53,892 ) 60,924 Income tax effect (1,564 ) — 33 (33 ) (1,564 ) Other comprehensive income 59,360 31,258 22,667 (53,925 ) 59,360 Total comprehensive income $ 19,047 $ 2,421 $ 31,468 $ (33,889 ) $ 19,047 Condensed Consolidating Balance Sheet As of December 31, 2015 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 58,421 $ (3,647 ) $ 60,619 $ — $ 115,393 Restricted cash — 791 — — 791 Accounts receivable - net 104 8,891 480 — 9,475 Due from affiliates 13 14,493 2,911 — 17,417 Inventories 180 148,280 85,937 (2,525 ) 231,872 Prepaid and other current assets 7,713 16,242 18,457 — 42,412 Assets held for sale — — 30,697 — 30,697 Total current assets 66,431 185,050 199,101 (2,525 ) 448,057 Property, plant and equipment - net 9,188 361,626 861,442 — 1,232,256 Investment in subsidiaries 593,604 — — (593,604 ) — Due from affiliates - less current portion 632,170 — — (632,170 ) — Other assets 29,536 19,153 16,047 7,419 72,155 TOTAL $ 1,330,929 $ 565,829 $ 1,076,590 $ (1,220,880 ) $ 1,752,468 Accounts payable, trade $ 2,380 $ 53,145 $ 34,964 $ — $ 90,489 Due to affiliates 2,143 7,167 735 — 10,045 Accrued and other current liabilities 11,247 14,759 22,816 — 48,822 Accrued employee benefits costs 1,824 7,644 680 — 10,148 Industrial revenue bonds — 7,815 — — 7,815 Total current liabilities 17,594 90,530 59,195 — 167,319 Senior notes payable 247,278 — — — 247,278 Accrued pension benefits costs cost - less current portion 39,831 (11,021 ) 15,189 — 43,999 Accrued postretirement benefits costs - less current portion 4,524 119,911 1,564 — 125,999 Other liabilities 3,307 30,505 11,779 7,418 53,009 Intercompany loan — 124,518 509,652 (634,170 ) — Deferred taxes — — 96,994 — 96,994 Total noncurrent liabilities 294,940 263,913 635,178 (626,752 ) 567,279 Series A Preferred stock 1 — — — 1 Common stock 942 — 224,424 (224,424 ) 942 Additional paid-in capital 2,513,631 191,023 2,038,138 (2,229,161 ) 2,513,631 Treasury stock, at cost (86,276 ) — — — (86,276 ) Accumulated other comprehensive loss (13,125 ) (60,026 ) (39,499 ) — (112,650 ) Accumulated deficit (1,396,778 ) 80,389 (1,840,846 ) 1,859,457 (1,297,778 ) Total shareholder's equity 1,018,395 211,386 382,217 (594,128 ) 1,017,870 TOTAL $ 1,330,929 $ 565,829 $ 1,076,590 $ (1,220,880 ) $ 1,752,468 Condensed Consolidating Balance Sheet As of December 31, 2014 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 70,683 $ (1,187 ) $ 93,746 $ — $ 163,242 Restricted cash — 787 14 — 801 Accounts receivable - net — 77,173 494 — 77,667 Due from affiliates 9 30,126 1,368 — 31,503 Inventories 180 192,803 80,194 10,303 283,480 Prepaid and other current assets 4,311 10,199 13,393 1,865 29,768 Deferred taxes — 14,281 — — 14,281 Total current assets 75,183 324,182 189,209 12,168 600,742 Property, plant and equipment - net 1,788 380,234 923,961 (440 ) 1,305,543 Investment in subsidiaries 589,532 — — (589,532 ) — Due from affiliates - less current portion 719,258 — — (719,258 ) — Other assets 31,233 33,422 48,553 5,565 118,773 TOTAL $ 1,416,994 $ 737,838 $ 1,161,723 $ (1,291,497 ) $ 2,025,058 Accounts payable, trade $ 2,252 $ 109,376 $ 38,124 $ 1,691 $ 151,443 Due to affiliates — 18,730 3,531 — 22,261 Accrued and other current liabilities 13,048 64,104 22,817 3,838 103,807 Accrued employee benefits costs 1,823 7,805 531 — 10,159 Industrial revenue bonds — 7,815 — — 7,815 Total current liabilities 17,123 207,830 65,003 5,529 295,485 Senior notes payable 246,888 — — — 246,888 Accrued pension benefits costs cost - less current portion 32,136 13,942 13,828 — 59,906 Accrued postretirement benefits costs - less current portion 5,821 145,267 1,806 — 152,894 Other liabilities 3,630 32,035 11,963 5,644 53,272 Intercompany loan — 164,610 542,259 (706,869 ) — Deferred taxes — — 111,486 — 111,486 Total noncurrent liabilities 288,475 355,854 681,342 (701,225 ) 624,446 Series A Preferred stock 1 — — — 1 Common stock 939 — 215,424 (215,424 ) 939 Additional paid-in capital 2,510,261 150,861 2,136,138 (2,286,999 ) 2,510,261 Treasury stock, at cost (49,924 ) — — — (49,924 ) Accumulated other comprehensive loss (4,484 ) (74,780 ) (38,418 ) — (117,682 ) Accumulated deficit (1,345,397 ) 98,073 (1,897,766 ) 1,906,622 (1,238,468 ) Total shareholder's equity 1,111,396 174,154 415,378 (595,801 ) 1,105,127 TOTAL $ 1,416,994 $ 737,838 $ 1,161,723 $ (1,291,497 ) $ 2,025,058 Condensed Consolidating Statement of Cash Flows For the year ended December 31, 2015 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by operating activities $ 25,423 $ 30,890 $ 65,085 $ (89,532 ) $ 31,866 Purchase of property, plant and equipment (8,574 ) (21,477 ) (24,209 ) (440 ) (54,700 ) Purchase of remaining interest in Mt. Holly smelter 11,313 — — — 11,313 Proceeds from sale of property, plant and equipment — 14 — — 14 Restricted and other cash deposits — (4 ) 14 — 10 Intercompany transactions (4,072 ) — — 4,072 — Net cash used in investing activities (1,333 ) (21,467 ) (24,195 ) 3,632 (43,363 ) Borrowings under revolving credit facilities 1,737 — — — 1,737 Repayments under revolving credit facilities (1,737 ) — — — (1,737 ) Repurchase of common stock (36,352 ) — — — (36,352 ) Intercompany transactions — (11,883 ) (74,017 ) 85,900 — Net cash used in financing activities (36,352 ) (11,883 ) (74,017 ) 85,900 (36,352 ) CHANGE IN CASH AND CASH EQUIVALENTS (12,262 ) (2,460 ) (33,127 ) — (47,849 ) Cash and cash equivalents, beginning of year 70,683 (1,187 ) 93,746 — 163,242 Cash and cash equivalents, end of year $ 58,421 $ (3,647 ) $ 60,619 $ — $ 115,393 Condensed Consolidating Statement of Cash Flows For the year ended December 31, 2014 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by operating activities $ 92,338 $ 40,711 $ 139,896 $ (65,265 ) $ 207,680 Purchase of property, plant and equipment (587 ) (22,939 ) (31,603 ) 3 (55,126 ) Purchase of Sebree smelter (1,042 ) — — — (1,042 ) Purchase of remaining interest in Mt. Holly smelter (65,100 ) — — — (65,100 ) Proceeds from sale of property, plant and equipment — — 46 — 46 Restricted and other cash deposits — — 896 — 896 Net cash used in investing activities (66,729 ) (22,939 ) (30,661 ) 3 (120,326 ) Repayment of debt (2,603 ) — — — (2,603 ) Borrowings under revolving credit facilities 92,423 — — — 92,423 Repayments under revolving credit facilities (92,423 ) — (6,000 ) — (98,423 ) Issuance of common stock 403 — — — 403 Intercompany transactions — (17,801 ) (47,461 ) 65,262 — Net cash used in financing activities (2,200 ) (17,801 ) (53,461 ) 65,262 (8,200 ) CHANGE IN CASH AND CASH EQUIVALENTS 23,409 (29 ) 55,774 — 79,154 Cash and cash equivalents, beginning of year 47,274 (1,158 ) 37,972 — 84,088 Cash and cash equivalents, end of year $ 70,683 $ (1,187 ) $ 93,746 $ — $ 163,242 Condensed Consolidating Statement of Cash Flows For the year ended December 31, 2013 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ 30,462 $ (70,217 ) $ 82,776 $ (23,303 ) $ 19,718 Purchase of property, plant and equipment (1,229 ) (17,199 ) (49,649 ) — (68,077 ) Purchase of Sebree smelter (48,058 ) — — — (48,058 ) Investments and advances to joint ventures (125 ) — — — (125 ) Proceeds from sale of property, plant and equipment — 14 511 — 525 Restricted and other cash deposits — (787 ) (652 ) — (1,439 ) Net cash used in investing activities (49,412 ) (17,972 ) (49,790 ) — (117,174 ) Repayment of debt (249,604 ) — — — (249,604 ) Proceeds from issuance of debt 246,330 — — — 246,330 Borrowings under revolving credit facilities 16,725 — 6,000 — 22,725 Repayments under revolving credit facilities (16,725 ) — — — (16,725 ) Debt issuance costs (3,994 ) — — — (3,994 ) Debt retirement costs (1,208 ) — — — (1,208 ) Issuance of common stock 44 — — — 44 Intercompany transactions — 87,718 (111,021 ) 23,303 — Net cash provided by (used in) financing activities (8,432 ) 87,718 (105,021 ) 23,303 (2,432 ) CHANGE IN CASH AND CASH EQUIVALENTS (27,382 ) (471 ) (72,035 ) — (99,888 ) Cash and cash equivalents, beginning of year 74,656 (687 ) 110,007 — 183,976 Cash and cash equivalents, end of year $ 47,274 $ (1,158 ) $ 37,972 $ — $ 84,088

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS Balance at Beginning of Period Charged To Cost and Expense Charged to other accounts Deductions Balance at End of Period (Dollars in thousands) Year ended December 31, 2013 Allowance for doubtful trade accounts receivable $ 734 $ — $ — $ — $ 734 Deferred tax asset - valuation allowance $ 656,352 $ — $ 108,671 $ — $ 765,023 Year ended December 31, 2014 Allowance for doubtful trade accounts receivable $ 734 $ — $ 266 $ — $ 1,000 Deferred tax asset - valuation allowance $ 765,023 $ — $ (16,740 ) $ — $ 748,283 Year ended December 31, 2015 Allowance for doubtful trade accounts receivable $ 1,000 $ — $ — $ — $ 1,000 Deferred tax asset - valuation allowance $ 748,283 $ — $ 20,481 $ — $ 768,764

Summary of significant accoun28

Summary of significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation — The consolidated financial statements include the accounts of Century Aluminum Company and our subsidiaries, after elimination of all intercompany transactions and accounts. Our interest in the BHH joint venture is accounted for under the equity method. For BHH, we report our investment in its results of operations on a one-quarter lag. Prior to the acquisition of Mt. Holly, we accounted for our interest in Mt. Holly using the equity method of accounting.
Revenue recognition	Revenue recognition — In connection with our sales agreement with Glencore, we invoice Glencore prior to physical shipment of goods for substantially all production generated from each of our US domestic smelters. For those sales, revenue is recognized only when Glencore has specifically requested such treatment and has made a commitment to purchase the product. The goods must be complete, ready for shipment and separated from other inventory with title and risk of ownership passing to Glencore. We must retain no performance obligations. For all other shipments, including sales to Glencore from our smelter in Iceland, our tolling agreement with Glencore, revenue is recognized when title and risk of loss pass to the customer which is upon shipment.
Cash and Cash Equivalents	Cash and Cash Equivalents — Cash and cash equivalents are comprised of cash, money market funds and short-term investments having original maturities of three months or less. The carrying amount of cash equivalents approximates fair value.
Accounts Receivable and Due from Affiliates	Accounts Receivable and Due from Affiliates — These amounts are net of an allowance for uncollectible accounts and credit memos of $ 1,000 and $ 1,000 at December 31, 2015 and 2014 , respectively.
Inventories	Inventories — Our inventories are stated at the lower of cost or Net Realizable Value ("NRV"), using the first-in, first-out ("FIFO") method.
Property, Plant and Equipment	Property, Plant and Equipment — Property, plant and equipment is stated at cost. Additions, renewals and improvements are capitalized. Asset and accumulated depreciation accounts are relieved for dispositions with resulting gains or losses included in other income – net . Maintenance and repairs are expensed as incurred. We capitalize interest for the construction of qualifying assets. Depreciation of plant and equipment is provided for by the straight-line method over the following estimated useful lives: Building and improvements 10 to 45 years Machinery and equipment 5 to 35 years Technology and software 3 to 7 years
Impairment of long-lived assets	Impairment of long-lived assets — We evaluate our property, plant and equipment for potential impairment whenever events or circumstances indicate that the carrying amount of these assets may not be recoverable. If deemed unrecoverable, an impairment loss would be recognized for the amount by which the carrying amount exceeds the fair value of the assets. Impairment evaluation and fair value is based on estimates and assumptions that take into account our business plans and a long-term investment horizon.
Business Acquisitions	Business Acquisitions — We allocate the purchase price to the assets acquired and liabilities assumed based on their estimated fair values on the date of the acquisition. The difference between the fair value of the net assets acquired and the purchase price is recorded as either goodwill or a bargain purchase gain. We record the operating results of our acquired businesses in our consolidated statements of operations from the date of acquisition.
Income Taxes	Income Taxes — We account for income taxes using the asset and liability method, whereby deferred income taxes reflect the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. In evaluating our ability to realize deferred tax assets, we use judgment to determine if it is more likely than not that some portion or all of a deferred tax asset will not be realized, and if a corresponding valuation allowance is required. Accordingly, we have a valuation allowance against all of our net U.S. federal and state deferred tax assets, a portion of our Icelandic and all of our Hong Kong and Netherlands net operating loss ("NOL") deferred tax assets. Additionally, we have provided for deferred taxes on unremitted foreign earnings.
Defined Benefit Pension and Other Postretirement Benefits	Defined Benefit Pension and Other Postretirement Benefits — We sponsor defined benefit pension and other postretirement benefit ("OPEB") plans for certain of our domestic hourly and salaried employees and a SERB plan for certain current and former executive officers. We recognize expenses, assets and liabilities based on actuarial assumptions. We contribute to our defined benefit pension plans based upon actuarial and economic assumptions designed to achieve adequate funding of the projected benefit obligations and to meet the minimum funding requirements.
Postemployment Benefits	Postemployment Benefits — We provide certain postemployment benefits to certain former and inactive employees and their dependents during the period following employment, but before retirement. These benefits include salary continuance, supplemental unemployment and disability healthcare. We recognize the estimated future cost of providing postemployment benefits on an accrual basis over the active service life of the employee.
Foreign Currency	Foreign Currency – We are exposed to foreign currency risk due to fluctuations in the value of the U.S. dollar as compared to the euro, the Icelandic krona ("ISK") and the Chinese renminbi. Grundartangi and Vlissingen use the U.S. dollar as their functional currency, however a portion of the operating expenses of their respective facilities are denominated and payable in currencies other than the U.S. dollar. In addition, our joint venture, BHH, uses the Chinese renminbi as its functional currency. Grundartangi’s labor costs, part of its maintenance costs and other local services are denominated in ISK and a portion of its anode costs are denominated in euros. Labor costs, maintenance costs and other local services at Vlissingen are denominated in euros. Transactions denominated in currencies other than the functional currency are recorded based on exchange rates at the time such transactions arise and any transaction gains and losses are reflected in other income – net in the consolidated statements of operations. For our joint venture investments we record gains and losses associated with foreign currency exchange rates in equity in earnings of joint ventures .
Financial Instruments	Financial Instruments — Receivables, certain life insurance policies, payables, borrowings under revolving credit facilities and debt related to industrial revenue bonds ("IRBs") are carried at amounts that approximate fair value.
Earnings per share	Earnings per share — Basic earnings (loss) per share ("EPS") amounts are calculated by dividing earnings (loss) available to common stockholders by the weighted average number of common shares outstanding. Diluted EPS amounts assume the issuance of common stock for all potentially dilutive common shares outstanding. We calculate the amount of net income (loss) allocated to common stockholders and basic EPS using the Two-Class Method earnings allocation formula, allocating undistributed income to our Series A Convertible Preferred Stock shareholder consistent with their participation rights, and diluted EPS using the If-Converted Method when applicable. Our Series A Convertible Preferred Stock is a non-cumulative perpetual participating convertible preferred stock with no set dividend preferences. In periods where we report net losses, we do not allocate these losses to the convertible preferred stock for the computation of basic or diluted EPS.
Asset Retirement Obligations	Asset Retirement Obligations — We are subject to environmental regulations which create certain legal obligations related to the normal operations of our domestic primary aluminum smelter operations. Our asset retirement obligations ("AROs") consist primarily of costs associated with the disposal of spent pot liner used in the reduction cells of our domestic facilities. AROs are recorded on a discounted basis at the time the obligation is incurred (when the pot liner is put in service) and accreted over time for the change in the present value of the liability. We capitalize the asset retirement costs by increasing the carrying amount of the related long-lived assets and depreciating these assets over their remaining useful lives. Certain conditional asset retirement obligations ("CAROs") relate to the remediation of our primary aluminum facilities for hazardous material, such as landfill materials and asbestos which have not been recorded because they have an indeterminate settlement date. CAROs are a legal obligation to perform an asset retirement activity in which the timing and (or) method of settlement are conditional on a future event that may or may not be within our control.
Concentration of Credit Risk	Concentrations of Credit Risk — Financial instruments, which potentially expose us to concentrations of credit risk, consist principally of trade receivables. Our limited customer base increases our concentrations of credit risk with respect to trade receivables. We routinely assess the financial strength of our customers and collectability of our trade receivables.
Use of Estimates	Use of Estimates — The preparation of financial statements in conformity with generally accepted accounting principles in the United States ("GAAP") requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Share-Based Compensation	Share-Based Compensation — We measure the cost of employee services received in exchange for an award of equity instruments based on the fair value of the award on the grant date. We recognize the cost over the period during which an employee is required to provide service in exchange for the award. We issue shares to satisfy the requirements of our share-based compensation plans. At this time, we do not plan to issue treasury shares to support our share-based compensation plans, but we may in the future. We award performance units to certain officers and employees. The performance units may be settled in cash or common stock at the discretion of the Board. These awards have historically been settled in cash, although a portion of these awards were settled in common stock in 2015.
Recently Issued Accounting Standards	Recently Issued Accounting Standards On November 20, 2015, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes, requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as non-current on the balance sheet. The classification change for all deferred taxes as non-current simplifies entities’ processes as it eliminates the need to separately identify the net current and net non-current deferred tax asset or liability in each jurisdiction and allocate valuation allowances. We elected to prospectively adopt the accounting standard in the beginning of our fourth quarter of fiscal 2015. Prior periods in our Consolidated Financial Statements were not retrospectively adjusted. In May 2014, the 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" 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 for our fiscal year 2018 and thereafter. We are currently evaluating the impact of adoption on our consolidated financial position, results of operations and cash flows.
Fair value transfers	It is our policy to recognize transfers into and transfers out of Level 3 as of the actual date of the event or change in circumstances that caused the transfer.

