Century Aluminum (CENX) 10-Q 5 Nov 14 2014 Q3 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 31, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'CENTURY ALUMINUM CO	'
Entity Central Index Key	'0000949157	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	88,948,158

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
NET SALES:	'	'	'	'
Third-party customers	$175,857	$271,016	$480,872	$680,480
Related parties	324,775	128,912	898,931	372,659
Sales Revenue – net	500,632	399,928	1,379,803	1,053,139
Cost of goods sold	424,918	387,574	1,267,343	1,028,901
Gross profit	75,714	12,354	112,460	24,238
Other operating expense – net	1,417	2,174	5,705	6,288
Selling, general and administrative expenses	12,146	14,422	32,826	45,875
Operating income (loss)	62,151	-4,242	73,929	-27,925
Interest expense	-5,493	-5,406	-16,541	-17,706
Interest income	23	141	197	458
Net gain (loss) on forward and derivative contracts	353	440	-174	16,151
Gain on bargain purchase	0	0	0	5,253
Loss on early extinguishment of debt	0	0	0	-3,272
Other income (expense) – net	-470	213	-423	-1,001
Income (loss) before income taxes and equity in earnings of joint ventures	56,564	-8,854	56,988	-28,042
Income tax expense	-6,444	-1,384	-7,004	-4,714
Income (loss) before equity in earnings of joint ventures	50,120	-10,238	49,984	-32,756
Equity in earnings of joint ventures	285	731	661	2,118
Net income (loss)	50,405	-9,507	50,645	-30,638
Net income (loss) allocated to common stockholders	$46,277	($9,507)	$46,487	($30,638)
EARNINGS (LOSS) PER COMMON SHARE:	'	'	'	'
Basic and Diluted	$0.52	($0.11)	$0.52	($0.35)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:	'	'	'	'
Basic	88,827	88,611	88,777	88,588
Diluted	89,532	88,611	89,372	88,588

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Comprehensive income (loss):	'	'	'	'
Net income (loss)	$50,405	($9,507)	$50,645	($30,638)
Other comprehensive income (loss) before income tax effect:	'	'	'	'
Net gain on foreign currency cash flow hedges reclassified as income	-46	-46	-139	-139
Net gain arising during the period	'	0	440	10,349
Amortization of prior service benefit during the period	-952	-968	-2,856	-2,912
Amortization of net loss during the period	1,402	1,880	4,207	6,362
Other comprehensive income before income tax effect	404	866	1,652	13,660
Income tax effect	-557	-383	-1,837	-1,148
Other comprehensive income (loss)	-153	483	-185	12,512
Total comprehensive income (loss)	$50,252	($9,024)	$50,460	($18,126)

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS	'	'
Cash and cash equivalents	$133,410	$84,088
Restricted cash	1,217	1,697
Accounts receivable — net	50,576	56,184
Due from affiliates	52,452	43,587
Inventories	241,750	239,615
Prepaid and other current assets	29,101	32,276
Deferred taxes	13,614	13,614
Total current assets	522,120	471,061
Property, plant and equipment — net	1,221,705	1,247,661
Other assets	95,656	91,474
TOTAL	1,839,481	1,810,196
LIABILITIES:	'	'
Accounts payable, trade	89,918	108,490
Due to affiliates	64,917	53,582
Accrued and other current liabilities	46,007	69,466
Accrued employee benefits costs	8,672	8,410
Industrial revenue bonds	7,815	7,815
Total current liabilities	217,329	247,763
Senior notes payable	246,796	246,528
Accrued pension benefits costs — less current portion	40,322	39,848
Accrued postretirement benefits costs — less current portion	129,130	129,284
Other liabilities	38,879	37,743
Deferred taxes	112,694	106,218
Total noncurrent liabilities	567,821	559,621
COMMITMENTS AND CONTINGENCIES (NOTE 10)	'	'
SHAREHOLDERS' EQUITY:	'	'
Series A Preferred stock (one cent par value, 5,000,000 shares authorized; 160,000 issued and 78,670 outstanding at September 30, 2014; 160,000 issued and 79,620 outstanding at December 31, 2013)	1	1
Common stock (one cent par value, 195,000,000 shares authorized; 93,724,391 issued and 88,937,870 outstanding at September 30, 2014; 93,496,798 issued and 88,710,277 outstanding at December 31, 2013)	937	935
Additional paid-in capital	2,509,631	2,508,574
Treasury stock, at cost	-49,924	-49,924
Accumulated other comprehensive loss	-92,017	-91,832
Accumulated deficit	-1,314,297	-1,364,942
Total shareholders’ equity	1,054,331	1,002,812
TOTAL	$1,839,481	$1,810,196

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Series A Preferred stock, par value (in dollars per share)	$0.01	$0.01
Series A Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Series A Preferred stock, shares issued (in shares)	160,000	160,000
Series A Preferred stock, shares outstanding (in shares)	78,670	79,620
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized (in shares)	195,000,000	195,000,000
Common stock, shares issued (in shares)	93,724,391	93,496,798
Common stock, shares outstanding (in shares)	88,937,870	88,710,277

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net income (loss)	$50,645	($30,638)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:	'	'
Unrealized net gain on forward contracts	0	-762
Gain on bargain purchase	0	-5,253
Unrealized gain on E.ON contingent obligation	-1,059	-16,428
Accrued and other plant curtailment costs — net	3,267	3,380
Lower of cost or market inventory adjustment	-1,247	10,286
Depreciation	52,784	49,082
Sebree power contract amortization	-5,534	-14,461
Debt discount amortization	268	586
Pension and other postretirement benefits	1,432	-2,674
Deferred income taxes	6,502	-1,532
Stock-based compensation	957	961
Loss on early extinguishment of debt	0	3,272
Equity in earnings of joint ventures, net of dividends	-661	-2,118
Change in operating assets and liabilities:	'	'
Accounts receivable — net	5,608	-1,063
Due from affiliates	-8,866	12,915
Inventories	-889	-22,848
Prepaid and other current assets	3,035	-4,892
Accounts payable, trade	-8,885	26,547
Due to affiliates	11,336	32,002
Accrued and other current liabilities	-7,566	2,209
Other — net	-3,413	3,887
Net cash provided by operating activities	97,714	42,458
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Purchase of property, plant and equipment	-26,865	-31,994
Nordural expansion — Helguvik	-277	-2,855
Purchase of carbon anode assets and improvements	-12,280	-8,519
Purchase of Sebree smelter	-1,042	-48,058
Proceeds from sale of property, plant and equipment	46	515
Restricted and other cash deposits	480	-3,015
Net cash used in investing activities	-39,938	-93,926
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Repayment of debt	-2,603	-249,604
Proceeds from issuance of debt	0	246,330
Borrowings under revolving credit facilities	91,731	16,725
Repayments under revolving credit facilities	-97,731	0
Debt issuance costs	0	-3,994
Debt retirement costs	0	-1,208
Issuance of common stock	149	44
Net cash provided by (used in) financing activities	-8,454	8,293
CHANGE IN CASH AND CASH EQUIVALENTS	49,322	-43,175
Cash and cash equivalents, beginning of period	84,088	183,976
Cash and cash equivalents, end of period	$133,410	$140,801

General

General	9 Months Ended
	Sep. 30, 2014
General [Abstract]	'
General	'
	General
	The accompanying unaudited interim consolidated financial statements of Century Aluminum Company should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2013. In management’s opinion, the unaudited interim consolidated financial statements reflect all adjustments, which are of a normal and recurring nature, that are necessary for a fair presentation of financial results for the interim periods presented. Operating results for the first nine months of 2014 are not necessarily indicative of the results that may be expected for the year ending December 31, 2014. Throughout this Form 10-Q, and unless expressly stated otherwise or as the context otherwise requires, "Century Aluminum," "Century," the "Company", "we," "us," "our" and "ours" refer to Century Aluminum Company and its consolidated subsidiaries.

Acquisition_of_Sebree_aluminum

Acquisition of Sebree aluminum smelter	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Acquisition of Sebree aluminum smelter	'
	Acquisition of Sebree aluminum smelter
	On June 1, 2013, our wholly owned subsidiary, Century Aluminum Sebree LLC ("Century Sebree"), acquired the Sebree aluminum smelter ("Sebree") from a subsidiary of Rio Tinto Alcan, Inc. ("RTA"). Sebree, located in Robards, Kentucky, has an annualized hot metal production capacity of 205,000 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.
	Working Capital Adjustment
	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 defined under ASC 805, 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 (expense) - net, from the release of accrued amounts related to the acquisition.
	Purchase Price Allocation
	Allocating the purchase price to the acquired assets and liabilities involves management judgment. We allocated the purchase price in accordance with Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") 805 "Business Combinations" using the estimated fair values at the date of acquisition. Based on the final purchase price allocation, we 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 post retirement benefit costs	6,544
	Other liabilities	7,476
	Deferred taxes	3,233
	Total liabilities assumed	$	61,565
	Gain on bargain purchase:	$	5,253
	The following unaudited pro forma financial information for the three and nine months ended September 30, 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.
		Nine months ended September 30,
		2013
	Pro forma revenues	$	1,261,533
	Pro forma loss from continuing operations	(57,853		)
	Loss per common share, basic	(0.65		)
	Loss per common share, diluted	(0.65		)
	Our net income for the three months ended September 30, 2014 and 2013, includes a non-recurring credit for the amortization of the deferred power contract liability of $0 and $11,720, respectively. Our net income for the nine months ended September 30, 2014 and 2013 includes a non-recurring credit for the amortization of the deferred power contract liability of $5,534 and $14,461, 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.

