Century Aluminum (CENX) 10-Q 6 Aug 20 2020 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Aug. 05, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
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, Address Line Two	Suite 1000
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60606
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		89,484,834
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	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	2020
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
NET SALES
Related parties	$ 285.6	$ 305	$ 556.6	$ 616.4
Other customers	116.3	168.1	266.5	346.8
Total net sales	401.9	473.1	823.1	963.2
Cost of goods sold	414.9	477.2	831.3	980.1
Gross profit (loss)	(13)	(4.1)	(8.2)	(16.9)
Selling, general and administrative expenses	11.8	11.9	20.7	26.6
Other operating (income) expense - net	0.2	0.3	0.5	0.6
Operating income (loss)	(25)	(16.3)	(29.4)	(44.1)
Interest expense - term loan	(0.5)	(0.6)	(1.2)	(0.6)
Interest expense	(5.9)	(5.8)	(11.9)	(11.7)
Interest income	0.4	0.2	0.5	0.4
Net gain (loss) on forward and derivative contracts	3.7	6.1	7.5	0.4
Other income (expense) - net	1.3	(1.7)	3	(0.5)
Income (loss) before income taxes and equity in earnings of joint ventures	(26)	(18.1)	(31.5)	(56.1)
Income tax benefit (expense)	(0.9)	1.6	1.9	4.4
Income (loss) before equity in earnings of joint ventures	(26.9)	(16.5)	(29.6)	(51.7)
Loss on sale of BHH	0	(4.3)	0	(4.3)
Equity in earnings of joint ventures	0	0.1	0	0.7
Net income (loss)	$ (26.9)	$ (20.7)	$ (29.6)	$ (55.3)
EARNINGS (LOSS) PER COMMON SHARE:
Basic and diluted (USD per share)	$ (0.30)	$ (0.23)	$ (0.33)	$ (0.63)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING:
Basic and diluted (per share)	89.5	88.8	89.4	88.5

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Comprehensive income (loss):
Net income (loss)	$ (26.9)	$ (20.7)	$ (29.6)	$ (55.3)
Other comprehensive income before income tax effect:
Net income (loss) on foreign currency cash flow hedges reclassified as income	0	0	0	(0.1)
Defined benefit plans and other postretirement benefits:
Amortization of prior service benefit (cost) during the period	(0.8)	(1.3)	(1.6)	(2.5)
Amortization of net gain (loss) during the period	1.8	2.5	4.3	4.4
Other comprehensive income (loss) before income tax effect	1	1.2	2.7	1.8
Income tax effect	(0.3)	(0.2)	(0.6)	(0.5)
Other comprehensive income (loss)	0.7	1	2.1	1.3
Total comprehensive income (loss)	$ (26.2)	$ (19.7)	$ (27.5)	$ (54)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
ASSETS
Cash and cash equivalents	$ 174.1	$ 38.9
Restricted cash	3.7	0.8
Accounts receivable - net	35.9	70.1
Due from affiliates	9.8	30.1
Inventories	275	320.6
Derivative assets	18.3	14.6
Prepaid and other current assets	14.6	12.2
Total current assets	531.4	487.3
Property, plant and equipment - net	919	949.2
Due from affiliates - less current portion	3.9	0.5
Other assets	69.7	62.7
TOTAL	1,524	1,499.7
LIABILITIES:
Accounts payable, trade	87.7	97.1
Due to affiliates	1.8	32.9
Accrued and other current liabilities	76.9	61.5
Accrued employee benefits costs	10.4	10.4
Hawesville term loan	20	20
U.S. revolving credit facility	45	4
Industrial revenue bonds	7.8	7.8
Total current liabilities	249.6	233.7
Senior notes payable	249.5	249.2
Hawesville term loan - less current portion	10	20
Iceland revolving credit facility	45	0
Accrued pension benefits costs - less current portion	57.7	60.8
Accrued postretirement benefits costs - less current portion	99.3	100.7
Other liabilities	47.8	42.4
Leases - right of use liabilities	21.7	22.8
Deferred taxes	94.7	95.1
Total noncurrent liabilities	625.7	591
COMMITMENTS AND CONTINGENCIES	0	0
SHAREHOLDERS’ EQUITY:
Preferred stock	0	0
Common stock	1	1
Additional paid-in capital	2,527.6	2,526.5
Treasury stock, at cost	(86.3)	(86.3)
Accumulated other comprehensive loss	(107.6)	(109.8)
Accumulated deficit	(1,686)	(1,656.4)
Total shareholders’ equity	648.7	675
TOTAL	$ 1,524	$ 1,499.7