Related party transactions (Tab

Related party transactions (Tables)	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Schedule of related party transactions	A summary of the aforementioned related party transactions for the years ended December 31, 2015 , 2014 and 2013 is as follows: Year Ended December 31, 2015 2014 2013 Net sales to Glencore $ 1,867,711 $ 1,262,101 $ 511,051 Purchases from Glencore 393,158 285,167 173,693 Purchases from BHH 46,592 47,804 86,678

Business acquisitions (Tables)

Business acquisitions (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Summary of consideration transferred	The following table summarizes all of the elements of consideration for the transaction. December 1, 2014 Purchase price $ 67,500 Contingent consideration 13,780 Economic, working capital and other closing adjustments (13,513 ) Total consideration $ 67,767
Schedule of purchase price allocation	Below is the final purchase price allocation for Mt. Holly. Preliminary estimate of the acquisition date fair value as of December 1, 2014 Measurement period adjustments Final acquisition date fair value as of December 1, 2014 Assets Acquired: Inventories $ 26,105 $ (2,126 ) $ 23,979 Due from Alumax 20,786 (9,517 ) 11,269 Prepaid and other current assets 2,527 — 2,527 Intangible asset 2,580 — 2,580 Pension asset 30,842 — 30,842 Property, plant and equipment – net 127,089 15,748 142,837 Total assets acquired $ 209,929 $ 4,105 $ 214,034 Liabilities Assumed: Accounts payable, trade $ 41,471 $ — $ 41,471 Accrued and other current liabilities 8,335 255 8,590 Accrued pension benefit costs — 34,595 34,595 Accrued postretirement benefit costs 2,857 — 2,857 Asset retirement obligations 8,213 — 8,213 Deferred taxes 4,804 (2,118 ) 2,686 Total liabilities assumed $ 65,680 $ 32,732 $ 98,412 Goodwill $ 4,804 $ (4,804 ) $ — The following table summarizes the fair value of the assets acquired and the liabilities assumed as of the acquisition date: Acquisition Date Fair Value Consideration: Cash $ 48,083 Deferred purchase price 1,910 Assets Acquired: Inventories $ 59,018 Prepaid and other current assets 2,273 Property, plant and equipment – net 55,520 Total assets acquired $ 116,811 Liabilities Assumed: Accrued and other current liabilities $ 43,316 Accrued pension benefit costs 996 Accrued postretirement benefit costs 6,544 Other liabilities 7,476 Deferred taxes 3,233 Total liabilities assumed $ 61,565 Gain on bargain purchase: $ 5,253
Acquisitions, pro forma information	From the acquisition date of June 1, 2013 through December 31, 2013, the revenue and earnings that were attributable to Sebree included in the consolidated statement of operations is as follows: Year ended December 31, 2013 Sebree revenue $ 247,178 Sebree income from continuing operations 8,705 From the acquisition date of December 1, 2014 through December 31, 2014, the revenue and earnings that were attributable to the acquired Alcoa’s 50.3% stake in Mt. Holly included in the Consolidated Statements of Operations is as follows: Year ended December 31, 2014 Mt. Holly revenue $ 25,911 Mt. Holly income from continuing operations (1) $ 3,024 (1) The income attributable to the acquired Alcoa’s 50.3% stake in Mt. Holly excludes the gain on the fair value of the contingent consideration and the gain on remeasurement of the equity investment. The following unaudited pro forma financial information for the year ended December 31, 2013 reflects our results of continuing operations as if the acquisition of Sebree had been completed on January 1, 2013. This unaudited pro forma financial information is provided for informational purposes only and is not necessarily indicative of what the actual results of operations would have been had the transactions taken place on January 1, 2013, nor is it indicative of the future consolidated results of operations or financial position of the combined companies. Year ended December 31, 2013 Pro forma revenues $ 1,662,707 Pro forma loss from continuing operations (83,035 ) Pro forma loss per common share, basic (0.94 ) Pro forma loss per common share, diluted (0.94 ) The following unaudited pro forma financial information for the years ended December 31, 2014 and December 31, 2013 reflects our results of continuing operations as if the acquisition of the remaining interest in Mt. Holly had been completed on January 1, 2013. This unaudited pro forma financial information is provided for informational purposes only and is not necessarily indicative of what the actual results of operations would have been had the transactions taken place on January 1, 2013, nor is it indicative of the future consolidated results of operations or financial position of the combined companies. Year ended December 31, 2014 2013 Pro forma revenues $ 2,176,552 $ 1,707,838 Pro forma earnings from continuing operations 125,847 (38,819 ) Pro forma earnings per common share, basic 1.30 (0.44 ) Pro forma earnings per common share, diluted 1.29 (0.44 )

Fair value measurements (Tables

Fair value measurements (Tables)	12 Months Ended
	Dec. 31, 2015
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. 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 E.ON contingent obligation 3 Quoted LME forward market, 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. 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 actual date of the event or change in circumstances that caused the transfer. Recurring Fair Value Measurements As of December 31, 2015 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 102,675 $ — $ — $ 102,675 Trust assets 5,226 — — 5,226 Surety bonds 1,870 — — 1,870 TOTAL $ 109,771 $ — $ — $ 109,771 LIABILITIES: E.ON contingent obligation – net (1) $ — $ — $ — $ — TOTAL $ — $ — $ — $ — Recurring Fair Value Measurements As of December 31, 2014 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 137,712 $ — $ — $ 137,712 Trust assets 8,067 — — 8,067 Surety bonds 1,987 — — 1,987 TOTAL $ 147,766 $ — $ — $ 147,766 LIABILITIES: E.ON contingent obligation – net (1) $ — $ — $ — $ — TOTAL $ — $ — $ — $ — (1) See Note 5 Debt for additional information about the E.ON contingent obligation.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Schedule of debt	December 31, 2015 2014 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 $2,722 and $3,112, respectively, interest payable semiannually 247,278 246,888 Total $ 255,093 $ 254,703 (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 December 31, 2015 was 0.21% .
Schedule of line of credit facilities	Status of our U.S. revolving credit facility: December 31, 2015 Credit facility maximum amount $ 150,000 Borrowing availability 81,292 Outstanding letters of credit issued 46,346 Outstanding borrowings — Borrowing availability, net of outstanding letters of credit and borrowings 34,946 Status of our Iceland revolving credit facility: December 31, 2015 Credit Facility maximum amount $ 50,000 Borrowing availability 49,294 Outstanding letters of credit issued — Outstanding borrowings — Borrowing availability, net of outstanding letters of credit and borrowings 49,294
Debt Instrument Redemption	Prior to June 1, 2016, we may redeem the 2021 Notes, in whole or in part, at a redemption price equal to 100% of the principal amount plus a make-whole premium, and if redeemed during the twelve-month period beginning on June 1 of the years indicated below, at the following redemption prices plus accrued and unpaid interest: Year Percentage 2016 105.625% 2017 103.750% 2018 101.875% 2019 and thereafter 100.000%
Offsetting of financial instruments and derivatives	The following table provides information about the balance sheet location and gross amounts offset: Offsetting of financial instruments and derivatives Balance sheet location December 31, 2015 December 31, 2014 E.ON contingent obligation – principal Other liabilities $ (12,902 ) $ (12,902 ) E.ON contingent obligation – accrued interest Other liabilities (6,702 ) (5,291 ) E.ON contingent obligation – derivative asset Other liabilities 19,604 18,193 $ — $ —

Shareholders' equity (Tables)

Shareholders' equity (Tables)	12 Months Ended
	Dec. 31, 2015
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 2015 , 2014 and 2013 : Common and Preferred Stock Activity: Preferred stock Common stock (in shares) Series A Convertible Treasury Outstanding Balance as of December 31, 2012 80,283 4,786,521 88,548,637 Conversion of convertible preferred stock (663 ) — 66,244 Issuance for share-based compensation plans — — 95,396 Balance as of December 31, 2013 79,620 4,786,521 88,710,277 Conversion of convertible preferred stock (1,479 ) — 147,952 Issuance for share-based compensation plans — — 206,353 Balance as of December 31, 2014 78,141 4,786,521 89,064,582 Repurchase of common stock — 2,400,000 (2,400,000 ) Conversion of convertible preferred stock (1,602 ) — 160,162 Issuance for share-based compensation plans — — 213,306 Balance as of December 31, 2015 76,539 7,186,521 87,038,050

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2015
Inventory, Net [Abstract]
Schedule of Inventories	Inventories, at December 31, consist of the following: 2015 2014 Raw materials $ 52,121 $ 76,655 Work-in-process 34,025 43,248 Finished goods 15,988 19,969 Operating and other supplies 129,738 143,608 Inventories $ 231,872 $ 283,480

Property, plant and equipment (

Property, plant and equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Summary of property, plant and equipment	Property, plant and equipment, at December 31, consist of the following: 2015 2014 Land and improvements $ 42,654 $ 43,385 Buildings and improvements 325,580 345,271 Machinery and equipment 1,349,731 1,476,518 Construction in progress 173,418 182,393 1,891,383 2,047,567 Less accumulated depreciation (659,127 ) (742,024 ) Property, plant and equipment - net $ 1,232,256 $ 1,305,543

Supplemental financial statem36

Supplemental financial statement information (Tables)	12 Months Ended
	Dec. 31, 2015
Additional financial information disclosures [Abstract]
Components of Accumulated Other Comprehensive Loss	Components of Accumulated Other Comprehensive Loss: 2015 2014 Defined benefit plan liabilities $ (121,910 ) $ (128,664 ) Unrealized loss on financial instruments (1,435 ) (1,249 ) Other comprehensive loss before income tax effect (123,345 ) (129,913 ) Income tax effect (1) 10,695 12,231 Accumulated other comprehensive loss $ (112,650 ) $ (117,682 ) (1) The allocation of the income tax effect to the components of other comprehensive income is as follows: 2015 2014 Defined benefit plan liabilities $ 11,243 $ 12,812 Unrealized loss on financial instruments (548 ) (581 ) The following table summarizes the changes in the accumulated balances for each component of accumulated other comprehensive loss ("AOCI"): Defined benefit plan and other postretirement liabilities Equity in investee other comprehensive income Unrealized loss on financial instruments Total, net of tax Balance, December 31, 2012 $ (137,441 ) $ (12,224 ) $ (1,527 ) $ (151,192 ) Other comprehensive income (loss) before reclassifications 56,795 (8 ) — 56,787 Net amount reclassified to net income 2,725 — (152 ) 2,573 Balance, December 31, 2013 (77,921 ) (12,232 ) (1,679 ) (91,832 ) Other comprehensive income (loss) before reclassifications (42,926 ) (419 ) — (43,345 ) Net amount reclassified to net income 4,995 — (151 ) 4,844 Elimination of equity in investee resulting from acquisition — 12,651 — 12,651 Balance, December 31, 2014 (115,852 ) — (1,830 ) (117,682 ) Other comprehensive income before reclassifications 7,311 — — 7,311 Net amount reclassified to net income (2,126 ) — (153 ) (2,279 ) Balance, December 31, 2015 $ (110,667 ) $ — $ (1,983 ) $ (112,650 )
Reclassification out of AOCI	Reclassifications out of AOCI were included in the consolidated statements of operations as follows: Gains (Losses) Reclassified from AOCI to the Consolidated Statements of Operations AOCI Components Location 2015 2014 2013 Defined benefit plan and other postretirement liabilities Cost of goods sold $ (1,696 ) $ 6,237 $ 3,264 Selling, general and administrative expenses 235 569 990 Other operating expense, net 904 — — Income tax expense (1,569 ) (1,811 ) (1,529 ) Net of tax $ (2,126 ) $ 4,995 $ 2,725 Equity in investee other comprehensive income Cost of goods sold $ — $ — $ — Income tax expense — (419 ) (70 ) Net of tax $ — $ (419 ) $ (70 ) Unrealized loss on financial instruments Cost of goods sold $ (186 ) $ (185 ) $ (186 ) Income tax expense 33 34 34 Net of tax $ (153 ) $ (151 ) $ (152 )

Pension and other postretirem37

Pension and other postretirement benefits (Tables)	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Schedule of Changes in Projected Benefit Obligations	The change in benefit obligations and change in plan assets as of December 31 are as follows: Pension OPEB 2015 2014 2015 2014 Change in benefit obligation: Benefit obligation at beginning of year $ 336,292 $ 238,319 $ 158,781 $ 134,652 Service cost 6,346 5,605 1,970 1,591 Interest cost 13,388 11,629 5,985 6,420 Plan amendments — (5,308 ) (1,758 ) — Medicare Part D — — — 273 Actuarial loss (gain) (11,429 ) 32,772 (18,150 ) 17,669 Acquisition — 84,743 — 2,857 Benefits paid (19,247 ) (11,895 ) (5,878 ) (4,681 ) Curtailment 1,221 — (8,400 ) — Settlements — (19,573 ) — — Benefit obligation at end of year $ 326,571 $ 336,292 $ 132,550 $ 158,781
Schedule of Changes in Fair Value of Plan Assets	Pension OPEB 2015 2014 2015 2014 Change in plan assets: Fair value of plan assets at beginning of year $ 305,520 $ 199,304 $ — $ — Actual return on plan assets (11,321 ) 16,118 — — Acquisition — 115,982 — — Employer contributions 5,910 5,584 5,878 4,681 Benefits paid (19,247 ) (11,895 ) (5,878 ) (4,681 ) Settlements — (19,573 ) — — Fair value of assets at end of year $ 280,862 $ 305,520 $ — $ —
Schedule of Amounts Recognized in Balance Sheet	Pension OPEB 2015 2014 2015 2014 Funded status of plans: Funded status $ (45,709 ) $ (30,772 ) $ (132,550 ) $ (158,781 ) Amounts recognized in the Consolidated Balance Sheets: Non-current assets $ — $ 30,842 $ — $ — Current liabilities (1,743 ) (1,744 ) (6,551 ) (6,118 ) Non-current liabilities (43,966 ) (59,870 ) (125,999 ) (152,663 ) Net amount recognized $ (45,709 ) $ (30,772 ) $ (132,550 ) $ (158,781 ) Amounts recognized in accumulated other comprehensive loss (pre-tax): Net loss $ 80,514 $ 63,360 $ 49,562 $ 79,720 Prior service cost (benefit) 1,211 1,335 (9,377 ) (15,751 ) Total $ 81,725 $ 64,695 $ 40,185 $ 63,969
Schedule of Net Benefit Cost	Net Periodic Benefit Cost: Year Ended December 31, Pension OPEB 2015 2014 2013 2015 2014 2013 Service cost $ 6,346 $ 5,605 $ 4,735 $ 1,970 $ 1,591 $ 2,527 Interest cost 13,388 11,629 8,908 5,985 6,420 5,681 Expected return on plan assets (21,241 ) (14,694 ) (10,592 ) — — — Amortization of prior service costs 110 77 113 (3,728 ) (3,844 ) (3,995 ) Amortization of net loss 3,980 1,907 3,152 3,814 3,704 5,022 Settlements — 4,701 — — — — Curtailment cost (benefit) 1,235 263 (18 ) (4,266 ) — (20 ) Net periodic benefit cost $ 3,818 $ 9,488 $ 6,298 $ 3,775 $ 7,871 $ 9,215
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	Other changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Loss (pre-tax): Year Ended December 31, Pension OPEB 2015 2014 2015 2014 Net loss (gain) $ 21,133 $ 24,326 $ (26,686 ) $ 17,669 Prior service cost (benefit) — 1,299 (1,758 ) — Amortization of net loss, including recognition due to settlement (3,980 ) (6,608 ) (3,814 ) (3,704 ) Amortization of prior service benefit (cost), including recognition due to curtailment (124 ) (340 ) 8,475 3,844 Total amount recognized in other comprehensive loss 17,029 18,677 (23,783 ) 17,809 Net periodic benefit cost 3,818 9,488 3,775 7,871 Total recognized in net periodic benefit cost and other comprehensive loss $ 20,847 $ 28,165 $ (20,008 ) $ 25,680
Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year	Amounts in accumulated other comprehensive loss expected to be recognized as components of net periodic benefit cost during 2016: Pension OPEB Amortization of net loss $ 4,161 $ 3,518 Amortization of prior service cost (benefit) 106 (2,781 )
Weighted Average Assumptions Used in Calculating Benefit Obligation and Net Periodic Benefit Cost	Weighted average assumptions used to determine benefit obligations at December 31: Pension OPEB 2015 2014 2015 2014 Discount rate (1) 4.44% 4.05% 4.50% 4.00% Rate of compensation increase (2) 3%/4% 3%/4% 3%/4% 3%/4% Measurement date 12/31/2015 12/31/2014 12/31/2015 12/31/2014 Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31: Pension OPEB 2015 2014 2013 2015 2014 2013 Measurement date 12/31/2014 12/31/2013 12/31/2012 12/31/2014 12/31/2013 12/31/2012 Fiscal year end 12/31/2015 12/31/2014 12/31/2013 12/31/2015 12/31/2014 12/31/2013 Discount rate (1) 4.05% 4.89% 4.00% 4.00% 4.99% 4.01% Rate of compensation increase (2) 3%/4% 3%/4% 3%/4% 3%/4% 3%/4% 3%/4% Expected return on plan assets (3) 7.16% 7.25% 7.25% — — — (1) We use the Ryan Discount Rate Curve ("Ryan Curve") to determine the discount rate. (2) For 2015, the rate of compensation increase is 3% per year for the first three years and 4% per year for year four and thereafter. For 2014, the rate of compensation increase is 3% per year for the first four years and 4% per year for year five and thereafter. For 2013, the rate of compensation increase is 3% per year for the first five years and 4% per year for year six and thereafter. (3) The rate for each of our defined benefit plans was selected by taking into account our expected asset mix and is based on historical performance as well as expected future rates of return on plan assets.
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	A one-percentage-point change in the assumed health care cost trend rate would have had the following effects in 2015 : 1% Increase 1% Decrease Effect on total of service and interest cost $ 1,403 $ (1,108 ) Effect on accumulated postretirement benefit obligation 18,170 (15,086 )
Schedule of Allocation of Plan Assets	The Pension Plans’ weighted average long-term strategic asset allocation policy targets are as follows: Pension Plan Asset Allocation 2015 Target December 31, 2015 December 31, 2014 Equities: U.S. equities 31% 30% 42% International equities 21% 20% 18% Fixed income 48% 50% 40% 100% 100% Fair Value of Pension Plans’ assets included under the fair value hierarchy: As of December 31, 2015 Level 1 Level 2 Level 3 Total Equities: U.S. equities $ 86,723 $ — $ — $ 86,723 International equities 54,769 — — 54,769 Fixed income 139,370 — — 139,370 Total $ 280,862 $ — $ — $ 280,862 As of December 31, 2014 Equities: U.S. equities $ 79,148 $ — $ — $ 79,148 International equities 33,720 — — 33,720 Fixed income 76,204 — — 76,204 Plan Receivable (1) — — 116,448 116,448 Total $ 189,072 $ — $ 116,448 $ 305,520 (1) Represents the receivable to the Century Aluminum of South Carolina defined benefit plan related to pension funding obligations under the Stock Purchase Agreement which was received in 2015. The plan receivable was considered a Level 3 asset because determining the fair value requires significant unobservable inputs, including census data and various actuarial assumptions.
Schedule Of Expected Benefit Plan Contributions	We expect to make the following contributions for 2016 : 2016 Expected pension plan contributions $ 1,769 Expected OPEB benefits payments 6,551
Schedule of Expected Benefit Payments	The following table provides the estimated future benefit payments for the pension and other postretirement benefit plans: Pension Benefits OPEB Benefits 2016 $ 26,438 $ 6,551 2017 19,755 6,789 2018 20,228 7,099 2019 21,229 7,388 2020 21,655 7,508 2021 – 2025 105,301 39,031
Schedule of Multiemployer Plans	Century’s participation in the plan for the year ended December 31, 2015 , is outlined in the table below. Fund Steelworkers Pension Trust EIN / PN 23-6648508/499 Pension Protection Act Zone Status 2015 (1) Green Pension Protection Act Zone Status 2014 (1) Green Subject to Financial Improvement/Rehabilitation Plan No Contributions of Century Aluminum 2015 $1,618 Contributions of Century Aluminum 2014 $2,164 Contributions of Century Aluminum 2013 $2,171 Withdrawal from Plan Probable No Surcharge Imposed No Expiration Date of Collective Bargaining Agreement April 1, 2020 (1) The most recent Pension Protection Act zone status available in 2015 and 2014 is for the plan's year-end December 31, 2014 and December 31, 2013 , respectively. The zone status is based on information that Century received from the plan as well as publicly available information per the Department of Labor and is certified by the plan’s actuary. Among other factors, plans in the green zone are at least 80 percent funded.