Fair_value_measurements

Fair value measurements	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair value measurements	'
	Fair value measurements
	The following section describes the valuation methodology used to measure our financial assets and liabilities that were accounted for at fair value and are categorized based on the fair value hierarchy described in ASC 820 "Fair Value Measurements and Disclosures."
	Overview of Century’s valuation methodology
		Level	Significant inputs
	Cash equivalents	1	Quoted market prices
	Trust assets (1)	1	Quoted market prices
	Surety bonds	1	Quoted market prices
	E.ON ("E.ON") contingent obligation	3	Quoted London Metal Exchange ("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 at Century Aluminum of Kentucky, our wholly owned subsidiary ("CAKY")
	Primary aluminum sales contract	3	Management’s estimates of future U.S. Midwest premium and risk-adjusted discount rates
	Midwest premium contracts	3	Management’s estimates of future U.S. Midwest premium
	-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.
	Fair value measurements
	Our fair value measurements include the consideration of market risks that other market participants might consider in pricing the particular asset or liability, specifically non-performance risk and counterparty credit risk. Consideration of the non-performance risk and counterparty credit risk are used to establish the appropriate risk-adjusted discount rates used in our fair value measurements.
	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.  As required by generally accepted accounting principles in the United States ("GAAP") for fair value measurements and disclosures, financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.  Our assessment of the significance of a particular input to the fair value measurement requires judgment, and may affect the valuation of fair value assets and liabilities and the placement within the fair value hierarchy levels. There were no transfers between Level 1 and 2 during the periods presented. There were no transfers into or out of Level 3 during the periods presented. It is our policy to recognize transfers into and transfers out of Level 3 as of the actual date of the event or change in circumstances that caused the transfer.
	Recurring Fair Value Measurements	As of September 30, 2014
		Level 1			Level 2			Level 3		Total
	ASSETS:
	Cash equivalents	$	125,960		$	—		$	—	$	125,960
	Trust assets	8,835			—			—		8,835
	Surety bonds	1,987			—			—		1,987
	TOTAL	$	136,782		$	—		$	—	$	136,782
	LIABILITIES:
	E.ON contingent obligation – net (1)	$	—		$	—		$	—	$	—
	TOTAL	$	—		$	—		$	—	$	—
	Recurring Fair Value Measurements	As of December 31, 2013
		Level 1			Level 2			Level 3		Total
	ASSETS:
	Cash equivalents	$	49,658		$	—		$	—	$	49,658
	Trust assets	11,151			—			—		11,151
	Surety bonds	2,002			—			—		2,002
	Midwest premium contracts	—			—			140		140
	TOTAL	$	62,811		$	—		$	140	$	62,951
	LIABILITIES:
	E.ON contingent obligation – net (1)	$	—		$	—		$	—	$	—
	Primary aluminum sales contract	—			—			140		140
	TOTAL	$	—		$	—		$	140	$	140
	-1	See Note 9 Debt for additional information about the E.ON contingent obligation.
	Change in Level 3 Fair Value Measurements during the three months ended September 30,
		Derivative liabilities - net
		2014			2013
	Beginning balance, July 1,	$	—		$	(773	)
	Total gain included in earnings	—			365
	Ending balance, September 30,	$	—		$	(408	)
	Amount of gain included in earnings attributable to the change in unrealized losses relating to assets and liabilities held at September 30,	$	—		$	365
	Change in Level 3 Fair Value Measurements during the nine months ended September 30,
		Derivative liabilities - net
		2014			2013
	Beginning balance, January 1,	$	—		$	(16,539	)
	Total gain (loss) included in earnings	(940		)	16,131
	Settlements	940			—
	Ending balance, September 30,	$	—		$	(408	)
	Amount of gain included in earnings attributable to the change in unrealized losses relating to assets and liabilities held at September 30,	$	—		$	16,131
	The net gain (loss) on our derivative assets and liabilities is recorded in our consolidated statements of operations under net gain (loss) on forward and derivative contracts. See Note 4 Derivative and hedging instruments for the location of our Level 3 derivative assets and liabilities within our consolidated balance sheets.

Derivative_and_hedging_instrum

Derivative and hedging instruments	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative and hedging instruments	'
	Derivative and hedging instruments
	The following table provides the fair value and balance sheet classification of our derivatives:
	Fair Value of Derivative Assets and Liabilities
		Balance sheet location	September 30, 2014			December 31, 2013
	DERIVATIVE ASSETS:
	Midwest premium contracts	Prepaid and other current assets	$	—		$	140
	TOTAL		$	—		$	140
	DERIVATIVE LIABILITIES:
	Primary aluminum sales contract	Accrued and other current liabilities	$	—		$	140
	E.ON contingent obligation – net (1)	Other liabilities	—			—
	TOTAL		$	—		$	140
	-1	See Note 9 Debt for additional information about the E.ON contingent obligation.
	Midwest premium contracts
	We entered into a fixed-price forward contract that settled monthly from January 2014 to March 2014 based on the
	Midwest premium price published in the Platts Metals Week for the applicable period. Losses associated with the settlements of the U.S. Midwest premium contracts were recorded in net gain (loss) on forward and derivative contracts on the consolidated
	statement of operations.
	Primary aluminum sales contract
	We had a contract to sell to Glencore plc (together with its subsidiaries, "Glencore") primary aluminum produced at Mt. Holly, Hawesville and Sebree through December 31, 2013 (the "Glencore Metal Agreement"). The Glencore Metal Agreement was a physical delivery contract for primary aluminum with variable, LME-based pricing.  Under the Glencore Metal Agreement, pricing was based on market prices, adjusted by a negotiated U.S. Midwest premium with a cap and a floor as applied to the current U.S. Midwest premium.  We accounted for the Glencore Metal Agreement as a derivative instrument under ASC 815 "Derivatives and Hedging."  Gains and losses on the derivative were based on the difference between the contracted U.S. Midwest premium and actual and forecasted U.S. Midwest premiums.  Settlements were recorded in related party sales.  Unrealized gains (losses) based on forecasted U.S. Midwest premiums were recorded in net gain (loss) on forward and derivative contracts on the consolidated statements of operations.
	Derivatives not designated as hedging instruments:
		Gain (loss) recognized in income from derivatives
			Three months ended September 30,						Nine months ended September 30,
		Location	2014			2013			2014			2013
	E.ON contingent obligation – net	Net gain (loss) on forward and derivative contracts	$	353		$	353		$	1,059		$	16,428
	Midwest premium contracts	Net gain (loss) on forward and derivative contracts	—			363			(1,080		)	363
	Primary aluminum sales contract	Related party sales	—			278			292			1,039
	Primary aluminum sales contract	Net gain (loss) on forward and derivative contracts	—			(276		)	(153		)	(640		)
	E.ON contingent obligation – net	Interest expense – third party	(353		)	(353		)	(1,059		)	(1,059		)
	We had the following outstanding forward contracts that were not designated as hedging instruments:
		September 30, 2014		December 31, 2013
	Primary aluminum sales contract premium (tonnes) (1)	—		1,782
	Midwest premium contracts (tonnes)	—		6,000
	-1	Represents the remaining physical deliveries under the Glencore Metal Agreement.
	Counterparty credit risk. Forward financial contracts are subject to counterparty credit risk.  However, we only enter into forward financial contracts with counterparties we determine to be creditworthy at the time of entering into the contract.  If any counterparty failed to perform according to the terms of the contract, the impact would be limited to the difference between the contract price and the market price applied to the contract volume on the date of settlement.

Earnings_per_share

Earnings per share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings (loss) per share	'
	Earnings (loss) per share
	Basic earnings (loss) per share ("EPS") amounts are calculated by dividing earnings 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.
	Our Series A Convertible Preferred Stock has similar characteristics to a "participating security" as described by ASC 260 "Earnings Per Share" and we calculate the amount of earnings (loss) available to common shareholders and basic EPS using the Two-Class Method earnings allocation formula, allocating undistributed income to our preferred 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.  The holders of our convertible preferred stock do not have a contractual obligation to share in our losses.  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.
	The following table shows the basic and diluted earnings (loss) per share for the three and nine months ended September 30, 2014 and 2013:
		For the three months ended September 30,
		2014							2013
		Income			Shares (000)		Per-Share		Loss			Shares (000)	Per-Share
	Net income (loss)	$	50,405						$	(9,507	)
	Amount allocated to common stockholders (1)	91.81		%					100		%
	Basic EPS:
	Income (loss) allocable to common stockholders	46,277			88,827		$	0.52	(9,507		)	88,611	$	(0.11	)
	Effect of Dilutive Securities:
	Share-based compensation plans	—			705				—			—
	Diluted EPS:
	Income (loss) applicable to common stockholders with assumed conversion	$	46,277		89,532		$	0.52	$	(9,507	)	88,611	$	(0.11	)
		For the nine months ended September 30,
		2014							2013
		Income			Shares (000)		Per-Share		Loss			Shares (000)	Per-Share
	Net income (loss)	$	50,645						$	(30,638	)
	Amount allocated to common stockholders (1)	91.79		%					100		%
	Basic EPS:
	Income (loss) allocable to common stockholders	46,487			88,777		$	0.52	(30,638		)	88,588	$	(0.35	)
	Effect of Dilutive Securities:
	Share-based compensation plans	—			595				—			—
	Diluted EPS:
	Income (loss) applicable to common stockholders with assumed conversion	$	46,487		89,372		$	0.52	$	(30,638	)	88,588	$	(0.35	)
	-1	We have not allocated net losses between common and preferred stockholders, as the holders of our preferred shares do not have a contractual obligation to share in the loss.
	Securities excluded from the calculation of diluted EPS:	Three months ended September 30,				Nine months ended September 30,
		2014		2013		2014		2013
	Stock options (1)	338,433		620,334		344,433		620,334
	Service-based share awards (1)	—		573,628		—		522,032
	-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.

Shareholders_equity

Shareholders' equity	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Shareholders' equity	'
	Shareholders’ equity
	Common Stock
	Under our Restated Certificate of Incorporation, our Board of Directors is authorized to issue up to 195,000,000 shares of our common stock.
	The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock which are currently outstanding, including our Series A Convertible Preferred Stock, or which we may designate and issue in the future.
	Stock Repurchase Program
	In August 2011, our Board of Directors approved a stock repurchase program. Under the program, we may repurchase up to $60,000 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 is determined by our management based on its evaluation of market conditions, the trading price of the stock and other factors. The repurchase program may be expanded, 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.
	From August 11, 2011 through September 30, 2014, we repurchased 4,786,521 shares of common stock for an aggregate purchase price of $49,924. We have made no repurchases since March 2012 and had approximately $10,076 remaining under the repurchase program authorization as of September 30, 2014.
	Series A Convertible Preferred Stock
	Glencore holds all of the issued and outstanding Series A Convertible Preferred Stock. 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 Common and Preferred Stock Activity table below contains additional information about preferred stock conversions during the nine months ended September 30, 2014 and 2013.
	Common and Preferred Stock Activity:	Preferred stock		Common stock
	(in shares)	Series A convertible		Treasury	Outstanding
	Beginning balance as of December 31, 2013	79,620		4,786,521	88,710,277
	Conversion of convertible preferred stock	(950	)	—	95,039
	Issuance for share-based compensation plans	—		—	132,554
	Ending balance as of September 30, 2014	78,670		4,786,521	88,937,870
	Beginning balance as of December 31, 2012	80,283		4,786,521	88,548,637
	Conversion of convertible preferred stock	(549	)	—	54,825
	Issuance for share-based compensation plans	—		—	79,469
	Ending balance as of September 30, 2013	79,734		4,786,521	88,682,931

Income_taxes

Income taxes	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income taxes	'
	Income taxes
	We recorded income tax expense for the nine months ended September 30, 2014 of $7,004, which primarily consisted of foreign and state income taxes. Our domestic deferred tax assets, net of deferred tax liabilities, are subject to a valuation allowance; therefore, the domestic losses were not benefited.
	We recorded income tax expense for the nine months ended September 30, 2013 of $4,714, which primarily consisted of foreign and state income taxes.
	Our income tax benefit or expense is based on an annual effective tax rate forecast, including estimates and assumptions that could change during the year. The application of the requirements for accounting for income taxes in interim periods, after consideration of our valuation allowance, causes a significant variation in the typical relationship between income tax expense and pretax accounting income.
	As of September 30, 2014, all of Century's U.S. and certain foreign deferred tax assets, net of deferred tax liabilities, continue to be subject to a valuation allowance. The realization of these assets is dependent on substantial future taxable income which, at September 30, 2014, is not more likely than not to be achieved.
	Our Icelandic tax returns are subject to examination beginning with the 2008 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.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2014
Inventory, Net [Abstract]	'
Inventories	'
	Inventories
	Inventories consist of the following:	September 30, 2014		December 31, 2013
	Raw materials	$	67,145	$	69,776
	Work-in-process	21,597		22,183
	Finished goods	16,722		17,661
	Operating and other supplies	136,286		129,995
	Inventories	$	241,750	$	239,615
	Inventories are stated at the lower of cost or market, using the first-in, first-out method.