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (29.6)	$ (55.3)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Loss on sale of BHH	0	4.3
Unrealized (gain) loss on derivative instruments	(3.6)	(0.8)
Lower of cost or NRV inventory adjustment	37.1	13.4
Depreciation and amortization	40.4	43.1
Other non-cash items - net	1.9	(5.1)
Change in operating assets and liabilities:
Accounts receivable - net	34.1	0.7
Due from affiliates	21.6	1.6
Inventories	8.4	(8.9)
Prepaid and other current assets	(1.1)	2.1
Accounts payable, trade	(10)	(23.1)
Due to affiliates	(31)	2.9
Accrued and other current liabilities	0.1	(1.6)
Other - net	3.3	1.1
Net cash provided by (used in) operating activities	71.6	(25.6)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(9.6)	(23.3)
Proceeds from sales of property, plant & equipment	0.1	0
Proceeds from sale of joint venture	0	10.5
Net cash provided by (used in) investing activities	(9.5)	(12.8)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowing under term loan	0	40
Repayments on term loan	(10)	0
Borrowings under revolving credit facilities	122.4	288.2
Repayments under revolving credit facilities	(36.4)	(303.3)
Other short-term borrowings	0	3.4
Repayment on other short-term borrowings	0	(3.4)
Issuance of common stock	0	0.3
Net cash provided by (used in) financing activities	76	25.2
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	138.1	(13.2)
Cash, cash equivalents and restricted cash, beginning of period	39.7	39.7
Cash, cash equivalents and restricted cash, end of period	177.8	26.5
Cash paid for:
Interest	11	10.6
Taxes	0.1	0.3
Non-cash investing activities:
Capital expenditures	$ 0.6	$ 2.1

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Cumulative effect, period of adoption, adjustment [Member]		Preferred stock [Member]	Common stock [Member]	Additional paid-in capital [Member]	Treasury stock, at cost [Member]	Accumulated other comprehensive loss [Member]	Accumulated other comprehensive loss [Member]Cumulative effect, period of adoption, adjustment [Member]		Accumulated deficit [Member]	Accumulated deficit [Member]Cumulative effect, period of adoption, adjustment [Member]
Balance, start at Dec. 31, 2018	$ 762.2	$ 0	[1]	$ 0	$ 1	$ 2,523	$ (86.3)	$ (98.7)	$ (1.3)	[1]	$ (1,576.8)	$ 1.3	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(55.3)										(55.3)
Other comprehensive income (loss)	1.3							1.3
Share-based compensation	1.3				0	1.3
Conversion of preferred stock to common stock	0			0	0	0
Balance, end 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]
Accounting Standards Update	us-gaap:AccountingStandardsUpdate201802Member
Balance, start at Mar. 31, 2019	$ 728.1	$ 0		0	1	2,523.3	(86.3)	(99.7)	$ 0		(1,610.1)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(20.7)										(20.7)
Other comprehensive income (loss)	1							1
Share-based compensation	1				0	1
Conversion of preferred stock to common stock	0			0	0	0
Balance, end 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]
Accounting Standards Update	us-gaap:AccountingStandardsUpdate201802Member
Balance, start at Dec. 31, 2019	$ 675			0	1	2,526.5	(86.3)	(109.8)			(1,656.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(29.6)										(29.6)
Other comprehensive income (loss)	2.1							2.1
Share-based compensation	1.1				0	1.1
Conversion of preferred stock to common stock	0			0	0	0
Balance, end at Jun. 30, 2020	648.7			0	1	2,527.6	(86.3)	(107.6)			(1,686)
Balance, start at Mar. 31, 2020	673.8			0	1	2,526.6	(86.3)	(108.4)			(1,659.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(26.9)										(26.9)
Other comprehensive income (loss)	0.7							0.7
Share-based compensation	1.1			0	0	1.1
Conversion of preferred stock to common stock	0			0	0	0
Balance, end at Jun. 30, 2020	$ 648.7			$ 0	$ 1	$ 2,527.6	$ (86.3)	$ (107.6)			$ (1,686)
[1]	ASU 2018-02. See Note 7. Income Taxes for further information regarding our adoption of ASU 2018-02.