Share-based compensation (Table

Share-based compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of options, fully vested and exercisable	A summary of activity under our Stock Incentive Plan during the year ended December 31, 2015 is presented below: Options Number Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2015 544,171 $ 26.85 Exercised — — Forfeited/expired (100,434 ) 25.95 Outstanding, fully vested and exercisable at December 31, 2015 (1) 443,737 $ 27.06 2.19 $ — (1) As the result of actions in 2011 that were determined to be a "change of control" under the Stock Incentive Plan, all options will remain exercisable for their respective remaining term, regardless of whether the awardees remain employees of Century.
Summary of service-based share awards activity	Service-based share awards Outstanding at January 1, 2015 464,485 Granted 478,798 Vested (354,688 ) Forfeited (47,291 ) Outstanding at December 31, 2015 541,304 Year ended December 31, 2015 2014 2013 Weighted average per share fair value of service-based share grants $ 4.21 $ 15.31 $ 8.19 Total intrinsic value of option exercises — 1,011 13
Share-based compensation expense	The following table summarizes the compensation cost recognized for the years ended December 31, 2015 , 2014 and 2013 for all options, service-based share and performance-based share awards. This expense is included as part of selling, general and administrative expenses in our Consolidated Statements of Operations. Year ended December 31, 2015 2014 2013 Share-based compensation expense reported: Performance-based share expense $ 1,587 $ 1,090 $ 475 Service-based share expense 257 244 603 Stock option expense — — — Total share-based compensation expense before income tax 1,844 1,334 1,078 Income tax — — — Total share-based compensation expense, net of income tax $ 1,844 $ 1,334 $ 1,078

Earnings (loss) per share (Tabl

Earnings (loss) per share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Basic and diluted earnings (loss) per share	The following table shows the basic and diluted earnings (loss) per share for 2015 , 2014 , and 2013 : For the year ended December 31, 2015 Net loss Shares (000) Per-Share Net loss $ (59,310 ) Amount allocated to common stockholders 100.00 % Basic and Diluted EPS: Net loss allocated to common stockholders (59,310 ) 87,375 $ (0.68 ) For the year ended December 31, 2014 Net income Shares (000) Per-Share Net income $ 126,474 Amount allocated to common stockholders 91.81 % Basic EPS: Net income allocated to common stockholders 116,118 88,823 $ 1.31 Effect of Dilutive Securities: Share-based compensation plans 605 Diluted EPS: $ 116,118 89,428 $ 1.30 For the year ended December 31, 2013 Net loss Shares (000) Per-Share Net loss $ (40,313 ) Amount allocated to common stockholders 100.00 % Basic and Diluted EPS: Net loss allocated to common stockholders $ (40,313 ) 88,612 $ (0.45 )
Antidilutive securities excluded from calculation of diluted EPS	Securities excluded from the calculation of diluted EPS: 2015 2014 2013 Stock options (1) 356,634 320,553 619,833 Service-based share awards (1) 608,914 — 442,737 (1) In periods when we report a net loss, all share awards are excluded from the calculation of diluted weighted average shares outstanding because of their antidilutive effect on earnings (loss) per share.

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Components of pre-tax book income (loss)	The components of pre-tax book income (loss) consist of the following: Year Ended December 31, 2015 2014 2013 U.S. $ (62,203 ) $ 91,026 $ (47,080 ) Foreign 21,081 52,451 7,236 Total $ (41,122 ) $ 143,477 $ (39,844 )
Significant components of the income before income tax expense	Significant components of the income tax expense consist of the following: Year Ended December 31, 2015 2014 2013 Current: U.S. federal current expense (benefit) $ — $ (112 ) $ 532 State current expense (benefit) (706 ) 2,252 (445 ) Foreign current expense 13,473 15,098 6,198 Total current expense 12,767 17,238 6,285 Deferred: U.S. federal deferred benefit (1,564 ) (1,696 ) (3,905 ) State deferred benefit — (12 ) (207 ) Foreign deferred tax expense (1,927 ) 2,778 958 Total deferred benefit (3,491 ) 1,070 (3,154 ) Total income tax expense $ 9,276 $ 18,308 $ 3,131
Reconciliation of the statutory U.S. Federal income tax rate to the effective income tax rate on income (loss)	A reconciliation of the statutory U.S. Federal income tax rate to the effective income tax rate on income (loss) is as follows: 2015 2014 2013 Federal Statutory Rate 35.0 % 35.0 % 35.0 % Permanent differences 1.9 4.3 54.5 State taxes, net of Federal benefit (16.0 ) (6.2 ) 97.2 Foreign earnings taxed at different rates than U.S. 3.0 (1.3 ) 17.4 Valuation allowance (56.6 ) (26.0 ) (265.9 ) Changes in uncertain tax reserves (4.2 ) 0.6 40.5 Other 14.3 6.4 13.4 Effective tax rate (22.6 )% 12.8 % (7.9 )%
Significant components of deferred tax assets and liabilities	Significant components of our deferred tax assets and liabilities as of December 31 are as follows: 2015 2014 Deferred tax assets: Accrued postretirement benefit cost $ 14,825 $ 15,683 Accrued liabilities 1,080 4,494 Share-based compensation 6,421 7,350 Derivative and hedging contracts — 58,687 Goodwill 7,949 10,521 Pension and post-retirement obligations in other comprehensive income 78,753 81,567 Net operating losses and tax credits 700,819 646,158 Foreign basis differences 2,083 668 Other 10,676 8,748 Total deferred tax assets 822,606 833,876 Valuation allowance (768,764 ) (748,283 ) Net deferred tax assets $ 53,842 $ 85,593 Deferred tax liabilities: Tax over financial statement depreciation $ (116,327 ) $ (142,627 ) Pension (15,608 ) (14,222 ) Unremitted foreign earnings (18,901 ) (30,308 ) Total deferred tax liabilities (150,836 ) (187,157 ) Net deferred tax liability $ (96,994 ) $ (101,564 )
Changes in valuation allowance	The changes in the valuation allowance are as follows: 2015 2014 Beginning balance, valuation allowance $ 748,283 $ 765,023 Change in valuation allowance 20,481 (16,740 ) Ending balance, valuation allowance $ 768,764 $ 748,283
Significant components of Net Operating Loss Carryforwards	The significant components of our NOL carryforwards are as follows: 2015 2014 Federal (1) $ 1,470,251 $ 1,306,482 State (2) 2,094,687 2,078,105 Foreign (3) 466,743 446,234 (1) The federal NOL begins to expire in 2028 . (2) The state NOLs begin to expire in 2027 . (3) The Icelandic NOL begins to expire in 2017 ; Dutch NOL begins to expire in 2022 .
Reconciliation of beginning and ending amounts of gross unrecognized tax benefits	A reconciliation of the beginning and ending amounts of gross unrecognized tax benefits (excluding interest) is as follows: 2015 2014 2013 Balance as of January 1, $ 2,000 $ 1,200 $ 17,600 Additions based on tax positions related to the current year 1,800 1,100 700 Decreases due to lapse of applicable statute of limitations — (300 ) (2,800 ) Settlements — — (14,300 ) Balance as of December 31, $ 3,800 $ 2,000 $ 1,200
Significant components of unrecognized tax positions	The components of our unrecognized tax positions are as follows: 2015 2014 2013 Highly certain tax positions $ 3,700 $ 1,900 $ 1,100 Other unrecognized tax benefits 100 100 100 Gross unrecognized tax benefits $ 3,800 $ 2,000 $ 1,200 Accrued interest and penalties related to unrecognized tax benefits $ — $ — $ 100

Asset retirement obligations 41

Asset retirement obligations ('ARO') (Tables)	12 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Schedule of changes in asset retirement obligations	The reconciliation of the changes in the asset retirement obligations is presented below: Year ended December 31, 2015 2014 Beginning balance, ARO liability $ 36,950 $ 27,113 Additional ARO liability incurred 3,797 2,548 ARO liabilities settled (5,514 ) (4,731 ) Accretion expense 1,818 1,517 Adjustments (1,886 ) — ARO liability from Mt. Holly acquisition — 10,503 Ending balance, ARO liability $ 35,165 $ 36,950

Supplemental cash flow inform42

Supplemental cash flow information (Tables)	12 Months Ended
	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Summary of supplemental cash flow information	Year Ended December 31, 2015 2014 2013 Cash paid for: Interest $ 18,781 $ 19,066 $ 20,539 Income/withholding taxes (1) 24,125 12,189 28,654 Non-cash investing activities: Accrued capital costs $ 777 $ 744 $ 9,409 (1) We paid withholding taxes in Iceland on intercompany dividends of $8,388 , $5,491 and $18,067 during the years ended December 31, 2015 , 2014 and 2013, respectively. Such withholding taxes are then refunded to us in the following year.

Quarterly information (Unaudi43

Quarterly information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Data [Abstract]
Schedule of Quarterly Financial Information	Financial results by quarter for the years ended December 31, 2015 and 2014 are as follows: Net sales Gross profit (loss) Net income (loss) Net income (loss) allocated to common stockholders Basic earnings (loss) per share Diluted earnings (loss) per share 2015 4th Quarter (1) $ 383,915 $ (18,701 ) $ (43,080 ) $ (43,080 ) $ (0.50 ) $ (0.50 ) 3rd Quarter (2) 454,540 (42,423 ) (56,112 ) (56,112 ) (0.65 ) (0.65 ) 2nd Quarter (3) 523,491 8,342 (33,897 ) (33,897 ) (0.39 ) (0.39 ) 1st Quarter (4) 587,911 94,095 73,779 67,813 0.76 0.76 2014 4th Quarter (5) 551,239 89,339 75,829 69,669 0.78 0.78 3rd Quarter (6) 500,632 75,714 50,405 46,277 0.52 0.52 2nd Quarter (7) 458,324 38,504 20,344 18,675 0.21 0.21 1st Quarter (8) 420,847 (1,758 ) (20,104 ) (20,104 ) (0.23 ) (0.23 ) (1) The fourth quarter of 2015 was favorably impacted by a $23,474 lower of cost or market inventory adjustment, $3,400 related to non-cash, non-recurring post-retirement benefits. Results were negatively impacted by a $3,500 charge related to the partial curtailment of operations at Hawesville and Mt. Holly, a $5,000 charge for depreciation related to Mt. Holly purchase accounting and an $11,584 impairment charge at BHH. (2) The third quarter of 2015 was impacted by a $5,324 unfavorable lower of cost or market adjustment to cost of goods sold, $1,400 for labor disruption and $2,900 for partial curtailment expenses at Hawesville. (3) The second quarter of 2015 was impacted by a $25,689 unfavorable LCM adjustment to cost of goods sold and a $30,850 impairment reserve related to the permanent closure of our Ravenswood facility and $11,700 of labor disruption expenses associated with a new union contract at our Hawesville location in partially offset by a $10,287 gain on fair value of contingent consideration on our Mt. Holly acquisition. (4) The first quarter of 2015 included a $6,527 gain on fair value of contingent consideration partially offset by $1,570 of signing bonuses related to a new labor contract at Grundartangi and a $1,000 severance charge for a former executive. (5) The fourth quarter of 2014 net income included a benefit of $7,943 for the gain on remeasurement of contingent consideration and a benefit of $15,955 for gain on remeasurement of our equity investment in Mt. Holly. Results were negatively impacted by $4,964 in non-cash, non-recurring pension charges and by $2,616 related to the separation of former senior executives. (6) The third quarter of 2014 net income reflects higher aluminum prices and lower power prices in the Midwestern U.S. (7) The second quarter of 2014 net income reflects higher aluminum prices and lower power prices in the Midwestern U.S. Results were negatively impacted by a charge of $500 for the finalization of a legal settlement. (8) The first quarter of 2014 cost of sales included a benefit of $5,534 related to deferred power contract liability amortization. Results were negatively impacted by a $3,100 charge for increased legal reserves.

