Century Aluminum (CENX) 10-Q 8 Nov 19 2019 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 04, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-34474
Entity Registrant Name	Century Aluminum Company
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3070826
Entity Address, Address Line One	One South Wacker Drive
Entity Address, Postal Zip Code	60606
Entity Address, Address Line Two	Suite 1000
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
City Area Code	312
Local Phone Number	696-3101
Title of 12(b) Security	Common Stock, $0.01 par value per share
Entity Trading Symbol	CENX
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		88,893,767
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0000949157
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
NET SALES
Related parties	$ 282.3	$ 305.3	$ 898.7	$ 884.2
Other customers	155.7	176.5	502.5	522.1
Total net sales	438	481.8	1,401.2	1,406.3
Cost of goods sold	451.7	493.6	1,431.8	1,369.9
Gross profit (loss)	(13.7)	(11.8)	(30.6)	36.4
Selling, general and administrative expenses	11.6	8.8	38.2	31.5
Helguvik (gains)	0	(4.5)	0	(4.5)
Other operating expense, net	(0.1)	(0.5)	0.4	0
Operating income (loss)	(25.2)	(15.6)	(69.2)	9.4
Interest expense - term loan	(0.8)	0	(1.3)	0
Interest expense	(5.6)	(5.6)	(17.3)	(16.7)
Interest income	0.2	0.4	0.6	1.3
Net gain (loss) on forward and derivative contracts	10.3	0.8	10.7	2.8
Other income (expense) - net	(0.9)	0.7	(1.6)	1.8
Income (loss) before income taxes and equity in earnings of joint ventures	(22)	(19.3)	(78.1)	(1.4)
Income tax benefit (expense)	1.3	(1.7)	5.7	(3)
Income (loss) before equity in earnings of joint ventures	(20.7)	(21)	(72.4)	(4.4)
Loss on sale of BHH	0	0	(4.3)	0
Equity in earnings of joint ventures	0	0.7	0.7	3.2
Net income (loss)	(20.7)	(20.3)	(76)	(1.2)
Net income (loss) allocated to common stockholders	$ (20.7)	$ (20.3)	$ (76)	$ (1.2)
EARNINGS (LOSS) PER COMMON SHARE:
Basic and diluted (per share)	$ (0.23)	$ (0.23)	$ (0.86)	$ (0.01)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic and diluted (per share)	88.9	87.6	88.6	87.6

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Comprehensive income (loss):
Net income (loss)	$ (20.7)	$ (20.3)	$ (76)	$ (1.2)
Other comprehensive income before income tax effect:
Net loss on foreign currency cash flow hedges reclassified as income	0	0	(0.1)	(0.2)
Defined benefit plans and other postretirement benefits:
Amortization of prior service benefit (cost) during the period	(1.2)	(1.8)	(3.8)	(5)
Amortization of net gain (loss) during the period	2.2	2.3	6.7	9.4
Other comprehensive income before income tax effect	1	0.5	2.8	4.2
Income tax effect	(0.3)	(0.4)	(0.8)	(1.1)
Other comprehensive income	0.7	0.1	2	3.1
Total comprehensive income (loss)	$ (20)	$ (20.2)	$ (74)	$ 1.9

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
ASSETS
Cash and cash equivalents	$ 22.5	$ 38.9
Restricted cash	0.8	0.8
Accounts receivable - net	81.9	82.5
Due from affiliates	23.3	22.7
Inventories	322.3	343.8
Prepaid and other current assets	23.3	18
Total current assets	474.1	506.7
Property, plant and equipment - net	950.1	967.3
Leases - right of use assets	24.2
Due from affiliates - less current portion	1.4	0
Other assets	42	63.5
TOTAL	1,491.8	1,537.5
LIABILITIES:
Accounts payable, trade	112	119.4
Due to affiliates	0	10.3
Accrued and other current liabilities	66.1	52.5
Accrued employee benefits costs	11	11
Term loan - current	15	0
Revolving credit facility	0.4	23.3
Industrial revenue bonds	7.8	7.8
Total current liabilities	212.3	224.3
Senior notes payable	249	248.6
Term loan - less current portion	25	0
Accrued pension benefits costs - less current portion	48.4	50.9
Accrued postretirement benefits costs - less current portion	101.2	101.2
Other liabilities	45.4	46
Leases - right of use liabilities	21.9
Deferred taxes	98.7	104.3
Total noncurrent liabilities	589.6	551
COMMITMENTS AND CONTINGENCIES	0	0
SHAREHOLDERS’ EQUITY:
Preferred stock	0	0
Common stock	1	1
Additional paid-in capital	2,524.8	2,523
Treasury stock, at cost	(86.3)	(86.3)
Accumulated other comprehensive loss	(98)	(98.7)
Accumulated deficit	(1,651.6)	(1,576.8)
Total shareholders’ equity	689.9	762.2
TOTAL	$ 1,491.8	$ 1,537.5

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (76)	$ (1.2)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Loss on sale of BHH	4.3	0
Unrealized (gain) loss on derivative instruments	(10.9)	(1.9)
Lower of cost or NRV inventory adjustment	15.8	5.9
Depreciation and amortization	63	67.5
Helguvik (gains)	0	(4.5)
Other non-cash items - net	(5.9)	(4)
Change in operating assets and liabilities:
Accounts receivable - net	10.7	(48.3)
Due from affiliates	(0.2)	(10.1)
Inventories	5.7	(78.8)
Prepaid and other current assets	3.8	1.8
Accounts payable, trade	(11.3)	23.4
Due to affiliates	(10.3)	(3.8)
Accrued and other current liabilities	8.4	1.7
Ravenswood retiree medical settlement	(2)	(2)
Other - net	0.5	(4.7)
Net cash provided by (used in) operating activities	(4.4)	(59)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(39.9)	(49.3)
Proceeds from sale of joint venture	10.5	0
Net cash provided by (used in) investing activities	(29.4)	(49.3)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings under term loan	40	0
Borrowings under revolving credit facilities	314.6	14.3
Repayments under revolving credit facilities	(337.5)	0
Other short-term borrowings	3.4	0
Repayment on other short-term borrowings	(3.4)	0
Issuance of common stock	0.3	0.2
Net cash provided by (used in) financing activities	17.4	14.5
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(16.4)	(93.8)
Cash, cash equivalents and restricted cash, beginning of period	39.7	168
Cash, cash equivalents and restricted cash, end of period	23.3	74.2
Cash paid for:
Interest	11.6	9.9
Taxes	0.3	4.6
Non-cash investing activities:
Capital expenditures	$ 3.9	$ 6.5

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Preferred stock [Member]	Common stock [Member]	Additional paid-in capital [Member]	Treasury stock, at cost [Member]	Accumulated other comprehensive loss [Member]	Accumulated deficit [Member]
Balance, start at Dec. 31, 2017	$ 829.6	$ 0	$ 0.9	$ 2,517.4	$ (86.3)	$ (91.7)	$ (1,510.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(1.2)
Other comprehensive income (loss)	3.1					3.1
Share-based compensation	2.1		0	2.1
Conversion of preferred stock to common stock	0	0	0	0
Balance, end at Sep. 30, 2018	833.5	0	0.9	2,519.5	(86.3)	(88.7)	(1,511.9)
Balance, start at Jun. 30, 2018	853.1	0	0.9	2,518.8	(86.3)	(88.7)	(1,491.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(20.3)						(20.3)
Other comprehensive income (loss)	0.1					0.1
Share-based compensation	0.7		0	0.7
Conversion of preferred stock to common stock	0		0	0
Balance, end at Sep. 30, 2018	833.5	0	0.9	2,519.5	(86.3)	(88.7)	(1,511.9)
Balance, start at Dec. 31, 2018	762.2	0	1	2,523	(86.3)	(98.7)	(1,576.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(76)						(76)
Other comprehensive income (loss)	2					2
Share-based compensation	1.8		0	1.8
Conversion of preferred stock to common stock	0	0	0	0
Balance, end at Sep. 30, 2019	689.9	0	1	2,524.8	(86.3)	(98)	(1,651.6)
Balance, start at Jun. 30, 2019	709.4	0	1	2,524.3	(86.3)	(98.7)	(1,630.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(20.7)						(20.7)
Other comprehensive income (loss)	0.7					0.7
Share-based compensation	0.5			0.5
Conversion of preferred stock to common stock				0	0
Balance, end at Sep. 30, 2019	$ 689.9	$ 0	$ 1	$ 2,524.8	$ (86.3)	$ (98)	$ (1,651.6)

General

General	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
General	General The accompanying unaudited interim consolidated financial statements of Century Aluminum Company should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2018 . 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 2019

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The significant related party transactions occurring during the nine months ended September 30, 2019 and 2018 are described below. We believe all of our transactions with Glencore and BHH are at prices that approximate market. Glencore ownership As of September 30, 2019 , Glencore plc and its affiliates (together "Glencore") beneficially owned 42.9% of Century’s outstanding common stock ( 47.0% on a fully-diluted basis assuming the conversion of all of the Series A Convertible Preferred Stock) and all of our outstanding Series A Convertible Preferred Stock. See Note 7. Shareholders' Equity for a description of our outstanding Series A Convertible Preferred Stock. From time to time Century and Glencore enter into various transactions for the purchase and sale of primary aluminum, purchase and sale of alumina, certain forward financial contracts and loan agreements. Sales to Glencore For the three months ended September 30, 2019 and 2018, 64.5% and 63.4% , respectively, of our consolidated net sales were made to Glencore, while for the nine months ended September 30, 2019 and 2018, 64.1% and 62.9% , respectively, of our consolidated net sales were made to Glencore. Glencore purchases the aluminum we produce for resale. Glencore purchases aluminum produced at our North American smelters at prices based on the London Metal Exchange (the "LME") plus the Midwest regional delivery premium and any product premiums. Glencore purchases aluminum produced at our Grundartangi, Iceland smelter at prices based on the LME plus the European Duty Paid premium and any applicable product premiums. We have also entered into agreements with Glencore pursuant to which we sell certain amounts of alumina at market prices. For the three months ended September 30, 2019 , we recorded $4.5 million of revenue related to 12,737 tonnes, and for the nine months ended September 30, 2019 , we recorded $26.2 million of revenue related to 72,506 tonnes. Purchases from Glencore We purchase a portion of our alumina requirements from Glencore. Alumina purchases from Glencore during the nine months ended September 30, 2019 were priced based on a published alumina index. Financial contracts with Glencore We have certain financial contracts with Glencore. See Note 14. Derivatives regarding these forward financial sales contracts. Hawesville Term Loan On April 29, 2019, we entered into a loan agreement with Glencore pursuant to which the Company borrowed $40.0 million (the "Hawesville Term Loan”). See Note 10. Debt for additional information. Borrowings under the Hawesville Term Loan are being used to partially finance the second phase of the Hawesville restart project. Ownership in Baise Haohai Carbon Co., Ltd. ("BHH") On May 22, 2019, Century Aluminum Asia Holdings Ltd. ("CAHL"), a wholly-owned subsidiary of Century Aluminum Company, entered into an equity transfer agreement (the "Equity Transfer Agreement") with Guangxi Qiangqiang Carbon Co., Ltd. ("GQQ") pursuant to which GQQ agreed to acquire all of our 40% interest in BHH. We previously owned a 40% stake in BHH, with an agreement to purchase carbon anodes from them for use in our manufacturing operations. As consideration for the sale, GQQ has agreed to pay RMB 144.9 million in cash, payable in two equal installments. The first payment was received in June 2019 and the second payment is due not later than December 31, 2019. In connection with this sale, we recorded a loss of $4.3 million , included in the Consolidated Statements of Operations for the nine months ended September 30, 2019. As of September 30, 2019, we have an outstanding $10.1 million receivable for the second payment, included in Accounts receivable - net, in the Consolidated Balance Sheets. Summary A summary of the aforementioned significant related party transactions is as follows: Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 Net sales to Glencore $ 282.3 $ 305.3 $ 898.7 $ 884.2 Purchases from Glencore 43.6 57.2 249.8 205.6 Purchases from BHH 2.2 5.9 16.8 21.4

Revenue

Revenue	9 Months Ended
	Sep. 30, 2019
Revenue Recognition and Deferred Revenue [Abstract]
Revenue	Revenue We recognize revenue in accordance with ASC 606, “Revenue from Contracts with Customers” and the related amendments (“ASC 606”). We disaggregate our revenue by geographical region as follows: Net Sales Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 United States $ 277.1 $ 286.6 $ 911.9 $ 834.2 Iceland 160.9 195.2 489.3 572.1 Total $ 438.0 $ 481.8 $ 1,401.2 $ 1,406.3 Trade accounts receivable - net as of September 30, 2019 decreased by $10.9 million from December 31, 2018 due to a decrease in sales resulting from lower realized LME prices.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases On January 1, 2019, we adopted ASC 842, “Leases” and the related amendments (“ASC 842”) using the modified retrospective transition method. Accordingly, the comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. The cumulative effect to retained earnings of initially applying this standard was zero. In adopting ASC 842, we have not separated lease and non-lease components within our contracts and we have not recognized the impact of leases with terms of less than one year in the right of use asset (“ROUA”) and right of use liability (“ROUL”) balances recorded as part of the adoption of ASC 842. Furthermore, we elected the package of three practical expedients, which allowed us to not reassess whether expired or existing contracts contain leases, lease classification of existing leases, and whether previously capitalized initial direct costs would qualify for capitalization under Topic 842. We do not have any initial direct costs that were previously capitalized. As of September 30, 2019, our ROUA balance recorded in Leases-right of use assets as part of Non-current assets is $ 24.2 million , our ROUL balance recorded as part of Accrued and other current liabilities is $2.8 million and our ROUL balance recorded as part of noncurrent liabilities is $ 21.9 million . The undiscounted maturities of our operating lease liability balances are as follows (in millions): Year As of September 30, 2019 2019 $ — 2020 1.6 2021 0.5 2022 0.9 2023 0.2 Thereafter 38.5 Total 41.7 Less: Interest (17.0 ) ROUL $ 24.7 We are a lessee in various agreements for the lease of office space, land, automobiles, and mobile equipment. All our leases are considered operating leases. The terms of our leases vary, including the lease term and the ability to renew or extend certain leases. As part of determining the lease term and potential extensions for purposes of calculating the ROUA and ROUL, we considered our historical practices related to renewal of certain leases. The weighted average remaining lease term for our operating leases as of September 30, 2019 is 14.1 years . Certain lease payment amounts are variable in nature and change periodically based on the local market consumer price index. We used our incremental borrowing rate as the basis for the discount rate used to calculate the ROUA and ROUL for our operating leases. The incremental borrowing rate was determined on a lease-by-lease basis and is based on the rate of interest that we would have to pay to borrow on a collateralized basis over a similar term for an amount equal to our lease payments. We have considered the most likely financing options available for each lease based on the leased asset, legal entity party to the lease, economic environment in which the lease is denominated, the market conditions relative to the leased asset and our historical practices of obtaining financing for similar types of costs. The weighted average discount rate for our operating leases as of September 30, 2019 is 7.3% . Total operating lease expense for the three and nine months ended September 30, 2019 was $ 1.9 million and $ 6.5 million , respectively, which includes short term lease expense of $ 0.8 million and $ 2.9 million , respectively. Total lease expense is included in cost of goods sold and selling, general, and administrative expenses on the Consolidated Statements of Operations. The full balance of operating lease expense is included in operating income on the Consolidated Statements of Operations. During the nine months ended September 30, 2019 , we had cash outflows of $ 3.1 million for amounts included in the ROUL balance at the beginning of the period related to our operating leases. During the three and nine months ended September 30, 2019 , we entered into new lease obligations, which resulted in $0.8 million of additional right of use assets.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We measure certain of our assets and liabilities at fair value. Fair value represents the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy provides transparency regarding the inputs we use to measure fair value. We categorize each fair value measurement in its entirety into the following three levels, based on the lowest level input that is significant to the entire measurement: • Level 1 Inputs - quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity can access at the measurement date. • Level 2 Inputs - inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. • Level 3 Inputs - unobservable inputs for the asset or liability. Recurring Fair Value Measurements As of September 30, 2019 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 15.4 $ — $ — $ 15.4 Trust assets (1) 0.7 — — 0.7 Surety bonds 1.8 — — 1.8 Derivative instruments — 6.1 15.7 21.8 TOTAL $ 17.9 $ 6.1 $ 15.7 $ 39.7 LIABILITIES: Contingent obligation – net $ — $ — $ — $ — Derivative instruments — 3.8 1.5 5.3 TOTAL $ — $ 3.8 $ 1.5 $ 5.3 Recurring Fair Value Measurements As of December 31, 2018 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 7.5 $ — $ — $ 7.5 Trust assets (1) 0.1 — — 0.1 Surety bonds 2.1 — — 2.1 Derivative instruments — 3.2 5.0 8.2 TOTAL $ 9.7 $ 3.2 $ 5.0 $ 17.9 LIABILITIES: Contingent obligation – net $ — $ — $ — $ — Derivative instruments — 2.0 0.5 2.5 TOTAL $ — $ 2.0 $ 0.5 $ 2.5 (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 following section describes the valuation techniques and inputs used for fair value measurements categorized within Level 2 or Level 3 of the fair value hierarchy: Level 2 and Level 3 Fair Value Measurements: Asset / Liability Level Valuation Techniques Inputs LME forward financial sales contracts - ST 2 Discounted cash flows Quoted LME forward market LME forward financial sales contracts - LT 3 Discounted cash flows Quoted LME forward market, discount rate MWP forward financial sales contracts 2 Discounted cash flows Quoted MWP forward market Fixed for floating swaps 2 Discounted cash flows Quoted LME forward market, quoted MWP forward market Nord Pool Power price swaps 2 Discounted cash flows Quoted Nord Pool forward market FX swaps 2 Discounted cash flows Euro/USD forward exchange rate Contingent obligation 3 Discounted cash flows Quoted LME forward market, management’s estimates of the LME forward market prices for periods beyond the quoted periods, management’s estimates of future level of operations Hawesville L4 power price swaps 3 Discounted cash flows Quoted Indy hub forward market, management's estimates of the locational marginal prices during the terms of the contracts