General

General	6 Months Ended
	Jun. 30, 2020
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, 2019. In management’s opinion, the unaudited interim consolidated financial statements reflect all adjustments, which are of a normal and recurring nature, that are necessary for a fair presentation of financial results for the interim periods presented. Operating results for the first six months of 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020. Throughout this Form 10-Q, and unless expressly stated otherwise or as the context otherwise requires, "Century Aluminum," "Century," the "Company," "we," "us," "our" and "ours" refer to Century Aluminum Company and its consolidated subsidiaries. Recently Issued Accounting Standards In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes." Amendments include the removal of certain exceptions to the general principles of ASC 740 and to improve and simplify accounting for income taxes by clarifying and amending existing guidance. Updates are related to intraperiod tax allocation, interim period tax calculations, tax laws or rate changes in interim periods, and income taxes related to employee stock ownership plans. The ASU is effective for fiscal years beginning after December 15, 2020, including interim periods therein and early adoption is permitted. The Company is currently evaluating the impacts of ASU 2019-12 and we do not expect the adoption to have a material effect on the consolidated financial statements. In March 2020, the Securities and Exchange Commission (“SEC”) issued a final rule that amends the disclosure requirements related issuers and guarantors of certain registered securities under SEC Regulation S-X Rule 3-10. The final rule allows registrants to provide alternative financial disclosures in either the registrant’s MD&A or financial statements, rather than the previous requirement under Rule 3-10, which required condensed consolidating financial information within the financial statements. It also simplifies the requirements in Rule 3-10 that currently must be met for a parent company to qualify for exceptions allowing it to provide alternative disclosures rather than full audited financial statements. The ruling also reduces the periods for which summarized financial information is required to be presented to the most recent (1) annual period and (2) year-to-date interim period. The final rule applies to annual reports on Form 10-K for fiscal years ending after January 4, 2021 and quarterly reports on Form 10-Q for quarterly periods ending after January 4, 2021 and registrants may voluntarily comply with the final rule before the effective date. The Company does not expect the future adoption, which is limited to disclosures only, to have a material effect on the Company’s consolidated financial statements.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The significant related party transactions occurring during the six months ended June 30, 2020 and 2019 are described below. We believe all of our transactions with related parties are at prices that approximate market. Glencore ownership As of June 30, 2020 , Glencore plc and its affiliates (together "Glencore") beneficially owned 42.9% of Century’s outstanding common stock (46.8% 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 6. 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, tolling agreements, certain forward financial contracts and loan agreements. Sales to Glencore For the three months ended June 30, 2020 and 2019, approximately 71.0% and 64.5%, respectively, of our consolidated net sales were made to Glencore, while for the six months ended June 30, 2020 and 2019, we derived 67.6% and 64.0%, respectively, of our consolidated net sales from sales to Glencore. Glencore purchases aluminum produced at our U.S smelters at prices based on the London Metal Exchange (the "LME") plus the Midwest regional delivery premium plus any additional market-based product premiums. Glencore purchases aluminum produced at our Grundartangi, Iceland smelter at prices based on the LME plus the European Duty Paid premium plus any additional market-based product premiums. We have also entered into agreements with Glencore pursuant to which we sell certain amounts of alumina at market-based prices. For the three months and six months ended June 30, 2020, we recorded $0.9 million and $1.2 million of revenue related to alumina sales to Glencore, respectively. For the three months and six months ended June 30, 2019, we recorded $13.6 million and $21.7 million of revenue related to alumina sales to Glencore, respectively. Purchases from Glencore We purchase a portion of our alumina requirements from Glencore. Alumina purchases from Glencore during the six months ended June 30, 2020 were priced based on published alumina and aluminum indices. Financial contracts with Glencore We have certain financial contracts with Glencore. See Note 13. Derivatives regarding these forward financial sales contracts. Hawesville Term Loan On April 29, 2019, we entered into a loan agreement with Glencore Ltd. pursuant to which the Company borrowed $40.0 million (the "Hawesville Term Loan”). See Note 9. Debt for additional information. Borrowings under the Hawesville Term Loan were used to partially finance the second phase of the Hawesville restart project. Summary A summary of the aforementioned significant related party transactions is as follows: Three months ended June 30, Six months ended June 30, 2020 2019 2020 2019 Net sales to Glencore $ 285.6 $ 305.0 $ 556.6 $ 616.4 Purchases from Glencore 33.4 115.6 73.6 206.3 Purchases from BHH (1) — 8.5 — 14.6 (1) We previously owned a 40% interest in Baise Haohai Carbon Co. Ltd. ("BHH") and purchased carbon anodes from them for use in our operations. Purchases represented herein were prior to the divestiture of our interest in BHH in May 2019.