Business segments (Tables)

Business segments (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Reconciliation of assets from segment to consolidated	A reconciliation of our consolidated assets to the total of primary aluminum segment assets is provided below. Segment assets (1) 2015 2014 2013 Primary $ 1,706,032 $ 1,987,727 $ 1,770,749 Corporate, unallocated 46,436 37,331 39,447 Total assets $ 1,752,468 $ 2,025,058 $ 1,810,196 (1) Segment assets include accounts receivable, due from affiliates, prepaid and other current assets, inventory, intangible assets and property, plant and equipment — net; the remaining assets are unallocated corporate assets.
Schedule of revenue from external customers and long-lived assets, by geographical areas	Included in the consolidated financial statements are the following amounts related to geographic locations: 2015 2014 2013 Net sales: United States $ 1,373,714 $ 1,370,570 $ 1,022,081 Iceland 576,143 560,472 432,232 Long-lived assets: (1) United States $ 408,722 $ 497,057 $ 392,424 Iceland 801,268 831,507 853,636 Other 94,421 95,752 93,075 (1) Includes long-lived assets other than financial instruments.
Schedule of revenue by major customers by reporting segments	The following table shows our major customers whose sales revenue exceeded 10% of our net sales. A loss of any of these customers could have a material adverse effect on our results of operations. The net sales revenue for these customers is as follows: Year Ended December 31, 2015 2014 2013 Glencore $ 1,867,711 $ 1,262,101 $ 511,051 Southwire — 226,740 312,102 RTA — — 223,353 BHP Billiton — — 191,445

Condensed consolidating finan45

Condensed consolidating financial information (Tables)	12 Months Ended
	Dec. 31, 2015
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 year ended December 31, 2015 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 1,277,474 $ 632,597 $ (42,360 ) $ 1,867,711 Third-party customers — 82,327 43 (224 ) 82,146 — 1,359,801 632,640 (42,584 ) 1,949,857 Cost of goods sold — 1,388,400 564,380 (44,236 ) 1,908,544 Gross profit (loss) — (28,599 ) 68,260 1,652 41,313 Selling, general and administrative expenses 28,000 8,798 5,317 — 42,115 Ravenswood impairment — — 30,850 — 30,850 Other operating expense - net — — 7,436 — 7,436 Operating income (loss) (28,000 ) (37,397 ) 24,657 1,652 (39,088 ) Interest expense - third parties (20,201 ) (1,567 ) (186 ) — (21,954 ) Interest income (expense) - affiliates 37,626 — (37,626 ) — — Interest income - third parties 65 4 270 — 339 Net gain on forward and derivative contracts — 1,411 189 — 1,600 Unrealized gain on fair value of contingent consideration — 18,337 — — 18,337 Other income (expense) - net 1,356 (658 ) 2,356 (3,410 ) (356 ) Loss before income taxes and equity in earnings (loss) of joint ventures (9,154 ) (19,870 ) (10,340 ) (1,758 ) (41,122 ) Income tax benefit (expense) 2,140 — (11,416 ) — (9,276 ) Loss before equity in earnings (loss) of joint ventures (7,014 ) (19,870 ) (21,756 ) (1,758 ) (50,398 ) BHH impairment — — (11,584 ) — (11,584 ) Equity in earnings (loss) of joint ventures (52,296 ) — 2,672 52,296 2,672 Net loss $ (59,310 ) $ (19,870 ) $ (30,668 ) $ 50,538 $ (59,310 ) Other comprehensive income (loss) before income tax effect 6,568 14,754 (1,114 ) (13,640 ) 6,568 Income tax effect (1,536 ) — 33 (33 ) (1,536 ) Other comprehensive income (loss) 5,032 14,754 (1,081 ) (13,673 ) 5,032 Total comprehensive loss $ (54,278 ) $ (5,116 ) $ (31,749 ) $ 36,865 $ (54,278 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the year ended December 31, 2014 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 715,796 $ 625,076 $ (78,771 ) $ 1,262,101 Third-party customers — 669,466 31 (556 ) 668,941 — 1,385,262 625,107 (79,327 ) 1,931,042 Cost of goods sold — 1,282,194 522,543 (75,494 ) 1,729,243 Gross profit — 103,068 102,564 (3,833 ) 201,799 Selling, general and administrative expenses 32,840 11,353 5,002 — 49,195 Other operating expense - net — — 12,481 — 12,481 Operating income (loss) (32,840 ) 91,715 85,081 (3,833 ) 140,123 Interest expense - third parties (20,228 ) (1,555 ) (232 ) — (22,015 ) Interest income (expense) - affiliates 43,688 — (43,688 ) — — Interest income - third parties 15 — 286 — 301 Net gain (loss) on forward and derivative contracts (1,080 ) 1,259 — — 179 Unrealized gain on fair value of contingent consideration — 7,943 — — 7,943 Gain on remeasurement of equity investment — 15,955 — — 15,955 Other income (expense) - net 518 (459 ) 4,564 (3,632 ) 991 Income (loss) before income taxes and equity in earnings of joint ventures (9,927 ) 114,858 46,011 (7,465 ) 143,477 Income tax expense (4,777 ) (493 ) (13,211 ) 173 (18,308 ) Income (loss) before equity in earnings of joint ventures (14,704 ) 114,365 32,800 (7,292 ) 125,169 Equity in earnings of joint ventures 141,178 — 1,305 (141,178 ) 1,305 Net income $ 126,474 $ 114,365 $ 34,105 $ (148,470 ) $ 126,474 Other comprehensive loss before income tax effect (24,022 ) (28,955 ) (2,662 ) 18,967 (36,672 ) Income tax effect (1,829 ) — 33 (33 ) (1,829 ) Other comprehensive loss (25,851 ) (28,955 ) (2,629 ) 18,934 (38,501 ) Total comprehensive income $ 100,623 $ 85,410 $ 31,476 $ (129,536 ) $ 87,973 Condensed Consolidating Statements of Comprehensive Income (Loss) For the year ended December 31, 2013 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 270,314 $ 244,680 $ (3,943 ) $ 511,051 Third-party customers — 752,808 191,495 (1,041 ) 943,262 — 1,023,122 436,175 (4,984 ) 1,454,313 Cost of goods sold — 1,061,597 358,124 (4,931 ) 1,414,790 Gross profit (loss) — (38,475 ) 78,051 (53 ) 39,523 Selling, general and administrative expenses 40,831 10,456 16,190 — 67,477 Other operating expense - net — — 8,602 — 8,602 Operating income (loss) (40,831 ) (48,931 ) 53,259 (53 ) (36,556 ) Interest expense - third parties (21,543 ) (1,510 ) (38 ) — (23,091 ) Interest income (expense) - affiliates 48,126 — (48,126 ) — — Interest income - third parties 27 6 695 — 728 Net gain on forward and derivative contracts 140 16,458 — — 16,598 Gain on bargain purchase — 5,253 — — 5,253 Loss on early extinguishment of debt (3,272 ) — — — (3,272 ) Other income (expense) - net 138,548 (113 ) 94 (138,033 ) 496 Income (loss) before income taxes and equity in earnings (loss) of joint ventures 121,195 (28,837 ) 5,884 (138,086 ) (39,844 ) Income tax benefit (expense) (3,386 ) — 255 — (3,131 ) Income (loss) before equity in earnings (loss) of joint ventures 117,809 (28,837 ) 6,139 (138,086 ) (42,975 ) Equity in earnings (loss) of joint ventures (158,122 ) — 2,662 158,122 2,662 Net income (loss) $ (40,313 ) $ (28,837 ) $ 8,801 $ 20,036 $ (40,313 ) Other comprehensive income before income tax effect 60,924 31,258 22,634 (53,892 ) 60,924 Income tax effect (1,564 ) — 33 (33 ) (1,564 ) Other comprehensive income 59,360 31,258 22,667 (53,925 ) 59,360 Total comprehensive income $ 19,047 $ 2,421 $ 31,468 $ (33,889 ) $ 19,047
Condensed Consolidating Balance Sheet	Condensed Consolidating Balance Sheet As of December 31, 2015 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 58,421 $ (3,647 ) $ 60,619 $ — $ 115,393 Restricted cash — 791 — — 791 Accounts receivable - net 104 8,891 480 — 9,475 Due from affiliates 13 14,493 2,911 — 17,417 Inventories 180 148,280 85,937 (2,525 ) 231,872 Prepaid and other current assets 7,713 16,242 18,457 — 42,412 Assets held for sale — — 30,697 — 30,697 Total current assets 66,431 185,050 199,101 (2,525 ) 448,057 Property, plant and equipment - net 9,188 361,626 861,442 — 1,232,256 Investment in subsidiaries 593,604 — — (593,604 ) — Due from affiliates - less current portion 632,170 — — (632,170 ) — Other assets 29,536 19,153 16,047 7,419 72,155 TOTAL $ 1,330,929 $ 565,829 $ 1,076,590 $ (1,220,880 ) $ 1,752,468 Accounts payable, trade $ 2,380 $ 53,145 $ 34,964 $ — $ 90,489 Due to affiliates 2,143 7,167 735 — 10,045 Accrued and other current liabilities 11,247 14,759 22,816 — 48,822 Accrued employee benefits costs 1,824 7,644 680 — 10,148 Industrial revenue bonds — 7,815 — — 7,815 Total current liabilities 17,594 90,530 59,195 — 167,319 Senior notes payable 247,278 — — — 247,278 Accrued pension benefits costs cost - less current portion 39,831 (11,021 ) 15,189 — 43,999 Accrued postretirement benefits costs - less current portion 4,524 119,911 1,564 — 125,999 Other liabilities 3,307 30,505 11,779 7,418 53,009 Intercompany loan — 124,518 509,652 (634,170 ) — Deferred taxes — — 96,994 — 96,994 Total noncurrent liabilities 294,940 263,913 635,178 (626,752 ) 567,279 Series A Preferred stock 1 — — — 1 Common stock 942 — 224,424 (224,424 ) 942 Additional paid-in capital 2,513,631 191,023 2,038,138 (2,229,161 ) 2,513,631 Treasury stock, at cost (86,276 ) — — — (86,276 ) Accumulated other comprehensive loss (13,125 ) (60,026 ) (39,499 ) — (112,650 ) Accumulated deficit (1,396,778 ) 80,389 (1,840,846 ) 1,859,457 (1,297,778 ) Total shareholder's equity 1,018,395 211,386 382,217 (594,128 ) 1,017,870 TOTAL $ 1,330,929 $ 565,829 $ 1,076,590 $ (1,220,880 ) $ 1,752,468 Condensed Consolidating Balance Sheet As of December 31, 2014 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 70,683 $ (1,187 ) $ 93,746 $ — $ 163,242 Restricted cash — 787 14 — 801 Accounts receivable - net — 77,173 494 — 77,667 Due from affiliates 9 30,126 1,368 — 31,503 Inventories 180 192,803 80,194 10,303 283,480 Prepaid and other current assets 4,311 10,199 13,393 1,865 29,768 Deferred taxes — 14,281 — — 14,281 Total current assets 75,183 324,182 189,209 12,168 600,742 Property, plant and equipment - net 1,788 380,234 923,961 (440 ) 1,305,543 Investment in subsidiaries 589,532 — — (589,532 ) — Due from affiliates - less current portion 719,258 — — (719,258 ) — Other assets 31,233 33,422 48,553 5,565 118,773 TOTAL $ 1,416,994 $ 737,838 $ 1,161,723 $ (1,291,497 ) $ 2,025,058 Accounts payable, trade $ 2,252 $ 109,376 $ 38,124 $ 1,691 $ 151,443 Due to affiliates — 18,730 3,531 — 22,261 Accrued and other current liabilities 13,048 64,104 22,817 3,838 103,807 Accrued employee benefits costs 1,823 7,805 531 — 10,159 Industrial revenue bonds — 7,815 — — 7,815 Total current liabilities 17,123 207,830 65,003 5,529 295,485 Senior notes payable 246,888 — — — 246,888 Accrued pension benefits costs cost - less current portion 32,136 13,942 13,828 — 59,906 Accrued postretirement benefits costs - less current portion 5,821 145,267 1,806 — 152,894 Other liabilities 3,630 32,035 11,963 5,644 53,272 Intercompany loan — 164,610 542,259 (706,869 ) — Deferred taxes — — 111,486 — 111,486 Total noncurrent liabilities 288,475 355,854 681,342 (701,225 ) 624,446 Series A Preferred stock 1 — — — 1 Common stock 939 — 215,424 (215,424 ) 939 Additional paid-in capital 2,510,261 150,861 2,136,138 (2,286,999 ) 2,510,261 Treasury stock, at cost (49,924 ) — — — (49,924 ) Accumulated other comprehensive loss (4,484 ) (74,780 ) (38,418 ) — (117,682 ) Accumulated deficit (1,345,397 ) 98,073 (1,897,766 ) 1,906,622 (1,238,468 ) Total shareholder's equity 1,111,396 174,154 415,378 (595,801 ) 1,105,127 TOTAL $ 1,416,994 $ 737,838 $ 1,161,723 $ (1,291,497 ) $ 2,025,058
Condensed Consolidating Statement of Cash Flows	Condensed Consolidating Statement of Cash Flows For the year ended December 31, 2015 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by operating activities $ 25,423 $ 30,890 $ 65,085 $ (89,532 ) $ 31,866 Purchase of property, plant and equipment (8,574 ) (21,477 ) (24,209 ) (440 ) (54,700 ) Purchase of remaining interest in Mt. Holly smelter 11,313 — — — 11,313 Proceeds from sale of property, plant and equipment — 14 — — 14 Restricted and other cash deposits — (4 ) 14 — 10 Intercompany transactions (4,072 ) — — 4,072 — Net cash used in investing activities (1,333 ) (21,467 ) (24,195 ) 3,632 (43,363 ) Borrowings under revolving credit facilities 1,737 — — — 1,737 Repayments under revolving credit facilities (1,737 ) — — — (1,737 ) Repurchase of common stock (36,352 ) — — — (36,352 ) Intercompany transactions — (11,883 ) (74,017 ) 85,900 — Net cash used in financing activities (36,352 ) (11,883 ) (74,017 ) 85,900 (36,352 ) CHANGE IN CASH AND CASH EQUIVALENTS (12,262 ) (2,460 ) (33,127 ) — (47,849 ) Cash and cash equivalents, beginning of year 70,683 (1,187 ) 93,746 — 163,242 Cash and cash equivalents, end of year $ 58,421 $ (3,647 ) $ 60,619 $ — $ 115,393 Condensed Consolidating Statement of Cash Flows For the year ended December 31, 2014 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by operating activities $ 92,338 $ 40,711 $ 139,896 $ (65,265 ) $ 207,680 Purchase of property, plant and equipment (587 ) (22,939 ) (31,603 ) 3 (55,126 ) Purchase of Sebree smelter (1,042 ) — — — (1,042 ) Purchase of remaining interest in Mt. Holly smelter (65,100 ) — — — (65,100 ) Proceeds from sale of property, plant and equipment — — 46 — 46 Restricted and other cash deposits — — 896 — 896 Net cash used in investing activities (66,729 ) (22,939 ) (30,661 ) 3 (120,326 ) Repayment of debt (2,603 ) — — — (2,603 ) Borrowings under revolving credit facilities 92,423 — — — 92,423 Repayments under revolving credit facilities (92,423 ) — (6,000 ) — (98,423 ) Issuance of common stock 403 — — — 403 Intercompany transactions — (17,801 ) (47,461 ) 65,262 — Net cash used in financing activities (2,200 ) (17,801 ) (53,461 ) 65,262 (8,200 ) CHANGE IN CASH AND CASH EQUIVALENTS 23,409 (29 ) 55,774 — 79,154 Cash and cash equivalents, beginning of year 47,274 (1,158 ) 37,972 — 84,088 Cash and cash equivalents, end of year $ 70,683 $ (1,187 ) $ 93,746 $ — $ 163,242 Condensed Consolidating Statement of Cash Flows For the year ended December 31, 2013 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ 30,462 $ (70,217 ) $ 82,776 $ (23,303 ) $ 19,718 Purchase of property, plant and equipment (1,229 ) (17,199 ) (49,649 ) — (68,077 ) Purchase of Sebree smelter (48,058 ) — — — (48,058 ) Investments and advances to joint ventures (125 ) — — — (125 ) Proceeds from sale of property, plant and equipment — 14 511 — 525 Restricted and other cash deposits — (787 ) (652 ) — (1,439 ) Net cash used in investing activities (49,412 ) (17,972 ) (49,790 ) — (117,174 ) Repayment of debt (249,604 ) — — — (249,604 ) Proceeds from issuance of debt 246,330 — — — 246,330 Borrowings under revolving credit facilities 16,725 — 6,000 — 22,725 Repayments under revolving credit facilities (16,725 ) — — — (16,725 ) Debt issuance costs (3,994 ) — — — (3,994 ) Debt retirement costs (1,208 ) — — — (1,208 ) Issuance of common stock 44 — — — 44 Intercompany transactions — 87,718 (111,021 ) 23,303 — Net cash provided by (used in) financing activities (8,432 ) 87,718 (105,021 ) 23,303 (2,432 ) CHANGE IN CASH AND CASH EQUIVALENTS (27,382 ) (471 ) (72,035 ) — (99,888 ) Cash and cash equivalents, beginning of year 74,656 (687 ) 110,007 — 183,976 Cash and cash equivalents, end of year $ 47,274 $ (1,158 ) $ 37,972 $ — $ 84,088

Summary of significant accoun46

Summary of significant accounting policies (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 30, 2015	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Glencore beneficial ownership		42.90%		42.90%
Glencore economic ownership		47.50%		47.50%
Allowance for doubtful accounts receivable		$ 1,000		$ 1,000	$ 1,000
BHH impairment				11,584	0	$ 0
Property, Plant and Equipment [Line Items]
Impairment charge				$ 30,850	$ 0	$ 0
Ravenswood Aluminum Smelter [Member]
Property, Plant and Equipment [Line Items]
Impairment charge	$ 30,850		$ 30,850
Minimum [Member] | Building and Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful life				10 years
Minimum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful life				5 years
Minimum [Member] | Technology and Software [Member]
Property, Plant and Equipment [Line Items]
Useful life				3 years
Maximum [Member] | Building and Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful life				45 years
Maximum [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful life				35 years
Maximum [Member] | Technology and Software [Member]
Property, Plant and Equipment [Line Items]
Useful life				7 years
Baise Haohi Carbon Co Ltd [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage, equity method		40.00%		40.00%
BHH [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage, equity method		40.00%		40.00%
BHH impairment		$ 11,584		$ 11,584

Related party transactions - Na

Related party transactions - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2015USD ($)t	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Related Party Transaction [Line Items]
BHH impairment		$ 11,584	$ 0	$ 0
Glencore [Member]
Related Party Transaction [Line Items]
Ownership percentage	47.50%	47.50%
BHH [Member]
Related Party Transaction [Line Items]
Ownership percentage, equity method	40.00%	40.00%
BHH impairment	$ 11,584	$ 11,584
Glencore [Member] | Long-Term Tolling Contracts [Member]
Related Party Transaction [Line Items]
Annual primary aluminum physical delivery contract, maximum (in tonnes) | t		90,000

Related party transactions (Det

Related party transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Net sales to Glencore	$ 1,867,711	$ 1,262,101	$ 511,051
Glencore [Member]
Related Party Transaction [Line Items]
Net sales to Glencore	1,867,711	1,262,101	511,051
Purchases from Glencore	393,158	285,167	173,693
BHH [Member]
Related Party Transaction [Line Items]
Purchases from BHH	$ 46,592	$ 47,804	$ 86,678