Earnings (Loss) Per Share

Earnings (Loss) Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings (Loss) Per Share	Earnings (Loss) Per Share Basic earnings (loss) per share ("EPS") amounts are calculated by dividing net income (loss) allocated to common stockholders by the weighted average number of common shares outstanding during the period. Diluted EPS amounts assume the issuance of common stock for all potentially dilutive securities. The following table shows the basic and diluted earnings (loss) per share: For the three months ended September 30, 2019 2018 Net Income (Loss) Shares (in millions) Per Share Net Income (Loss) Shares (in millions) Per Share Net income (loss) $ (20.7 ) $ (20.3 ) Amount allocated to common stockholders 100.0 % 100.0 % Basic and diluted EPS (1) $ (20.7 ) 88.9 $ (0.23 ) $ (20.3 ) 87.6 $ (0.23 ) For the nine months ended September 30, 2019 2018 Net Income (Loss) Shares (in millions) Per Share Net Income (Loss) Shares (in millions) Per Share Net income (loss) $ (76.0 ) $ (1.2 ) Amount allocated to common stockholders 100.0 % 100.0 % Basic and diluted EPS(1) $ (76.0 ) 88.6 $ (0.86 ) $ (1.2 ) 87.6 $ (0.01 ) Three months ended September 30, Nine months ended September 30, Securities excluded from the calculation of diluted EPS (in millions) (1) : 2019 2018 2019 2018 Share-based compensation 0.7 1.3 0.6 1.4 (1) In periods when we report a net loss, all share-based compensation awards are excluded from the calculation of diluted weighted average shares outstanding because of their anti-dilutive effect on earnings (loss) per share.

Shareholders_ Equity

Shareholders’ Equity	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
Shareholders’ Equity	Shareholders’ Equity Common Stock As of September 30, 2019 and December 31, 2018 , we had 195,000,000 shares of common stock, $0.01 par value per share, authorized under our Restated Certificate of Incorporation, of which 96,080,288 shares were issued and 88,893,767 shares were outstanding at September 30, 2019 ; 95,289,961 shares were issued and 88,103,440 shares were outstanding at December 31, 2018 . The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock which are currently outstanding, including our Series A Convertible Preferred Stock, or which we may designate and issue in the future. Preferred Stock As of September 30, 2019 and December 31, 2018 , we had 5,000,000 shares of preferred stock, $0.01 par value per share, authorized under our Restated Certificate of Incorporation. In 2008, we issued 160,000 shares of our Series A Convertible Preferred Stock. At September 30, 2019 and December 31, 2018 , there were 68,575 and 71,967 shares of Series A Convertible Preferred Stock outstanding, respectively, and held by Glencore. The issuance of common stock under our stock incentive programs, debt exchange transactions and any stock offering that excludes Glencore participation triggers anti-dilution provisions of the preferred stock agreement and results in the automatic conversion of Series A Convertible Preferred Stock shares into shares of common stock. The conversion of preferred to common shares is 100 shares of common stock for each share of preferred stock. The Common and Preferred Stock table below contains additional information about preferred stock conversions during the nine months ended September 30, 2019 and 2018 . Preferred stock Common stock Common and Preferred Stock Activity (in shares): Series A convertible Treasury Outstanding Beginning balance as of December 31, 2018 71,967 7,186,521 88,103,440 Conversion of convertible preferred stock (3,392 ) — 339,166 Issuance for share-based compensation plans — — 451,161 Ending balance as of September 30, 2019 68,575 7,186,521 88,893,767 Beginning balance as of December 31, 2017 74,364 7,186,521 87,544,777 Conversion of convertible preferred stock (272 ) — 27,263 Issuance for share-based compensation plans — — 36,266 Ending balance as of September 30, 2018 74,092 7,186,521 87,608,306 Stock Repurchase Program In 2011, our Board of Directors authorized a $60.0 million common stock repurchase program and during the first quarter of 2015, our Board of Directors increased the size of the program by $70.0 million . Under the program, Century is authorized to repurchase up to $130.0 million of our outstanding shares of common stock, from time to time, on the open market at prevailing market prices, in block trades or otherwise. The timing and amount of any shares repurchased will be determined by our management based on its evaluation of market conditions, the trading price of our common stock and other factors. The stock repurchase program may be suspended or discontinued at any time. Shares of common stock repurchased are recorded at cost as treasury stock and result in a reduction of shareholders’ equity in the consolidated balance sheets. From time to time, treasury shares may be reissued as contributions to our employee benefit plans and for the conversion of convertible preferred stock. When shares are reissued, we use an average cost method for determining cost. The difference between the cost of the shares and the reissuance price is added to or deducted from additional paid-in capital. Through September 30, 2019 , we had repurchased 7,186,521 shares of common stock for an aggregate purchase price of $86.3 million . We have made no share repurchases since April 2015 and we have $43.7 million remaining under the repurchase program authorization as of September 30, 2019

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recorded an income tax benefit of $ 1.3 million and tax expense of $1.7 million for the three months ended September 30, 2019 and September 30, 2018 , respectively. For the nine months ended September 30, 2019 and 2018, we recorded an income tax benefit of $5.7 million and tax expense of $3.0 million , respectively, which primarily consisted of tax impacts from foreign operations in each period. Our income tax benefit or expense is based on an annual effective tax rate forecast, including estimates and assumptions that could change during the year. The application of the accounting requirements for income taxes in interim periods, after consideration of our valuation allowance, causes a significant variation in the typical relationship between income tax expense/benefit and pre-tax accounting income/loss. As of September 30, 2019 , 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. On December 22, 2017, the President of the United States signed into law tax reform legislation (informally known as the Tax Cuts and Jobs Act (the "Act" or "Tax Act")) that made significant changes to various areas of U.S. federal income tax law. On January 1, 2019, the Company adopted ASU 2018-02, "Income Statement-Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," which provides for the reclassification from accumulated other comprehensive income to retained earnings of stranded tax effects resulting from the Tax Act. In accordance with the provisions of the ASU, $1.3 million of stranded tax effects related to the Tax Act were reclassified from accumulated other comprehensive loss to retained earnings in the first quarter of 2019. This reclassification includes the impact of the change in the federal corporate income tax rate and the related federal benefit of state taxes. The Company’s accounting policy with respect to releasing income tax effects from accumulated other comprehensive income is to apply a security by security approach whereby the tax effects are measured based on the change in the unrealized gains or losses reflected in other comprehensive loss.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2019
Inventory, Net [Abstract]
Inventories	Inventories Inventories consist of the following: September 30, 2019 December 31, 2018 Raw materials $ 88.4 $ 100.7 Work-in-process 50.7 49.5 Finished goods 36.2 47.3 Operating and other supplies 147.0 146.3 Total inventories $ 322.3 $ 343.8 Inventories are stated at the lower of cost or Net Realizable Value ("NRV") using the first-in, first-out ("FIFO") or the weighted average cost method.

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt September 30, 2019 December 31, 2018 Debt classified as current liabilities: Term loan - current portion (1) , interest payable monthly $ 15.0 $ — Hancock County industrial revenue bonds ("IRBs") due April 1, 2028, interest payable quarterly (variable interest rates (not to exceed 12%)) (2) 7.8 7.8 U.S. revolving credit facility (3) 0.4 23.3 Debt classified as non-current liabilities: 7.5% senior secured notes due June 1, 2021, net of debt discount of $1.0 million and $1.4 million, respectively, interest payable semiannually 249.0 248.6 Term loan - less current portion (1) , interest payable monthly 25.0 — Total $ 297.2 $ 279.7 (1) See "Hawesville Term Loan" paragraph below. At September 30, 2019 , the applicable interest rate was LIBOR of 2.16% plus margin of 5.375% . (2) 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, 2019 was 1.77% . (3) The U.S. revolving credit facility is classified as a current liability because we repay amounts outstanding and reborrow funds based on our working capital requirements. Borrowings bear interest at our option of either LIBOR or a base rate, plus, in each case, an applicable interest margin. At September 30, 2019 , all outstanding borrowings were subject to a rate of 5.25% . 7.5% Notes due 2021 General. On June 4, 2013, we issued $250.0 million of our 7.5% Notes due June 1, 2021 (the "2021 Notes") in a private offering exempt from the registration requirements of the Securities Act of 1933, as amended. The 2021 Notes were issued at a discount and bear interest at the rate of 7.5% per annum on the principal amount, payable semi-annually in arrears in cash on June 1st and December 1st of each year. Fair Value. Fair value for our 2021 Notes was based on the latest trading data available and was $249.0 million and $247.9 million , as of September 30, 2019 and December 31, 2018 , respectively. Although we use quoted market prices for identical debt instruments, the markets on which they trade are not considered to be active and are therefore considered Level 2 fair value measurements. Hawesville Term Loan On April 29, 2019, we entered into a loan agreement with Glencore pursuant to which the Company borrowed $40.0 million . Borrowings under the Hawesville Term Loan are being used to partially finance the second phase of the Hawesville restart project. The Hawesville Term Loan matures on December 31, 2021, and is to be repaid in twenty-four ( 24 ) equal monthly installments of principal, beginning on January 31, 2020. The Hawesville Term Loan bears interest, due monthly beginning at inception, at a floating rate equal to LIBOR plus 5.375% and is not secured by any collateral. U.S. Revolving Credit Facility We and certain of our direct and indirect domestic subsidiaries have a senior secured revolving credit facility with a syndicate of lenders (the "U.S. revolving credit facility"). The U.S. revolving credit facility provides for borrowings of up to $175.0 million in the aggregate, including up to $110.0 million under a letter of credit sub-facility, and also includes an uncommitted accordion feature whereby borrowers may increase the capacity of the U.S. revolving credit facility by up to $50.0 million , subject to agreement with the lenders. The U.S. revolving credit facility matures on the earlier of May 2023 or six months before the stated maturity of our outstanding senior secured notes. Any letters of credit issued and outstanding under the U.S. revolving credit facility reduce our borrowing availability on a dollar-for-dollar basis. At September 30, 2019 , there were $0.4 million in outstanding borrowings under our U.S. revolving credit facility. Principal payments, if any, are due upon maturity of the U.S. revolving credit facility. Status of our U.S. revolving credit facility: September 30, 2019 Credit facility maximum amount $ 175.0 Borrowing availability 169.7 Outstanding letters of credit issued 41.7 Outstanding borrowings 0.4 Borrowing availability, net of outstanding letters of credit and borrowings 127.6 Iceland Revolving Credit Facility Our wholly-owned subsidiary, Nordural Grundartangi ehf ("Grundartangi"), has a $50.0 million revolving credit facility agreement with Landsbankinn hf., dated November 2013, as amended (the "Iceland revolving credit facility"). Under the terms of the Iceland revolving credit facility, when Grundartangi borrows funds it will designate a repayment date, which may be any date prior to the maturity of the Iceland revolving credit facility. The Iceland revolving credit facility has a term through November 2022. Status of our Iceland revolving credit facility: September 30, 2019 Credit facility maximum amount $ 50.0 Borrowing availability 50.0 Outstanding letters of credit issued — Outstanding borrowings — Borrowing availability, net of borrowings 50.0