Revenue

Revenue	6 Months Ended
	Jun. 30, 2020
Revenue Recognition and Deferred Revenue [Abstract]
Revenue	RevenueWe disaggregate our revenue by geographical region as follows: Net Sales Three months ended June 30, Six months ended June 30, 2020 2019 2020 2019 United States $ 247.9 $ 309.5 $ 522.0 $ 634.8 Iceland 154.0 163.6 301.1 328.4 Total $ 401.9 $ 473.1 $ 823.1 $ 963.2 Trade accounts receivable - net as of June 30, 2020 decreased by $34.2 million from December 31, 2019 due to a decrease in sales resulting from lower regional premiums and realized LME prices, and timing of receivable collections.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2020
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 - significant unobservable inputs for the asset or liability. Recurring Fair Value Measurements As of June 30, 2020 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 162.2 $ — $ — $ 162.2 Trust assets (1) 0.8 — — 0.8 Derivative instruments — 28.5 6.1 34.6 TOTAL $ 163.0 $ 28.5 $ 6.1 $ 197.6 LIABILITIES: Contingent obligation – net $ — $ — $ — $ — Derivative instruments — 14.2 1.5 15.7 TOTAL $ — $ 14.2 $ 1.5 $ 15.7 (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. (2) Surety bonds were invested in U.S. treasury bills and represent collateral against our workers' compensation insurance policy. Recurring Fair Value Measurements As of December 31, 2019 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 23.3 $ — $ — $ 23.3 Trust assets (1) 0.2 — — 0.2 Surety bonds (2) 1.8 — — 1.8 Derivative instruments — 9.1 10.6 19.7 TOTAL $ 25.3 $ 9.1 $ 10.6 $ 45.0 LIABILITIES: Contingent obligation – net $ — $ — $ — $ — Derivative instruments — 1.3 2.9 4.2 TOTAL $ — $ 1.3 $ 2.9 $ 4.2 (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. (2) Surety bonds were invested in U.S. treasury bills and represent collateral against our workers' compensation insurance policy. We use the following valuation techniques and inputs for fair value measurements categorized within Level 2 of the fair value hierarchy: Level 2 Fair Value Measurements: Asset / Liability Level Valuation Techniques Inputs LME forward financial sales contracts 2 Discounted cash flows Quoted LME forward market 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 NYMEX Henry Hub natural gas price swaps 2 Discounted cash flows Quoted Henry Hub forward market MISO Indiana Hub power price swaps 2 Discounted cash flows Quoted Indy Hub forward market FX swaps 2 Discounted cash flows Euro/USD forward exchange rate When valuing Level 3 assets and liabilities, we use certain significant unobservable inputs. Management incorporates various inputs and assumptions including forward commodity prices, commodity price volatility, and macroeconomic conditions, including interest rates and discount rates. Our estimates of significant unobservable inputs are ultimately based on our estimates of risks that market participants would consider when valuing our assets and liabilities. The following table presents the inputs for fair value measurements categorized within Level 3 of the fair value hierarchy, along with information regarding significant unobservable inputs used to value Level 3 assets and liabilities: Level 3 Fair Value Measurements: Asset / Liability Fair Value at June 30, 2020 Valuation Technique Observable Inputs Significant Unobservable Input Value/Range of Unobservable Input LME forward financial sales contracts $ 6.1 Discounted cash flows Quoted LME forward market prices Discount rate (1) 10.00% Contingent obligation $ — Discounted cash flows Quoted LME forward market prices