Business acquisitions - Acquisi

Business acquisitions - Acquisition of Mt. Holly aluminum smelter narrative (Details) t in Thousands, $ in Thousands	Dec. 01, 2014USD ($)employeet	Apr. 30, 2015USD ($)	Dec. 31, 2014USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Gain on fair value of contingent consideration					$ 6,527	$ 7,943	$ 18,337	$ 7,943	$ 0
Gain on remeasurement of equity investment						15,955	$ 0	15,955	$ 0
Mt. Holly Smelter [Member]
Business Acquisition [Line Items]
Percentage of voting interests acquired	50.30%
Percentage of ownership after acquisition (percentage)							100.00%			100.00%
Employees | employee	600
Primary aluminum capacity (in tonnes) | t	231
Purchase price	$ 67,500
Acquisition-related costs			$ 1,087			$ 1,087	$ 452	$ 1,087		$ 452
Contingent consideration, maximum	22,500
Contingent consideration arrangements	12,500
Contingent consideration	13,780
Gain on fair value of contingent consideration				$ 10,287			18,337
Contingent consideration receivable							$ 12,500			12,500
Consideration receivable, economic adjustment		$ 11,189
Consideration received for working capital adjustments		124
Consideration received for expected future post-employment benefits	$ 2,400
Equity interest in acquiree (percentage)	49.70%
Fair value of equity interest in acquiree	$ 47,855
Gain on remeasurement of equity investment			$ 15,955							$ 14,637
Pension funding total		$ 34,595
Due from Alumax, purchase price credit	$ 11,269

Business acquisitions - Summary

Business acquisitions - Summary of Consideration Transferred (Details) - USD ($) $ in Thousands	Dec. 01, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Purchase price		$ 0	$ 1,042	$ 48,058
Mt. Holly Smelter [Member]
Business Acquisition [Line Items]
Purchase price	$ 67,500
Contingent consideration	13,780
Economic, working capital and other closing adjustments	(13,513)
Total consideration	$ 67,767

Business acquisitions - Acqui51

Business acquisitions - Acquisition of Mt. Holly aluminum smelter (Details) - Mt. Holly Smelter [Member] - USD ($) $ / shares in Units, $ in Thousands	10 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 01, 2014
Assets Acquired:
Inventories				$ 23,979
Due from Alumax				11,269
Prepaid and other current assets				2,527
Intangible asset				2,580
Pension asset				30,842
Property, plant and equipment – net				142,837
Total assets acquired				214,034
Liabilities Assumed:
Accounts payable, trade				41,471
Accrued and other current liabilities				8,590
Accrued pension benefit costs				34,595
Accrued postretirement benefit costs				2,857
Asset retirement obligations				8,213
Deferred taxes				2,686
Total liabilities assumed				98,412
Goodwill				0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Inventories	$ (2,126)
Due from Alumax	(9,517)
Property, plant and equipment – net	15,748
Total assets acquired	4,105
Accrued and other current liabilities	255
Accrued pension benefit costs	34,595
Deferred taxes	(2,118)
Total liabilities assumed	32,732
Goodwill	$ (4,804)
Business Acquisition, Pro Forma Information [Abstract]
Mt. Holly revenue		$ 25,911
Mt. Holly income from continuing operations		3,024
Pro forma revenues		2,176,552	$ 1,707,838
Pro forma earnings from continuing operations		$ 125,847	$ (38,819)
Pro forma earnings per common share, basic (in dollars per share)		$ 1.30	$ (0.44)
Pro forma earnings per common share, diluted (in dollars per share)		$ 1.29	$ (0.44)
Preliminary estimate [Member]
Assets Acquired:
Inventories				26,105
Due from Alumax				20,786
Prepaid and other current assets				2,527
Intangible asset				2,580
Pension asset				30,842
Property, plant and equipment – net				127,089
Total assets acquired				209,929
Liabilities Assumed:
Accounts payable, trade				41,471
Accrued and other current liabilities				8,335
Accrued pension benefit costs				0
Accrued postretirement benefit costs				2,857
Asset retirement obligations				8,213
Deferred taxes				4,804
Total liabilities assumed				65,680
Goodwill				$ 4,804

Business acquisitions - Acqui52

Business acquisitions - Acquisition of Sebree aluminum smelter (Details) $ / shares in Units, t in Thousands, $ in Thousands	Dec. 01, 2014USD ($)employeet	Jun. 01, 2013USD ($)employeet	Jul. 31, 2014USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)$ / shares	Dec. 31, 2013USD ($)$ / shares
Business Acquisition [Line Items]
Purchase price									$ 0	$ 1,042	$ 48,058
Unrealized gain on fair value of contingent consideration					$ 6,527	$ 7,943			18,337	7,943	0
Gain on bargain purchase									0	0	5,253
Business Acquisition, Pro Forma Information [Abstract]
Sebree power contract amortization								$ 5,534	0	5,534	31,031
Mt. Holly Smelter [Member]
Business Acquisition [Line Items]
Primary aluminum capacity (in tonnes) | t	231
Employees | employee	600
Purchase price	$ 67,500
Purchase price	67,500
Unrealized gain on fair value of contingent consideration				$ 10,287					$ 18,337
Consideration:
Total consideration	67,767
Assets Acquired:
Inventories	23,979
Prepaid and other current assets	2,527
Property, plant and equipment – net	142,837
Total assets acquired	214,034
Liabilities Assumed:
Accrued and other current liabilities	8,590
Accrued pension benefit costs	34,595
Accrued postretirement benefit costs	2,857
Other liabilities	8,213
Deferred taxes	2,686
Total liabilities assumed	$ 98,412
Business Acquisition, Pro Forma Information [Abstract]
Sebree revenue										25,911
Sebree income from continuing operations										3,024
Pro forma revenues										2,176,552	1,707,838
Pro forma loss from continuing operations										$ 125,847	$ (38,819)
Pro forma loss per common share, basic (in dollars per share) | $ / shares										$ 1.30	$ (0.44)
Pro forma loss per common share, diluted (in dollars per share) | $ / shares										$ 1.29	$ (0.44)
Sebree Smelter [Member]
Business Acquisition [Line Items]
Primary aluminum capacity (in tonnes) | t		218
Employees | employee		500
Purchase price		$ 61,000
Purchase price			$ 49,035
Unrealized gain on fair value of contingent consideration							$ 965
Gain on bargain purchase		5,253									$ 5,253
Consideration:
Total consideration		48,083
Deferred purchase price		1,910
Assets Acquired:
Inventories		59,018
Prepaid and other current assets		2,273
Property, plant and equipment – net		55,520
Total assets acquired		116,811
Liabilities Assumed:
Accrued and other current liabilities		43,316
Accrued pension benefit costs		996
Accrued postretirement benefit costs		6,544
Other liabilities		7,476
Deferred taxes		3,233
Total liabilities assumed		$ 61,565
Business Acquisition, Pro Forma Information [Abstract]
Sebree revenue											247,178
Sebree income from continuing operations											8,705
Sebree power contract amortization										$ 5,534	31,031
Pro forma revenues											1,662,707
Pro forma loss from continuing operations											$ (83,035)
Pro forma loss per common share, basic (in dollars per share) | $ / shares											$ (0.94)
Pro forma loss per common share, diluted (in dollars per share) | $ / shares											$ (0.94)

Fair value measurements (Detail

Fair value measurements (Details) - Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
ASSETS:
Cash equivalents	$ 102,675	$ 137,712
Trust assets	5,226	8,067
Surety bonds	1,870	1,987
TOTAL	109,771	147,766
LIABILITIES:
E.ON contingent obligation – net	0	0
TOTAL	0	0
Level 1 [Member]
ASSETS:
Cash equivalents	102,675	137,712
Trust assets	5,226	8,067
Surety bonds	1,870	1,987
TOTAL	109,771	147,766
LIABILITIES:
E.ON contingent obligation – net	0	0
TOTAL	0	0
Level 2 [Member]
ASSETS:
Cash equivalents	0	0
Trust assets	0	0
Surety bonds	0	0
TOTAL	0	0
LIABILITIES:
E.ON contingent obligation – net	0	0
TOTAL	0	0
Level 3 [Member]
ASSETS:
Cash equivalents	0	0
Trust assets	0	0
Surety bonds	0	0
TOTAL	0	0
LIABILITIES:
E.ON contingent obligation – net	0	0
TOTAL	$ 0	$ 0

Debt (Details)

Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Jun. 04, 2013
Debt Instrument [Line Items]
Industrial revenue bonds	$ 7,815	$ 7,815
Total	255,093	254,703
Industrial revenue bonds due 2028 [Member] | Short-term Debt [Member]
Debt Instrument [Line Items]
Industrial revenue bonds	$ 7,815	$ 7,815
Effective interest rate, maximum	12.00%	12.00%
Stated interest rate	0.21%
Maturity date	Apr. 1, 2028	Apr. 1, 2028
Senior secured notes due June 01, 2021 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior secured notes	$ 247,278	$ 246,888
Stated interest rate	7.50%	7.50%	7.50%
Maturity date	Jun. 1, 2021	Jun. 1, 2021
Debt discount	$ 2,722	$ 3,112

Debt - Credit Facility (Details

Debt - Credit Facility (Details) - Long-term Debt [Member] - USD ($)	12 Months Ended
	Dec. 31, 2015	Jun. 26, 2015	Nov. 27, 2013
U.S revolving credit facility [Member]
Line of Credit Facility [Line Items]
Credit facility face amount		$ 150,000,000
Credit facility maximum amount	$ 150,000,000
Borrowing availability	81,292,000
Borrowing availability, net of outstanding letters of credit and borrowings	34,946,000
Letters of credit [Member]
Line of Credit Facility [Line Items]
Letter of credit sub-facility amount		$ 110,000,000
Outstanding letters of credit issued	46,346,000
Outstanding borrowings	0
Iceland revolving credit facility [Member]
Line of Credit Facility [Line Items]
Credit facility face amount			$ 50,000,000
Credit facility maximum amount	50,000,000
Borrowing availability	49,294,000
Outstanding letters of credit issued	0
Outstanding borrowings	0
Borrowing availability, net of outstanding letters of credit and borrowings	$ 49,294,000
Prepayment terms	Any outstanding borrowings may be prepaid without penalty or premium (except incurred breakage costs) in whole or in part.

Debt - 7.5% Notes Due 2021 (Det

Debt - 7.5% Notes Due 2021 (Details) - Long-term Debt [Member] - Senior secured notes due June 01, 2021 [Member] - USD ($)	Jun. 04, 2013	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Face amount	$ 250,000,000
Proceeds from debt issuance	$ 246,330,000
Stated interest rate	7.50%	7.50%	7.50%
Fair value of debt instrument		$ 169,220,000	$ 256,408,000
Equity interests in foreign subsidiaries, percentage		65.00%

Debt - 7.5% Notes Redemption (D

Debt - 7.5% Notes Redemption (Details) - Long-term Debt [Member] - Senior secured notes due June 01, 2021 [Member]	12 Months Ended
	Dec. 31, 2015
Debt Instrument, Redemption [Line Items]
Redemptions rights after control change, percentage	101.00%
Prior to June 1, 2016 [Member]
Debt Instrument, Redemption [Line Items]
Redemption price, percentage	100.00%
2016 [Member]
Debt Instrument, Redemption [Line Items]
Redemption price, percentage	105.625%
2017 [Member]
Debt Instrument, Redemption [Line Items]
Redemption price, percentage	103.75%
2018 [Member]
Debt Instrument, Redemption [Line Items]
Redemption price, percentage	101.875%
2019 and thereafter [Member]
Debt Instrument, Redemption [Line Items]
Redemption price, percentage	100.00%

Debt - 7.5% Notes Due 2014 (Det

Debt - 7.5% Notes Due 2014 (Details) - Long-term Debt [Member] - Senior unsecured notes due August 15, 2014 [Member] $ in Thousands	1 Months Ended
	Aug. 31, 2004USD ($)
Debt Instrument [Line Items]
Proceeds from debt issuance	$ 250,000
Stated interest rate	7.50%

Debt - E.ON contingent obligati

Debt - E.ON contingent obligation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)payment	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Debt Instrument [Line Items]
Unrealized gain (loss) on E.ON obligation	$ 1,411	$ 1,412	$ 16,781
Long-term Debt [Member] | Contingent obligation [Member]
Debt Instrument [Line Items]
Payment terms	72 monthly payments
Stated interest rate	10.94%
Long-term Debt [Member] | E.ON Contingent Obligation [Member]
Debt Instrument [Line Items]
Number of monthly payments | payment	72
Unrealized gain (loss) on E.ON obligation	$ 1,411	1,412
Other Liabilities [Member] | E.ON Contingent Obligation [Member]
Debt Instrument [Line Items]
E.ON contingent obligation – principal	(12,902)	(12,902)
E.ON contingent obligation – accrued interest	(6,702)	(5,291)
E.ON contingent obligation – derivative asset	19,604	18,193
E.ON Contingent Obligation	$ 0	$ 0

Debt - Industrial Revenue Bonds

Debt - Industrial Revenue Bonds (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Short-term Debt [Member] | Industrial revenue bonds due 2028 [Member]
Short-term Debt [Line Items]
Effective interest rate, maximum	12.00%	12.00%

Debt - Principal payments on lo

Debt - Principal payments on long term debt (Details)	Dec. 31, 2015USD ($)
Long-term Debt [Member]
Debt Instrument [Line Items]
Principal payments on long term debt during next 5 years	$ 0

Shareholders' equity (Details)

Shareholders' equity (Details) - USD ($)	8 Months Ended	12 Months Ended			60 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2011	Dec. 31, 2008
Class of Stock [Line Items]
Common stock, shares authorized (shares)	195,000,000	195,000,000	195,000,000		195,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01		$ 0.01
Common stock, shares issued	94,224,571	94,224,571	93,851,103		94,224,571
Common stock, shares outstanding	87,038,050	87,038,050	89,064,582		87,038,050
Preferred stock, shares authorized (shares)	5,000,000	5,000,000	5,000,000		5,000,000
Preferred stock, shares issued (shares)								160,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01		$ 0.01
Liquidation preference (in dollars per share)	$ 0.01	$ 0.01			$ 0.01
Conversion of convertible preferred stock (shares)	100	100			100
Authorized repurchase amount	$ 130,000,000	$ 130,000,000			$ 130,000,000		$ 60,000,000
Additional repurchase amount						$ 70,000,000
Treasury stock acquired, Aggregate purchase price		36,352,000			86,276,000
Stock repurchase program, Remaining authorized repurchase amount	$ 43,724,000	$ 43,724,000			$ 43,724,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (shares)	0				7,186,521
Series A Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	76,539	76,539	78,141		76,539
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01			$ 0.01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance		78,141	79,620	80,283
Repurchase of common stock (shares)		0
Conversion of convertible preferred stock (shares)		(1,602)	(1,479)	(663)
Issuance for share-based compensation plans (shares)		0	0	0
Shares, Ending balance	76,539	76,539	78,141	79,620	76,539
Treasury [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance		4,786,521	4,786,521	4,786,521
Repurchase of common stock (shares)		2,400,000
Conversion of convertible preferred stock (shares)		0	0	0
Issuance for share-based compensation plans (shares)		0	0	0
Shares, Ending balance	7,186,521	7,186,521	4,786,521	4,786,521	7,186,521
Common stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance		89,064,582	88,710,277	88,548,637
Repurchase of common stock (shares)		(2,400,000)
Conversion of convertible preferred stock (shares)		160,162	147,952	66,244
Issuance for share-based compensation plans (shares)		213,306	206,353	95,396
Shares, Ending balance	87,038,050	87,038,050	89,064,582	88,710,277	87,038,050

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Inventory, Net [Abstract]
Raw materials	$ 52,121	$ 76,655
Work-in-process	34,025	43,248
Finished goods	15,988	19,969
Operating and other supplies	129,738	143,608
Inventories	$ 231,872	$ 283,480

Property, plant and equipment64

Property, plant and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Land and improvements	$ 42,654	$ 43,385
Buildings and improvements	325,580	345,271
Machinery and equipment	1,349,731	1,476,518
Construction in progress	173,418	182,393
Property, plant and equipment, gross	1,891,383	2,047,567
Less accumulated depreciation	(659,127)	(742,024)
Property, plant and equipment - net	$ 1,232,256	$ 1,305,543

Property, plant and equipment65

Property, plant and equipment (Detail Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Depreciation	$ 80,117	$ 70,827	$ 66,570

Supplemental financial statem66

Supplemental financial statement information - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	$ (123,345)	$ (129,913)
Income tax effect	10,695	12,231
Accumulated other comprehensive loss	(112,650)	(117,682)	$ (91,832)	$ (151,192)
Defined benefit plan liabilities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	(121,910)	(128,664)
Income tax effect	11,243	12,812
Accumulated other comprehensive loss	(110,667)	(115,852)	(77,921)	(137,441)
Unrealized loss on financial instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	(1,435)	(1,249)
Income tax effect	(548)	(581)
Accumulated other comprehensive loss	$ (1,983)	$ (1,830)	$ (1,679)	$ (1,527)