Debt

Debt	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
		September 30, 2014			December 31, 2013
	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
	7.5% senior unsecured notes due August 15, 2014, interest payable semiannually (2)(3)	—			2,603
	Iceland revolving credit facility (3)(4)	—			6,000
	Debt classified as non-current liabilities:
	7.5% senior secured notes due June 1, 2021, net of debt discount of $3,204 and $3,472, respectively, interest payable semiannually	246,796			246,528
	TOTAL	$	254,611		$	262,946
	-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 September 30, 2014 was 0.24%.
	-2	The amount outstanding was repaid upon maturity.
	-3	These items are recorded in accrued and other current liabilities based on the repayment terms and expected maturity.
	-4	Borrowings under the Iceland revolving credit facility bear variable interest based on LIBOR plus the applicable margin per annum. The interest rate at December 31, 2013 was 3.92%.
	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 (the "U.S. revolving credit facility"), dated May 24, 2013, as amended. The U.S. revolving credit facility has a term through May 24, 2018 and provides for borrowings of up to $150,000 in the aggregate, including up to $80,000 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. See Note 17 Subsequent events for additional information about an amendment to the U.S. revolving credit facility.
	Status of our U.S. revolving credit facility:
		September 30, 2014
	Credit facility maximum amount	$	148,560
	Borrowing availability, net of outstanding letters of credit	76,327
	Outstanding borrowings	—
	Letter of credit sub-facility amount	80,000
	Outstanding letters of credit issued	72,233
	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 that varies depending on whether the letter of credit exposure is cash collateralized.
	Iceland Revolving Credit Facility
	General. Nordural Grundartangi ehf, as borrower, and Landsbankinn hf., as lender, entered into a three-year $50,000 Committed Revolving Credit Facility agreement (the "Iceland revolving credit facility"), dated November 27, 2013. Grundartangi may in the future use the Iceland revolving credit facility to repay existing indebtedness or to finance capital expenditures and for ongoing working capital needs and other general corporate purposes. 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:
		September 30, 2014
	Credit Facility maximum amount	$	50,000
	Borrowing availability	50,000
	Outstanding borrowings	—
	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 the margin per annum.
	7.5% Notes due 2021
	General.  On June 4, 2013, we issued $250,000 of our 7.5% Notes due 2021 (the "7.5% Notes") in a private offering exempt from the registration requirements of the Securities Act of 1933, as amended.  The 7.5% Notes were issued at a discount and we received proceeds of $246,330, prior to payment of financing fees and related expenses.
	Interest rate.  The 7.5% Notes bear interest at 7.5% per annum on the principal amount, payable semi-annually in arrears in cash on June 1 and December 1 of each year.
	Maturity.  The 7.5% Notes mature on June 1, 2021.
	E.ON contingent obligation
	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.
	Based on the LME forward market prices for primary aluminum at September 30, 2014 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 $1,059 and $16,428 in net gain (loss) on forward and derivative contracts for the nine months ended September 30, 2014 and 2013, respectively. 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	30-Sep-14			31-Dec-13
	E.ON contingent obligation – principal	Other liabilities	$	(12,902	)	$	(12,902	)
	E.ON contingent obligation – accrued interest	Other liabilities	(4,938		)	(3,879		)
	E.ON contingent obligation – derivative asset	Other liabilities	17,840			16,781
			$	—		$	—

Commitments_and_contingencies

Commitments and contingencies	9 Months Ended
	Sep. 30, 2014
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.
	It is our policy to accrue for costs associated with environmental assessments and remedial efforts when it becomes probable that a liability has been incurred and the costs can be reasonably estimated. The aggregate environmental-related accrued liabilities were $1,340 and $999 at September 30, 2014 and December 31, 2013, 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 September 30, 2014, we have expended approximately $1,033 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, but the Superior Court of the Virgin Islands, Division of St. Croix has not yet ruled on the motions. At this time, it is not practicable 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, Century Aluminum of West Virginia ("CAWV") filed a class action complaint for declaratory judgment against the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union ("USWA"), the USWA’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 USWA 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 January 2010, the USWA filed a motion for preliminary injunction to prevent us from implementing any modifications to the retiree medical benefits while these lawsuits are pending, which was dismissed by the trial court, and affirmed upon appeal. CAWV has filed a motion for summary judgment of these actions. The case in chief is currently proceeding in the trial court, subject to the court’s ruling on the motion for summary judgment.
	PBGC Settlement
	In June 2011, the Pension Benefit Guaranty Corporation (the "PBGC") informed us that it believed a "cessation of operations" under ERISA had occurred at our Ravenswood facility as a result of the curtailment of operations at the facility. Although we disagree that a "cessation of operations" occurred, we entered into a settlement agreement with the PBGC in April 2013 to resolve the matter. Pursuant to the terms of the agreement, we will make additional contributions (above any minimum required contributions) to our defined benefit pension plans totaling approximately $17,400 over the term of the agreement. During 2013, we made contributions pursuant to this agreement of approximately $6,700. 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. In the first quarter of 2014, we elected to defer contributions for 2014 under the PBGC agreement and have provided the PBGC with the appropriate security.
	Power Commitments and Contingencies
	Hawesville
	We are party to a power supply arrangement with Kenergy and Big Rivers, in effect since August 2013, which provides market-based power to the Hawesville smelter. Under this arrangement, the power companies purchase power on the open market and pass it through to Hawesville at Midcontinent Independent System Operator ("MISO") pricing plus transmission and other costs incurred by them. In connection with this power arrangement, CAKY has received approval from applicable regional transmission organizations and regulatory bodies regarding grid stability and energy import capability.
	Sebree
	We are party to a power supply arrangement with Kenergy and Big Rivers, effective since January 2013, which provides market-based power to the Sebree smelter. Similar to the arrangement at Hawesville, the power companies purchase power on the open market and pass it through to Sebree at MISO pricing plus transmission and other costs incurred by them.
	Mt. Holly
	Mt. Holly has a power purchase agreement (the "Santee Cooper Agreement") with the South Carolina Public Service Authority ("Santee Cooper") with a term through December 2015.  The Santee Cooper Agreement provides power for Mt. Holly’s full production capacity requirements at prices based on published rate schedules (which are subject to change), with adjustments for fuel prices and other items.  The Santee Cooper Agreement restricts Mt. Holly’s ability to reduce its power consumption (or the associated payment obligations) below contracted levels and to terminate the agreement, unless, in each case, the LME falls below certain negotiated levels.
	In 2012, Mt. Holly and Santee Cooper amended the terms of the Santee Cooper Agreement in order to allow Mt. Holly to receive all or a portion of Mt. Holly's supplemental power requirements from an off-system natural gas-fired power generation facility (the "off-system facility").  The energy charge for supplemental power from the off-system facility is based, among other factors, on the cost of natural gas rather than Santee Cooper's system average fuel costs, which are primarily coal-based. The amended power agreement provides that Mt. Holly may continue to receive its supplemental power requirements from the off-system facility through December 31, 2015.
	On June 30, 2014, Mt. Holly gave notice to Santee Cooper under the Santee Cooper Agreement to reduce the contract demand to zero effective December 31, 2015. We are continuing discussions with Santee Cooper and other parties regarding power arrangements for Mt. Holly following December 31, 2015.
	Ravenswood
	CAWV has a power purchase agreement (the "APCo Agreement") with the Appalachian Power Company ("APCo").  CAWV currently purchases a limited amount of power under the APCo Agreement as necessary to maintain its Ravenswood smelter, which is presently curtailed.  Power is supplied under the APCo Agreement at prices set forth in published tariffs (which are subject to change), with certain adjustments.
	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 the fourth quarter of 2011, an additional 47.5 MW of power became available under a power purchase agreement with OR. This power can be used at either Grundartangi or Helguvik and is currently being utilized at Grundartangi.
	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 has agreed to make 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 September 30, 2014, these power prepayments totaled approximately $2,267. We do not expect to realize the benefits from the prepayments in the near term.
	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 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.
	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.  Nordural Helguvik ehf is in discussions with both HS and OR with respect to such conditions and other matters pertaining to these agreements.
	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' renewed claims are without merit and intends to defend itself against them.
	In June 2014, Nordural Helguvik ehf entered into a supplemental power contract with OR. The supplemental power contract 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
	Approximately 73% of our U.S. based work force is represented by the USWA. CAKY’s Hawesville employees represented by the USWA are under a collective bargaining agreement that expires on March 31, 2015. The Sebree employees represented by the USWA are under a collective bargaining agreement that expires on October 28, 2019.
	Approximately 82% of Grundartangi’s work force is represented by five labor unions, governed by a labor agreement that expires on December 31, 2014.
	Approximately 77% of Vlissingen's work force is represented by the Federation for the Metal and Electrical Industry ("FME"), governed by a labor agreement that expires on May 1, 2015.
	The labor agreement for CAWV’s Ravenswood plant employees represented by the USWA expired on August 31, 2010.

Forward_delivery_contracts_and

Forward delivery contracts and financial instruments	9 Months Ended
	Sep. 30, 2014
Forward Delivery Contracts and Financial Instruments [Abstract]	'
Forward delivery contracts and financial instruments	'
		Forward delivery contracts and financial instruments
	As a producer of primary aluminum, we are exposed to fluctuating raw material and primary aluminum prices. From time to time we enter into fixed and market priced contracts for the sale of primary aluminum and the purchase of raw materials in future periods.
	Forward Physical Delivery Agreements
	Primary Aluminum Sales Contracts
	Contract	Customer	Volume	Term	Pricing
	Glencore Grundartangi Metal Agreement (1)	Glencore	All primary aluminum produced at Grundartangi, net of tolling and other sales commitments	January 1, 2014 through December 31, 2017	Variable, based on LME and European Duty Paid premium
	Southwire Metal Agreement (2)	Southwire	216 million pounds per year (high conductivity molten aluminum)	January 1, 2014 through December 31, 2014	Variable, based on U.S. Midwest Transaction Price
	-1	The Glencore Grundartangi Metal Agreement is for all metal produced at Grundartangi from 2014 through 2017 less commitments under existing tolling and other sales contracts.  Grundartangi currently estimates that it will sell Glencore approximately 155,000 tonnes of aluminum under this agreement in 2014.
	-2	Southwire may, at its option, increase the volume purchased under the agreement by up to four percent by adjusting their monthly metal commitment.
	Tolling Contracts
	Contract	Customer	Volume	Term	Pricing
	Glencore Toll Agreement	Glencore	90,000 tonnes per year ("tpy")	Through July 2016	Variable, based on LME and European Duty Paid premium
	Glencore Toll Agreement	Glencore	49,000 tpy	Through December 31, 2014	Variable, based on LME and European Duty Paid premium
	Apart from the Glencore Grundartangi Metal Agreement, the Southwire Metal Agreement and the Glencore Sweep
	Agreement (a contract for all metal produced in the U.S. in 2013, less existing sales agreements and valued-added metal sales, which expired at the end of 2013), we had the following forward delivery contractual commitments:
	Other forward delivery contracts
		September 30, 2014		December 31, 2013
		(in tonnes)
	Other forward delivery contracts – total	72,025		118,373
	Other forward delivery contracts – Glencore	40,760		20,008
	Other forward delivery contracts – fixed price	500		—
	Other forward delivery contracts – fixed price with Glencore	480		—
	We had no outstanding primary aluminum forward financial sales contracts at September 30, 2014. We had no fixed price forward financial contracts to purchase aluminum at September 30, 2014.
	Forward Financial Instruments
	We are party to various forward financial and physical delivery contracts, which are accounted for as derivative instruments. See Note 4 Derivative and hedging instruments for additional information about these instruments.