Management's estimates of the LME forward market price beyond the quoted periods (2) $1,594/T-$2,179/T Hawesville L4 power price swaps $ (1.5) Discounted cash flows Quoted Indy Hub forward market prices Estimates of locational margin prices during contract term in megawatt hours (MWh) (3) $0.52/MWh (1) Represents risk adjusted discount rate. (2) Represents the range of estimated forward LME prices of primary aluminum through the term of the agreement in December 2028. (3) Represents historical average of locational margin prices in the past three years. The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis. Level 3 Assets Level 3 Liabilities For the three months ended June 30, 2020 LME forward financial sales contracts Hawesville L4 power price swaps Balance as of April 1, 2020 $ 7.8 $ (3.2) Total realized/unrealized gains (losses) Included in net income (loss) (1) (1.7) 0.0 Purchases, sales, settlements Purchases — — Sales — — Settlements — 1.7 Transfers into Level 3 — — Transfers out of Level 3 — — Balance as of June 30, 2020 $ 6.1 $ (1.5) Change in unrealized gains (losses) (1) $ (1.7) $ 1.7 (1) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts." For the three months ended June 30, 2019 Level 3 Assets Level 3 Liabilities Nord Pool power price swaps U.S. LME forward financial sales contracts Hawesville L4 Power Price Swaps Iceland LME forward financial sales contracts MWP forward financial sales contracts FX Swaps Balance as of April 1, 2019 $ 3.7 $ (1.8) $ — $ (0.3) $ (0.9) $ (0.6) Total realized/unrealized gains (losses) Included in Net Income (2) — 8.7 — — — — Purchases, sales, settlements Purchases — — — — — — Sales — — — — — — Settlements — — — — — — Transfers into Level 3 (1) — — (2.7) — — — Transfers out of Level 3 (3.7) — — 0.3 0.9 0.6 Balance as of June 30, 2019 $ — $ 6.9 $ (2.7) $ — $ — $ — Change in unrealized gains (losses) (2) $ — $ 8.7 $ (2.7) $ — $ — $ — (1) Transfer into Level 3 resulting from derivative contracts entered into during the second quarter of 2019. (2) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts." Level 3 Assets Level 3 Liabilities For the six months ended June 30, 2020 LME forward financial sales contracts Hawesville L4 power price swaps Balance as of January 1, 2020 $ 10.6 $ (2.9) Total realized/unrealized gains (losses) Included in net income (loss) (2) 5.0 (1.4) Purchases, sales, settlements Purchases — — Sales — — Settlements — 2.8 Transfers into Level 3 — — Transfers out of Level 3 (1) (9.5) — Balance as of June 30, 2020 $ 6.1 $ (1.5) Change in unrealized gains (losses) (2) $ 5.0 $ 1.4 (1) Transfer out of Level 3 due to period of time remaining in derivative contract. (2) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts." For the six months ended June 30, 2019 Level 3 Assets Level 3 Liabilities Nord Pool power price swaps US LME forward financial sales contracts Hawesville L4 Power Price Swaps Iceland LME forward financial sales contracts FX Swaps Balance as of January 1, 2019 $ 4.7 $ 0.3 $ — $ (0.2) $ (0.3) Total realized/unrealized gains (losses) Included in Net Income (2) (1.0) 6.8 — (0.1) (0.3) Purchases, sales, settlements Purchases — — — — — Sales — — — — — Settlements — — — — — Transfers into Level 3 (1) — (0.2) (2.7) — — Transfers out of Level 3 (3.7) — — 0.3 0.6 Balance as of June 30, 2019 $ — $ 6.9 $ (2.7) $ — $ — Change in unrealized gains (losses) (2) $ (1.0) $ 6.6 $ (2.7) $ (0.1) $ (0.3) (1) Transfer into Level 3 resulting from derivative contracts entered into during the first six months of 2019. (2) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts".