Supplemental financial statem67

Supplemental financial statement information - Changes in components of Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				$ (117,682)				$ (91,832)	$ (117,682)	$ (91,832)	$ (151,192)
Other comprehensive income (loss) before reclassifications									7,311	(43,345)	56,787
Elimination of equity in investee resulting from acquisition										12,651
Net amount reclassified to net income									(2,279)	4,844	2,573
Ending Balance	$ (112,650)				$ (117,682)				(112,650)	(117,682)	(91,832)
Cost of goods sold									1,908,544	1,729,243	1,414,790
Selling, general and administrative expenses									42,115	49,195	67,477
Other operating expense, net									(356)	991	496
Income tax expense									9,276	18,308	3,131
Net income (loss)	(43,080)	$ (56,112)	$ (33,897)	73,779	75,829	$ 50,405	$ 20,344	(20,104)	(59,310)	126,474	(40,313)
Defined benefit plan liabilities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				(115,852)				(77,921)	(115,852)	(77,921)	(137,441)
Other comprehensive income (loss) before reclassifications									7,311	(42,926)	56,795
Elimination of equity in investee resulting from acquisition										0
Net amount reclassified to net income									(2,126)	4,995	2,725
Ending Balance	(110,667)				(115,852)				(110,667)	(115,852)	(77,921)
Equity in investee other comprehensive income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				0				(12,232)	0	(12,232)	(12,224)
Other comprehensive income (loss) before reclassifications									0	(419)	(8)
Elimination of equity in investee resulting from acquisition										12,651
Net amount reclassified to net income									0	0	0
Ending Balance	0				0				0	0	(12,232)
Unrealized loss on financial instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				$ (1,830)				$ (1,679)	(1,830)	(1,679)	(1,527)
Other comprehensive income (loss) before reclassifications									0	0	0
Elimination of equity in investee resulting from acquisition										0
Net amount reclassified to net income									(153)	(151)	(152)
Ending Balance	$ (1,983)				$ (1,830)				(1,983)	(1,830)	(1,679)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined benefit plan liabilities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cost of goods sold									(1,696)	6,237	3,264
Selling, general and administrative expenses									235	569	990
Other operating expense, net									904	0	0
Income tax expense									(1,569)	(1,811)	(1,529)
Net income (loss)									(2,126)	4,995	2,725
Reclassification out of Accumulated Other Comprehensive Income [Member] | Equity in investee other comprehensive income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cost of goods sold									0	0	0
Income tax expense									0	(419)	(70)
Net income (loss)									0	(419)	(70)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized loss on financial instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cost of goods sold									(186)	(185)	(186)
Income tax expense									33	34	34
Net income (loss)									$ (153)	$ (151)	$ (152)

Pension and other postretirem68

Pension and other postretirement benefits - Pension Benefits (Details) - Defined Benefit Pension Plans [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Age requirement for future pension accruals			50 years
Projected benefit obligation change due to curtailments			$ (6,600)
Curtailment charge		$ 1,235	263	$ (18)
Settlements		0	(4,701)	$ 0
Projected benefit obligation change due to settlements	$ (19,573)	$ 0	$ (19,573)

Pension and other postretirem69

Pension and other postretirement benefits - Employer contributions (Details) - USD ($)	12 Months Ended				45 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Pension Contributions		$ 34,595,000	$ 0	$ 0
PBGC Agreement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Pension Contributions		$ 1,100,000	$ 0	$ 6,700,000
PBGC Agreement [Member] | Forecast [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Required pension contributions above minimum					$ 17,400,000
Pension contributions above minimum remaining	$ 9,600,000

Pension and other postretirem70

Pension and other postretirement benefits - Change in benefit obligation (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Pension Plans [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation at beginning of year		$ 336,292	$ 238,319
Service cost		6,346	5,605	$ 4,735
Interest cost		13,388	11,629	8,908
Plan amendments		0	(5,308)
Medicare Part D		0	0
Actuarial loss (gain)		(11,429)	32,772
Acquisition		0	84,743
Benefits paid		(19,247)	(11,895)
Curtailment		1,221	0
Settlements	$ (19,573)	0	(19,573)
Benefit obligation at end of year	336,292	326,571	336,292	238,319
Other Postretirement Benefit Plans [Member]
Change in benefit obligation [Roll Forward]
Benefit obligation at beginning of year		158,781	134,652
Service cost		1,970	1,591	2,527
Interest cost		5,985	6,420	5,681
Plan amendments		(1,758)	0
Medicare Part D		0	273
Actuarial loss (gain)		(18,150)	17,669
Acquisition		0	2,857
Benefits paid		(5,878)	(4,681)
Curtailment		(8,400)	0
Settlements		0	0
Benefit obligation at end of year	$ 158,781	$ 132,550	$ 158,781	$ 134,652

Pension and other postretirem71

Pension and other postretirement benefits - Change in Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Change in fair value of plan assets [Roll Forward]
Fair value of plan assets at beginning of year	$ 305,520
Fair value of assets at end of year	280,862	$ 305,520
Defined Benefit Pension Plans [Member]
Change in fair value of plan assets [Roll Forward]
Fair value of plan assets at beginning of year	305,520	199,304
Actual return on plan assets	(11,321)	16,118
Acquisition	0	115,982
Employer contributions	5,910	5,584
Benefits paid	(19,247)	(11,895)
Settlements	0	(19,573)
Fair value of assets at end of year	280,862	305,520
Other Postretirement Benefit Plans [Member]
Change in fair value of plan assets [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Acquisition	0	0
Employer contributions	5,878	4,681
Benefits paid	(5,878)	(4,681)
Settlements	0	0
Fair value of assets at end of year	$ 0	$ 0

Pension and other postretirem72

Pension and other postretirement benefits - Funded status of plans (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Current liabilities	$ (10,148)	$ (10,159)
Defined Benefit Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Funded status	(45,709)	(30,772)
Non-current assets	0	30,842
Current liabilities	(1,743)	(1,744)
Non-current liabilities	(43,966)	(59,870)
Net amount recognized	(45,709)	(30,772)
Net loss	80,514	63,360
Prior service cost (benefit)	1,211	1,335
Total	81,725	64,695
Projected benefit obligation for plans with accumulated benefit obligations in excess of plan assets	326,571	336,292
Accumulated benefit obligation for plans with accumulated benefit obligations in excess of plan assets	319,873	328,963
Fair value of plan assets for plans with accumulated benefit obligations in excess of plan assets	280,862	305,520
Other Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Funded status	(132,550)	(158,781)
Non-current assets	0	0
Current liabilities	(6,551)	(6,118)
Non-current liabilities	(125,999)	(152,663)
Net amount recognized	(132,550)	(158,781)
Net loss	49,562	79,720
Prior service cost (benefit)	(9,377)	(15,751)
Total	$ 40,185	$ 63,969

Pension and other postretirem73

Pension and other postretirement benefits - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost	$ 6,346	$ 5,605	$ 4,735
Interest cost	13,388	11,629	8,908
Expected return on plan assets	(21,241)	(14,694)	(10,592)
Amortization of prior service costs	110	77	113
Amortization of net loss	3,980	1,907	3,152
Settlements	0	4,701	0
Curtailment cost (benefit)	1,235	263	(18)
Net periodic benefit cost	3,818	9,488	6,298
Other Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost	1,970	1,591	2,527
Interest cost	5,985	6,420	5,681
Expected return on plan assets	0	0	0
Amortization of prior service costs	(3,728)	(3,844)	(3,995)
Amortization of net loss	3,814	3,704	5,022
Settlements	0	0	0
Curtailment cost (benefit)	(4,266)	0	(20)
Net periodic benefit cost	$ 3,775	$ 7,871	$ 9,215

Pension and other postretirem74

Pension and other postretirement benefits - Changes in Plan Assets & Benefit Obligation Recognized in OCI (pre-taxed) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net loss (gain)	$ (5,553)	$ 41,995	$ (56,795)
Prior service cost (benefit)	(1,758)	1,299	0
Amortization of prior service benefit (cost), including recognition due to curtailment	8,351	3,504	3,920
Defined Benefit Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net loss (gain)	21,133	24,326
Prior service cost (benefit)	0	1,299
Amortization of net loss, including recognition due to settlement	(3,980)	(6,608)
Amortization of prior service benefit (cost), including recognition due to curtailment	(124)	(340)
Total amount recognized in other comprehensive loss	17,029	18,677
Net periodic benefit cost	3,818	9,488	6,298
Total recognized in net periodic benefit cost and other comprehensive loss	20,847	28,165
Other Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Net loss (gain)	(26,686)	17,669
Prior service cost (benefit)	(1,758)	0
Amortization of net loss, including recognition due to settlement	(3,814)	(3,704)
Amortization of prior service benefit (cost), including recognition due to curtailment	8,475	3,844
Total amount recognized in other comprehensive loss	(23,783)	17,809
Net periodic benefit cost	3,775	7,871	$ 9,215
Total recognized in net periodic benefit cost and other comprehensive loss	$ (20,008)	$ 25,680

Pension and other postretirem75

Pension and other postretirement benefits - Amortized from AOCI during the next fiscal year (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Defined Benefit Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Amortization of net loss	$ 4,161
Amortization of prior service cost (benefit)	106
Other Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Amortization of net loss	3,518
Amortization of prior service cost (benefit)	$ (2,781)

Pension and other postretirem76

Pension and other postretirement benefits - Weighted Average assumptions used in calculating benefit obligations (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Discount rate	4.44%	4.05%
Rate of compensation increase, minimum	3.00%	3.00%
Rate of compensation increase, maximum	4.00%	4.00%
Measurement date	12/31/2015	12/31/2014
Other Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Discount rate	4.50%	4.00%
Rate of compensation increase, minimum	3.00%	3.00%
Rate of compensation increase, maximum	4.00%	4.00%
Measurement date	12/31/2015	12/31/2014

Pension and other postretirem77

Pension and other postretirement benefits - Weighted average assumptions used to determine net periodic benefit cost (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Rate of compensation increase, year one through three	3.00%
Rate of compensation increase, year four and thereafter	4.00%
Rate of compensation increase, year one through four		3.00%	3.00%
Rate of compensation increase, year five and thereafter		4.00%	4.00%
Rate of compensation increase, year one through five			3.00%
Rate of compensation increase, year six and thereafter			4.00%
Defined Benefit Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Measurement date	12/31/2014	12/31/2013	12/31/2012
Fiscal year end	12/31/2015	12/31/2014	12/31/2013
Discount rate	4.05%	4.89%	4.00%
Rate of compensation increase, group 1	3.00%	3.00%	3.00%
Rate of compensation increase, group 2	4.00%	4.00%	4.00%
Expected return on plan assets	7.16%	7.25%	7.25%
Other Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Measurement date	12/31/2014	12/31/2013	12/31/2012
Fiscal year end	12/31/2015	12/31/2014	12/31/2013
Discount rate	4.00%	4.99%	4.01%
Rate of compensation increase, group 1	3.00%	3.00%	3.00%
Rate of compensation increase, group 2	4.00%	4.00%	4.00%
Expected return on plan assets	0.00%	0.00%	0.00%

Pension and other postretirem78

Pension and other postretirement benefits - Assumed health care trend rates (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Medical cost inflation rate	8.00%
Medical cost inflation, years 7 and thereafter	5.00%
Effect of one percentage point increase on total service and interest cost	$ 1,403
Effect of one percentage point decrease on total service and interest cost	(1,108)
Effect of one percentage point increase on accumulated postretirement benefit obligation	18,170
Effect of one percentage point decrease on accumulated postretirement benefit obligation	$ (15,086)

Pension and other postretirem79

Pension and other postretirement benefits - Pension Plan Asset Allocation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Actual Plan Asset Allocations	100.00%	100.00%
Fair Value of Plan assets	$ 280,862	$ 305,520
U.S. Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Target Allocation Percentage Of Assets	31.00%
Actual Plan Asset Allocations	30.00%	42.00%
Fair Value of Plan assets	$ 86,723	$ 79,148
International Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Target Allocation Percentage Of Assets	21.00%
Actual Plan Asset Allocations	20.00%	18.00%
Fair Value of Plan assets	$ 54,769	$ 33,720
Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Target Allocation Percentage Of Assets	48.00%
Actual Plan Asset Allocations	50.00%	40.00%
Fair Value of Plan assets	$ 139,370	$ 76,204
Plan receivable [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets		116,448
Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	280,862	189,072
Level 1 [Member] | U.S. Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	86,723	79,148
Level 1 [Member] | International Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	54,769	33,720
Level 1 [Member] | Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	139,370	76,204
Level 1 [Member] | Plan receivable [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets		0
Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	0	0
Level 2 [Member] | U.S. Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	0	0
Level 2 [Member] | International Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	0	0
Level 2 [Member] | Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	0	0
Level 2 [Member] | Plan receivable [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets		0
Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	0	116,448
Level 3 [Member] | U.S. Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	0	0
Level 3 [Member] | International Equities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	0	0
Level 3 [Member] | Fixed Income Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets	$ 0	0
Level 3 [Member] | Plan receivable [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Fair Value of Plan assets		$ 116,448

Pension and other postretirem80

Pension and other postretirement benefits - Expected Contribution Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Employer contributions	$ 5,910	$ 5,584
Expected contributions in next twelve months	1,769
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	26,438
2,017	19,755
2,018	20,228
2,019	21,229
2,020	21,655
2021-2025	105,301
Other Postretirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Employer contributions	5,878	$ 4,681
Expected contributions in next twelve months	6,551
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	6,551
2,017	6,789
2,018	7,099
2,019	7,388
2,020	7,508
2021-2025	$ 39,031

Pension and other postretirem81

Pension and other postretirement benefits - Participation in Multi-Employer Pension Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
EIN / PN	23-6648508/499
Pension Protection Act Zone Status	Green	Green
Subject to Financial Improvement/Rehabilitation Plan	No
Contributions of Century Aluminum Company	$ 1,618	$ 2,164	$ 2,171
Withdrawal from Plan Probable	No
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	Apr. 1, 2020
Funded status of Green zone	At least 80 percent

Pension and other postretirem82

Pension and other postretirement benefits - Company matching contribution to defined contribution 401(K) plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Age requirement for future accruals	50 years
Company matching contribution to defined contribution (401(k)) plans	$ 5,446	$ 1,547	$ 1,138

Share-based compensation (Detai

Share-based compensation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)award_typeshares	Dec. 31, 2014USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase common stock (shares)		544,171
Service-Based Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service-based share awards outstanding (shares)	541,304	464,485
Amended and Restated Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (shares)	10,000,000
Shares remaining (shares)	6,832,000
Share based compensation, vesting rights (in time period)	3 years
Expected term (years)	10 years
Options to purchase common stock (shares)	443,737
Amended and Restated Stock Option Plan [Member] | Non-employee director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, vesting rights (in time period)	12 months
Amended and Restated Stock Option Plan [Member] | Service-Based Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service-based share awards outstanding (shares)	541,304
Amended and Restated Stock Option Plan [Member] | Initial vesting -grant date [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights	33.33%
Amended and Restated Stock Option Plan [Member] | Year one [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights	33.33%
Amended and Restated Stock Option Plan [Member] | Year two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights	33.33%
Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, vesting rights (in time period)	3 years
Number of award types provided | award_type	2
Performance unit liability | $	$ 4,853	$ 6,251

Share-based compensation - Serv

Share-based compensation - Service-Based Awards - Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options to purchase common stock (shares)		544,171
Options exercised (shares)	0
Options forfeited/expired (shares)	(100,434)
Outstanding, fully vested and exercisable (shares)	443,737
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options outstanding, Weighted Average Exercise Price (in dollars per share)		$ 26.85
Options exercised, Weighted Average Exercise Price (in dollars per share)	$ 0
Options forfeited/expired, Weighted Average Exercise Price (in dollars per share)	25.95
Outstanding, fully vested and exercisable, Weighted Average Exercise Price (in dollars per share)	$ 27.06
Outstanding, fully vested and exercisable, Weighted Average Remaining Contractual Term (years)	2 years 2 months 8 days
Outstanding, fully vested and exercisable, Aggregate Intrinsic Value	$ 0

Share-based compensation - Se85

Share-based compensation - Service Based Awards Rollforward (Details) - Service-Based Share Awards [Member]	12 Months Ended
	Dec. 31, 2015shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Service-based share awards outstanding, beginning of period (shares)	464,485
Granted (shares)	478,798
Vested (shares)	(354,688)
Forfeited (shares)	(47,291)
Service-based share awards outstanding, end of period (shares)	541,304

Share-based compensation - Se86

Share-based compensation - Service-Based Awards, Additional disclosures (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Service-Based Awards, Additional disclosures [Abstract]
Weighted average per share fair value of service-based share grants (in dollars per share)	$ 4.21	$ 15.31	$ 8.19
Total intrinsic value of option exercises	$ 0	$ 1,011	$ 13

Share-based compensation - Shar

Share-based compensation - Share and performance-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share and performance-based compensation expense [Abstract]
Performance-based share expense	$ 1,587	$ 1,090	$ 475
Service-based share expense	257	244	603
Stock option expense	0	0	0
Total share-based compensation expense before income tax	1,844	1,334	1,078
Income tax	0	0	0
Total share-based compensation expense, net of income tax	1,844	$ 1,334	$ 1,078
Unrecognized compensation expense	$ 2,334
Weighted average period of expense recognition	1 year

Earnings (loss) per share (Deta

Earnings (loss) per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income (loss)	$ (43,080)	$ (56,112)	$ (33,897)	$ 73,779	$ 75,829	$ 50,405	$ 20,344	$ (20,104)	$ (59,310)	$ 126,474	$ (40,313)
Amount allocated to common shareholders (in hundredths)									100.00%	91.81%	100.00%
Basic EPS:
Net income (loss) allocated to common stockholders	$ (43,080)	$ (56,112)	$ (33,897)	$ 67,813	$ 69,669	$ 46,277	$ 18,675	$ (20,104)		$ 116,118
Shares outstanding, basic										88,823
Basic (in dollars per share)	$ (0.50)	$ (0.65)	$ (0.39)	$ 0.76	$ 0.78	$ 0.52	$ 0.21	$ (0.23)	$ (0.68)	$ 1.31	$ (0.45)
Basic and Diluted EPS:
Net income (loss) allocated to common stockholders									$ (59,310)		$ (40,313)
Shares outstanding, basic and diluted									87,375		88,612
Basic and Diluted (in dollars per share)									$ (0.68)		$ (0.45)
Effect of Dilutive Securities:
Share-based compensation plans (shares)										605
Diluted EPS:
Net income (loss) allocated to common stockholders										$ 116,118
Shares outstanding, diluted										89,428
Diluted (in dollars per share)	$ (0.50)	$ (0.65)	$ (0.39)	$ 0.76	$ 0.78	$ 0.52	$ 0.21	$ (0.23)	$ (0.68)	$ 1.30	$ (0.45)