Supplemental_cash_flow_informa

Supplemental cash flow information	9 Months Ended
	Sep. 30, 2014
Supplemental Cash Flow Information [Abstract]	'
Supplemental cash flow information	'
	Supplemental cash flow information
		Nine months ended September 30,
		2014		2013
	Cash paid for:
	Interest	$	9,684	$	11,293
	Income/withholding taxes (1)	10,079		27,254
	Non-cash investing activities:
	Accrued capital costs	$	663	$	5,734
	-1	We paid withholding taxes in Iceland on intercompany dividends of $5,491 and $18,067 during the nine months ended September 30, 2014 and 2013, respectively. Our tax payments in Iceland for withholding taxes, income taxes and any associated refunds are denominated in Icelandic kronur ("ISK").

Asset_retirement_obligations_A

Asset retirement obligations (“ARO”)	9 Months Ended
	Sep. 30, 2014
Asset Retirement Obligation Disclosure [Abstract]	'
Asset retirement obligations (“ARO”)	'
	Asset retirement obligations ("ARO")
	Our asset retirement obligations consist primarily of costs associated with the disposal of spent pot liner used in the reduction cells of our domestic facilities.
	The reconciliation of the changes in the asset retirement obligations is presented below:
		Nine months ended September 30, 2014			Year ended December 31, 2013
	Beginning balance, ARO liability	$	27,113		$	16,124
	Additional ARO liability incurred	1,493			1,730
	ARO liabilities settled	(3,547		)	(2,580		)
	Accretion expense	1,114			1,733
	Additional ARO liability from Sebree acquisition	—			10,106
	Ending balance, ARO liability	$	26,173		$	27,113
	Certain conditional AROs related to the disposal costs of fixed assets at our primary aluminum facilities have not been recorded because they have an indeterminate settlement date. These conditional AROs will be initially recognized in the period in which sufficient information exists to estimate their fair value.

Components_of_Accumulated_othe

Components of Accumulated other comprehensive loss	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Components of accumulated other comprehensive loss	'
	Components of accumulated other comprehensive loss
		September 30, 2014			December 31, 2013
	Defined benefit plan liabilities	$	(90,386	)	$	(92,177	)
	Equity in investee other comprehensive income (1)	(12,651		)	(12,650		)
	Unrealized loss on financial instruments	(1,202		)	(1,064		)
	Other comprehensive loss before income tax effect	(104,239		)	(105,891		)
	Income tax effect (2)	12,222			14,059
	Accumulated other comprehensive loss	$	(92,017	)	$	(91,832	)
	-1	The amount includes our equity in the other comprehensive income of Mt. Holly.
	(2)The allocation of the income tax effect to the components of other comprehensive income is as follows:
		30-Sep-14			31-Dec-13
	Defined benefit plan liabilities	$	12,445		$	14,256
	Equity in investee other comprehensive income	368			418
	Unrealized loss on financial instruments	(591		)	(615		)
	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, July 1, 2014	$	(77,843	)	$	(12,266	)	$	(1,755	)	$	(91,864	)
	Other comprehensive income (loss) before reclassifications	—			(17		)	—			(17		)
	Net amount reclassified to net income	(98		)	—			(38		)	(136		)
	Balance, September 30, 2014	$	(77,941	)	$	(12,283	)	$	(1,793	)	$	(92,017	)
	Balance, July 1, 2013	$	(125,302	)	$	(12,258	)	$	(1,603	)	$	(139,163	)
	Other comprehensive income (loss) before reclassifications	—			(17		)	—			(17		)
	Net amount reclassified to net loss	538			—			(38		)	500
	Balance, September 30, 2013	$	(124,764	)	$	(12,275	)	$	(1,641	)	$	(138,680	)
	Balance, December 31, 2013	$	(77,921	)	$	(12,232	)	$	(1,679	)	$	(91,832	)
	Other comprehensive income (loss) before reclassifications	440			(51		)	—			389
	Net amount reclassified to net income	(460		)	—			(114		)	(574		)
	Balance, September 30, 2014	$	(77,941	)	$	(12,283	)	$	(1,793	)	$	(92,017	)
	Balance, December 31, 2012	$	(137,441	)	$	(12,224	)	$	(1,527	)	$	(151,192	)
	Other comprehensive income (loss) before reclassifications	10,349			(51		)	—			10,298
	Net amount reclassified to net loss	2,328			—			(114		)	2,214
	Balance, September 30, 2013	$	(124,764	)	$	(12,275	)	$	(1,641	)	$	(138,680	)
	Reclassifications out of AOCI were included in the consolidated statements of operations as follows:
			For the three months ended September 30,						For the nine months ended September 30,
	AOCI Components	Location	2014			2013			2014			2013
	Defined benefit plan and other postretirement liabilities	Cost of goods sold	$	308		$	764		$	924		$	2,758
		Selling, general and administrative expenses	142			148			427			692
		Income tax expense	(548		)	(374		)	(1,811		)	(1,122		)
		Net of tax	$	(98	)	$	538		$	(460	)	$	2,328
	Equity in investee other comprehensive income	Cost of goods sold	$	—		$	—		$	—		$	—
		Income tax expense	(17		)	(17		)	(51		)	(51		)
		Net of tax	$	(17	)	$	(17	)	$	(51	)	$	(51	)
	Unrealized loss on financial instruments	Cost of goods sold	$	(46	)	$	(46	)	$	(139	)	$	(139	)
		Income tax expense	8			8			25			25
		Net of tax	$	(38	)	$	(38	)	$	(114	)	$	(114	)

Components_of_net_periodic_ben

Components of net periodic benefit cost	9 Months Ended
	Sep. 30, 2014
Components of net periodic benefit cost [Abstract]	'
Components of net periodic benefit cost	'
	Components of net periodic benefit cost
		Pension Benefits
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Service cost	$	1,333		$	1,686		$	3,999		$	3,292
	Interest cost	2,871			2,903			8,612			6,293
	Expected return on plan assets	(3,550		)	(3,723		)	(10,648		)	(7,337		)
	Amortization of prior service costs	9			30			27			85
	Amortization of net loss	477			723			1,430			2,428
	Curtailment	—			—			—			(18		)
	Net periodic benefit cost	$	1,140		$	1,619		$	3,420		$	4,743
		Other Postretirement Benefits ("OPEB")
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Service cost	$	397		$	700		$	1,191		$	1,862
	Interest cost	1,603			1,474			4,809			4,230
	Amortization of prior service cost	(961		)	(998		)	(2,883		)	(2,997		)
	Amortization of net loss	925			1,157			2,777			3,934
	Curtailment	—			—			—			(20		)
	Net periodic benefit cost	$	1,964		$	2,333		$	5,894		$	7,009
	Employer contributions
	During the nine months ended September 30, 2014, we made contributions of approximately $3,296 to the qualified defined benefit plans we sponsor.

Recently_issued_accounting_sta

Recently issued accounting standards updates Recently issued accounting standards updates	9 Months Ended
	Sep. 30, 2014
New Accounting Pronouncement or Change in Accounting Principle, Current Period Disclosures [Abstract]	'
Recently issued accounting standards updates	'
	Recently issued accounting standards updates
	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.
	The core principal of the new revenue model is that "an entity recognizes revenue for the transfer of promised goods and services to customers in the amount that reflects the expected consideration for those goods and services." When applying the revenue model to contracts within the scope of the ASU, an entity:
	•	identifies the contract with a customer
	•	identifies the performance obligations in the contract
	•	determines the transaction price
	•	allocates the transaction price to the performance obligations in the contract
	•	recognizes revenue when (or as) the entity satisfies the performance obligations.
	Compared with current GAAP, the ASU requires significantly expanded disclosures about revenue recognition.
	The ASU is effective for Century for our fiscal year 2017 and thereafter. Early adoption is not permitted. We are currently evaluating the impact of adoption on our consolidated financial position, results of operations and cash flows.

Subsequent_events

Subsequent events	9 Months Ended
	Sep. 30, 2014
Subsequent Events [Abstract]	'
Subsequent events	'
	Subsequent events
	We have evaluated all subsequent events through the date the financial statements were issued.
	Agreement to acquire full ownership of Mt. Holly aluminum smelter
	On October 23, 2014, we announced that our wholly owned subsidiary, Berkeley Aluminum, Inc. ("Berkeley"), had entered into a stock purchase agreement (the "Stock Purchase Agreement") with Alumax Inc. ("Alumax"), a wholly-owned subsidiary of Alcoa Inc. ("Alcoa"), pursuant to which, upon closing, Century will acquire Alcoa’s 50.3% stake in Mt. Holly. Following the closing of the transaction, Century will own 100% of Mt. Holly. Mt. Holly, located in Berkeley County, South Carolina, employs approximately 600 people and has an annual production capacity of 229,000 tonnes of primary aluminum.
	Pursuant to the terms of the Stock Purchase Agreement, Berkeley has agreed to acquire all of the issued and outstanding shares of capital stock of Alumax of South Carolina Inc., a wholly owned subsidiary of Alumax for $67,500 in cash less certain amounts owed by Alumax to Mt. Holly and subject to working capital and other similar adjustments (the "Acquisition"). The Acquisition is expected to close in the fourth quarter of 2014 and is subject to customary closing conditions. Century expects to pay for the Acquisition with available cash on hand and borrowings under its revolving credit facility.
	Amendment to U.S. revolving credit facility
	On October 23, 2014, we entered into an amendment to the U.S. revolving credit facility, pursuant to which the participating banks consented to the Acquisition and revised certain covenants for a 120-day period following the Acquisition to permit the transaction. The amendment also increased Century’s letter of credit sub-facility from $80,000 to $100,000. See Note 9 Debt for additional information about the U.S. revolving credit facility.

Acquisition_of_Sebree_aluminum1

Acquisition of Sebree aluminum smelter (Policies)	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Purchase Price Allocation	'
	Purchase Price Allocation
	Allocating the purchase price to the acquired assets and liabilities involves management judgment. We allocated the purchase price in accordance with Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") 805 "Business Combinations" using the estimated fair values at the date of acquisition.

Fair_value_measurements_Level_

Fair value measurements Level 3 Transfers (Policies)	9 Months Ended
	Sep. 30, 2014
Fair Value Level 3 Transfer Disclosure [Abstract]	'
Fair Value Level 3 Transfer Policy	'
	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.

Acquisition_of_Sebree_aluminum2

Acquisition of Sebree aluminum smelter (Tables)	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Schedule of purchase price allocation	'
	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 post retirement benefit costs	6,544
	Other liabilities	7,476
	Deferred taxes	3,233
	Total liabilities assumed	$	61,565
	Gain on bargain purchase:	$	5,253
Sebree acquisition, pro forma information	'
	The following unaudited pro forma financial information for the three and nine months ended September 30, 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.
		Nine months ended September 30,
		2013
	Pro forma revenues	$	1,261,533
	Pro forma loss from continuing operations	(57,853		)
	Loss per common share, basic	(0.65		)
	Loss per common share, diluted	(0.65		)
	Our net income for the three months ended September 30, 2014 and 2013, includes a non-recurring credit for the amortization of the deferred power contract liability of $0 and $11,720, respectively. Our net income for the nine months ended September 30, 2014 and 2013 includes a non-recurring credit for the amortization of the deferred power contract liability of $5,534 and $14,461, 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.