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and Contingencies Environmental Contingencies Based upon all available information, we believe our current environmental liabilities do not have, and are not likely to have, a material adverse effect on our financial condition, results of operations or liquidity. However, because of the inherent uncertainties in estimating environmental liabilities primarily due to unknown facts and circumstances and changing governmental regulations and legal standards regarding liability, there can be no assurance that future capital expenditures and costs for environmental compliance at currently or formerly owned or operated properties will not result in liabilities that may have a material adverse effect on our financial condition, results of operations or liquidity. It is our policy to accrue for costs associated with environmental assessments and remedial efforts when it becomes probable that a liability has been incurred and the costs can be reasonably estimated. All accrued amounts have been recorded without giving effect to any possible future recoveries. Costs for ongoing environmental compliance, including maintenance and monitoring are expensed as incurred. Vernon In July 2006, we were named as a defendant, together with certain affiliates of Alcan Inc., in a lawsuit brought by Alcoa Inc. seeking to determine responsibility for certain environmental indemnity obligations related to the sale of a cast aluminum plate manufacturing facility located in Vernon, California, which we purchased from Alcoa Inc. in December 1998, and sold to Alcan Rolled Products-Ravenswood LLC in July 1999. The complaint also seeks costs and attorney fees. The matter was stayed by the court in 2008 to allow for the remediation of environmental areas at the site. On June 30, 2016, the U.S. District Court for the District of Delaware ordered the stay lifted and reopened the case. Discovery was completed in the third quarter of 2019, and the matter is currently in the summary judgment phase. Trial is currently set to begin in March 2020. At this stage, we cannot predict the ultimate outcome of this action or estimate a range of reasonably possible losses related to this matter. 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. At this time, we are not able to estimate the amount of any future potential payments under this indemnification to comply with the Order, but we do not anticipate that any such amounts will have a material adverse effect on our financial condition, results of operations or liquidity, regardless of the final outcome. In December 2010, Century was among several defendants named in a lawsuit filed by plaintiffs who either worked, resided or owned property in the area downwind from the St. Croix Alumina Refinery. In March 2011, Century was also named a defendant in a nearly identical suit brought by certain additional plaintiffs. The plaintiffs in both suits allege damages caused by the presence of red mud and other particulates coming from the alumina facility and are seeking unspecified monetary damages, costs and attorney fees as well as certain injunctive relief. We tendered indemnity and defense to St. Croix Alumina LLC and Alcoa Alumina & Chemical LLC under the terms of an acquisition agreement relating to the facility and have filed motions to dismiss plaintiffs’ claims. In August 2015, the Superior Court of the Virgin Islands, Division of St. Croix denied the motions to dismiss but ordered all plaintiffs to refile individual complaints. On February 28, 2018, plaintiffs in both cases filed a Motion for Voluntary Dismissal of Century without prejudice to refiling. At this time, it is not possible to predict the ultimate outcome of or to estimate a range of reasonably possible losses for any of the foregoing actions relating to the St. Croix Alumina Refinery. Legal Contingencies In addition to the foregoing matters, we have pending against us or may be subject to various lawsuits, claims and proceedings related primarily to employment, commercial, stockholder, safety and health matters. While the results of such litigation matters and claims cannot be predicted with certainty, we believe that the final outcome of such matters will not have a material adverse impact on our financial condition, results of operations or liquidity. However, because of the nature and inherent uncertainties of litigation, should the outcome of these actions be unfavorable, our business, financial condition, results of operations and liquidity could be materially and adversely affected. In evaluating whether to accrue for losses associated with legal contingencies, it is our policy to take into consideration factors such as the facts and circumstances asserted, our historical experience with contingencies of a similar nature, the likelihood of our prevailing and the severity of any potential loss. For some matters, no accrual is established because we have assessed our risk of loss to be remote. Where the risk of loss is probable and the amount of the loss can be reasonably estimated, we record an accrual, either on an individual basis or with respect to a group of matters involving similar claims, based on the factors set forth above. When we have assessed that a loss associated with legal contingencies is reasonably possible, we determine if estimates of possible losses or ranges of possible losses are in excess of related accrued liabilities, if any. Based on current knowledge, management has ascertained estimates for losses that are reasonably possible and management does not believe that any reasonably possible outcomes in excess of our accruals, if any, either individually or in aggregate, would be material to our financial condition, results of operations or liquidity. We reevaluate and update our assessments and accruals as matters progress over time. Ravenswood Retiree Medical Benefits Changes In November 2009, Century Aluminum of West Virginia ("CAWV") filed a class action complaint for declaratory judgment against the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union ("USW"), the USW’s local and certain CAWV retirees, individually and as class representatives ("CAWV Retirees"), seeking a declaration of CAWV’s rights to modify/terminate retiree medical benefits. Later in November 2009, the USW and representatives of a retiree class filed a separate suit against CAWV, Century Aluminum Company, Century Aluminum Master Welfare Benefit Plan, and various John Does with respect to the foregoing. On August 18, 2017, the District Court for the Southern District of West Virginia approved a settlement agreement in respect of these actions. Under the terms of the settlement agreement, CAWV agreed to make payments into a trust for the benefit of the CAWV Retirees in the aggregate amount of $23.0 million over the course of 10 years. Upon approval of the settlement, we paid $5.0 million to the aforementioned trust in September 2017 and recognized a gain of $5.5 million to arrive at the then net present value of the liability of $12.5 million . CAWV has agreed to pay the remaining amounts under the settlement agreement in annual increments of $2.0 million for nine years. As of September 30, 2019 , $2.0 million had been recorded in other current liabilities and $8.5 million was recorded in other liabilities. PBGC Settlement In 2013, we entered into a settlement agreement with the Pension Benefit Guarantee Corporation ("PBGC") regarding an alleged "cessation of operations" at our Ravenswood facility. Pursuant to the terms of the agreement, we agreed to make additional contributions (above any minimum required contributions) to our defined benefit pension plans totaling approximately $17.4 million . Under certain circumstances, in periods of lower primary aluminum prices relative to our cost of operations, we are able to defer one or more of these payments provided that we provide the PBGC with acceptable security for such deferred payments. We did not make any contributions for the nine month periods ended September 30, 2019 and 2018 . We have elected to defer certain payments under the PBGC agreement and have provided the PBGC with the appropriate security. The remaining contributions under this agreement are approximately $9.6 million . Power Commitments and Contingencies Hawesville Hawesville has a power supply arrangement with Kenergy and EDF Trading North America, LLC (“EDF") which provides market-based power to the Hawesville smelter. Under this arrangement, the power companies purchase power on the open market and pass it through to Hawesville at Midcontinent Independent System Operator ("MISO") pricing plus transmission and other costs. The power supply arrangement with Kenergy has an effective term through December 2023. The arrangement with EDF to act as our market participant with MISO has an effective term through May 2020. Each of these agreements provide for automatic extension on a year-to-year basis unless a one -year notice is given. Sebree Sebree has a power supply arrangement with Kenergy and EDF which provides market-based power to the Sebree smelter. Similar to the arrangement at Hawesville, the power companies purchase power on the open market and pass it through to Sebree at MISO pricing plus transmission and other costs. The power supply arrangement with Kenergy has an effective term through December 2023. The arrangement with EDF to act as our market participant with MISO has an effective term through May 2020. Each of these agreements provides for automatic extension on a year-to-year basis unless a one -year notice is given. Mt. Holly Mt. Holly has a power supply arrangement pursuant to which 25% of the Mt. Holly load is served from the South Carolina Public Service Authority’s ("Santee Cooper") generation at a cost-based industrial rate and 75% of the Mt. Holly load is sourced from a supplier that is outside Santee Cooper’s service territory at market prices that are tied to natural gas prices. The agreement with Santee Cooper has a term through December 31, 2020 and may be terminated by Mt. Holly on 120 days' notice. The agreement with the other power supplier has a term through December 31, 2020 and may be terminated by Mt. Holly on 60 days’ notice. Grundartangi Grundartangi has power purchase agreements for approximately 525 MW with HS Orka hf ("HS"), Landsvirkjun and Orkuveita Reykjavikur ("OR") to provide power to its Grundartangi smelter. These power purchase agreements expire on various dates from 2023 through 2036 (subject to extension). The power purchase agreements with HS and OR both provide power at LME-based variable rates for the duration of these agreements. The power purchase agreement with Landsvirkjun for 161 MW provides power at LME-based variable rates through October 2019 and at rates linked to the Nord Pool power market from November 2019 through the expiration of the agreement on December 31, 2023. Helguvik Nordural Helguvik ehf ("Helguvik") has a power purchase agreement with OR to provide a portion of the power requirements to the Helguvik project. The agreement would provide power at LME-based variable rates and contain take-or-pay obligations with respect to a significant percentage of the total committed and available power under such agreement. The first phase of power under the OR purchase agreement (approximately 47.5 MW) became available in the fourth quarter of 2011 and is currently being utilized at Grundartangi. The agreement contains certain conditions to OR’s obligations with respect to the remaining phases and OR has alleged that certain of these conditions have not been satisfied. Other Commitments and Contingencies Labor Commitments The bargaining unit employees at our Grundartangi, Vlissingen, Hawesville and Sebree facilities are represented by labor unions, representing approximately 65% of our total workforce. Approximately 87% of Grundartangi’s work force is represented by five labor unions, governed by a labor agreement which is effective through December 31, 2019 that establishes wages and work rules for covered employees. 100% of Vlissingen's work force is represented by the Federation for the Metal and Electrical Industry ("FME") by a labor agreement that is effective through December 1, 2020. Approximately 56% of our U.S. based work force is represented by USW. The labor agreement for Hawesville employees is effective through April 1, 2020. Century Sebree's labor agreement with the USW for its employees is effective through October 28, 2023. Mt. Holly employees are not represented by a labor union.

Components of Accumulated Other

Components of Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Components of Accumulated Other Comprehensive Loss	Components of Accumulated Other Comprehensive Loss Components of AOCL: September 30, 2019 December 31, 2018 Defined benefit plan liabilities $ (104.3 ) $ (107.3 ) Unrealized loss on financial instruments 2.3 2.5 Other comprehensive loss before income tax effect (102.0 ) (104.8 ) Income tax effect (1) 4.0 6.1 Accumulated other comprehensive loss $ (98.0 ) $ (98.7 ) (1) The allocation of the income tax effect to the components of other comprehensive loss is as follows: September 30, 2019 December 31, 2018 Defined benefit plan liabilities $ 4.5 $ 6.6 Unrealized loss on financial instruments (0.5 ) (0.5 ) The following table summarizes the changes in the accumulated balances for each component of AOCL: Defined benefit plan and other postretirement liabilities Unrealized gain (loss) on financial instruments Total, net of tax Balance, July 1, 2019 $ (100.7 ) $ 2.0 $ (98.7 ) Net amount reclassified to net income (loss) 0.7 0.0 0.7 Balance, September 30, 2019 $ (100.0 ) $ 2.0 $ (98.0 ) Balance, July 1, 2018 $ (90.8 ) $ 2.1 $ (88.7 ) Net amount reclassified to net income (loss) 0.1 0.0 0.1 Balance, September 30, 2018 $ (90.7 ) $ 2.1 $ (88.7 ) Balance, December 31, 2018 $ (100.7 ) $ 2.0 $ (98.7 ) Impact of ASU 2018-02* (1.3 ) — (1.3 ) Net amount reclassified to net income (loss) 2.1 (0.1 ) 2.0 Balance, September 30, 2019 $ (100.0 ) $ 2.0 $ (98.0 ) Balance, January 1, 2018 $ (93.8 ) $ 2.1 $ (91.7 ) Net amount reclassified to net income (loss) 3.2 (0.1 ) 3.1 Balance, September 30, 2018 $ (90.7 ) $ 2.1 $ (88.7 ) *ASU 2018-02. See Note 8. Income Taxes for further information regarding our adoption of ASU 2018-02. Reclassifications out of AOCL were included in the consolidated statements of operations as follows: Three months ended September 30, Nine months ended September 30, AOCL Components Location 2019 2018 2019 2018 Defined benefit plan and other postretirement liabilities Cost of goods sold $ 0.8 $ 0.5 $ 1.7 $ 3.9 Selling, general and administrative expenses (0.3 ) (0.4 ) (0.9 ) (0.9 ) Other operating expense, net 0.5 0.4 2.1 1.3 Income tax effect (0.3 ) (0.4 ) (0.8 ) (1.1 ) Net of tax $ 0.7 $ 0.1 $ 2.1 $ 3.2 Unrealized loss on financial instruments Cost of goods sold $ 0.0 $ 0.0 $ (0.1 ) $ (0.1 ) Income tax effect 0.0 0.0 0.0 0.0 Net of tax $ 0.0 $ 0.0 $ (0.1 ) $ (0.1 )

Components of Net Periodic Bene

Components of Net Periodic Benefit Cost	9 Months Ended
	Sep. 30, 2019
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, 2019 2018 2019 2018 Service cost $ 1.0 $ 1.1 $ 2.5 $ 3.2 Interest cost 3.3 3.1 10.0 9.2 Expected return on plan assets (4.5 ) (5.3 ) (13.7 ) (15.8 ) Amortization of prior service costs 0.0 0.0 0.6 0.1 Amortization of net loss 1.6 1.3 4.9 3.9 Net periodic benefit cost $ 1.4 $ 0.2 $ 4.3 $ 0.6 Other Postretirement Benefits ("OPEB") Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 Service cost $ 0.0 $ 0.1 $ 0.8 $ 0.2 Interest cost 1.1 1.0 3.4 0.4 Amortization of prior service cost (1.2 ) (1.8 ) (4.3 ) (5.1 ) Amortization of net loss 0.6 1.0 1.7 5.4 Net periodic benefit cost $ 0.5 $ 0.3 $ 1.6 $ 0.9

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives As of September 30, 2019 , we had an open position of 96,506 tonnes related to LME forward financial sales contracts, some of which are with Glencore, to fix the forward LME price. These contracts are expected to settle monthly, between November 2019 and December 2024. We also have an open position of 139,250 tonnes related to Midwest Premium ("MWP") forward financial sales contracts to fix the forward MWP as of September 30, 2019 . These contracts are expected to settle monthly through December 2020. In 2019, we entered into financial contracts to fix the forward price for power related to the expected production of Line 4 at Hawesville for the period of January 2020 through December 2020 ("Hawesville L4 power price swaps") of 790,560 MWh. The Hawesville L4 power price swaps are expected to settle monthly during the term of the contract. We have financial contracts with various counterparties to offset fixed price sales arrangements with certain of our customers (“fixed for floating swaps”) to remain exposed to the LME and MWP price. As of September 30, 2019 , we had open positions related to such arrangements of 8,793 tonnes settling at various dates through December 2020. In 2017, we entered into financial contracts to fix the forward price of approximately 4% of Grundartangi's total power requirements for the period November 2019 through December 2020 (“Nord Pool power price swaps”). As of September 30, 2019 , we had an open position of 256,200 MWh related to the Nord Pool power price swaps. Because the Nord Pool power price swaps are settled in euros, we entered into financial contracts to hedge the risk of fluctuations associated with the euro ("FX swaps"). As of September 30, 2019 , we had open positions related to the FX swaps for €5.6 million that settle monthly from November 2019 through December 2020. The following table sets forth the Company's derivative assets and liabilities that were accounted for at fair value and not designated as cashflow hedges as of September 30, 2019 and December 31, 2018: Asset Fair Value September 30, 2019 December 31, 2018 Commodity contracts (1) $ 21.8 $ 8.2 Foreign exchange contracts (2) — — Total $ 21.8 $ 8.2 Liability Fair Value September 30, 2019 December 31, 2018 Commodity contracts (1) $ 4.4 $ 2.2 Foreign exchange contracts (2) 0.9 0.3 Total $ 5.3 $ 2.5 (1) Commodity contracts reflect our outstanding LME forward financial sales contracts, MWP forward financial sales contracts, Hawesville L4 power price swaps, fixed for floating swaps, and Nord Pool power price swaps. (2) Foreign exchange contracts reflect our outstanding FX swaps. The following table summarizes the net (loss) gain on forward and derivative contracts: Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 Commodity contracts (3) $ 10.6 $ 1.0 $ 11.2 $ 3.0 Foreign exchange contracts (0.3 ) (0.2 ) (0.5 ) (0.2 ) Total $ 10.3 $ 0.8 $ 10.7 $ 2.8 (3) For the three months ended September 30, 2019 and 2018, $ 1.9 million and $ 0.0 million of the net (loss) gain, respectively, was with Glencore. For the nine months ended September 30, 2019 and 2018, $ 2.7 million and $ (0.1) million of the net (loss) gain, respectively, was with Glencore.