Earnings (loss) per share - Ant

Earnings (loss) per share - Antidilutive securities excluded from the calculation of diluted EPS (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from calculation of diluted EPS	356,634	320,553	619,833
Service-Based Share Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from calculation of diluted EPS	608,914	0	442,737

Income taxes (Details)

Income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
U.S.	$ (62,203)	$ 91,026	$ (47,080)
Foreign	21,081	52,451	7,236
Income (loss) before income taxes and equity in earnings of joint ventures	$ (41,122)	$ 143,477	$ (39,844)

Income taxes - Significant comp

Income taxes - Significant components of Income tax expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
U.S. federal current expense (benefit)	$ 0	$ (112)	$ 532
State current expense (benefit)	(706)	2,252	(445)
Foreign current expense	13,473	15,098	6,198
Total current expense	12,767	17,238	6,285
Deferred:
U.S. federal deferred benefit	(1,564)	(1,696)	(3,905)
State deferred benefit	0	(12)	(207)
Foreign deferred tax expense	(1,927)	2,778	958
Total deferred benefit	(3,491)	1,070	(3,154)
Total income tax expense	$ 9,276	$ 18,308	$ 3,131

Income taxes - Reconciliation o

Income taxes - Reconciliation of statutory to effective income tax rate (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal Statutory Rate	35.00%	35.00%	35.00%
Permanent differences	1.90%	4.30%	54.50%
State taxes, net of Federal benefit	(16.00%)	(6.20%)	97.20%
Foreign earnings taxed at different rates than U.S.	3.00%	(1.30%)	17.40%
Valuation allowance	(56.60%)	(26.00%)	(265.90%)
Changes in uncertain tax reserves	(4.20%)	0.60%	40.50%
Other	14.30%	6.40%	13.40%
Effective tax rate	(22.60%)	12.80%	(7.90%)

Income taxes - Significant Co93

Income taxes - Significant Components of our deferred tax assets & liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Accrued postretirement benefit cost	$ 14,825	$ 15,683
Accrued liabilities	1,080	4,494
Share-based compensation	6,421	7,350
Derivative and hedging contracts	0	58,687
Goodwill	7,949	10,521
Pension and post-retirement obligations in other comprehensive income	78,753	81,567
Net operating losses and tax credits	700,819	646,158
Foreign basis differences	2,083	668
Other	10,676	8,748
Total deferred tax assets	822,606	833,876
Valuation allowance	(768,764)	(748,283)
Net deferred tax assets	53,842	85,593
Deferred tax liabilities:
Tax over financial statement depreciation	(116,327)	(142,627)
Pension	(15,608)	(14,222)
Unremitted foreign earnings	(18,901)	(30,308)
Total deferred tax liabilities	(150,836)	(187,157)
Net deferred tax liability	$ (96,994)	$ (101,564)

Income taxes - Changes in Valua

Income taxes - Changes in Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, valuation allowance	$ 748,283	$ 765,023
Change in valuation allowance	20,481	(16,740)
Balance, valuation allowance	$ 768,764	$ 748,283

Income taxes - Significant Co95

Income taxes - Significant Components of our Deferred Tax Assets & Liabilities - Additional Info (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Income Tax Disclosure [Abstract]
Net operating losses that will increase equity if and when such deferred tax assets are realized	$ 7,746

Income taxes - Net Operating Lo

Income taxes - Net Operating Losses Carryforwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 1,470,251	$ 1,306,482
Expiration dates	Dec. 31, 2028
State [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 2,094,687	2,078,105
Expiration dates	Dec. 31, 2027
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 466,743	$ 446,234
Iceland [Member] | Foreign [Member]
Operating Loss Carryforwards [Line Items]
Expiration dates	Dec. 31, 2017
Netherlands [Member] | Foreign [Member]
Operating Loss Carryforwards [Line Items]
Expiration dates	Dec. 31, 2022

Income taxes - Gross Unrecogniz

Income taxes - Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1,	$ 2,000	$ 1,200	$ 17,600
Additions based on tax positions related to the current year	1,800	1,100	700
Decreases due to lapse of applicable statute of limitations	0	(300)	(2,800)
Settlements	0	0	(14,300)
Balance as of December 31,	$ 3,800	$ 2,000	$ 1,200

Income taxes - Components of un

Income taxes - Components of unrecognized tax positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Highly certain tax positions	$ 3,700	$ 1,900	$ 1,100
Other unrecognized tax benefits	100	100	100
Gross unrecognized tax benefits	3,800	2,000	1,200	$ 17,600
Accrued interest and penalties related to unrecognized tax benefits	$ 0	$ 0	$ 100

Income taxes - Additional incom

Income taxes - Additional income tax details (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Reduction in reserve for unrecognized tax benefits related to prior years		$ 14,300
Proceeds from income tax refunds	$ 5,009
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards			$ 1,470,251	$ 1,306,482
Accrued and Other Current Liabilities [Member]
Operating Loss Carryforwards [Line Items]
Income taxes payable			$ 13,092	$ 14,302

Commitments and contingencies -

Commitments and contingencies - Environmental Contingencies (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrual for Environmental Loss Contingencies [Abstract]
Environmental-related accrued liabilities	$ 1,112	$ 1,101

Commitments and contingencie101

Commitments and contingencies - Matters relating to the St. Croix Alumina Refining Facility (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Accrual for Environmental Loss Contingencies [Abstract]
Environmental remediation expense for Hydrocarbon Recovery Plan	$ 1,085

Commitments and contingencie102

Commitments and contingencies - Legal Contingencies (Details) - USD ($)	12 Months Ended				45 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2016
Loss Contingencies [Line Items]
Pension Contributions		$ 34,595,000	$ 0	$ 0
PBGC Agreement [Member]
Loss Contingencies [Line Items]
Pension Contributions		$ 1,100,000	$ 0	$ 6,700,000
PBGC Agreement [Member] | Forecast [Member]
Loss Contingencies [Line Items]
Required pension contributions above minimum					$ 17,400,000
Pension contributions above minimum remaining	$ 9,600,000

Commitments and contingencies (

Commitments and contingencies (Details) $ in Thousands	Dec. 18, 2015source	Dec. 31, 2015USD ($)MWlabor_union
OR Power Purchase Agreement Abstract]
Power prepayments | $		$ 1,477
Power currently available under the power purchase agreement (in megawatts) | MW		47.5
Labor Commitments [Abstract]
Percentage of Company's work force represented by a union		63.00%
Percentage of Grundartangi work force represented by the labor unions		84.00%
Number of labor unions under new agreement | labor_union		5
Percentage of Vlissingen work force represented by the labor union		100.00%
Percentage of U.S. based work force represented by a union		53.00%
South Carolina Public Service Authority [Member]
Short-term Agreement for Power Supply [Line Items]
Operating capacity under agreement, percentage	50.00%
Number of power sources | source	2
Power agreement, power supply from source one, percentage	25.00%
Power agreement, power supply from source two, percentage	75.00%
Agreement termination notice period	60 days

Asset retirement obligations104

Asset retirement obligations ('ARO') (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Asset Retirement Obligation [Roll Forward]
Beginning balance, ARO liability	$ 36,950	$ 27,113
Additional ARO liability incurred	3,797	2,548
ARO liabilities settled	(5,514)	(4,731)
Accretion expense	1,818	1,517
Adjustments	(1,886)	0
ARO liability from Mt. Holly acquisition	0	10,503
Ending balance, ARO liability	$ 35,165	$ 36,950

Supplemental cash flow infor105

Supplemental cash flow information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest	$ 18,781	$ 19,066	$ 20,539
Income/withholding taxes	24,125	12,189	28,654
Accrued capital costs	777	744	9,409
Iceland [Member]
Income/withholding taxes	$ 8,388	$ 5,491	$ 18,067

Quarterly information (Unaud106

Quarterly information (Unaudited) - Financial Results by Quarter (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data [Abstract]
Net sales	$ 383,915	$ 454,540	$ 523,491	$ 587,911	$ 551,239	$ 500,632	$ 458,324	$ 420,847	$ 1,949,857	$ 1,931,042	$ 1,454,313
Gross profit (loss)	(18,701)	(42,423)	8,342	94,095	89,339	75,714	38,504	(1,758)	41,313	201,799	39,523
Net income (loss)	(43,080)	(56,112)	(33,897)	73,779	75,829	50,405	20,344	(20,104)	$ (59,310)	126,474	$ (40,313)
Net income (loss) allocated to common stockholders	$ (43,080)	$ (56,112)	$ (33,897)	$ 67,813	$ 69,669	$ 46,277	$ 18,675	$ (20,104)		$ 116,118
Basic earnings (loss) per share (in dollars per share)	$ (0.50)	$ (0.65)	$ (0.39)	$ 0.76	$ 0.78	$ 0.52	$ 0.21	$ (0.23)	$ (0.68)	$ 1.31	$ (0.45)
Diluted earnings (loss) per share (in dollars per share)	$ (0.50)	$ (0.65)	$ (0.39)	$ 0.76	$ 0.78	$ 0.52	$ 0.21	$ (0.23)	$ (0.68)	$ 1.30	$ (0.45)

Quarterly information (Unaud107

Quarterly information (Unaudited) - 2015 Financial Results Overview (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended					12 Months Ended
	Jun. 30, 2015	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effect of Fourth Quarter Events [Line Items]
Lower cost or market inventory adjustment		$ 23,474	$ 5,324				$ 7,539	$ (1,247)	$ 1,247
Pension charges		3,400				$ 4,964
Depreciation							80,117	70,827	66,570
Impairment							11,584	0	0
Labor disruption costs			1,400	$ 11,700
Impairment charge							30,850	0	0
Gain on fair value of contingent consideration					$ 6,527	$ 7,943	18,337	$ 7,943	$ 0
Severance charge					1,000
Hawesville and Mt. Holly [Member]
Effect of Fourth Quarter Events [Line Items]
Curtailment expenses		3,500
Hawesville [Member]
Effect of Fourth Quarter Events [Line Items]
Curtailment expenses			$ 2,900
Ravenswood Aluminum Smelter [Member]
Effect of Fourth Quarter Events [Line Items]
Lower cost or market inventory adjustment				25,689
Impairment charge	$ 30,850			30,850
Grundartangi, Iceland [Member]
Effect of Fourth Quarter Events [Line Items]
Signing bonuses, amount					$ 1,570
Mt. Holly Smelter [Member]
Effect of Fourth Quarter Events [Line Items]
Depreciation		5,000
Gain on fair value of contingent consideration				$ 10,287			18,337
BHH [Member]
Effect of Fourth Quarter Events [Line Items]
Impairment		$ 11,584					$ 11,584

Quarterly information (Unaud108

Quarterly information (Unaudited) - 2014 Financial Results Overview (Details) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data [Abstract]
Unrealized gain on fair value of contingent consideration		$ 6,527	$ 7,943			$ 18,337	$ 7,943	$ 0
Gain on remeasurement of equity investment			15,955			0	15,955	0
Pension charges	$ 3,400		4,964
Litigation settlement expense			$ 2,616	$ 500
Sebree power contract amortization					$ 5,534	$ 0	$ 5,534	$ 31,031
Increase (decrease) in litigation reserve					$ (3,100)

Business segments (Details)

Business segments (Details)	12 Months Ended
	Dec. 31, 2015segment
Segment Reporting [Abstract]
Number of Operating Segments	4
Number of Reportable Segments	1

Business segments - Segment Ass

Business segments - Segment Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting [Abstract]
Primary	$ 1,706,032	$ 1,987,727	$ 1,770,749
Corporate, unallocated	46,436	37,331	39,447
TOTAL	$ 1,752,468	$ 2,025,058	$ 1,810,196

Business segments - Geography,

Business segments - Geography, Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 383,915	$ 454,540	$ 523,491	$ 587,911	$ 551,239	$ 500,632	$ 458,324	$ 420,847	$ 1,949,857	$ 1,931,042	$ 1,454,313
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									1,373,714	1,370,570	1,022,081
Long-Lived Assets	408,722				497,057				408,722	497,057	392,424
Iceland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									576,143	560,472	432,232
Long-Lived Assets	801,268				831,507				801,268	831,507	853,636
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 94,421				$ 95,752				$ 94,421	$ 95,752	$ 93,075

Business segments - Major Custo

Business segments - Major Customers (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue, Major Customer [Line Items]
Major customer, percentage revenue, net	10.00%
Glencore [Member]
Revenue, Major Customer [Line Items]
Major customer, Revenue, net	$ 1,867,711	$ 1,262,101	$ 511,051
Southwire [Member]
Revenue, Major Customer [Line Items]
Major customer, Revenue, net	0	226,740	312,102
RTA [Member]
Revenue, Major Customer [Line Items]
Major customer, Revenue, net	0	0	223,353
BHP Billiton [Member]
Revenue, Major Customer [Line Items]
Major customer, Revenue, net	$ 0	$ 0	$ 191,445

Condensed consolidating fina113

Condensed consolidating financial information - Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
NET SALES:
Related parties									$ 1,867,711	$ 1,262,101	$ 511,051
Third-party customers									82,146	668,941	943,262
Sales Revenue – net	$ 383,915	$ 454,540	$ 523,491	$ 587,911	$ 551,239	$ 500,632	$ 458,324	$ 420,847	1,949,857	1,931,042	1,454,313
Cost of goods sold									1,908,544	1,729,243	1,414,790
Gross profit	(18,701)	(42,423)	8,342	94,095	89,339	75,714	38,504	(1,758)	41,313	201,799	39,523
Selling, general and administrative expenses									42,115	49,195	67,477
Ravenswood impairment									30,850	0	0
Other operating expense – net									7,436	12,481	8,602
Operating income (loss)									(39,088)	140,123	(36,556)
Interest expense - third parties									(21,954)	(22,015)	(23,091)
Interest income (expense) - affiliates									0	0	0
Interest income - third parties									339	301	728
Net gain on forward and derivative contracts									1,600	179	16,598
Gain on bargain purchase									0	0	5,253
Unrealized gain on fair value of contingent consideration				6,527	7,943				18,337	7,943	0
Gain on remeasurement of equity investment					15,955				0	15,955	0
Loss on early extinguishment of debt									0	0	(3,272)
Other income (expense) – net									(356)	991	496
Income (loss) before income taxes and equity in earnings of joint ventures									(41,122)	143,477	(39,844)
Income tax benefit (expense)									(9,276)	(18,308)	(3,131)
Income (loss) before equity in earnings of joint ventures									(50,398)	125,169	(42,975)
BHH impairment									(11,584)	0	0
Equity in earnings of joint ventures									2,672	1,305	2,662
Net income (loss)	$ (43,080)	$ (56,112)	$ (33,897)	$ 73,779	$ 75,829	$ 50,405	$ 20,344	$ (20,104)	(59,310)	126,474	(40,313)
Other comprehensive income (loss) before income tax effect									6,568	(36,672)	60,924
Income tax effect									(1,536)	(1,829)	(1,564)
Other comprehensive income (loss)									5,032	(38,501)	59,360
Total comprehensive income (loss)									(54,278)	87,973	19,047
The Company [Member]
NET SALES:
Related parties									0	0	0
Third-party customers									0	0	0
Sales Revenue – net									0	0	0
Cost of goods sold									0	0	0
Gross profit									0	0	0
Selling, general and administrative expenses									28,000	32,840	40,831
Ravenswood impairment									0
Other operating expense – net									0	0	0
Operating income (loss)									(28,000)	(32,840)	(40,831)
Interest expense - third parties									(20,201)	(20,228)	(21,543)
Interest income (expense) - affiliates									37,626	43,688	48,126
Interest income - third parties									65	15	27
Net gain on forward and derivative contracts									0	(1,080)	140
Gain on bargain purchase											0
Unrealized gain on fair value of contingent consideration									0	0
Gain on remeasurement of equity investment										0
Loss on early extinguishment of debt											(3,272)
Other income (expense) – net									1,356	518	138,548
Income (loss) before income taxes and equity in earnings of joint ventures									(9,154)	(9,927)	121,195
Income tax benefit (expense)									2,140	(4,777)	(3,386)
Income (loss) before equity in earnings of joint ventures									(7,014)	(14,704)	117,809
BHH impairment									0
Equity in earnings of joint ventures									(52,296)	141,178	(158,122)
Net income (loss)									(59,310)	126,474	(40,313)
Other comprehensive income (loss) before income tax effect									6,568	(24,022)	60,924
Income tax effect									(1,536)	(1,829)	(1,564)
Other comprehensive income (loss)									5,032	(25,851)	59,360
Total comprehensive income (loss)									$ (54,278)	100,623	19,047
Combined Guarantor Subsidiaries [Member]
Condensed Statement of Income Captions [Line Items]
Ownership percentage	100.00%								100.00%
NET SALES:
Related parties									$ 1,277,474	715,796	270,314
Third-party customers									82,327	669,466	752,808
Sales Revenue – net									1,359,801	1,385,262	1,023,122
Cost of goods sold									1,388,400	1,282,194	1,061,597
Gross profit									(28,599)	103,068	(38,475)
Selling, general and administrative expenses									8,798	11,353	10,456
Ravenswood impairment									0
Other operating expense – net									0	0	0
Operating income (loss)									(37,397)	91,715	(48,931)
Interest expense - third parties									(1,567)	(1,555)	(1,510)
Interest income (expense) - affiliates									0	0	0
Interest income - third parties									4	0	6
Net gain on forward and derivative contracts									1,411	1,259	16,458
Gain on bargain purchase											5,253
Unrealized gain on fair value of contingent consideration									18,337	7,943
Gain on remeasurement of equity investment										15,955
Loss on early extinguishment of debt											0
Other income (expense) – net									(658)	(459)	(113)
Income (loss) before income taxes and equity in earnings of joint ventures									(19,870)	114,858	(28,837)
Income tax benefit (expense)									0	(493)	0
Income (loss) before equity in earnings of joint ventures									(19,870)	114,365	(28,837)
BHH impairment									0
Equity in earnings of joint ventures									0	0	0
Net income (loss)									(19,870)	114,365	(28,837)
Other comprehensive income (loss) before income tax effect									14,754	(28,955)	31,258
Income tax effect									0	0	0
Other comprehensive income (loss)									14,754	(28,955)	31,258
Total comprehensive income (loss)									(5,116)	85,410	2,421
Combined Non-Guarantor Subsidiaries [Member]
NET SALES:
Related parties									632,597	625,076	244,680
Third-party customers									43	31	191,495
Sales Revenue – net									632,640	625,107	436,175
Cost of goods sold									564,380	522,543	358,124
Gross profit									68,260	102,564	78,051
Selling, general and administrative expenses									5,317	5,002	16,190
Ravenswood impairment									30,850
Other operating expense – net									7,436	12,481	8,602
Operating income (loss)									24,657	85,081	53,259
Interest expense - third parties									(186)	(232)	(38)
Interest income (expense) - affiliates									(37,626)	(43,688)	(48,126)
Interest income - third parties									270	286	695
Net gain on forward and derivative contracts									189	0	0
Gain on bargain purchase											0
Unrealized gain on fair value of contingent consideration									0	0
Gain on remeasurement of equity investment										0
Loss on early extinguishment of debt											0
Other income (expense) – net									2,356	4,564	94
Income (loss) before income taxes and equity in earnings of joint ventures									(10,340)	46,011	5,884
Income tax benefit (expense)									(11,416)	(13,211)	255
Income (loss) before equity in earnings of joint ventures									(21,756)	32,800	6,139
BHH impairment									(11,584)
Equity in earnings of joint ventures									2,672	1,305	2,662
Net income (loss)									(30,668)	34,105	8,801
Other comprehensive income (loss) before income tax effect									(1,114)	(2,662)	22,634
Income tax effect									33	33	33
Other comprehensive income (loss)									(1,081)	(2,629)	22,667
Total comprehensive income (loss)									(31,749)	31,476	31,468
Consolidating Adjustments [Member]
NET SALES:
Related parties									(42,360)	(78,771)	(3,943)
Third-party customers									(224)	(556)	(1,041)
Sales Revenue – net									(42,584)	(79,327)	(4,984)
Cost of goods sold									(44,236)	(75,494)	(4,931)
Gross profit									1,652	(3,833)	(53)
Selling, general and administrative expenses									0	0	0
Ravenswood impairment									0
Other operating expense – net									0	0	0
Operating income (loss)									1,652	(3,833)	(53)
Interest expense - third parties									0	0	0
Interest income (expense) - affiliates									0	0	0
Interest income - third parties									0	0	0
Net gain on forward and derivative contracts									0	0	0
Gain on bargain purchase											0
Unrealized gain on fair value of contingent consideration									0	0
Gain on remeasurement of equity investment										0
Loss on early extinguishment of debt											0
Other income (expense) – net									(3,410)	(3,632)	(138,033)
Income (loss) before income taxes and equity in earnings of joint ventures									(1,758)	(7,465)	(138,086)
Income tax benefit (expense)									0	173	0
Income (loss) before equity in earnings of joint ventures									(1,758)	(7,292)	(138,086)
BHH impairment									0
Equity in earnings of joint ventures									52,296	(141,178)	158,122
Net income (loss)									50,538	(148,470)	20,036
Other comprehensive income (loss) before income tax effect									(13,640)	18,967	(53,892)
Income tax effect									(33)	(33)	(33)
Other comprehensive income (loss)									(13,673)	18,934	(53,925)
Total comprehensive income (loss)									$ 36,865	$ (129,536)	$ (33,889)