Fair_value_measurements_Tables

Fair value measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Schedule of valuation methodology for assets and liabilities at fair value	'
	The following section describes the valuation methodology used to measure our financial assets and liabilities that were accounted for at fair value and are categorized based on the fair value hierarchy described in ASC 820 "Fair Value Measurements and Disclosures."
	Overview of Century’s valuation methodology
		Level	Significant inputs
	Cash equivalents	1	Quoted market prices
	Trust assets (1)	1	Quoted market prices
	Surety bonds	1	Quoted market prices
	E.ON ("E.ON") contingent obligation	3	Quoted London Metal Exchange ("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 at Century Aluminum of Kentucky, our wholly owned subsidiary ("CAKY")
	Primary aluminum sales contract	3	Management’s estimates of future U.S. Midwest premium and risk-adjusted discount rates
	Midwest premium contracts	3	Management’s estimates of future U.S. Midwest premium
	-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.  As required by generally accepted accounting principles in the United States ("GAAP") for fair value measurements and disclosures, financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.  Our assessment of the significance of a particular input to the fair value measurement requires judgment, and may affect the valuation of fair value assets and liabilities and the placement within the fair value hierarchy levels. There were no transfers between Level 1 and 2 during the periods presented. There were no transfers into or out of Level 3 during the periods presented. It is our policy to recognize transfers into and transfers out of Level 3 as of the actual date of the event or change in circumstances that caused the transfer.
	Recurring Fair Value Measurements	As of September 30, 2014
		Level 1			Level 2			Level 3		Total
	ASSETS:
	Cash equivalents	$	125,960		$	—		$	—	$	125,960
	Trust assets	8,835			—			—		8,835
	Surety bonds	1,987			—			—		1,987
	TOTAL	$	136,782		$	—		$	—	$	136,782
	LIABILITIES:
	E.ON contingent obligation – net (1)	$	—		$	—		$	—	$	—
	TOTAL	$	—		$	—		$	—	$	—
	Recurring Fair Value Measurements	As of December 31, 2013
		Level 1			Level 2			Level 3		Total
	ASSETS:
	Cash equivalents	$	49,658		$	—		$	—	$	49,658
	Trust assets	11,151			—			—		11,151
	Surety bonds	2,002			—			—		2,002
	Midwest premium contracts	—			—			140		140
	TOTAL	$	62,811		$	—		$	140	$	62,951
	LIABILITIES:
	E.ON contingent obligation – net (1)	$	—		$	—		$	—	$	—
	Primary aluminum sales contract	—			—			140		140
	TOTAL	$	—		$	—		$	140	$	140
	-1	See Note 9 Debt for additional information about the E.ON contingent obligation.
Change in level 3 fair value measurements	'
	Change in Level 3 Fair Value Measurements during the three months ended September 30,
		Derivative liabilities - net
		2014			2013
	Beginning balance, July 1,	$	—		$	(773	)
	Total gain included in earnings	—			365
	Ending balance, September 30,	$	—		$	(408	)
	Amount of gain included in earnings attributable to the change in unrealized losses relating to assets and liabilities held at September 30,	$	—		$	365
	Change in Level 3 Fair Value Measurements during the nine months ended September 30,
		Derivative liabilities - net
		2014			2013
	Beginning balance, January 1,	$	—		$	(16,539	)
	Total gain (loss) included in earnings	(940		)	16,131
	Settlements	940			—
	Ending balance, September 30,	$	—		$	(408	)
	Amount of gain included in earnings attributable to the change in unrealized losses relating to assets and liabilities held at September 30,	$	—		$	16,131

Derivative_and_hedging_instrum1

Derivative and hedging instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Fair value of derivative assets and liabilities by balance sheet location	'
	The following table provides the fair value and balance sheet classification of our derivatives:
	Fair Value of Derivative Assets and Liabilities
		Balance sheet location	September 30, 2014			December 31, 2013
	DERIVATIVE ASSETS:
	Midwest premium contracts	Prepaid and other current assets	$	—		$	140
	TOTAL		$	—		$	140
	DERIVATIVE LIABILITIES:
	Primary aluminum sales contract	Accrued and other current liabilities	$	—		$	140
	E.ON contingent obligation – net (1)	Other liabilities	—			—
	TOTAL		$	—		$	140
	-1	See Note 9 Debt for additional information about the E.ON contingent obligation.
Derivatives not designated as hedging instruments	'
	Derivatives not designated as hedging instruments:
		Gain (loss) recognized in income from derivatives
			Three months ended September 30,						Nine months ended September 30,
		Location	2014			2013			2014			2013
	E.ON contingent obligation – net	Net gain (loss) on forward and derivative contracts	$	353		$	353		$	1,059		$	16,428
	Midwest premium contracts	Net gain (loss) on forward and derivative contracts	—			363			(1,080		)	363
	Primary aluminum sales contract	Related party sales	—			278			292			1,039
	Primary aluminum sales contract	Net gain (loss) on forward and derivative contracts	—			(276		)	(153		)	(640		)
	E.ON contingent obligation – net	Interest expense – third party	(353		)	(353		)	(1,059		)	(1,059		)
Outstanding forward contracts not designated as hedging instruments	'
	We had the following outstanding forward contracts that were not designated as hedging instruments:
		September 30, 2014		December 31, 2013
	Primary aluminum sales contract premium (tonnes) (1)	—		1,782
	Midwest premium contracts (tonnes)	—		6,000
	-1	Represents the remaining physical deliveries under the Glencore Metal Agreement.

Earnings_per_share_Tables

Earnings per share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Basic and diluted earnings (loss) per share	'
	The following table shows the basic and diluted earnings (loss) per share for the three and nine months ended September 30, 2014 and 2013:
		For the three months ended September 30,
		2014							2013
		Income			Shares (000)		Per-Share		Loss			Shares (000)	Per-Share
	Net income (loss)	$	50,405						$	(9,507	)
	Amount allocated to common stockholders (1)	91.81		%					100		%
	Basic EPS:
	Income (loss) allocable to common stockholders	46,277			88,827		$	0.52	(9,507		)	88,611	$	(0.11	)
	Effect of Dilutive Securities:
	Share-based compensation plans	—			705				—			—
	Diluted EPS:
	Income (loss) applicable to common stockholders with assumed conversion	$	46,277		89,532		$	0.52	$	(9,507	)	88,611	$	(0.11	)
		For the nine months ended September 30,
		2014							2013
		Income			Shares (000)		Per-Share		Loss			Shares (000)	Per-Share
	Net income (loss)	$	50,645						$	(30,638	)
	Amount allocated to common stockholders (1)	91.79		%					100		%
	Basic EPS:
	Income (loss) allocable to common stockholders	46,487			88,777		$	0.52	(30,638		)	88,588	$	(0.35	)
	Effect of Dilutive Securities:
	Share-based compensation plans	—			595				—			—
	Diluted EPS:
	Income (loss) applicable to common stockholders with assumed conversion	$	46,487		89,372		$	0.52	$	(30,638	)	88,588	$	(0.35	)
	-1	We have not allocated net losses between common and preferred stockholders, as the holders of our preferred shares do not have a contractual obligation to share in the loss.
Securities excluded from the calculation of diluted EPS	'
	Securities excluded from the calculation of diluted EPS:	Three months ended September 30,				Nine months ended September 30,
		2014		2013		2014		2013
	Stock options (1)	338,433		620,334		344,433		620,334
	Service-based share awards (1)	—		573,628		—		522,032
	-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.

Shareholders_equity_Tables

Shareholders’ equity (Tables)	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Common and Preferred Stock Activity	'
	The Common and Preferred Stock Activity table below contains additional information about preferred stock conversions during the nine months ended September 30, 2014 and 2013.
	Common and Preferred Stock Activity:	Preferred stock		Common stock
	(in shares)	Series A convertible		Treasury	Outstanding
	Beginning balance as of December 31, 2013	79,620		4,786,521	88,710,277
	Conversion of convertible preferred stock	(950	)	—	95,039
	Issuance for share-based compensation plans	—		—	132,554
	Ending balance as of September 30, 2014	78,670		4,786,521	88,937,870
	Beginning balance as of December 31, 2012	80,283		4,786,521	88,548,637
	Conversion of convertible preferred stock	(549	)	—	54,825
	Issuance for share-based compensation plans	—		—	79,469
	Ending balance as of September 30, 2013	79,734		4,786,521	88,682,931

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2014
Inventory, Net [Abstract]	'
Schedule of Inventories	'
	Inventories consist of the following:	September 30, 2014		December 31, 2013
	Raw materials	$	67,145	$	69,776
	Work-in-process	21,597		22,183
	Finished goods	16,722		17,661
	Operating and other supplies	136,286		129,995
	Inventories	$	241,750	$	239,615

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Schedule of Debt	'
		September 30, 2014			December 31, 2013
	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
	7.5% senior unsecured notes due August 15, 2014, interest payable semiannually (2)(3)	—			2,603
	Iceland revolving credit facility (3)(4)	—			6,000
	Debt classified as non-current liabilities:
	7.5% senior secured notes due June 1, 2021, net of debt discount of $3,204 and $3,472, respectively, interest payable semiannually	246,796			246,528
	TOTAL	$	254,611		$	262,946
	-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 September 30, 2014 was 0.24%.
	-2	The amount outstanding was repaid upon maturity.
	-3	These items are recorded in accrued and other current liabilities based on the repayment terms and expected maturity.
	-4	Borrowings under the Iceland revolving credit facility bear variable interest based on LIBOR plus the applicable margin per annum. The interest rate at December 31, 2013 was 3.92%.
Schedule of Line of Credit Facilities	'
	Status of our Iceland revolving credit facility:
		September 30, 2014
	Credit Facility maximum amount	$	50,000
	Borrowing availability	50,000
	Outstanding borrowings	—
	Status of our U.S. revolving credit facility:
		September 30, 2014
	Credit facility maximum amount	$	148,560
	Borrowing availability, net of outstanding letters of credit	76,327
	Outstanding borrowings	—
	Letter of credit sub-facility amount	80,000
	Outstanding letters of credit issued	72,233
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	30-Sep-14			31-Dec-13
	E.ON contingent obligation – principal	Other liabilities	$	(12,902	)	$	(12,902	)
	E.ON contingent obligation – accrued interest	Other liabilities	(4,938		)	(3,879		)
	E.ON contingent obligation – derivative asset	Other liabilities	17,840			16,781
			$	—		$	—