Condensed Consolidating Financi

Condensed Consolidating Financial Information	9 Months Ended
	Sep. 30, 2019
Condensed Financial Information Disclosure [Abstract]
Condensed Consolidating Financial Information	Condensed Consolidating Financial Information Our 2021 Notes are guaranteed by each of our material existing and future domestic subsidiaries (the "Guarantor Subsidiaries"), except for Nordural US LLC, Century Aluminum Development LLC and Century Aluminum of West Virginia, Inc. The Guarantor Subsidiaries are 100% owned by Century. All guarantees are full and unconditional; all guarantees are joint and several. These notes are not guaranteed by our foreign subsidiaries (such foreign subsidiaries, Nordural US LLC, Century Aluminum Development LLC and Century Aluminum of West Virginia, Inc., collectively the “Non-Guarantor Subsidiaries”). We allocate corporate expenses or income to our subsidiaries and charge interest on certain intercompany balances. The following summarized condensed consolidating statements of comprehensive income (loss) for the three and nine months ended September 30, 2019 and 2018 , condensed consolidating balance sheets as of September 30, 2019 and 2018 and the condensed consolidating statements of cash flows for the nine months ended September 30, 2019 and 2018 present separate results for Century, the Guarantor Subsidiaries, the Non-Guarantor Subsidiaries, consolidating adjustments and total consolidated amounts. Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended September 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 132.9 $ 149.4 $ — $ 282.3 Other customers — 144.2 11.5 — 155.7 Total net sales — 277.1 160.9 — 438.0 Cost of goods sold — 288.3 163.4 — 451.7 Gross profit (loss) — (11.2 ) (2.5 ) — (13.7 ) Selling, general and administrative expenses 11.3 — 0.3 — 11.6 Other operating (income) expense - net — — (0.1 ) — (0.1 ) Operating income (loss) (11.3 ) (11.2 ) (2.7 ) — (25.2 ) Interest expense - term loan (0.8 ) — — — (0.8 ) Interest expense (5.1 ) (0.4 ) (0.1 ) — (5.6 ) Intercompany interest 8.8 2.6 (11.4 ) — — Interest income 0.1 — 0.1 — 0.2 Net gain (loss) on forward and derivative contracts 10.2 0.3 (0.2 ) — 10.3 Other income (expense) - net 0.1 (0.1 ) (0.9 ) — (0.9 ) Income (loss) before income taxes and equity in earnings of joint ventures 2.0 (8.8 ) (15.2 ) — (22.0 ) Income tax benefit (expense) 0.7 — 0.6 — 1.3 Income (loss) before equity in earnings of joint ventures 2.7 (8.8 ) (14.6 ) — (20.7 ) Equity in earnings (loss) of joint ventures (23.4 ) 3.4 (0.1 ) 20.1 — Net income (loss) (20.7 ) (5.4 ) (14.7 ) 20.1 (20.7 ) Other comprehensive income before income tax effect 1.0 0.8 0.5 (1.3 ) 1.0 Income tax effect (0.3 ) — — — (0.3 ) Other comprehensive income 0.7 0.8 0.5 (1.3 ) 0.7 Total comprehensive income (loss) $ (20.0 ) $ (4.6 ) $ (14.2 ) $ 18.8 $ (20.0 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended September 30, 2018 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 110.8 $ 194.5 $ — $ 305.3 Other customers — 175.8 0.7 — 176.5 Total net sales — 286.6 195.2 — 481.8 Cost of goods sold — 301.5 192.1 — 493.6 Gross profit (loss) — (14.9 ) 3.1 — (11.8 ) Selling, general and administrative expenses 8.4 — 0.4 — 8.8 Helguvik (gains) losses — — (4.5 ) — (4.5 ) Other operating (income) expense - net — — (0.5 ) — (0.5 ) Operating income (loss) (8.4 ) (14.9 ) 7.7 — (15.6 ) Interest expense (5.0 ) (0.4 ) (0.2 ) — (5.6 ) Intercompany interest 9.3 2.4 (11.7 ) — — Interest income 0.1 — 0.3 — 0.4 Net gain (loss) on forward and derivative contracts (0.2 ) 0.4 0.6 — 0.8 Other income (expense) - net — — 0.7 — 0.7 Income (loss) before income taxes and equity in earnings of joint ventures (4.2 ) (12.5 ) (2.6 ) — (19.3 ) Income tax (expense) benefit 0.5 — (2.2 ) — (1.7 ) Income (loss) before equity in earnings of joint ventures (3.7 ) (12.5 ) (4.8 ) — (21.0 ) Equity in earnings (loss) of joint ventures (16.6 ) 2.8 0.7 13.8 0.7 Net income (loss) (20.3 ) (9.7 ) (4.1 ) 13.8 (20.3 ) Other comprehensive income (loss) before income tax effect 0.5 0.5 0.4 (0.9 ) 0.5 Income tax effect (0.4 ) — — — (0.4 ) Other comprehensive income 0.1 0.5 0.4 (0.9 ) 0.1 Total comprehensive income (loss) $ (20.2 ) $ (9.2 ) $ (3.7 ) $ 12.9 $ (20.2 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the nine months ended September 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 432.8 $ 465.9 $ — $ 898.7 Other customers — 479.1 23.4 — 502.5 Total net sales — 911.9 489.3 — 1,401.2 Cost of goods sold — 921.5 510.3 — 1,431.8 Gross profit (loss) — (9.6 ) (21.0 ) — (30.6 ) Selling, general and administrative expenses 36.9 — 1.3 — 38.2 Other operating (income) expense - net — — 0.4 — 0.4 Operating income (loss) (36.9 ) (9.6 ) (22.7 ) — (69.2 ) Interest expense - term loan (1.3 ) — — — (1.3 ) Interest expense (15.9 ) (1.2 ) (0.2 ) — (17.3 ) Intercompany interest 26.2 7.6 (33.8 ) — — Interest income 0.2 — 0.4 — 0.6 Net gain (loss) on forward and derivative contracts 10.3 1.0 (0.6 ) — 10.7 Other income (expense) - net 0.9 (2.0 ) (0.5 ) — (1.6 ) Income (loss) before income taxes and equity in earnings of joint ventures (16.5 ) (4.2 ) (57.4 ) — (78.1 ) Income tax benefit (expense) 1.6 — 4.1 — 5.7 Income (loss) before equity in earnings of joint ventures (14.9 ) (4.2 ) (53.3 ) — (72.4 ) Loss on sale of BHH — — (4.3 ) — (4.3 ) Equity in earnings (loss) of joint ventures (61.1 ) 3.1 0.7 58.0 0.7 Net income (loss) (76.0 ) (1.1 ) (56.9 ) 58.0 (76.0 ) Other comprehensive income (loss) before income tax effect 2.8 1.6 2.0 (3.6 ) 2.8 Income tax effect (0.8 ) — — — (0.8 ) Other comprehensive income 2.0 1.6 2.0 (3.6 ) 2.0 Total comprehensive income (loss) $ (74.0 ) $ 0.5 $ (54.9 ) $ 54.4 $ (74.0 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the nine months ended September 30, 2018 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 315.1 $ 569.1 $ — $ 884.2 Other customers — 519.1 3.0 — 522.1 Total net sales — 834.2 572.1 — 1,406.3 Cost of goods sold — 821.1 548.8 — 1,369.9 Gross profit — 13.1 23.3 — 36.4 Selling, general and administrative expenses 29.8 — 1.7 — 31.5 Helguvik (gains) losses — — (4.5 ) — (4.5 ) Other operating expense - net — — 0.0 — 0.0 Operating income (loss) (29.8 ) 13.1 26.1 — 9.4 Interest expense (15.4 ) (1.2 ) (0.1 ) — (16.7 ) Intercompany interest 27.4 7.0 (34.4 ) — — Interest income 0.3 — 1.0 — 1.3 Net gain (loss) on forward and derivative contracts (0.2 ) 1.1 1.9 — 2.8 Other income (expense) - net 0.6 (0.2 ) 1.4 — 1.8 Income (loss) before income taxes and equity in earnings of joint ventures (17.1 ) 19.8 (4.1 ) — (1.4 ) Income tax benefit expense 0.7 — (3.7 ) — (3.0 ) Income (loss) before equity in earnings of joint ventures (16.4 ) 19.8 (7.8 ) — (4.4 ) Equity in earnings (loss) of joint ventures 15.2 (0.3 ) 3.2 (14.9 ) 3.2 Net income (loss) (1.2 ) 19.5 (4.6 ) (14.9 ) (1.2 ) Other comprehensive income (loss) before income tax effect 4.2 3.9 1.2 (5.1 ) 4.2 Income tax effect (1.1 ) — — — (1.1 ) Other comprehensive income 3.1 3.9 1.2 (5.1 ) 3.1 Total comprehensive income (loss) $ 1.9 $ 23.4 $ (3.4 ) $ (20.0 ) $ 1.9 Condensed Consolidating Balance Sheet As of September 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 1.5 $ — $ 21.0 $ — $ 22.5 Restricted cash — 0.8 — — 0.8 Accounts receivable - net — 70.6 11.3 — 81.9 Due from affiliates — 22.9 0.4 — 23.3 Inventories — 199.0 123.3 — 322.3 Prepaid and other current assets 12.3 0.9 10.1 — 23.3 Total current assets 13.8 294.2 166.1 — 474.1 Property, plant and equipment - net 18.1 326.2 605.8 — 950.1 Investment in subsidiaries 625.1 57.7 — (682.8 ) — Leases - right of use assets 5.9 1.4 16.9 — 24.2 Due from affiliates - long term 742.2 526.6 5.3 (1,272.7 ) 1.4 Other assets 35.4 4.2 2.4 — 42.0 TOTAL $ 1,440.5 $ 1,210.3 $ 796.5 $ (1,955.5 ) $ 1,491.8 Accounts payable, trade $ 2.9 $ 86.3 $ 22.8 $ — $ 112.0 Due to affiliates — — — — — Accrued and other current liabilities 26.7 25.1 14.3 — 66.1 Accrued employee benefits costs 1.9 8.3 0.8 — 11.0 Term loan - current 15.0 — — — 15.0 Revolving credit facility 0.4 — — — 0.4 Industrial revenue bonds — 7.8 — — 7.8 Total current liabilities 46.9 127.5 37.9 — 212.3 Senior notes payable 249.0 — — — 249.0 Term loan - less current portion 25.0 — — — 25.0 Accrued pension benefits costs - less current portion 22.3 20.7 5.4 — 48.4 Accrued postretirement benefits costs - less current portion 1.0 98.6 1.6 — 101.2 Due to affiliates - long term 395.2 295.4 582.1 (1,272.7 ) — Other liabilities 5.9 22.0 17.5 — 45.4 Leases - right of use liabilities 5.6 0.2 16.1 — 21.9 Deferred taxes (0.3 ) 1.8 97.2 — 98.7 Total noncurrent liabilities 703.7 438.7 719.9 (1,272.7 ) 589.6 Preferred stock 0.0 — — — 0.0 Common stock 1.0 — 0.1 (0.1 ) 1.0 Other shareholders' equity 688.9 644.1 38.6 (682.7 ) 688.9 Total shareholders' equity 689.9 644.1 38.7 (682.8 ) 689.9 TOTAL $ 1,440.5 $ 1,210.3 $ 796.5 $ (1,955.5 ) $ 1,491.8 Condensed Consolidating Balance Sheet As of December 31, 2018 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 0.1 $ — $ 38.8 $ — $ 38.9 Restricted cash — 0.8 — — 0.8 Accounts receivable - net 0.5 81.8 0.2 — 82.5 Due from affiliates — 13.1 9.6 — 22.7 Inventories — 210.7 133.1 — 343.8 Prepaid and other current assets 6.4 3.4 8.2 — 18.0 Total current assets 7.0 309.8 189.9 — 506.7 Property, plant and equipment - net 20.6 320.7 626.0 — 967.3 Investment in subsidiaries 668.3 54.5 — (722.8 ) — Due from affiliates - long term 751.7 517.6 7.2 (1,276.5 ) — Other assets 29.8 2.1 31.6 — 63.5 TOTAL $ 1,477.4 $ 1,204.7 $ 854.7 $ (1,999.3 ) $ 1,537.5 Accounts payable, trade $ 3.7 $ 84.1 $ 31.6 $ — $ 119.4 Due to affiliates — — 10.3 — 10.3 Accrued and other current liabilities 15.8 22.8 13.9 — 52.5 Accrued employee benefits costs 1.9 8.3 0.8 — 11.0 Revolving credit facility 23.3 — — — 23.3 Industrial revenue bonds — 7.8 — — 7.8 Total current liabilities 44.7 123.0 56.6 — 224.3 Senior notes payable 248.6 — — — 248.6 Accrued pension benefits costs - less current portion 23.2 20.7 7.0 — 50.9 Accrued postretirement benefits costs - less current portion 0.7 98.9 1.6 — 101.2 Other liabilities 2.8 23.5 19.7 — 46.0 Due to affiliates - long term 395.4 307.6 573.5 (1,276.5 ) — Deferred taxes (0.2 ) 1.8 102.7 — 104.3 Total noncurrent liabilities 670.5 452.5 704.5 (1,276.5 ) 551.0 Preferred stock 0.0 — — — 0.0 Common stock 1.0 — 0.1 (0.1 ) 1.0 Other shareholders' equity 761.2 629.2 93.5 (722.7 ) 761.2 Total shareholders' equity 762.2 629.2 93.6 (722.8 ) 762.2 TOTAL $ 1,477.4 $ 1,204.7 $ 854.7 $ (1,999.3 ) $ 1,537.5 Condensed Consolidating Statement of Cash Flows For the nine months ended September 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (57.1 ) $ 45.0 $ 7.7 $ — $ (4.4 ) Purchase of property, plant and equipment (0.6 ) (26.4 ) (12.9 ) — (39.9 ) Proceeds from sale of joint venture — — 10.5 — 10.5 Intercompany transactions (9.3 ) (52.6 ) 2.0 59.9 — Net cash provided by (used in) investing activities (9.9 ) (79.0 ) (0.4 ) 59.9 (29.4 ) Borrowings under term loan 40.0 — — — 40.0 Borrowings under revolving credit facilities 295.1 — 19.5 — 314.6 Repayments under revolving credit facilities (318.0 ) — (19.5 ) — (337.5 ) Other short term borrowings 3.4 — — — 3.4 Repayment on other short term borrowings (3.4 ) — — — (3.4 ) Issuance of common stock 0.3 — — — 0.3 Intercompany transactions 51.0 34.0 (25.1 ) (59.9 ) — Net cash provided by (used in) financing activities 68.4 34.0 (25.1 ) (59.9 ) 17.4 CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH 1.4 — (17.8 ) — (16.4 ) Cash, cash equivalents and restricted cash, beginning of period 0.1 0.8 38.8 — 39.7 Cash, cash equivalents and restricted cash, end of period $ 1.5 $ 0.8 $ 21.0 $ — $ 23.3 Condensed Consolidating Statement of Cash Flows For the nine months ended September 30, 2018 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (51.2 ) $ (0.5 ) $ (7.3 ) $ — $ (59.0 ) Purchase of property, plant and equipment (4.0 ) (38.9 ) (6.4 ) — (49.3 ) Intercompany transactions 39.5 40.9 (0.4 ) (80.0 ) — Net cash provided by (used in) investing activities 35.5 2.0 (6.8 ) (80.0 ) (49.3 ) Borrowings under revolving credit facilities 14.3 — — — 14.3 Issuance of common stock 0.2 — — — 0.2 Intercompany transactions (37.1 ) (1.7 ) (41.2 ) 80.0 — Net cash provided by (used in) financing activities (22.6 ) (1.7 ) (41.2 ) 80.0 14.5 CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH (38.3 ) (0.2 ) (55.3 ) — (93.8 ) Cash, cash equivalents and restricted cash, beginning of period 64.3 0.7 103.0 — 168.0 Cash, cash equivalents and restricted cash, end of period $ 26.0 $ 0.5 $ 47.7 $ — $ 74.2

General (Policies)

General (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Commitments and contingencies	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. All accrued amounts have been recorded without giving effect to any possible future recoveries. Costs for ongoing environmental compliance, including maintenance and monitoring are expensed as incurred.