Condensed consolidating fina114

Condensed consolidating financial information - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets [Abstract]
Cash and cash equivalents	$ 115,393	$ 163,242	$ 84,088	$ 183,976
Restricted cash	791	801
Accounts receivable — net	9,475	77,667
Due from affiliates	17,417	31,503
Inventories	231,872	283,480
Prepaid and other current assets	42,412	29,768
Deferred taxes	0	14,281
Assets held for sale	30,697	0
Total current assets	448,057	600,742
Property, plant and equipment — net	1,232,256	1,305,543
Investment in subsidiaries	0	0
Due from affiliates - less current portion	0	0
Other assets	72,155	118,773
TOTAL	1,752,468	2,025,058	1,810,196
Accounts payable, trade	90,489	151,443
Due to affiliates	10,045	22,261
Accrued and other current liabilities	48,822	103,807
Accrued employee benefits costs	10,148	10,159
Industrial revenue bonds	7,815	7,815
Total current liabilities	167,319	295,485
Senior notes payable	247,278	246,888
Accrued pension benefits costs — less current portion	43,999	59,906
Accrued postretirement benefits costs — less current portion	125,999	152,894
Other liabilities	53,009	53,272
Intercompany loan	0	0
Deferred taxes	96,994	111,486
Total noncurrent liabilities	567,279	624,446
Series A Preferred stock	1	1
Common stock	942	939
Additional paid-in capital	2,513,631	2,510,261
Treasury stock, at cost	(86,276)	(49,924)
Accumulated other comprehensive loss	(112,650)	(117,682)	(91,832)	(151,192)
Retained Earnings (Accumulated Deficit)	(1,297,778)	(1,238,468)
Total shareholders’ equity	1,017,870	1,105,127	1,002,812	982,643
TOTAL	1,752,468	2,025,058
The Company [Member]
Assets [Abstract]
Cash and cash equivalents	58,421	70,683	47,274	74,656
Restricted cash	0	0
Accounts receivable — net	104	0
Due from affiliates	13	9
Inventories	180	180
Prepaid and other current assets	7,713	4,311
Deferred taxes		0
Assets held for sale	0
Total current assets	66,431	75,183
Property, plant and equipment — net	9,188	1,788
Investment in subsidiaries	593,604	589,532
Due from affiliates - less current portion	632,170	719,258
Other assets	29,536	31,233
TOTAL	1,330,929	1,416,994
Accounts payable, trade	2,380	2,252
Due to affiliates	2,143	0
Accrued and other current liabilities	11,247	13,048
Accrued employee benefits costs	1,824	1,823
Industrial revenue bonds	0	0
Total current liabilities	17,594	17,123
Senior notes payable	247,278	246,888
Accrued pension benefits costs — less current portion	39,831	32,136
Accrued postretirement benefits costs — less current portion	4,524	5,821
Other liabilities	3,307	3,630
Intercompany loan	0	0
Deferred taxes	0	0
Total noncurrent liabilities	294,940	288,475
Series A Preferred stock	1	1
Common stock	942	939
Additional paid-in capital	2,513,631	2,510,261
Treasury stock, at cost	(86,276)	(49,924)
Accumulated other comprehensive loss	(13,125)	(4,484)
Retained Earnings (Accumulated Deficit)	(1,396,778)	(1,345,397)
Total shareholders’ equity	1,018,395	1,111,396
TOTAL	1,330,929	1,416,994
Combined Guarantor Subsidiaries [Member]
Assets [Abstract]
Cash and cash equivalents	(3,647)	(1,187)	(1,158)	(687)
Restricted cash	791	787
Accounts receivable — net	8,891	77,173
Due from affiliates	14,493	30,126
Inventories	148,280	192,803
Prepaid and other current assets	16,242	10,199
Deferred taxes		14,281
Assets held for sale	0
Total current assets	185,050	324,182
Property, plant and equipment — net	361,626	380,234
Investment in subsidiaries	0	0
Due from affiliates - less current portion	0	0
Other assets	19,153	33,422
TOTAL	565,829	737,838
Accounts payable, trade	53,145	109,376
Due to affiliates	7,167	18,730
Accrued and other current liabilities	14,759	64,104
Accrued employee benefits costs	7,644	7,805
Industrial revenue bonds	7,815	7,815
Total current liabilities	90,530	207,830
Senior notes payable	0	0
Accrued pension benefits costs — less current portion	(11,021)	13,942
Accrued postretirement benefits costs — less current portion	119,911	145,267
Other liabilities	30,505	32,035
Intercompany loan	124,518	164,610
Deferred taxes	0	0
Total noncurrent liabilities	263,913	355,854
Series A Preferred stock	0	0
Common stock	0	0
Additional paid-in capital	191,023	150,861
Treasury stock, at cost	0	0
Accumulated other comprehensive loss	(60,026)	(74,780)
Retained Earnings (Accumulated Deficit)	80,389	98,073
Total shareholders’ equity	211,386	174,154
TOTAL	565,829	737,838
Combined Non-Guarantor Subsidiaries [Member]
Assets [Abstract]
Cash and cash equivalents	60,619	93,746	37,972	110,007
Restricted cash	0	14
Accounts receivable — net	480	494
Due from affiliates	2,911	1,368
Inventories	85,937	80,194
Prepaid and other current assets	18,457	13,393
Deferred taxes		0
Assets held for sale	30,697
Total current assets	199,101	189,209
Property, plant and equipment — net	861,442	923,961
Investment in subsidiaries	0	0
Due from affiliates - less current portion	0	0
Other assets	16,047	48,553
TOTAL	1,076,590	1,161,723
Accounts payable, trade	34,964	38,124
Due to affiliates	735	3,531
Accrued and other current liabilities	22,816	22,817
Accrued employee benefits costs	680	531
Industrial revenue bonds	0	0
Total current liabilities	59,195	65,003
Senior notes payable	0	0
Accrued pension benefits costs — less current portion	15,189	13,828
Accrued postretirement benefits costs — less current portion	1,564	1,806
Other liabilities	11,779	11,963
Intercompany loan	509,652	542,259
Deferred taxes	96,994	111,486
Total noncurrent liabilities	635,178	681,342
Series A Preferred stock	0	0
Common stock	224,424	215,424
Additional paid-in capital	2,038,138	2,136,138
Treasury stock, at cost	0	0
Accumulated other comprehensive loss	(39,499)	(38,418)
Retained Earnings (Accumulated Deficit)	(1,840,846)	(1,897,766)
Total shareholders’ equity	382,217	415,378
TOTAL	1,076,590	1,161,723
Consolidating Adjustments [Member]
Assets [Abstract]
Cash and cash equivalents	0	0	$ 0	$ 0
Restricted cash	0	0
Accounts receivable — net	0	0
Due from affiliates	0	0
Inventories	(2,525)	10,303
Prepaid and other current assets	0	1,865
Deferred taxes		0
Assets held for sale	0
Total current assets	(2,525)	12,168
Property, plant and equipment — net	0	(440)
Investment in subsidiaries	(593,604)	(589,532)
Due from affiliates - less current portion	(632,170)	(719,258)
Other assets	7,419	5,565
TOTAL	(1,220,880)	(1,291,497)
Accounts payable, trade	0	1,691
Due to affiliates	0	0
Accrued and other current liabilities	0	3,838
Accrued employee benefits costs	0	0
Industrial revenue bonds	0	0
Total current liabilities	0	5,529
Senior notes payable	0	0
Accrued pension benefits costs — less current portion	0	0
Accrued postretirement benefits costs — less current portion	0	0
Other liabilities	7,418	5,644
Intercompany loan	(634,170)	(706,869)
Deferred taxes	0	0
Total noncurrent liabilities	(626,752)	(701,225)
Series A Preferred stock	0	0
Common stock	(224,424)	(215,424)
Additional paid-in capital	(2,229,161)	(2,286,999)
Treasury stock, at cost	0	0
Accumulated other comprehensive loss	0	0
Retained Earnings (Accumulated Deficit)	1,859,457	1,906,622
Total shareholders’ equity	(594,128)	(595,801)
TOTAL	$ (1,220,880)	$ (1,291,497)

Condensed consolidating fina115

Condensed consolidating financial information - Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities	$ 31,866	$ 207,680	$ 19,718
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(54,700)	(55,126)	(68,077)
Purchase of Sebree smelter	0	(1,042)	(48,058)
Investments in and advances to joint ventures	0	0	(125)
Purchase of remaining interest in Mt. Holly smelter	11,313	(65,100)	0
Proceeds from sale of property, plant and equipment	14	46	525
Restricted and other cash deposits	10	896	(1,439)
Intercompany transactions	0
Net cash used in investing activities	(43,363)	(120,326)	(117,174)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of debt	0	(2,603)	(249,604)
Proceeds from issuance of debt	0	0	246,330
Borrowings under revolving credit facilities	1,737	92,423	22,725
Repayments under revolving credit facilities	(1,737)	(98,423)	(16,725)
Repurchase of common stock	(36,352)	0	0
Debt issuance costs	0	0	(3,994)
Debt retirement costs	0	0	(1,208)
Issuance of common stock	0	403	44
Intercompany transactions	0	0	0
Net cash used in financing activities	(36,352)	(8,200)	(2,432)
CHANGE IN CASH AND CASH EQUIVALENTS	(47,849)	79,154	(99,888)
Cash and cash equivalents, beginning of year	163,242	84,088	183,976
Cash and cash equivalents, end of year	115,393	163,242	84,088
The Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities	25,423	92,338	30,462
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(8,574)	(587)	(1,229)
Purchase of Sebree smelter		(1,042)	(48,058)
Investments in and advances to joint ventures			(125)
Purchase of remaining interest in Mt. Holly smelter	11,313	(65,100)
Proceeds from sale of property, plant and equipment	0	0	0
Restricted and other cash deposits	0	0	0
Intercompany transactions	(4,072)
Net cash used in investing activities	(1,333)	(66,729)	(49,412)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of debt		(2,603)	(249,604)
Proceeds from issuance of debt			246,330
Borrowings under revolving credit facilities	1,737	92,423	16,725
Repayments under revolving credit facilities	(1,737)	(92,423)	(16,725)
Repurchase of common stock	(36,352)
Debt issuance costs			(3,994)
Debt retirement costs			(1,208)
Issuance of common stock		403	44
Intercompany transactions	0	0	0
Net cash used in financing activities	(36,352)	(2,200)	(8,432)
CHANGE IN CASH AND CASH EQUIVALENTS	(12,262)	23,409	(27,382)
Cash and cash equivalents, beginning of year	70,683	47,274	74,656
Cash and cash equivalents, end of year	58,421	70,683	47,274
Combined Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities	30,890	40,711	(70,217)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(21,477)	(22,939)	(17,199)
Purchase of Sebree smelter		0	0
Investments in and advances to joint ventures			0
Purchase of remaining interest in Mt. Holly smelter	0	0
Proceeds from sale of property, plant and equipment	14	0	14
Restricted and other cash deposits	(4)	0	(787)
Intercompany transactions	0
Net cash used in investing activities	(21,467)	(22,939)	(17,972)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of debt		0	0
Proceeds from issuance of debt			0
Borrowings under revolving credit facilities	0	0	0
Repayments under revolving credit facilities	0	0	0
Repurchase of common stock	0
Debt issuance costs			0
Debt retirement costs			0
Issuance of common stock		0	0
Intercompany transactions	(11,883)	(17,801)	87,718
Net cash used in financing activities	(11,883)	(17,801)	87,718
CHANGE IN CASH AND CASH EQUIVALENTS	(2,460)	(29)	(471)
Cash and cash equivalents, beginning of year	(1,187)	(1,158)	(687)
Cash and cash equivalents, end of year	(3,647)	(1,187)	(1,158)
Combined Non-Guarantor Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities	65,085	139,896	82,776
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(24,209)	(31,603)	(49,649)
Purchase of Sebree smelter		0	0
Investments in and advances to joint ventures			0
Purchase of remaining interest in Mt. Holly smelter	0	0
Proceeds from sale of property, plant and equipment	0	46	511
Restricted and other cash deposits	14	896	(652)
Intercompany transactions	0
Net cash used in investing activities	(24,195)	(30,661)	(49,790)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of debt		0	0
Proceeds from issuance of debt			0
Borrowings under revolving credit facilities	0	0	6,000
Repayments under revolving credit facilities	0	(6,000)	0
Repurchase of common stock	0
Debt issuance costs			0
Debt retirement costs			0
Issuance of common stock		0	0
Intercompany transactions	(74,017)	(47,461)	(111,021)
Net cash used in financing activities	(74,017)	(53,461)	(105,021)
CHANGE IN CASH AND CASH EQUIVALENTS	(33,127)	55,774	(72,035)
Cash and cash equivalents, beginning of year	93,746	37,972	110,007
Cash and cash equivalents, end of year	60,619	93,746	37,972
Consolidating Adjustments [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by operating activities	(89,532)	(65,265)	(23,303)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(440)	3	0
Purchase of Sebree smelter		0	0
Investments in and advances to joint ventures			0
Purchase of remaining interest in Mt. Holly smelter	0	0
Proceeds from sale of property, plant and equipment	0	0	0
Restricted and other cash deposits	0	0	0
Intercompany transactions	4,072
Net cash used in investing activities	3,632	3	0
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of debt		0	0
Proceeds from issuance of debt			0
Borrowings under revolving credit facilities	0	0	0
Repayments under revolving credit facilities	0	0	0
Repurchase of common stock	0
Debt issuance costs			0
Debt retirement costs			0
Issuance of common stock		0	0
Intercompany transactions	85,900	65,262	23,303
Net cash used in financing activities	85,900	65,262	23,303
CHANGE IN CASH AND CASH EQUIVALENTS	0	0	0
Cash and cash equivalents, beginning of year	0	0	0
Cash and cash equivalents, end of year	$ 0	$ 0	$ 0

Schedule II - Valuation and 116

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, valuation allowance	$ 748,283	$ 765,023
Balance, valuation allowance	768,764	748,283	$ 765,023
Allowance for doubtful trade accounts receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, valuation allowance	1,000	734	734
Charged to Cost and Expense	0	0	0
Charged to Other Accounts	0	266	0
Deductions	0	0	0
Balance, valuation allowance	1,000	1,000	734
Deferred tax asset - valuation allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, valuation allowance	748,283	765,023	656,352
Charged to Cost and Expense	0	0	0
Charged to Other Accounts	20,481	(16,740)	108,671
Deductions	0	0	0
Balance, valuation allowance	$ 768,764	$ 748,283	$ 765,023