Forward_delivery_contracts_and1

Forward delivery contracts and financial instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Forward Delivery Contracts and Financial Instruments [Abstract]	'
Schedule of Forward Physical Delivery Agreements	'
	Forward Physical Delivery Agreements
	Primary Aluminum Sales Contracts
	Contract	Customer	Volume	Term	Pricing
	Glencore Grundartangi Metal Agreement (1)	Glencore	All primary aluminum produced at Grundartangi, net of tolling and other sales commitments	January 1, 2014 through December 31, 2017	Variable, based on LME and European Duty Paid premium
	Southwire Metal Agreement (2)	Southwire	216 million pounds per year (high conductivity molten aluminum)	January 1, 2014 through December 31, 2014	Variable, based on U.S. Midwest Transaction Price
	-1	The Glencore Grundartangi Metal Agreement is for all metal produced at Grundartangi from 2014 through 2017 less commitments under existing tolling and other sales contracts.  Grundartangi currently estimates that it will sell Glencore approximately 155,000 tonnes of aluminum under this agreement in 2014.
	-2	Southwire may, at its option, increase the volume purchased under the agreement by up to four percent by adjusting their monthly metal commitment.
	Tolling Contracts
	Contract	Customer	Volume	Term	Pricing
	Glencore Toll Agreement	Glencore	90,000 tonnes per year ("tpy")	Through July 2016	Variable, based on LME and European Duty Paid premium
	Glencore Toll Agreement	Glencore	49,000 tpy	Through December 31, 2014	Variable, based on LME and European Duty Paid premium
	Apart from the Glencore Grundartangi Metal Agreement, the Southwire Metal Agreement and the Glencore Sweep
	Agreement (a contract for all metal produced in the U.S. in 2013, less existing sales agreements and valued-added metal sales, which expired at the end of 2013), we had the following forward delivery contractual commitments:
	Other forward delivery contracts
		September 30, 2014		December 31, 2013
		(in tonnes)
	Other forward delivery contracts – total	72,025		118,373
	Other forward delivery contracts – Glencore	40,760		20,008
	Other forward delivery contracts – fixed price	500		—
	Other forward delivery contracts – fixed price with Glencore	480		—

Supplemental_cash_flow_informa1

Supplemental cash flow information (Tables)	9 Months Ended
	Sep. 30, 2014
Supplemental Cash Flow Information [Abstract]	'
Supplemental cash flow information	'
		Nine months ended September 30,
		2014		2013
	Cash paid for:
	Interest	$	9,684	$	11,293
	Income/withholding taxes (1)	10,079		27,254
	Non-cash investing activities:
	Accrued capital costs	$	663	$	5,734
	-1	We paid withholding taxes in Iceland on intercompany dividends of $5,491 and $18,067 during the nine months ended September 30, 2014 and 2013, respectively. Our tax payments in Iceland for withholding taxes, income taxes and any associated refunds are denominated in Icelandic kronur ("ISK").

Asset_retirement_obligations_A1

Asset retirement obligations (“ARO”) (Tables)	9 Months Ended
	Sep. 30, 2014
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:
		Nine months ended September 30, 2014			Year ended December 31, 2013
	Beginning balance, ARO liability	$	27,113		$	16,124
	Additional ARO liability incurred	1,493			1,730
	ARO liabilities settled	(3,547		)	(2,580		)
	Accretion expense	1,114			1,733
	Additional ARO liability from Sebree acquisition	—			10,106
	Ending balance, ARO liability	$	26,173		$	27,113

Components_of_Accumulated_othe1

Components of Accumulated other comprehensive loss (Tables)	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Components of Accumulated Other Comprehensive Loss	'
		September 30, 2014			December 31, 2013
	Defined benefit plan liabilities	$	(90,386	)	$	(92,177	)
	Equity in investee other comprehensive income (1)	(12,651		)	(12,650		)
	Unrealized loss on financial instruments	(1,202		)	(1,064		)
	Other comprehensive loss before income tax effect	(104,239		)	(105,891		)
	Income tax effect (2)	12,222			14,059
	Accumulated other comprehensive loss	$	(92,017	)	$	(91,832	)
	-1	The amount includes our equity in the other comprehensive income of Mt. Holly.
	(2)The allocation of the income tax effect to the components of other comprehensive income is as follows:
		30-Sep-14			31-Dec-13
	Defined benefit plan liabilities	$	12,445		$	14,256
	Equity in investee other comprehensive income	368			418
	Unrealized loss on financial instruments	(591		)	(615		)
Accumulated balances for each component of AOCI	'
	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, July 1, 2014	$	(77,843	)	$	(12,266	)	$	(1,755	)	$	(91,864	)
	Other comprehensive income (loss) before reclassifications	—			(17		)	—			(17		)
	Net amount reclassified to net income	(98		)	—			(38		)	(136		)
	Balance, September 30, 2014	$	(77,941	)	$	(12,283	)	$	(1,793	)	$	(92,017	)
	Balance, July 1, 2013	$	(125,302	)	$	(12,258	)	$	(1,603	)	$	(139,163	)
	Other comprehensive income (loss) before reclassifications	—			(17		)	—			(17		)
	Net amount reclassified to net loss	538			—			(38		)	500
	Balance, September 30, 2013	$	(124,764	)	$	(12,275	)	$	(1,641	)	$	(138,680	)
	Balance, December 31, 2013	$	(77,921	)	$	(12,232	)	$	(1,679	)	$	(91,832	)
	Other comprehensive income (loss) before reclassifications	440			(51		)	—			389
	Net amount reclassified to net income	(460		)	—			(114		)	(574		)
	Balance, September 30, 2014	$	(77,941	)	$	(12,283	)	$	(1,793	)	$	(92,017	)
	Balance, December 31, 2012	$	(137,441	)	$	(12,224	)	$	(1,527	)	$	(151,192	)
	Other comprehensive income (loss) before reclassifications	10,349			(51		)	—			10,298
	Net amount reclassified to net loss	2,328			—			(114		)	2,214
	Balance, September 30, 2013	$	(124,764	)	$	(12,275	)	$	(1,641	)	$	(138,680	)
Reclassification out of AOCI	'
	Reclassifications out of AOCI were included in the consolidated statements of operations as follows:
			For the three months ended September 30,						For the nine months ended September 30,
	AOCI Components	Location	2014			2013			2014			2013
	Defined benefit plan and other postretirement liabilities	Cost of goods sold	$	308		$	764		$	924		$	2,758
		Selling, general and administrative expenses	142			148			427			692
		Income tax expense	(548		)	(374		)	(1,811		)	(1,122		)
		Net of tax	$	(98	)	$	538		$	(460	)	$	2,328
	Equity in investee other comprehensive income	Cost of goods sold	$	—		$	—		$	—		$	—
		Income tax expense	(17		)	(17		)	(51		)	(51		)
		Net of tax	$	(17	)	$	(17	)	$	(51	)	$	(51	)
	Unrealized loss on financial instruments	Cost of goods sold	$	(46	)	$	(46	)	$	(139	)	$	(139	)
		Income tax expense	8			8			25			25
		Net of tax	$	(38	)	$	(38	)	$	(114	)	$	(114	)

Components_of_net_periodic_ben1

Components of net periodic benefit cost (Tables)	9 Months Ended
	Sep. 30, 2014
Components of net periodic benefit cost [Abstract]	'
Schedule of net periodic benefit cost	'
		Pension Benefits
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Service cost	$	1,333		$	1,686		$	3,999		$	3,292
	Interest cost	2,871			2,903			8,612			6,293
	Expected return on plan assets	(3,550		)	(3,723		)	(10,648		)	(7,337		)
	Amortization of prior service costs	9			30			27			85
	Amortization of net loss	477			723			1,430			2,428
	Curtailment	—			—			—			(18		)
	Net periodic benefit cost	$	1,140		$	1,619		$	3,420		$	4,743
		Other Postretirement Benefits ("OPEB")
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
	Service cost	$	397		$	700		$	1,191		$	1,862
	Interest cost	1,603			1,474			4,809			4,230
	Amortization of prior service cost	(961		)	(998		)	(2,883		)	(2,997		)
	Amortization of net loss	925			1,157			2,777			3,934
	Curtailment	—			—			—			(20		)
	Net periodic benefit cost	$	1,964		$	2,333		$	5,894		$	7,009

Acquisition_of_Sebree_aluminum3

Acquisition of Sebree aluminum smelter (Employee Headcount) (Details) (Sebree Smelter [Member])	Jun. 01, 2013
Sebree Smelter [Member]	'
Business Acquisition [Line Items]	'
Sebree employees	500

Acquisition_of_Sebree_aluminum4

Acquisition of Sebree aluminum smelter (Details) (USD $)	3 Months Ended			9 Months Ended		16 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Jun. 01, 2013
							t
Business Acquisition [Line Items]	'	'	'	'	'	'	'
Purchase price cash paid	'	'	'	$1,042	$48,058	'	'
Gain on bargain purchase	0	'	0	0	5,253	'	'
Sebree power contract amortization	'	'	'	-5,534	-14,461	'	'
Sebree Smelter [Member]	'	'	'	'	'	'	'
Business Acquisition [Line Items]	'	'	'	'	'	'	'
Sebree primary aluminum capacity (tonnes)	'	'	'	'	'	'	205,000
Purchase price for acquisition	'	'	'	'	'	'	61,000
Purchase price cash paid	'	'	'	'	'	49,035	'
Separately recognized transactions, gains recognized	'	965	'	'	'	'	'
Gain on bargain purchase	'	'	'	'	'	5,253	'
Cash	'	'	'	'	'	48,083	'
Deferred purchase price	'	'	'	'	'	1,910	'
Inventories	59,018	'	'	59,018	'	59,018	'
Prepaid and other current assets	2,273	'	'	2,273	'	2,273	'
Property, plant and equipment – net	55,520	'	'	55,520	'	55,520	'
Total assets acquired	116,811	'	'	116,811	'	116,811	'
Accrued and other current liabilities	43,316	'	'	43,316	'	43,316	'
Accrued pension benefit costs	996	'	'	996	'	996	'
Accrued post retirement benefit costs	6,544	'	'	6,544	'	6,544	'
Other liabilities	7,476	'	'	7,476	'	7,476	'
Deferred taxes	3,233	'	'	3,233	'	3,233	'
Total liabilities assumed	61,565	'	'	61,565	'	61,565	'
Sebree power contract amortization	0	'	11,720	5,534	14,461	'	'
Pro forma revenues	'	'	'	'	1,261,533	'	'
Pro forma loss from continuing operations	'	'	'	'	($57,853)	'	'
Loss per common share, basic	'	'	'	'	($0.65)	'	'
Loss per common share, diluted	'	'	'	'	($0.65)	'	'

Fair_value_measurements_Detail

Fair value measurements (Details) (USD $)

3 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Derivative Liabilities - Net [Member]

Derivative Liabilities - Net [Member]

Derivative Liabilities - Net [Member]

Derivative Liabilities - Net [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

ASSETS:

'

'

'

'

'

'

'

'

'

'

'

'

Cash equivalents

'

'

'

'

$125,960

$49,658

$125,960

$49,658

$0

$0

$0

$0

Trust assets

'

'

'

'

8,835

11,151

8,835

11,151

0

0

0

0

Surety bonds

'

'

'

'

1,987

2,002

1,987

2,002

0

0

0

0

Midwest premium contracts

'

'

'

'

'

140

'

0

'

0

'

140

TOTAL

'

'

'

'

136,782

62,951

136,782

62,811

0

0

0

140

LIABILITIES:

'

'

'

'

'

'

'

'

'

'

'

'

E.ON contingent obligation – net (1)

'

'

'

'

0

[1]

0

[1]

0

[1]

0

[1]

0

[1]

0

[1]

0

[1]

0

[1]

Primary aluminum sales contract

'

'

'

'

'

140

'

0

'

0

'

140

TOTAL

'

'

'

'

0

140

0

0

0

0

0

140

Level 3 fair value measurements [Roll Forward]

'

'

'

'

'

'

'

'

'

'

'

'

Beginning balance, period start

0

-773

0

-16,539

'

'

'

'

'

'

'

'

Total gain (loss) included in earnings

0

365

-940

16,131

'

'

'

'

'

'

'

'

Settlements

'

'

940

0

'

'

'

'

'

'

'

'

Ending balance, September 30,

0

-408

0

-408

'

'

'

'

'

'

'

'

Amount of gain included in earnings attributable to the change in unrealized losses relating to assets and liabilities held at September 30,

$0

$365

$0

$16,131

'

'

'

'

'

'

'

'

[1]

See Note 9 Debt for additional information about the E.ON contingent obligation.