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Schedule of related party transactions	A summary of the aforementioned significant related party transactions is as follows: Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 Net sales to Glencore $ 282.3 $ 305.3 $ 898.7 $ 884.2 Purchases from Glencore 43.6 57.2 249.8 205.6 Purchases from BHH 2.2 5.9 16.8 21.4

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue Recognition and Deferred Revenue [Abstract]
Disaggregation of revenue	We disaggregate our revenue by geographical region as follows: Net Sales Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 United States $ 277.1 $ 286.6 $ 911.9 $ 834.2 Iceland 160.9 195.2 489.3 572.1 Total $ 438.0 $ 481.8 $ 1,401.2 $ 1,406.3

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lessee, Operating Lease, Liability, Maturity	The undiscounted maturities of our operating lease liability balances are as follows (in millions): Year As of September 30, 2019 2019 $ — 2020 1.6 2021 0.5 2022 0.9 2023 0.2 Thereafter 38.5 Total 41.7 Less: Interest (17.0 ) ROUL $ 24.7

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Financial assets and liabilities at fair value on a recurring basis	Recurring Fair Value Measurements As of September 30, 2019 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 15.4 $ — $ — $ 15.4 Trust assets (1) 0.7 — — 0.7 Surety bonds 1.8 — — 1.8 Derivative instruments — 6.1 15.7 21.8 TOTAL $ 17.9 $ 6.1 $ 15.7 $ 39.7 LIABILITIES: Contingent obligation – net $ — $ — $ — $ — Derivative instruments — 3.8 1.5 5.3 TOTAL $ — $ 3.8 $ 1.5 $ 5.3 Recurring Fair Value Measurements As of December 31, 2018 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 7.5 $ — $ — $ 7.5 Trust assets (1) 0.1 — — 0.1 Surety bonds 2.1 — — 2.1 Derivative instruments — 3.2 5.0 8.2 TOTAL $ 9.7 $ 3.2 $ 5.0 $ 17.9 LIABILITIES: Contingent obligation – net $ — $ — $ — $ — Derivative instruments — 2.0 0.5 2.5 TOTAL $ — $ 2.0 $ 0.5 $ 2.5 (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.
Schedule of valuation methodology for assets and liabilities at fair value	The following section describes the valuation techniques and inputs used for fair value measurements categorized within Level 2 or Level 3 of the fair value hierarchy: Level 2 and Level 3 Fair Value Measurements: Asset / Liability Level Valuation Techniques Inputs LME forward financial sales contracts - ST 2 Discounted cash flows Quoted LME forward market LME forward financial sales contracts - LT 3 Discounted cash flows Quoted LME forward market, discount rate MWP forward financial sales contracts 2 Discounted cash flows Quoted MWP forward market Fixed for floating swaps 2 Discounted cash flows Quoted LME forward market, quoted MWP forward market Nord Pool Power price swaps 2 Discounted cash flows Quoted Nord Pool forward market FX swaps 2 Discounted cash flows Euro/USD forward exchange rate Contingent obligation 3 Discounted cash flows Quoted LME forward market, management’s estimates of the LME forward market prices for periods beyond the quoted periods, management’s estimates of future level of operations Hawesville L4 power price swaps 3 Discounted cash flows Quoted Indy hub forward market, management's estimates of the locational marginal prices during the terms of the contracts

Earnings (Loss) Per Share (Tabl

Earnings (Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Basic and diluted earnings (loss) per share	(1) In periods when we report a net loss, all share-based compensation awards are excluded from the calculation of diluted weighted average shares outstanding because of their anti-dilutive effect on earnings (loss) per share. The following table shows the basic and diluted earnings (loss) per share: For the three months ended September 30, 2019 2018 Net Income (Loss) Shares (in millions) Per Share Net Income (Loss) Shares (in millions) Per Share Net income (loss) $ (20.7 ) $ (20.3 ) Amount allocated to common stockholders 100.0 % 100.0 % Basic and diluted EPS (1) $ (20.7 ) 88.9 $ (0.23 ) $ (20.3 ) 87.6 $ (0.23 ) For the nine months ended September 30, 2019 2018 Net Income (Loss) Shares (in millions) Per Share Net Income (Loss) Shares (in millions) Per Share Net income (loss) $ (76.0 ) $ (1.2 ) Amount allocated to common stockholders 100.0 % 100.0 % Basic and diluted EPS(1) $ (76.0 ) 88.6 $ (0.86 ) $ (1.2 ) 87.6 $ (0.01 )
Securities excluded from the calculation of diluted EPS	Three months ended September 30, Nine months ended September 30, Securities excluded from the calculation of diluted EPS (in millions) (1) : 2019 2018 2019 2018 Share-based compensation 0.7 1.3 0.6 1.4 (1) In periods when we report a net loss, all share-based compensation awards are excluded from the calculation of diluted weighted average shares outstanding because of their anti-dilutive effect on earnings (loss) per share.

Shareholders_ Equity (Tables)

Shareholders’ Equity (Tables)	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
Common and Preferred Stock Activity	The Common and Preferred Stock table below contains additional information about preferred stock conversions during the nine months ended September 30, 2019 and 2018 . Preferred stock Common stock Common and Preferred Stock Activity (in shares): Series A convertible Treasury Outstanding Beginning balance as of December 31, 2018 71,967 7,186,521 88,103,440 Conversion of convertible preferred stock (3,392 ) — 339,166 Issuance for share-based compensation plans — — 451,161 Ending balance as of September 30, 2019 68,575 7,186,521 88,893,767 Beginning balance as of December 31, 2017 74,364 7,186,521 87,544,777 Conversion of convertible preferred stock (272 ) — 27,263 Issuance for share-based compensation plans — — 36,266 Ending balance as of September 30, 2018 74,092 7,186,521 87,608,306

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2019
Inventory, Net [Abstract]
Schedule of Inventories	September 30, 2019 December 31, 2018 Raw materials $ 88.4 $ 100.7 Work-in-process 50.7 49.5 Finished goods 36.2 47.3 Operating and other supplies 147.0 146.3 Total inventories $ 322.3 $ 343.8

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of Debt	September 30, 2019 December 31, 2018 Debt classified as current liabilities: Term loan - current portion (1) , interest payable monthly $ 15.0 $ — Hancock County industrial revenue bonds ("IRBs") due April 1, 2028, interest payable quarterly (variable interest rates (not to exceed 12%)) (2) 7.8 7.8 U.S. revolving credit facility (3) 0.4 23.3 Debt classified as non-current liabilities: 7.5% senior secured notes due June 1, 2021, net of debt discount of $1.0 million and $1.4 million, respectively, interest payable semiannually 249.0 248.6 Term loan - less current portion (1) , interest payable monthly 25.0 — Total $ 297.2 $ 279.7 (1) See "Hawesville Term Loan" paragraph below. At September 30, 2019 , the applicable interest rate was LIBOR of 2.16% plus margin of 5.375% . (2) 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, 2019 was 1.77% . (3) The U.S. revolving credit facility is classified as a current liability because we repay amounts outstanding and reborrow funds based on our working capital requirements. Borrowings bear interest at our option of either LIBOR or a base rate, plus, in each case, an applicable interest margin. At September 30, 2019 , all outstanding borrowings were subject to a rate of
Schedule of Line of Credit Facilities	Status of our U.S. revolving credit facility: September 30, 2019 Credit facility maximum amount $ 175.0 Borrowing availability 169.7 Outstanding letters of credit issued 41.7 Outstanding borrowings 0.4 Borrowing availability, net of outstanding letters of credit and borrowings 127.6 Status of our Iceland revolving credit facility: September 30, 2019 Credit facility maximum amount $ 50.0 Borrowing availability 50.0 Outstanding letters of credit issued — Outstanding borrowings — Borrowing availability, net of borrowings 50.0

Components of Accumulated Oth_2

Components of Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated balances for each component of AOCI	Components of AOCL: September 30, 2019 December 31, 2018 Defined benefit plan liabilities $ (104.3 ) $ (107.3 ) Unrealized loss on financial instruments 2.3 2.5 Other comprehensive loss before income tax effect (102.0 ) (104.8 ) Income tax effect (1) 4.0 6.1 Accumulated other comprehensive loss $ (98.0 ) $ (98.7 ) (1) The allocation of the income tax effect to the components of other comprehensive loss is as follows: September 30, 2019 December 31, 2018 Defined benefit plan liabilities $ 4.5 $ 6.6 Unrealized loss on financial instruments (0.5 ) (0.5 ) The following table summarizes the changes in the accumulated balances for each component of AOCL: Defined benefit plan and other postretirement liabilities Unrealized gain (loss) on financial instruments Total, net of tax Balance, July 1, 2019 $ (100.7 ) $ 2.0 $ (98.7 ) Net amount reclassified to net income (loss) 0.7 0.0 0.7 Balance, September 30, 2019 $ (100.0 ) $ 2.0 $ (98.0 ) Balance, July 1, 2018 $ (90.8 ) $ 2.1 $ (88.7 ) Net amount reclassified to net income (loss) 0.1 0.0 0.1 Balance, September 30, 2018 $ (90.7 ) $ 2.1 $ (88.7 ) Balance, December 31, 2018 $ (100.7 ) $ 2.0 $ (98.7 ) Impact of ASU 2018-02* (1.3 ) — (1.3 ) Net amount reclassified to net income (loss) 2.1 (0.1 ) 2.0 Balance, September 30, 2019 $ (100.0 ) $ 2.0 $ (98.0 ) Balance, January 1, 2018 $ (93.8 ) $ 2.1 $ (91.7 ) Net amount reclassified to net income (loss) 3.2 (0.1 ) 3.1 Balance, September 30, 2018 $ (90.7 ) $ 2.1 $ (88.7 ) *ASU 2018-02. See Note 8. Income Taxes for further information regarding our adoption of ASU 2018-02.
Reclassification out of AOCI	Reclassifications out of AOCL were included in the consolidated statements of operations as follows: Three months ended September 30, Nine months ended September 30, AOCL Components Location 2019 2018 2019 2018 Defined benefit plan and other postretirement liabilities Cost of goods sold $ 0.8 $ 0.5 $ 1.7 $ 3.9 Selling, general and administrative expenses (0.3 ) (0.4 ) (0.9 ) (0.9 ) Other operating expense, net 0.5 0.4 2.1 1.3 Income tax effect (0.3 ) (0.4 ) (0.8 ) (1.1 ) Net of tax $ 0.7 $ 0.1 $ 2.1 $ 3.2 Unrealized loss on financial instruments Cost of goods sold $ 0.0 $ 0.0 $ (0.1 ) $ (0.1 ) Income tax effect 0.0 0.0 0.0 0.0 Net of tax $ 0.0 $ 0.0 $ (0.1 ) $ (0.1 )

Components of Net Periodic Be_2

Components of Net Periodic Benefit Cost (Tables)	9 Months Ended
	Sep. 30, 2019
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, 2019 2018 2019 2018 Service cost $ 1.0 $ 1.1 $ 2.5 $ 3.2 Interest cost 3.3 3.1 10.0 9.2 Expected return on plan assets (4.5 ) (5.3 ) (13.7 ) (15.8 ) Amortization of prior service costs 0.0 0.0 0.6 0.1 Amortization of net loss 1.6 1.3 4.9 3.9 Net periodic benefit cost $ 1.4 $ 0.2 $ 4.3 $ 0.6 Other Postretirement Benefits ("OPEB") Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 Service cost $ 0.0 $ 0.1 $ 0.8 $ 0.2 Interest cost 1.1 1.0 3.4 0.4 Amortization of prior service cost (1.2 ) (1.8 ) (4.3 ) (5.1 ) Amortization of net loss 0.6 1.0 1.7 5.4 Net periodic benefit cost $ 0.5 $ 0.3 $ 1.6 $ 0.9

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives Not Designated as Hedging Instruments	The following table sets forth the Company's derivative assets and liabilities that were accounted for at fair value and not designated as cashflow hedges as of September 30, 2019 and December 31, 2018: Asset Fair Value September 30, 2019 December 31, 2018 Commodity contracts (1) $ 21.8 $ 8.2 Foreign exchange contracts (2) — — Total $ 21.8 $ 8.2 Liability Fair Value September 30, 2019 December 31, 2018 Commodity contracts (1) $ 4.4 $ 2.2 Foreign exchange contracts (2) 0.9 0.3 Total $ 5.3 $ 2.5 (1) Commodity contracts reflect our outstanding LME forward financial sales contracts, MWP forward financial sales contracts, Hawesville L4 power price swaps, fixed for floating swaps, and Nord Pool power price swaps. (2) Foreign exchange contracts reflect our outstanding FX swaps.
Schedule of Derivative Instruments	The following table summarizes the net (loss) gain on forward and derivative contracts: Three months ended September 30, Nine months ended September 30, 2019 2018 2019 2018 Commodity contracts (3) $ 10.6 $ 1.0 $ 11.2 $ 3.0 Foreign exchange contracts (0.3 ) (0.2 ) (0.5 ) (0.2 ) Total $ 10.3 $ 0.8 $ 10.7 $ 2.8 (3) For the three months ended September 30, 2019 and 2018, $ 1.9 million and $ 0.0 million of the net (loss) gain, respectively, was with Glencore. For the nine months ended September 30, 2019 and 2018, $ 2.7 million and $ (0.1) million of the net (loss) gain, respectively, was with Glencore.

Condensed Consolidating Finan_2

Condensed Consolidating Financial Information (Tables)	9 Months Ended
	Sep. 30, 2019
Condensed Financial Information Disclosure [Abstract]
Condensed Consolidating Statements of Comprehensive Income (Loss)	Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended September 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 132.9 $ 149.4 $ — $ 282.3 Other customers — 144.2 11.5 — 155.7 Total net sales — 277.1 160.9 — 438.0 Cost of goods sold — 288.3 163.4 — 451.7 Gross profit (loss) — (11.2 ) (2.5 ) — (13.7 ) Selling, general and administrative expenses 11.3 — 0.3 — 11.6 Other operating (income) expense - net — — (0.1 ) — (0.1 ) Operating income (loss) (11.3 ) (11.2 ) (2.7 ) — (25.2 ) Interest expense - term loan (0.8 ) — — — (0.8 ) Interest expense (5.1 ) (0.4 ) (0.1 ) — (5.6 ) Intercompany interest 8.8 2.6 (11.4 ) — — Interest income 0.1 — 0.1 — 0.2 Net gain (loss) on forward and derivative contracts 10.2 0.3 (0.2 ) — 10.3 Other income (expense) - net 0.1 (0.1 ) (0.9 ) — (0.9 ) Income (loss) before income taxes and equity in earnings of joint ventures 2.0 (8.8 ) (15.2 ) — (22.0 ) Income tax benefit (expense) 0.7 — 0.6 — 1.3 Income (loss) before equity in earnings of joint ventures 2.7 (8.8 ) (14.6 ) — (20.7 ) Equity in earnings (loss) of joint ventures (23.4 ) 3.4 (0.1 ) 20.1 — Net income (loss) (20.7 ) (5.4 ) (14.7 ) 20.1 (20.7 ) Other comprehensive income before income tax effect 1.0 0.8 0.5 (1.3 ) 1.0 Income tax effect (0.3 ) — — — (0.3 ) Other comprehensive income 0.7 0.8 0.5 (1.3 ) 0.7 Total comprehensive income (loss) $ (20.0 ) $ (4.6 ) $ (14.2 ) $ 18.8 $ (20.0 ) Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended September 30, 2018 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 110.8 $ 194.5 $ — $ 305.3 Other customers — 175.8 0.7 — 176.5 Total net sales — 286.6 195.2 — 481.8 Cost of goods sold — 301.5 192.1 — 493.6 Gross profit (loss) — (14.9 ) 3.1 — (11.8 ) Selling, general and administrative expenses 8.4 — 0.4 — 8.8 Helguvik (gains) losses — — (4.5 ) — (4.5 ) Other operating (income) expense - net — — (0.5 ) — (0.5 ) Operating income (loss) (8.4 ) (14.9 ) 7.7 — (15.6 ) Interest expense (5.0 ) (0.4 ) (0.2 ) — (5.6 ) Intercompany interest 9.3 2.4 (11.7 ) — — Interest income 0.1 — 0.3 — 0.4 Net gain (loss) on forward and derivative contracts (0.2 ) 0.4 0.6 — 0.8 Other income (expense) - net — — 0.7 — 0.7 Income (loss) before income taxes and equity in earnings of joint ventures (4.2 ) (12.5 ) (2.6 ) — (19.3 ) Income tax (expense) benefit 0.5 — (2.2 ) — (1.7 ) Income (loss) before equity in earnings of joint ventures (3.7 ) (12.5 ) (4.8 ) — (21.0 ) Equity in earnings (loss) of joint ventures (16.6 ) 2.8 0.7 13.8 0.7 Net income (loss) (20.3 ) (9.7 ) (4.1 ) 13.8 (20.3 ) Other comprehensive income (loss) before income tax effect 0.5 0.5 0.4 (0.9 ) 0.5 Income tax effect (0.4 ) — — — (0.4 ) Other comprehensive income 0.1 0.5 0.4 (0.9 ) 0.1 Total comprehensive income (loss) $ (20.2 ) $ (9.2 ) $ (3.7 ) $ 12.9 $ (20.2 )
Condensed Consolidating Balance Sheet	Condensed Consolidating Balance Sheet As of September 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 1.5 $ — $ 21.0 $ — $ 22.5 Restricted cash — 0.8 — — 0.8 Accounts receivable - net — 70.6 11.3 — 81.9 Due from affiliates — 22.9 0.4 — 23.3 Inventories — 199.0 123.3 — 322.3 Prepaid and other current assets 12.3 0.9 10.1 — 23.3 Total current assets 13.8 294.2 166.1 — 474.1 Property, plant and equipment - net 18.1 326.2 605.8 — 950.1 Investment in subsidiaries 625.1 57.7 — (682.8 ) — Leases - right of use assets 5.9 1.4 16.9 — 24.2 Due from affiliates - long term 742.2 526.6 5.3 (1,272.7 ) 1.4 Other assets 35.4 4.2 2.4 — 42.0 TOTAL $ 1,440.5 $ 1,210.3 $ 796.5 $ (1,955.5 ) $ 1,491.8 Accounts payable, trade $ 2.9 $ 86.3 $ 22.8 $ — $ 112.0 Due to affiliates — — — — — Accrued and other current liabilities 26.7 25.1 14.3 — 66.1 Accrued employee benefits costs 1.9 8.3 0.8 — 11.0 Term loan - current 15.0 — — — 15.0 Revolving credit facility 0.4 — — — 0.4 Industrial revenue bonds — 7.8 — — 7.8 Total current liabilities 46.9 127.5 37.9 — 212.3 Senior notes payable 249.0 — — — 249.0 Term loan - less current portion 25.0 — — — 25.0 Accrued pension benefits costs - less current portion 22.3 20.7 5.4 — 48.4 Accrued postretirement benefits costs - less current portion 1.0 98.6 1.6 — 101.2 Due to affiliates - long term 395.2 295.4 582.1 (1,272.7 ) — Other liabilities 5.9 22.0 17.5 — 45.4 Leases - right of use liabilities 5.6 0.2 16.1 — 21.9 Deferred taxes (0.3 ) 1.8 97.2 — 98.7 Total noncurrent liabilities 703.7 438.7 719.9 (1,272.7 ) 589.6 Preferred stock 0.0 — — — 0.0 Common stock 1.0 — 0.1 (0.1 ) 1.0 Other shareholders' equity 688.9 644.1 38.6 (682.7 ) 688.9 Total shareholders' equity 689.9 644.1 38.7 (682.8 ) 689.9 TOTAL $ 1,440.5 $ 1,210.3 $ 796.5 $ (1,955.5 ) $ 1,491.8 Condensed Consolidating Balance Sheet As of December 31, 2018 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 0.1 $ — $ 38.8 $ — $ 38.9 Restricted cash — 0.8 — — 0.8 Accounts receivable - net 0.5 81.8 0.2 — 82.5 Due from affiliates — 13.1 9.6 — 22.7 Inventories — 210.7 133.1 — 343.8 Prepaid and other current assets 6.4 3.4 8.2 — 18.0 Total current assets 7.0 309.8 189.9 — 506.7 Property, plant and equipment - net 20.6 320.7 626.0 — 967.3 Investment in subsidiaries 668.3 54.5 — (722.8 ) — Due from affiliates - long term 751.7 517.6 7.2 (1,276.5 ) — Other assets 29.8 2.1 31.6 — 63.5 TOTAL $ 1,477.4 $ 1,204.7 $ 854.7 $ (1,999.3 ) $ 1,537.5 Accounts payable, trade $ 3.7 $ 84.1 $ 31.6 $ — $ 119.4 Due to affiliates — — 10.3 — 10.3 Accrued and other current liabilities 15.8 22.8 13.9 — 52.5 Accrued employee benefits costs 1.9 8.3 0.8 — 11.0 Revolving credit facility 23.3 — — — 23.3 Industrial revenue bonds — 7.8 — — 7.8 Total current liabilities 44.7 123.0 56.6 — 224.3 Senior notes payable 248.6 — — — 248.6 Accrued pension benefits costs - less current portion 23.2 20.7 7.0 — 50.9 Accrued postretirement benefits costs - less current portion 0.7 98.9 1.6 — 101.2 Other liabilities 2.8 23.5 19.7 — 46.0 Due to affiliates - long term 395.4 307.6 573.5 (1,276.5 ) — Deferred taxes (0.2 ) 1.8 102.7 — 104.3 Total noncurrent liabilities 670.5 452.5 704.5 (1,276.5 ) 551.0 Preferred stock 0.0 — — — 0.0 Common stock 1.0 — 0.1 (0.1 ) 1.0 Other shareholders' equity 761.2 629.2 93.5 (722.7 ) 761.2 Total shareholders' equity 762.2 629.2 93.6 (722.8 ) 762.2 TOTAL $ 1,477.4 $ 1,204.7 $ 854.7 $ (1,999.3 ) $ 1,537.5
Condensed Consolidating Statement of Cash Flows	Condensed Consolidating Statement of Cash Flows For the nine months ended September 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (57.1 ) $ 45.0 $ 7.7 $ — $ (4.4 ) Purchase of property, plant and equipment (0.6 ) (26.4 ) (12.9 ) — (39.9 ) Proceeds from sale of joint venture — — 10.5 — 10.5 Intercompany transactions (9.3 ) (52.6 ) 2.0 59.9 — Net cash provided by (used in) investing activities (9.9 ) (79.0 ) (0.4 ) 59.9 (29.4 ) Borrowings under term loan 40.0 — — — 40.0 Borrowings under revolving credit facilities 295.1 — 19.5 — 314.6 Repayments under revolving credit facilities (318.0 ) — (19.5 ) — (337.5 ) Other short term borrowings 3.4 — — — 3.4 Repayment on other short term borrowings (3.4 ) — — — (3.4 ) Issuance of common stock 0.3 — — — 0.3 Intercompany transactions 51.0 34.0 (25.1 ) (59.9 ) — Net cash provided by (used in) financing activities 68.4 34.0 (25.1 ) (59.9 ) 17.4 CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH 1.4 — (17.8 ) — (16.4 ) Cash, cash equivalents and restricted cash, beginning of period 0.1 0.8 38.8 — 39.7 Cash, cash equivalents and restricted cash, end of period $ 1.5 $ 0.8 $ 21.0 $ — $ 23.3 Condensed Consolidating Statement of Cash Flows For the nine months ended September 30, 2018 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (51.2 ) $ (0.5 ) $ (7.3 ) $ — $ (59.0 ) Purchase of property, plant and equipment (4.0 ) (38.9 ) (6.4 ) — (49.3 ) Intercompany transactions 39.5 40.9 (0.4 ) (80.0 ) — Net cash provided by (used in) investing activities 35.5 2.0 (6.8 ) (80.0 ) (49.3 ) Borrowings under revolving credit facilities 14.3 — — — 14.3 Issuance of common stock 0.2 — — — 0.2 Intercompany transactions (37.1 ) (1.7 ) (41.2 ) 80.0 — Net cash provided by (used in) financing activities (22.6 ) (1.7 ) (41.2 ) 80.0 14.5 CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH (38.3 ) (0.2 ) (55.3 ) — (93.8 ) Cash, cash equivalents and restricted cash, beginning of period 64.3 0.7 103.0 — 168.0 Cash, cash equivalents and restricted cash, end of period $ 26.0 $ 0.5 $ 47.7 $ — $ 74.2

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) ¥ in Millions, $ in Millions	3 Months Ended		7 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)t	Sep. 30, 2018USD ($)	Dec. 31, 2019CNY (¥)	Sep. 30, 2019USD ($)t	Sep. 30, 2018USD ($)	May 22, 2019payment	Apr. 29, 2019USD ($)
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	42.90%			42.90%
Economic ownership percentage by related party	47.00%			47.00%
Related parties	$ 282.3	$ 305.3		$ 898.7	$ 884.2
Payments receivable	10.1			10.1
BHH [Member] | GQQ [Member]
Related Party Transaction [Line Items]
Ownership percentage						40.00%
Number of payments | payment						2
Loss on sale of equity investments				4.3
Glencore [Member]
Related Party Transaction [Line Items]
Related parties	282.3	$ 305.3		898.7	$ 884.2
Hawesville [Member]
Related Party Transaction [Line Items]
Term loan - less current portion							$ 40
Aluminum [Member] | Glencore [Member]
Related Party Transaction [Line Items]
Related parties	$ 4.5			$ 26.2
Number of metric tonnes | t	12,737			72,506
Consolidated Sales [Member] | Customer Concentration Risk [Member] | Glencore [Member]
Related Party Transaction [Line Items]
Major customer, percentage of revenue, net (percent)	64.50%	63.40%		64.10%	62.90%
Forecast [Member] | BHH [Member] | GQQ [Member]
Related Party Transaction [Line Items]
Consideration | ¥			¥ 144.9

Related Party Transactions - Su

Related Party Transactions - Summary of related party transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Related Party Transaction [Line Items]
Net sales to Glencore	$ 282.3	$ 305.3	$ 898.7	$ 884.2
Glencore [Member]
Related Party Transaction [Line Items]
Net sales to Glencore	282.3	305.3	898.7	884.2
Purchases from Glencore	43.6	57.2	249.8	205.6
BHH [Member]
Related Party Transaction [Line Items]
Purchases from BHH	$ 2.2	$ 5.9	$ 16.8	$ 21.4

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 438	$ 481.8	$ 1,401.2	$ 1,406.3
Accounts receivable - net			10.7	(48.3)
United States [Member]
Disaggregation of Revenue [Line Items]
Revenue	277.1	286.6	911.9	834.2
Iceland [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 160.9	$ 195.2	489.3	$ 572.1
Trade Accounts Receivable
Disaggregation of Revenue [Line Items]
Accounts receivable - net			$ 10.9

Leases (Details)

Leases (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Leases [Abstract]
Leases - right of use assets	$ 24.2	$ 24.2
Leases - right of use liabilities, current	2.8	2.8
Leases - right of use liabilities, noncurrent	$ 21.9	$ 21.9
Operating lease, weighted average remaining lease term	14 years 1 month 6 days	14 years 1 month 6 days
Operating lease, weighted average discount rate, percent	7.30%	7.30%
Operating lease, expense	$ 1.9	$ 6.5
Short-term lease, cost	0.8	2.9
Operating lease, payments		3.1
Right-of-use asset obtained in exchange for operating lease liability	$ 0.8	$ 0.8

Leases - Maturities (Details)

Leases - Maturities (Details) $ in Millions	Sep. 30, 2019USD ($)
Leases [Abstract]
2019	$ 0
2020	1.6
2021	0.5
2022	0.9
2023	0.2
Thereafter	38.5
Total	41.7
Less: Interest	(17)
ROUL	$ 24.7

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
ASSETS:
Cash equivalents	$ 15.4	$ 7.5
Trust assets	0.7	0.1
Surety bonds	1.8	2.1
Derivative instruments	21.8	8.2
TOTAL	39.7	17.9
LIABILITIES:
Contingent obligation – net	0	0
Derivative instruments	5.3	2.5
TOTAL	5.3	2.5
Fair Value, Inputs, Level 1 [Member]
ASSETS:
Cash equivalents	15.4	7.5
Trust assets	0.7	0.1
Surety bonds	1.8	2.1
Derivative instruments	0	0
TOTAL	17.9	9.7
LIABILITIES:
Contingent obligation – net	0	0
Derivative instruments	0	0
TOTAL	0	0
Fair Value, Inputs, Level 2 [Member]
ASSETS:
Cash equivalents	0	0
Trust assets	0	0
Surety bonds	0	0
Derivative instruments	6.1	3.2
TOTAL	6.1	3.2
LIABILITIES:
Contingent obligation – net	0	0
Derivative instruments	3.8	2
TOTAL	3.8	2
Fair Value, Inputs, Level 3 [Member]
ASSETS:
Cash equivalents	0	0
Trust assets	0	0
Surety bonds	0	0
Derivative instruments	15.7	5
TOTAL	15.7	5
LIABILITIES:
Contingent obligation – net	0	0
Derivative instruments	1.5	0.5
TOTAL	$ 1.5	$ 0.5

Earnings (Loss) Per Share (Deta

Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income (loss)	$ (20.7)	$ (20.3)	$ (76)	$ (1.2)
Amount allocated to common stockholders (as percent)	100.00%	100.00%	100.00%	100.00%
Basic and diluted EPS
Net income (loss) allocated to common stockholders	$ (20.7)	$ (20.3)	$ (76)	$ (1.2)
Net income (loss) allocated to common stockholders (shares)	88.9	87.6	88.6	87.6
Basic and diluted (per share)	$ (0.23)	$ (0.23)	$ (0.86)	$ (0.01)
Securities excluded from calculation of diluted EPS (shares)	0.7	1.3	0.6	1.4

Shareholders_ Equity (Details)

Shareholders’ Equity (Details) - USD ($)	9 Months Ended		54 Months Ended	105 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018	Mar. 31, 2015	Dec. 31, 2011	Dec. 31, 2008
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	195,000,000		195,000,000	195,000,000	195,000,000
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01	$ 0.01	$ 0.01
Common stock, shares issued (in shares)	96,080,288		96,080,288	96,080,288	95,289,961
Common stock, shares, outstanding (in shares)	88,893,767		88,893,767	88,893,767	88,103,440
Preferred stock, shares authorized (in shares)	5,000,000		5,000,000	5,000,000	5,000,000
Preferred stock par value (in dollars per share)	$ 0.01		$ 0.01	$ 0.01	$ 0.01
Preferred shares issued (in shares)								160,000
Number of shares issued for each share of preferred stock (in shares)	100		100	100
Stock repurchase program, authorized amount	$ 130,000,000		$ 130,000,000	$ 130,000,000		$ 70,000,000	$ 60,000,000
Treasury stock, shares, acquired (in shares)			0	7,186,521
Treasury stock, value, acquired, cost method				$ 86,300,000
Stock repurchase program, remaining authorized repurchase amount	$ 43,700,000		$ 43,700,000	$ 43,700,000
Series A Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares outstanding (in shares)	68,575		68,575	68,575	71,967
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance (in shares)	71,967	74,364
Conversion of convertible preferred stock (in shares)	(3,392)	(272)
Issuance for stock compensation plans (in shares)	0	0
Shares, Ending balance (in shares)	68,575	74,092	68,575	68,575
Treasury [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance (in shares)	7,186,521	7,186,521
Conversion of convertible preferred stock (in shares)	0	0
Issuance for stock compensation plans (in shares)	0	0
Shares, Ending balance (in shares)	7,186,521	7,186,521	7,186,521	7,186,521
Common stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Beginning balance (in shares)	88,103,440	87,544,777
Conversion of convertible preferred stock (in shares)	339,166	27,263
Issuance for stock compensation plans (in shares)	451,161	36,266
Shares, Ending balance (in shares)	88,893,767	87,608,306	88,893,767	88,893,767