Derivative_and_hedging_instrum2

Derivative and hedging instruments (Details) (Not Designated as Hedging Instrument [Member], USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Fair value of derivative assets and liabilities by balance sheet location [Abstract]	'		'
DERIVATIVE ASSETS	$0		$140
DERIVATIVE LIABILITIES	0		140
Midwest Premium Contracts [Member]	'		'
Outstanding forward contracts not designated as hedging instruments [Abstract]	'		'
Midwest premium contracts (tonnes)	0		6,000
Midwest Premium Contracts [Member] | Prepaid and Other Current Assets [Member]	'		'
Fair value of derivative assets and liabilities by balance sheet location [Abstract]	'		'
DERIVATIVE ASSETS	0		140
Primary Aluminum Sales Contracts [Member] | Accrued and Other Current Liabilities [Member]	'		'
Fair value of derivative assets and liabilities by balance sheet location [Abstract]	'		'
DERIVATIVE LIABILITIES	0		140
E.ON Contingent Obligation - Net [Member] | Other Liabilities [Member]	'		'
Fair value of derivative assets and liabilities by balance sheet location [Abstract]	'		'
DERIVATIVE LIABILITIES	$0	[1]	$0	[1]
Primary Aluminum Sales Contract Premium [Member]	'		'
Outstanding forward contracts not designated as hedging instruments [Abstract]	'		'
Primary aluminum sales contract premium (tonnes) (1)	0	[2]	1,782	[2]
[1]	See Note 9 Debt for additional information about the E.ON contingent obligation.
[2]	Represents the remaining physical deliveries under the Glencore Metal Agreement.

Derivative_and_hedging_instrum3

Derivative and hedging instruments Part 2 (Details) (Not Designated as Hedging Instrument [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Primary Aluminum Sales Contracts [Member] | Net Gain (Loss) on Forward and Derivative Contracts [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (loss) recognized in income from derivatives	$0	($276)	($153)	($640)
Primary Aluminum Sales Contracts [Member] | Related Party Sales [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (loss) recognized in income from derivatives	0	278	292	1,039
E.ON Contingent Obligation - Net [Member] | Net Gain (Loss) on Forward and Derivative Contracts [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (loss) recognized in income from derivatives	353	353	1,059	16,428
E.ON Contingent Obligation - Net [Member] | Interest Expense - Third Party [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (loss) recognized in income from derivatives	-353	-353	-1,059	-1,059
Midwest Premium Contracts [Member] | Net Gain (Loss) on Forward and Derivative Contracts [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (loss) recognized in income from derivatives	$0	$363	($1,080)	$363

Earnings_per_share_Details

Earnings per share (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Earnings Per Share [Abstract]	'		'		'		'
Net income (loss)	$50,405		($9,507)		$50,645		($30,638)
Amount allocated to common stockholders (in hundredths)	91.81%	[1]	100.00%	[1]	91.79%	[1]	100.00%	[1]
Basic EPS:	'		'		'		'
Income (loss) allocable to common stockholders	46,277		-9,507		46,487		-30,638
Income (loss) allocable to common stockholders - (in Shares)	88,827,000		88,611,000		88,777,000		88,588,000
Earnings Per Share, Basic	$0.52		($0.11)		$0.52		($0.35)
Effect of Dilutive Securities:	'		'		'		'
Share-based compensation plans	0		0		0		0
Share-based compensation plans - (in Shares)	705,000		0		595,000		0
Diluted EPS:	'		'		'		'
Income (loss) applicable to common stockholders with assumed conversion	$46,277		($9,507)		$46,487		($30,638)
Income (loss) applicable to common stockholders with assumed conversion - (in Shares)	89,532,000		88,611,000		89,372,000		88,588,000
Earnings Per Share, Diluted	$0.52		($0.11)		$0.52		($0.35)
Stock Options [Member]	'		'		'		'
Securities Excluded from Computation of Earnings Per Share [Line Items]	'		'		'		'
Securities excluded from calculation of diluted EPS (in shares)	338,433	[2]	620,334	[2]	344,433	[2]	620,334	[2]
Service-based share awards [Member]	'		'		'		'
Securities Excluded from Computation of Earnings Per Share [Line Items]	'		'		'		'
Securities excluded from calculation of diluted EPS (in shares)	0	[2]	573,628	[2]	0	[2]	522,032	[2]
[1]	We have not allocated net losses between common and preferred stockholders, as the holders of our preferred shares do not have a contractual obligation to share in the loss.
[2]	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.

Shareholders_equity_Details

Shareholders’ equity (Details) (USD $)	1 Months Ended	9 Months Ended	38 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Aug. 31, 2011	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
					Series A Convertible Preferred Stock [Member]	Series A Convertible Preferred Stock [Member]	Treasury Stock [Member]	Treasury Stock [Member]	Common Stock [Member]	Common Stock [Member]
Class of Stock [Line Items]	'	'	'	'	'	'	'	'	'	'
Common stock, shares authorized (in shares)	'	195,000,000	195,000,000	195,000,000	'	'	'	'	'	'
Stock repurchase program, authorized amount	$60,000	'	'	'	'	'	'	'	'	'
Repurchase of common stock (in shares)	'	'	4,786,521	'	'	'	'	'	'	'
Repurchase of common stock, aggregate purchase price	'	'	49,924	'	'	'	'	'	'	'
Stock repurchase program, remaining authorized repurchase amount	'	$10,076	'	'	'	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'	'
Shares, Beginning balance	'	'	'	'	79,620	80,283	4,786,521	4,786,521	88,710,277	88,548,637
Conversion of convertible preferred stock (in shares)	'	'	'	'	-950	-549	0	0	95,039	54,825
Issuance for stock compensation plans (in shares)	'	'	'	'	0	0	0	0	132,554	79,469
Shares, Ending balance	'	'	'	'	78,670	79,734	4,786,521	4,786,521	88,937,870	88,682,931

Income_taxes_Details

Income taxes (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Income tax expense	$6,444	$1,384	$7,004	$4,714

Inventories_Details

Inventories (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory, Net [Abstract]	'	'
Raw materials	$67,145	$69,776
Work-in-process	21,597	22,183
Finished goods	16,722	17,661
Operating and other supplies	136,286	129,995
Inventories	$241,750	$239,615

Debt_Details

Debt (Details) (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Schedule of Debt Instruments [Line Items]	'		'
Industrial revenue bonds	$7,815		$7,815
TOTAL	254,611		262,946
Industrial revenue bonds due 2028 [Member] | Short-term Debt [Member]	'		'
Schedule of Debt Instruments [Line Items]	'		'
Debt Instrument, Unamortized Discount	0	[1]	0	[1]
Debt Instrument, Maturity Date	1-Apr-28	[1]	1-Apr-28	[1]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum	12.00%	[1]	12.00%	[1]
Industrial revenue bonds	7,815	[1]	7,815	[1]
Debt Instrument, Interest Rate, Stated Percentage	0.24%	[1]	'
Senior unsecured notes due August 15, 2014 [Member] | Short-term Debt [Member]	'		'
Schedule of Debt Instruments [Line Items]	'		'
Debt Instrument, Unamortized Discount	0	[2],[3]	0	[2],[3]
Debt Instrument, Maturity Date	15-Aug-14	[2],[3]	15-Aug-14	[2],[3]
Senior unsecured notes, current	0	[2],[3]	2,603	[2],[3]
Debt Instrument, Interest Rate, Stated Percentage	7.50%	[2],[3]	7.50%	[2],[3]
Iceland revolving line of credit [Member] | Short-term Debt [Member]	'		'
Schedule of Debt Instruments [Line Items]	'		'
Revolving credit facility	0	[3],[4]	6,000	[3],[4]
Debt Instrument, Interest Rate, Stated Percentage	'		3.92%	[3],[4]
Senior secured notes due June 01, 2021 [Member] | Long-term Debt [Member]	'		'
Schedule of Debt Instruments [Line Items]	'		'
Debt Instrument, Unamortized Discount	3,204		3,472
Debt Instrument, Maturity Date	1-Jun-21		1-Jun-21
Senior secured notes, noncurrent	$246,796		$246,528
Debt Instrument, Interest Rate, Stated Percentage	7.50%		7.50%
[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 September 30, 2014 was 0.24%.
[2]	The amount outstanding was repaid upon maturity.
[3]	These items are recorded in accrued and other current liabilities based on the repayment terms and expected maturity.
[4]	Borrowings under the Iceland revolving credit facility bear variable interest based on LIBOR plus the applicable margin per annum. The interest rate at December 31, 2013 was 3.92%.

Debt_Credit_Facility_Details

Debt Credit Facility (Details) (USD $)	9 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014		Dec. 31, 2013
	U.S. revolving credit facility [Member]	U.S. letter of credit [Member]	U.S. letter of credit [Member]	Iceland revolving line of credit [Member]	Short-term Debt [Member]		Short-term Debt [Member]
	Long-term Debt [Member]		Long-term Debt [Member]	Long-term Debt [Member]	Iceland revolving line of credit [Member]		Iceland revolving line of credit [Member]
Line of Credit Facility [Line Items]	'	'	'	'	'		'
Credit facility face amount	$150,000	'	'	$50,000	'		'
Credit facility maximum amount	148,560	'	'	50,000	'		'
Borrowing availability	76,327	'	'	50,000	'		'
Outstanding borrowings	0	'	'	0	0	[1],[2]	6,000	[1],[2]
Letter of credit sub-facility amount	'	80,000	80,000	'	'		'
Outstanding letters of credit issued	'	'	$72,233	'	'		'
Credit facility term	'5 years	'	'	'3 years	'		'
[1]	Borrowings under the Iceland revolving credit facility bear variable interest based on LIBOR plus the applicable margin per annum. The interest rate at December 31, 2013 was 3.92%.
[2]	These items are recorded in accrued and other current liabilities based on the repayment terms and expected maturity.