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income tax benefit (expense)	$ 1.3		$ (1.7)	$ 5.7	$ (3)
Foreign income tax expense (benefit)				$ 5.7	$ (3)
Tax cuts and jobs act, reclassification from aoci to retained earnings, tax effect		$ 1.3

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Inventory, Net [Abstract]
Raw materials	$ 88.4	$ 100.7
Work-in-process	50.7	49.5
Finished goods	36.2	47.3
Operating and other supplies	147	146.3
Total inventories	$ 322.3	$ 343.8

Debt (Details)

Debt (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Jun. 04, 2013
Debt Instrument [Line Items]
Term loan - current portion, interest payable monthly	$ 15	$ 0
Hancock County industrial revenue bonds (IRBs) due 2028, interest payable quarterly (variable interest rates (not to exceed 12%)) (1)	7.8	7.8
Term loan - less current portion, interest payable monthly	25	0
Total debt	297.2	279.7
Hawesville [Member]
Debt Instrument [Line Items]
Term loan - current portion, interest payable monthly	15	0
Term loan - less current portion, interest payable monthly	25	0
Long-term Debt [Member] | Senior secured notes due June 01, 2021 [Member]
Debt Instrument [Line Items]
7.5% senior secured notes due June 1, 2021, net of debt discount of $1.0 million and $1.4 million, respectively, interest payable semiannually	$ 249	248.6
Maturity date	Jun. 1, 2021
Stated interest rate, percentage	7.50%		7.50%
Debt discount	$ 1	1.4
Short-term Debt [Member] | Industrial revenue bonds due 2028 [Member]
Debt Instrument [Line Items]
Hancock County industrial revenue bonds (IRBs) due 2028, interest payable quarterly (variable interest rates (not to exceed 12%)) (1)	$ 7.8	7.8
Maturity date	Apr. 1, 2028
Stated interest rate, percentage	1.77%
Short-term Debt [Member] | Industrial revenue bonds due 2028 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Effective interest rate, maximum	12.00%
Short-term Debt [Member] | Revolving Credit Facility, Portion Subject To Base Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate at period end	5.25%
Short-term Debt [Member] | U.S. revolving credit facility borrowings [Member]
Debt Instrument [Line Items]
U.S revolving credit facility	$ 0.4	$ 23.3
Stated interest rate, percentage	5.375%
Short-term Debt [Member] | U.S. revolving credit facility borrowings [Member] | Revolving Credit Facility, Portion Subject To LIBOR Rate [Member]
Debt Instrument [Line Items]
Stated interest rate, percentage	2.16%

Debt - Credit Facility (Details

Debt - Credit Facility (Details)	Apr. 29, 2019USD ($)payment	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)	Jun. 04, 2013USD ($)
Line of Credit Facility [Line Items]
Fair value of debt instrument		$ 249,000,000	$ 247,900,000
U.S. revolving credit facility [Member]
Line of Credit Facility [Line Items]
Credit facility maximum amount		175,000,000
Borrowing availability		169,700,000
Borrowing availability, net of outstanding letters of credit and borrowings		41,700,000
U.S. revolving credit facility [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Credit facility face amount		175,000,000
U.S. letter of credit [Member]
Line of Credit Facility [Line Items]
Letter of credit sub-facility amount		127,600,000
U.S. letter of credit [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Letter of credit sub-facility amount		110,000,000
U.S. revolving credit facility, accordion [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Credit facility face amount		50,000,000
Iceland revolving line of credit [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Credit facility maximum amount		50,000,000
Borrowing availability		50,000,000
Borrowing availability, net of outstanding letters of credit and borrowings		0
Borrowing availability, net of borrowings		$ 50,000,000
Senior secured notes due June 01, 2021 [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Face amount				$ 250,000,000
Stated interest rate, percentage		7.50%		7.50%
Short-term Debt [Member] | U.S. letter of credit [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings		$ 400,000
Short-term Debt [Member] | Iceland revolving line of credit [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings		$ 0
Short-term Debt [Member] | U.S. revolving credit facility borrowings [Member]
Line of Credit Facility [Line Items]
Stated interest rate, percentage		5.375%
U.S revolving credit facility		$ 400,000	$ 23,300,000
Hawesville [Member]
Line of Credit Facility [Line Items]
Due to related parties, noncurrent	$ 40,000,000
Debt instrument, payment terms, number of monthly payments | payment	24
London Interbank Offered Rate (LIBOR) [Member] | Hawesville [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	5.375%

Commitments and Contingencies (

Commitments and Contingencies (Details)	Aug. 18, 2017USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2019USD ($)Labor_UnionMW	Sep. 30, 2018USD ($)	Dec. 31, 2013USD ($)
Labor Commitments [Abstract]
Percentage of total work force in union			65.00%
Percentage of Grundartangi work force represented by the labor unions (in hundredths)			87.00%
Number of labor unions Grundartangi subsidiary entered into a new labor agreement with | Labor_Union			5
Percentage of U.S. based work force represented by a union (in hundredths)			56.00%
Ravenswood Retiree Medical Benefits Changes [Member]
Ravenswood litigation [Abstract]
Gain (loss) related to litigation settlement		$ 5,500,000
Loss contingency accrual		12,500,000
PBGC Agreement [Member]
PBGC Settlement [Abstract]
Required pension contributions above minimum					$ 17,400,000
Payment for pension benefits			$ 0	$ 0
Pension contributions above minimum remaining			$ 9,600,000
Hawesville [Member]
Power Contingencies [Abstract]
Power supply agreement, termination notice period			1 year
Sebree [Member]
Power Contingencies [Abstract]
Power supply agreement, termination notice period			1 year
South Carolina Public Service Authority [Member]
Power Contingencies [Abstract]
Power supply agreement, termination notice period			120 days
Power agreement, power supply from source one, percentage			25.00%
Power agreement, power supply from source two, percentage			75.00%
Other Power Suppliers [Member]
Power Contingencies [Abstract]
Power supply agreement, termination notice period			60 days
Grundartangi - HS, Landsvirkjun and OR [Member]
Power Contingencies [Abstract]
Power currently available under the power purchase agreement (in megawatts) | MW			525
Grundartangi - Landsvirkjun [Member]
Power Contingencies [Abstract]
Power currently available under the power purchase agreement (in megawatts) | MW			161
Helguvik [Member]
Power Contingencies [Abstract]
Power currently available under the power purchase agreement (in megawatts) | MW			47.5
NETHERLANDS
Labor Commitments [Abstract]
Percentage of Vlissingen work force represented by the labor union (in hundredths)			100.00%
Ravenswood Retiree Medical Benefits Changes [Member]
Ravenswood litigation [Abstract]
Ravenswood litigation settlement amount	$ 23,000,000
Ravenswood litigation settlement installment period	10 years		9 years
Litigation payment to trust		$ 5,000,000
Litigation settlement, amount awarded to other party, annual payments			$ 2,000,000
Other Current Liabilities [Member] | Ravenswood Retiree Medical Benefits Changes [Member]
Ravenswood litigation [Abstract]
Litigation settlement, amount awarded to other party, annual payments			2,000,000
Other Liabilities [Member] | Ravenswood Retiree Medical Benefits Changes [Member]
Ravenswood litigation [Abstract]
Litigation settlement, amount awarded to other party, annual payments			$ 8,500,000

Components of Accumulated Oth_3

Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Jan. 01, 2019	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect		$ (102)			$ (102)		$ (104.8)
Income tax effect		4			4		6.1
Accumulated other comprehensive loss		(98)			(98)		(98.7)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, start	$ 762.2	709.4	$ 762.2	$ 853.1	762.2	$ 829.6
Impact of ASU 2018-02			1.3
Balance, end		689.9		833.5	689.9	833.5
Defined benefit plan and other postretirement liabilities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect		(104.3)			(104.3)		(107.3)
Income tax effect		(4.5)			(4.5)		(6.6)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, start	(100.7)	(100.7)	(100.7)	(90.8)	(100.7)	(93.8)
Impact of ASU 2018-02	(1.3)
Net amount reclassified to net income (loss)		0.7		0.1	2.1	3.2
Balance, end		(100)		(90.7)	(100)	(90.7)
Unrealized gain (loss) on financial instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect		2.3			2.3		2.5
Income tax effect		0.5			0.5		$ 0.5
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, start	2	2	2	2.1	2	2.1
Impact of ASU 2018-02	0
Net amount reclassified to net income (loss)		0		0	(0.1)	(0.1)
Balance, end		2		2.1	2	2.1
Accumulated other comprehensive loss [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, start	(98.7)	(98.7)	$ (98.7)	(88.7)	(98.7)	(91.7)
Impact of ASU 2018-02	$ (1.3)
Net amount reclassified to net income (loss)		0.7		0.1	2	3.1
Balance, end		$ (98)		$ (88.7)	$ (98)	$ (88.7)

Components of Accumulated Oth_4

Components of Accumulated Other Comprehensive Loss - Reclassifications out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of goods sold	$ 451.7	$ 493.6	$ 1,431.8	$ 1,369.9
Selling, general and administrative expenses	11.6	8.8	38.2	31.5
Other operating expense, net	(0.1)	(0.5)	0.4	0
Income tax effect	(1.3)	1.7	(5.7)	3
Net of tax	20.7	20.3	76	1.2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined benefit plan and other postretirement liabilities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of goods sold	0.8	0.5	1.7	3.9
Selling, general and administrative expenses	(0.3)	(0.4)	(0.9)	(0.9)
Other operating expense, net	0.5	0.4	2.1	1.3
Income tax effect	(0.3)	(0.4)	(0.8)	(1.1)
Net of tax	0.7	0.1	2.1	3.2
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized loss on financial instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of goods sold	0	0	(0.1)	(0.1)
Income tax effect	0	0	0	0
Net of tax	$ 0	$ 0	$ (0.1)	$ (0.1)

Components of Net Periodic Be_3

Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1	$ 1.1	$ 2.5	$ 3.2
Interest cost	3.3	3.1	10	9.2
Expected return on plan assets	(4.5)	(5.3)	(13.7)	(15.8)
Amortization of prior service costs	0	0	0.6	0.1
Amortization of net loss	1.6	1.3	4.9	3.9
Net periodic benefit cost	1.4	0.2	4.3	0.6
Other Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0	0.1	0.8	0.2
Interest cost	1.1	1	3.4	0.4
Amortization of prior service costs	(1.2)	(1.8)	(4.3)	(5.1)
Amortization of net loss	0.6	1	1.7	5.4
Net periodic benefit cost	$ 0.5	$ 0.3	$ 1.6	$ 0.9

Derivatives (Details)

Derivatives (Details) € in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019EUR (€)MWht	Dec. 31, 2017
LME Swap [Member]
Derivative [Line Items]
Other forward delivery contracts to sell primary aluminum, open (in tonnes)	96,506
Midwest Premium (MWP) [Member]
Derivative [Line Items]
Open position to offset fixed prices	139,250
Hawesville L4 Power Price Swaps [Member]
Derivative [Line Items]
Power available | MWh	790,560
Price Swap [Member]
Derivative [Line Items]
Open position to offset fixed prices	8,793
Nordpool Power Price Swap [Member] | Grundartangi [Member]
Derivative [Line Items]
Power available | MWh	256,200
Percentage of power purchases included in forward price contract (percent)		4.00%
FX Swap [Member]
Derivative [Line Items]
Derivative asset | €	€ 5.6

Derivatives Assets and Liabilit

Derivatives Assets and Liabilities (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative asset	$ 21.8	$ 8.2
Derivative liability	5.3	2.5
Commodity Contract [Member]
Derivative [Line Items]
Derivative asset	21.8	8.2
Derivative liability	4.4	2.2
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative asset	0	0
Derivative liability	$ 0.9	$ 0.3

Derivatives Net Gain (Loss) (De

Derivatives Net Gain (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	$ 10.3	$ 0.8	$ 10.7	$ 2.8
Commodity Contract [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	10.6	1	11.2	3
Commodity Contract [Member] | Glencore [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	1.9	0	2.7	(0.1)
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	$ (0.3)	$ (0.2)	$ (0.5)	$ (0.2)

Condensed Consolidating Finan_3

Condensed Consolidating Financial Information - Statement of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
NET SALES
Related parties	$ 282.3	$ 305.3	$ 898.7	$ 884.2
Other customers	155.7	176.5	502.5	522.1
Total net sales	438	481.8	1,401.2	1,406.3
Cost of goods sold	451.7	493.6	1,431.8	1,369.9
Gross profit (loss)	(13.7)	(11.8)	(30.6)	36.4
Selling, general and administrative expenses	11.6	8.8	38.2	31.5
Helguvik (gains)	0	(4.5)	0	(4.5)
Other operating expense, net	(0.1)	(0.5)	0.4	0
Operating income (loss)	(25.2)	(15.6)	(69.2)	9.4
Interest expense - term loan	(0.8)	0	(1.3)	0
Interest expense	(5.6)	(5.6)	(17.3)	(16.7)
Intercompany interest	0	0	0	0
Interest income	0.2	0.4	0.6	1.3
Net gain (loss) on forward and derivative contracts	10.3	0.8	10.7	2.8
Other income (expense) - net	(0.9)	0.7	(1.6)	1.8
Income (loss) before income taxes and equity in earnings of joint ventures	(22)	(19.3)	(78.1)	(1.4)
Income tax benefit (expense)	1.3	(1.7)	5.7	(3)
Income (loss) before equity in earnings of joint ventures	(20.7)	(21)	(72.4)	(4.4)
Loss on sale of BHH	0	0	(4.3)	0
Equity in earnings of joint ventures	0	0.7	0.7	3.2
Net income (loss)	(20.7)	(20.3)	(76)	(1.2)
Other comprehensive income before income tax effect	1	0.5	2.8	4.2
Income tax effect	(0.3)	(0.4)	(0.8)	(1.1)
Other comprehensive income	0.7	0.1	2	3.1
Total comprehensive income (loss)	(20)	(20.2)	(74)	1.9
Consolidating Adjustments [Member]
NET SALES
Related parties	0	0	0	0
Other customers	0	0	0	0
Total net sales	0	0	0	0
Cost of goods sold	0	0	0	0
Gross profit (loss)	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Helguvik (gains)		0		0
Other operating expense, net	0	0	0	0
Operating income (loss)	0	0	0	0
Interest expense - term loan	0		0
Interest expense	0	0	0	0
Intercompany interest	0	0	0	0
Interest income	0	0	0	0
Net gain (loss) on forward and derivative contracts	0	0	0	0
Other income (expense) - net	0	0	0	0
Income (loss) before income taxes and equity in earnings of joint ventures	0	0	0	0
Income tax benefit (expense)	0	0	0	0
Income (loss) before equity in earnings of joint ventures	0	0	0	0
Loss on sale of BHH			0
Equity in earnings of joint ventures	20.1	13.8	58	(14.9)
Net income (loss)	20.1	13.8	58	(14.9)
Other comprehensive income before income tax effect	(1.3)	(0.9)	(3.6)	(5.1)
Income tax effect	0	0	0	0
Other comprehensive income	(1.3)	(0.9)	(3.6)	(5.1)
Total comprehensive income (loss)	18.8	12.9	54.4	(20)
The Company [Member] | Reportable Legal Entities [Member]
NET SALES
Related parties	0	0	0	0
Other customers	0	0	0	0
Total net sales	0	0	0	0
Cost of goods sold	0	0	0	0
Gross profit (loss)	0	0	0	0
Selling, general and administrative expenses	11.3	8.4	36.9	29.8
Helguvik (gains)		0		0
Other operating expense, net	0	0	0	0
Operating income (loss)	(11.3)	(8.4)	(36.9)	(29.8)
Interest expense - term loan	(0.8)		(1.3)
Interest expense	(5.1)	(5)	(15.9)	(15.4)
Intercompany interest	8.8	9.3	26.2	27.4
Interest income	0.1	0.1	0.2	0.3
Net gain (loss) on forward and derivative contracts	10.2	(0.2)	10.3	(0.2)
Other income (expense) - net	0.1	0	0.9	0.6
Income (loss) before income taxes and equity in earnings of joint ventures	2	(4.2)	(16.5)	(17.1)
Income tax benefit (expense)	0.7	0.5	1.6	0.7
Income (loss) before equity in earnings of joint ventures	2.7	(3.7)	(14.9)	(16.4)
Loss on sale of BHH			0
Equity in earnings of joint ventures	(23.4)	(16.6)	(61.1)	15.2
Net income (loss)	(20.7)	(20.3)	(76)	(1.2)
Other comprehensive income before income tax effect	1	0.5	2.8	4.2
Income tax effect	(0.3)	(0.4)	(0.8)	(1.1)
Other comprehensive income	0.7	0.1	2	3.1
Total comprehensive income (loss)	(20)	(20.2)	(74)	1.9
Combined Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
NET SALES
Related parties	132.9	110.8	432.8	315.1
Other customers	144.2	175.8	479.1	519.1
Total net sales	277.1	286.6	911.9	834.2
Cost of goods sold	288.3	301.5	921.5	821.1
Gross profit (loss)	(11.2)	(14.9)	(9.6)	13.1
Selling, general and administrative expenses	0	0	0	0
Helguvik (gains)		0		0
Other operating expense, net	0	0	0	0
Operating income (loss)	(11.2)	(14.9)	(9.6)	13.1
Interest expense - term loan	0		0
Interest expense	(0.4)	(0.4)	(1.2)	(1.2)
Intercompany interest	2.6	2.4	7.6	7
Interest income	0	0	0	0
Net gain (loss) on forward and derivative contracts	0.3	0.4	1	1.1
Other income (expense) - net	(0.1)	0	(2)	(0.2)
Income (loss) before income taxes and equity in earnings of joint ventures	(8.8)	(12.5)	(4.2)	19.8
Income tax benefit (expense)	0	0	0	0
Income (loss) before equity in earnings of joint ventures	(8.8)	(12.5)	(4.2)	19.8
Loss on sale of BHH			0
Equity in earnings of joint ventures	3.4	2.8	3.1	(0.3)
Net income (loss)	(5.4)	(9.7)	(1.1)	19.5
Other comprehensive income before income tax effect	0.8	0.5	1.6	3.9
Income tax effect	0	0	0	0
Other comprehensive income	0.8	0.5	1.6	3.9
Total comprehensive income (loss)	(4.6)	(9.2)	0.5	23.4
Combined Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
NET SALES
Related parties	149.4	194.5	465.9	569.1
Other customers	11.5	0.7	23.4	3
Total net sales	160.9	195.2	489.3	572.1
Cost of goods sold	163.4	192.1	510.3	548.8
Gross profit (loss)	(2.5)	3.1	(21)	23.3
Selling, general and administrative expenses	0.3	0.4	1.3	1.7
Helguvik (gains)		(4.5)		(4.5)
Other operating expense, net	(0.1)	(0.5)	0.4	0
Operating income (loss)	(2.7)	7.7	(22.7)	26.1
Interest expense - term loan	0		0
Interest expense	(0.1)	(0.2)	(0.2)	(0.1)
Intercompany interest	(11.4)	(11.7)	(33.8)	(34.4)
Interest income	0.1	0.3	0.4	1
Net gain (loss) on forward and derivative contracts	(0.2)	0.6	(0.6)	1.9
Other income (expense) - net	(0.9)	0.7	(0.5)	1.4
Income (loss) before income taxes and equity in earnings of joint ventures	(15.2)	(2.6)	(57.4)	(4.1)
Income tax benefit (expense)	0.6	(2.2)	4.1	(3.7)
Income (loss) before equity in earnings of joint ventures	(14.6)	(4.8)	(53.3)	(7.8)
Loss on sale of BHH			(4.3)
Equity in earnings of joint ventures	(0.1)	0.7	0.7	3.2
Net income (loss)	(14.7)	(4.1)	(56.9)	(4.6)
Other comprehensive income before income tax effect	0.5	0.4	2	1.2
Income tax effect	0	0	0	0
Other comprehensive income	0.5	0.4	2	1.2
Total comprehensive income (loss)	$ (14.2)	$ (3.7)	$ (54.9)	$ (3.4)
Century Aluminum [Member] | Combined Guarantor Subsidiaries [Member]
Condensed Statement of Income Captions [Line Items]
Ownership percentage	100.00%		100.00%

Condensed Consolidating Finan_4

Condensed Consolidating Financial Information - Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	$ 22.5		$ 38.9
Restricted cash	0.8		0.8
Accounts receivable - net	81.9		82.5
Due from affiliates	23.3		22.7
Inventories	322.3		343.8
Prepaid and other current assets	23.3		18
Total current assets	474.1		506.7
Property, plant and equipment - net	950.1		967.3
Investment in subsidiaries	0		0
Leases - right of use assets	24.2
Due from affiliates - long term	1.4		0
Other assets	42		63.5
TOTAL	1,491.8		1,537.5
Accounts payable, trade	112		119.4
Due to affiliates	0		10.3
Accrued and other current liabilities	66.1		52.5
Accrued employee benefits costs	11		11
Term loan - current	15		0
Revolving credit facility	0.4		23.3
Industrial revenue bonds	7.8		7.8
Total current liabilities	212.3		224.3
Senior notes payable	249		248.6
Term loan - less current portion	25		0
Accrued pension benefits costs - less current portion	48.4		50.9
Accrued postretirement benefits costs - less current portion	101.2		101.2
Due to affiliates - long term	0		0
Other liabilities	45.4		46
Leases - right of use liabilities	21.9
Deferred taxes	98.7		104.3
Total noncurrent liabilities	589.6		551
Preferred stock	0		0
Common stock	1		1
Other shareholders' equity	688.9		761.2
Total shareholders’ equity	689.9	$ 709.4	762.2	$ 833.5	$ 853.1	$ 829.6
TOTAL	1,491.8		1,537.5
Consolidating Adjustments [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	0		0
Restricted cash	0		0
Accounts receivable - net	0		0
Due from affiliates	0		0
Inventories	0		0
Prepaid and other current assets	0		0
Total current assets	0		0
Property, plant and equipment - net	0		0
Investment in subsidiaries	(682.8)		(722.8)
Leases - right of use assets	0
Due from affiliates - long term	(1,272.7)		(1,276.5)
Other assets	0		0
TOTAL	(1,955.5)		(1,999.3)
Accounts payable, trade	0		0
Due to affiliates	0		0
Accrued and other current liabilities	0		0
Accrued employee benefits costs	0		0
Term loan - current	0
Revolving credit facility	0		0
Industrial revenue bonds	0		0
Total current liabilities	0		0
Senior notes payable	0		0
Term loan - less current portion	0
Accrued pension benefits costs - less current portion	0		0
Accrued postretirement benefits costs - less current portion	0		0
Due to affiliates - long term	(1,272.7)		(1,276.5)
Other liabilities	0		0
Leases - right of use liabilities	0
Deferred taxes	0		0
Total noncurrent liabilities	(1,272.7)		(1,276.5)
Preferred stock	0		0
Common stock	(0.1)		(0.1)
Other shareholders' equity	(682.7)		(722.7)
Total shareholders’ equity	(682.8)		(722.8)
TOTAL	(1,955.5)		(1,999.3)
The Company [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	1.5		0.1
Restricted cash	0		0
Accounts receivable - net	0		0.5
Due from affiliates	0		0
Inventories	0		0
Prepaid and other current assets	12.3		6.4
Total current assets	13.8		7
Property, plant and equipment - net	18.1		20.6
Investment in subsidiaries	625.1		668.3
Leases - right of use assets	5.9
Due from affiliates - long term	742.2		751.7
Other assets	35.4		29.8
TOTAL	1,440.5		1,477.4
Accounts payable, trade	2.9		3.7
Due to affiliates	0		0
Accrued and other current liabilities	26.7		15.8
Accrued employee benefits costs	1.9		1.9
Term loan - current	15
Revolving credit facility	0.4		23.3
Industrial revenue bonds	0		0
Total current liabilities	46.9		44.7
Senior notes payable	249		248.6
Term loan - less current portion	25
Accrued pension benefits costs - less current portion	22.3		23.2
Accrued postretirement benefits costs - less current portion	1		0.7
Due to affiliates - long term	395.2		395.4
Other liabilities	5.9		2.8
Leases - right of use liabilities	5.6
Deferred taxes	(0.3)		(0.2)
Total noncurrent liabilities	703.7		670.5
Preferred stock	0		0
Common stock	1		1
Other shareholders' equity	688.9		761.2
Total shareholders’ equity	689.9		762.2
TOTAL	1,440.5		1,477.4
Combined Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	0		0
Restricted cash	0.8		0.8
Accounts receivable - net	70.6		81.8
Due from affiliates	22.9		13.1
Inventories	199		210.7
Prepaid and other current assets	0.9		3.4
Total current assets	294.2		309.8
Property, plant and equipment - net	326.2		320.7
Investment in subsidiaries	57.7		54.5
Leases - right of use assets	1.4
Due from affiliates - long term	526.6		517.6
Other assets	4.2		2.1
TOTAL	1,210.3		1,204.7
Accounts payable, trade	86.3		84.1
Due to affiliates	0		0
Accrued and other current liabilities	25.1		22.8
Accrued employee benefits costs	8.3		8.3
Term loan - current	0
Revolving credit facility	0		0
Industrial revenue bonds	7.8		7.8
Total current liabilities	127.5		123
Senior notes payable	0		0
Term loan - less current portion	0
Accrued pension benefits costs - less current portion	20.7		20.7
Accrued postretirement benefits costs - less current portion	98.6		98.9
Due to affiliates - long term	295.4		307.6
Other liabilities	22		23.5
Leases - right of use liabilities	0.2
Deferred taxes	1.8		1.8
Total noncurrent liabilities	438.7		452.5
Preferred stock	0		0
Common stock	0		0
Other shareholders' equity	644.1		629.2
Total shareholders’ equity	644.1		629.2
TOTAL	1,210.3		1,204.7
Combined Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	21		38.8
Restricted cash	0		0
Accounts receivable - net	11.3		0.2
Due from affiliates	0.4		9.6
Inventories	123.3		133.1
Prepaid and other current assets	10.1		8.2
Total current assets	166.1		189.9
Property, plant and equipment - net	605.8		626
Investment in subsidiaries	0		0
Leases - right of use assets	16.9
Due from affiliates - long term	5.3		7.2
Other assets	2.4		31.6
TOTAL	796.5		854.7
Accounts payable, trade	22.8		31.6
Due to affiliates	0		10.3
Accrued and other current liabilities	14.3		13.9
Accrued employee benefits costs	0.8		0.8
Term loan - current	0
Revolving credit facility	0		0
Industrial revenue bonds	0		0
Total current liabilities	37.9		56.6
Senior notes payable	0		0
Term loan - less current portion	0
Accrued pension benefits costs - less current portion	5.4		7
Accrued postretirement benefits costs - less current portion	1.6		1.6
Due to affiliates - long term	582.1		573.5
Other liabilities	17.5		19.7
Leases - right of use liabilities	16.1
Deferred taxes	97.2		102.7
Total noncurrent liabilities	719.9		704.5
Preferred stock	0		0
Common stock	0.1		0.1
Other shareholders' equity	38.6		93.5
Total shareholders’ equity	38.7		93.6
TOTAL	$ 796.5		$ 854.7

Condensed Consolidating Finan_5

Condensed Consolidating Financial Information - Cash Flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	$ (4.4)	$ (59)
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	(39.9)	(49.3)
Proceeds from sale of joint venture	10.5	0
Intercompany transactions	0	0
Net cash provided by (used in) investing activities	(29.4)	(49.3)
Net cash provided by (used in) financing activities
Borrowings under term loan	40	0
Borrowings under revolving credit facilities	314.6	14.3
Repayments under revolving credit facilities	(337.5)	0
Other short-term borrowings	3.4	0
Repayment on other short-term borrowings	(3.4)	0
Issuance of common stock	0.3	0.2
Intercompany transactions	0	0
Net cash provided by (used in) financing activities	17.4	14.5
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(16.4)	(93.8)
Cash, cash equivalents and restricted cash, beginning of period	39.7	168
Cash, cash equivalents and restricted cash, end of period	23.3	74.2
Consolidating Adjustments [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	0	0
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	0	0
Proceeds from sale of joint venture	0
Intercompany transactions	59.9	(80)
Net cash provided by (used in) investing activities	59.9	(80)
Net cash provided by (used in) financing activities
Borrowings under term loan	0
Borrowings under revolving credit facilities	0	0
Repayments under revolving credit facilities	0
Other short-term borrowings	0
Repayment on other short-term borrowings	0
Issuance of common stock	0	0
Intercompany transactions	(59.9)	80
Net cash provided by (used in) financing activities	(59.9)	80
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	0	0
Cash, cash equivalents and restricted cash, beginning of period	0	0
Cash, cash equivalents and restricted cash, end of period	0	0
The Company [Member] | Reportable Legal Entities [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	(57.1)	(51.2)
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	(0.6)	(4)
Proceeds from sale of joint venture	0
Intercompany transactions	(9.3)	39.5
Net cash provided by (used in) investing activities	(9.9)	35.5
Net cash provided by (used in) financing activities
Borrowings under term loan	40
Borrowings under revolving credit facilities	295.1	14.3
Repayments under revolving credit facilities	(318)
Other short-term borrowings	3.4
Repayment on other short-term borrowings	(3.4)
Issuance of common stock	0.3	0.2
Intercompany transactions	51	(37.1)
Net cash provided by (used in) financing activities	68.4	(22.6)
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	1.4	(38.3)
Cash, cash equivalents and restricted cash, beginning of period	0.1	64.3
Cash, cash equivalents and restricted cash, end of period	1.5	26
Combined Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	45	(0.5)
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	(26.4)	(38.9)
Proceeds from sale of joint venture	0
Intercompany transactions	(52.6)	40.9
Net cash provided by (used in) investing activities	(79)	2
Net cash provided by (used in) financing activities
Borrowings under term loan	0
Borrowings under revolving credit facilities	0	0
Repayments under revolving credit facilities	0
Other short-term borrowings	0
Repayment on other short-term borrowings	0
Issuance of common stock	0	0
Intercompany transactions	34	(1.7)
Net cash provided by (used in) financing activities	34	(1.7)
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	0	(0.2)
Cash, cash equivalents and restricted cash, beginning of period	0.8	0.7
Cash, cash equivalents and restricted cash, end of period	0.8	0.5
Combined Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	7.7	(7.3)
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	(12.9)	(6.4)
Proceeds from sale of joint venture	10.5
Intercompany transactions	2	(0.4)
Net cash provided by (used in) investing activities	(0.4)	(6.8)
Net cash provided by (used in) financing activities
Borrowings under term loan	0
Borrowings under revolving credit facilities	19.5	0
Repayments under revolving credit facilities	(19.5)
Other short-term borrowings	0
Repayment on other short-term borrowings	0
Issuance of common stock	0	0
Intercompany transactions	(25.1)	(41.2)
Net cash provided by (used in) financing activities	(25.1)	(41.2)
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(17.8)	(55.3)
Cash, cash equivalents and restricted cash, beginning of period	38.8	103
Cash, cash equivalents and restricted cash, end of period	$ 21	$ 47.7

Uncategorized Items - a20190930

Label	Element	Value	[1]
AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (1,300,000)
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 1,300,000
[1]	ASU 2018-02 Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. See Note 8. Income Taxes for further information regarding our adoption of ASU 2018-02.