Debt_75_Notes_Details

Debt 7.5% Notes (Details) (Long-term Debt [Member], Senior secured notes due June 01, 2021 [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2014	Jun. 04, 2013
Long-term Debt [Member] | Senior secured notes due June 01, 2021 [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Debt Instrument, Face Amount	'	'	$250,000
Proceeds from Issuance of Debt	$246,330	'	'
Debt Instrument, Interest Rate, Stated Percentage	7.50%	7.50%	'

Debt_EON_Contingent_Obligation

Debt E.ON Contingent Obligation (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Dec. 31, 2013
			Other Liabilities [Member]	Other Liabilities [Member]
			E.ON contingent obligation [Member]	E.ON contingent obligation [Member]
Debt Instrument [Line Items]	'	'	'	'
Unrealized gain on E.ON obligation	$1,059	$16,428	'	'
E.ON contingent obligation – principal	'	'	-12,902	-12,902
E.ON contingent obligation – accrued interest	'	'	-4,938	-3,879
E.ON contingent obligation – derivative asset	'	'	17,840	16,781
E.ON contingent obligation	'	'	$0	$0

Commitments_and_contingencies_

Commitments and contingencies (Details) (USD $)	159 Months Ended		12 Months Ended	45 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2016
	MW		PBGC Agreement [Member]	PBGC Forecast [Member]
				PBGC Agreement [Member]
Environmental Contingencies [Abstract]	'	'	'	'
Environmental-related accrued liabilities	$1,340	$999	'	'
Environmental remediation expense for Hydrocarbon Recovery Plan	1,033	'	'	'
PBCG Settlement [Abstract]	'	'	'	'
Pension contributions above required minimum, total	'	'	'	17,400
Pension contributions	'	'	6,700	'
OR Power Agreement [Abstract]	'	'	'	'
Power currently available under the power purchase agreement (in megawatts)	47.5	'	'	'
Power prepayments	$2,267	'	'	'
Labor Commitments [Abstract]	'	'	'	'
Percentage of U.S. based work force represented by a union (in hundredths)	73.00%	'	'	'
Number of labor unions Grundartangi subsidiary entered into a new labor agreement with	5	'	'	'
Percentage of Grundartangi work force represented by the labor unions (in hundredths)	82.00%	'	'	'
Percentage of Vlissingen work force represented by the labor union (in hundredths)	77.00%	'	'	'

Forward_delivery_contracts_and2

Forward delivery contracts and financial instruments (Details)	9 Months Ended
	Sep. 30, 2014		Sep. 30, 2014		Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Dec. 31, 2013
	Primary Aluminum Sales Contracts [Member]		Primary Aluminum Sales Contracts [Member]		Long-Term Tolling Conctracts [Member]	Long-Term Tolling Conctracts [Member]	Other Forward Delivery Contracts [Member]	Other Forward Delivery Contracts [Member]	Glencore [Member]	Glencore [Member]
	Glencore Nordural Metal Agreement [Member]		Southwire Metal Agreement [Member]		Glencore Toll Agreement 1 [Member]	Glencore Toll Agreement 2 [Member]	t	t	Other Forward Delivery Contracts [Member]	Other Forward Delivery Contracts [Member]
	t		lb		t	t			t	t
Supply Commitment [Line Items]	'		'		'	'	'	'	'	'
Customer	'Glencore	[1]	'Southwire	[2]	'Glencore	'Glencore	'	'	'	'
Volume	'All primary aluminum produced at Grundartangi, net of tolling and other sales commitments	[1]	'216 million pounds per year (high conductivity molten aluminum)	[2]	'90,000 tonnes per year ("tpy")	'49,000 tpy	'	'	'	'
Volume (in tpy and lbs per year)	155,000		216,000,000		90,000	49,000	'	'	'	'
Volume adjustment (in percent)	'		4.00%		'	'	'	'	'	'
Term	'January 1, 2014 through December 31, 2017	[1]	'January 1, 2014 through December 31, 2014	[2]	'Through July 2016	'Through December 31, 2014	'	'	'	'
Pricing	'Variable, based on LME and European Duty Paid premium	[1]	'Variable, based on U.S. Midwest Transaction Price	[2]	'Variable, based on LME and European Duty Paid premium	'Variable, based on LME and European Duty Paid premium	'	'	'	'
Other forward delivery contracts to sell primary aluminum (in tonnes)	'		'		'	'	72,025	118,373	40,760	20,008
Other forward delivery contracts to sell primary aluminum at fixed price (in tonnes)	'		'		'	'	500	0	480	0
[1]	The Glencore Grundartangi Metal Agreement is for all metal produced at Grundartangi from 2014 through 2017 less commitments under existing tolling and other sales contracts. Grundartangi currently estimates that it will sell Glencore approximately 155,000 tonnes of aluminum under this agreement in 2014.
[2]	Southwire may, at its option, increase the volume purchased under the agreement by up to four percent by adjusting their monthly metal commitment.

Supplemental_cash_flow_informa2

Supplemental cash flow information (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013
Interest	$9,684		$11,293
Income/withholding taxes (1)	10,079	[1]	27,254	[1]
Accrued capital costs	663		5,734
Iceland [Member]	'		'
Income/withholding taxes (1)	$5,491		$18,067
[1]	We paid withholding taxes in Iceland on intercompany dividends of $5,491 and $18,067 during the nine months ended September 30, 2014 and 2013, respectively. Our tax payments in Iceland for withholding taxes, income taxes and any associated refunds are denominated in Icelandic kronur ("ISK").

Asset_retirement_obligations_A2

Asset retirement obligations (“ARO”) (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Asset Retirement Obligation [Roll Forward]	'	'
Beginning balance, ARO liability	$27,113	$16,124
Additional ARO liability incurred	1,493	1,730
ARO liabilities settled	-3,547	-2,580
Accretion expense	1,114	1,733
Additional ARO liability from Sebree acquisition	0	10,106
Ending balance, ARO liability	$26,173	$27,113

Components_of_Accumulated_othe2

Components of Accumulated other comprehensive loss (Details) (USD $)	3 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Jun. 30, 2014	Dec. 31, 2013		Jun. 30, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'	'	'		'	'
Other comprehensive loss before income tax effect	($104,239)		'	($104,239)		'	'	($105,891)		'	'
Income tax effect	12,222	[1]	'	12,222	[1]	'	'	14,059	[1]	'	'
Accumulated other comprehensive loss	-92,017		-138,680	-92,017		-138,680	-91,864	-91,832		-139,163	-151,192
Other comprehensive income (loss) before reclassifications	-17		-17	389		10,298	'	'		'	'
Net amount reclassified to net income (loss)	-136		500	-574		2,214	'	'		'	'
Cost of goods sold	424,918		387,574	1,267,343		1,028,901	'	'		'	'
Selling, general and administrative expenses	12,146		14,422	32,826		45,875	'	'		'	'
Income tax benefit (expense)	6,444		1,384	7,004		4,714	'	'		'	'
Net of tax	50,405		-9,507	50,645		-30,638	'	'		'	'
Defined benefit plans liabilities [Member]	'		'	'		'	'	'		'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'	'	'		'	'
Other comprehensive loss before income tax effect	-90,386		'	-90,386		'	'	-92,177		'	'
Income tax effect	12,445		'	12,445		'	'	14,256		'	'
Accumulated other comprehensive loss	-77,941		-124,764	-77,941		-124,764	-77,843	-77,921		-125,302	-137,441
Other comprehensive income (loss) before reclassifications	0		0	440		10,349	'	'		'	'
Net amount reclassified to net income (loss)	-98		538	-460		2,328	'	'		'	'
Equity in investee other comprehensive income [Member]	'		'	'		'	'	'		'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'	'	'		'	'
Other comprehensive loss before income tax effect	-12,651	[2]	'	-12,651	[2]	'	'	-12,650	[2]	'	'
Income tax effect	368		'	368		'	'	418		'	'
Accumulated other comprehensive loss	-12,283		-12,275	-12,283		-12,275	-12,266	-12,232		-12,258	-12,224
Other comprehensive income (loss) before reclassifications	-17		-17	-51		-51	'	'		'	'
Net amount reclassified to net income (loss)	0		0	0		0	'	'		'	'
Unrealized loss on financial instruments [Member]	'		'	'		'	'	'		'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'	'	'		'	'
Other comprehensive loss before income tax effect	-1,202		'	-1,202		'	'	-1,064		'	'
Income tax effect	-591		'	-591		'	'	-615		'	'
Accumulated other comprehensive loss	-1,793		-1,641	-1,793		-1,641	-1,755	-1,679		-1,603	-1,527
Other comprehensive income (loss) before reclassifications	0		0	0		0	'	'		'	'
Net amount reclassified to net income (loss)	-38		-38	-114		-114	'	'		'	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined benefit plans liabilities [Member]	'		'	'		'	'	'		'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'	'	'		'	'
Cost of goods sold	308		764	924		2,758	'	'		'	'
Selling, general and administrative expenses	142		148	427		692	'	'		'	'
Income tax benefit (expense)	-548		-374	-1,811		-1,122	'	'		'	'
Net of tax	-98		538	-460		2,328	'	'		'	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Equity in investee other comprehensive income [Member]	'		'	'		'	'	'		'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'	'	'		'	'
Cost of goods sold	0		0	0		0	'	'		'	'
Income tax benefit (expense)	-17		-17	-51		-51	'	'		'	'
Net of tax	-17		-17	-51		-51	'	'		'	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized loss on financial instruments [Member]	'		'	'		'	'	'		'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'	'		'	'	'		'	'
Cost of goods sold	-46		-46	-139		-139	'	'		'	'
Income tax benefit (expense)	8		8	25		25	'	'		'	'
Net of tax	($38)		($38)	($114)		($114)	'	'		'	'
[1]	The allocation of the income tax effect to the components of other comprehensive income is as follows: September 30, 2014December 31, 2013Defined benefit plan liabilities$12,445$14,256Equity in investee other comprehensive income368418Unrealized loss on financial instruments(591)(615)
[2]	The amount includes our equity in the other comprehensive income of Mt. Holly.

Components_of_net_periodic_ben2

Components of net periodic benefit cost (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'
Employer contributions	'	'	$3,296	'
Pension Benefits [Member]	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'
Service cost	1,333	1,686	3,999	3,292
Interest cost	2,871	2,903	8,612	6,293
Expected return on plan assets	-3,550	-3,723	-10,648	-7,337
Amortization of prior service costs	9	30	27	85
Amortization of net loss	477	723	1,430	2,428
Curtailment	0	0	0	-18
Net periodic benefit cost	1,140	1,619	3,420	4,743
Other Postretirement Benefits [Member]	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'
Service cost	397	700	1,191	1,862
Interest cost	1,603	1,474	4,809	4,230
Amortization of prior service costs	-961	-998	-2,883	-2,997
Amortization of net loss	925	1,157	2,777	3,934
Curtailment	0	0	0	-20
Net periodic benefit cost	$1,964	$2,333	$5,894	$7,009

Subsequent_events_Employees_De

Subsequent events Employees (Details) (Mt. Holly [Member])	Oct. 23, 2014
Mt. Holly [Member]	'
Subsequent Event [Line Items]	'
Mt. Holly employees	600

Subsequent_events_Details

Subsequent events (Details) (USD $)	Sep. 30, 2014	Oct. 23, 2014	Oct. 23, 2014
In Thousands, unless otherwise specified	U.S. letter of credit [Member]	Mt. Holly [Member]	U.S. letter of credit [Member]
		t
Subsequent Event [Line Items]	'	'	'
Mt. Holly ownership percent acquired	'	50.30%	'
Mt. Holly ownership percent after acquisition	'	100.00%	'
Primary aluminum capacity - (in tonnes)	'	229,000	'
Purchase price for acquisition	'	$67,500	'
Debt Covenants, revised period (in days)	'	'	'120 days
Letter of credit sub-facility amount	$80,000	'	$100,000