Earnings (Loss) Per Share

Earnings (Loss) Per Share	6 Months Ended
	Jun. 30, 2020
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 June 30, 2020 2019 Net Income (Loss) Shares (in millions) Per Share Net Income (Loss) Shares (in millions) Per Share Net income (loss) $ (26.9) $ (20.7) Amount allocated to common stockholders 100.0 % 100.0 % Basic and diluted EPS (1) $ (26.9) 89.5 $ (0.30) $ (20.7) 88.8 $ (0.23) For the six months ended June 30, 2020 2019 Net Income (Loss) Shares (in millions) Per Share Net Income (Loss) Shares (in millions) Per Share Net income (loss) $ (29.6) $ (55.3) Amount allocated to common stockholders 100.0 % 100.0 % Basic and diluted EPS (1) $ (29.6) 89.4 $ (0.33) $ (55.3) 88.5 $ (0.63) Three months ended June 30, Six months ended June 30, Securities excluded from the calculation of diluted EPS (in millions) (1) : 2020 2019 2020 2019 Share-based compensation 0.6 0.7 0.7 0.6 (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	6 Months Ended
	Jun. 30, 2020
Stockholders' Equity Note [Abstract]
Shareholders’ Equity	Shareholders’ Equity Common Stock As of June 30, 2020 and December 31, 2019, we had 195,000,000 shares of common stock, $0.01 par value per share, authorized under our Restated Certificate of Incorporation, of which 96,671,355 shares were issued and 89,484,834 shares were outstanding at June 30, 2020; 96,372,182 shares were issued and 89,185,661 shares were outstanding at December 31, 2019. 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 June 30, 2020 and December 31, 2019, 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. Glencore holds all of the issued and outstanding Series A Convertible Preferred Stock. At June 30, 2020 and December 31, 2019, there were 66,039 and 67,323 shares of Series A Convertible Preferred Stock outstanding, respectively. The issuance of common stock under our stock incentive programs, debt exchange transactions and any stock offering that excludes Glencore participation triggers anti-dilution provisions of the preferred stock agreement and results in the automatic conversion of Series A Convertible Preferred Stock shares into shares of common stock. The conversion ratio 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 six months ended June 30, 2020 and 2019. Preferred stock Common stock Common and Preferred Stock Activity (in shares): Series A Convertible Treasury Outstanding Beginning balance as of December 31, 2019 67,323 7,186,521 89,185,661 Conversion of convertible preferred stock (1,284) — 128,389 Issuance for share-based compensation plans — — 170,784 Ending balance as of June 30, 2020 66,039 7,186,521 89,484,834 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 June 30, 2019 68,575 7,186,521 88,893,767 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.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recorded an income tax expense of $0.9 million and tax benefit of $1.6 million for the three months ended June 30, 2020 and 2019, respectively. The change is primarily due to improved operational results from foreign operations in the current quarter. For the six months ended June 30, 2020 and 2019, we recorded an income tax benefit of $1.9 million and $4.4 million, respectively, which is primarily the result of overall losses from our foreign operations. 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 June 30, 2020, 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 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 Cuts and Jobs Act ("the Act"). In accordance with the provisions of ASU 2018-02, $1.3 million of stranded tax effects related to the Act were reclassified from accumulated other comprehensive loss to retained earnings in the first quarter of 2019. This reclassification included 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. On March 27, 2020, the Coronavirus Aid, Relief and Economic Security Act (the "CARES Act") was enacted in response to the coronavirus ("COVID-19") pandemic. The CARES Act is aimed at providing assistance and health care for individuals, families, and businesses affected by COVID-19 and generally supporting the U.S. economy. The CARES Act, among other things, includes provisions related to refundable payroll tax credits, deferment of the employer portion of social security payments, net operating loss carryback periods, modifications to the net interest deduction limitations, and technical corrections to tax depreciation methods for qualified improvement property. We continue to analyze the various aspects of the CARES Act to determine the impact specific provisions may have on us and our operations. As of June 30, 2020, Century does not expect to record material benefits from the CARES Act.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2020
Inventory, Net [Abstract]
Inventories	Inventories Inventories consist of the following: June 30, 2020 December 31, 2019 Raw materials $ 81.8 $ 101.3 Work-in-process 32.2 44.1 Finished goods 26.1 34.3 Operating and other supplies 134.9 140.9 Total inventories $ 275.0 $ 320.6 Inventories are stated at the lower of cost or Net Realizable Value ("NRV") using the first-in, first-out ("FIFO") or the weighted average cost method.

Debt

Debt	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Debt	Debt June 30, 2020 December 31, 2019 Debt classified as current liabilities: Hawesville Term Loan - current portion (1) $ 20.0 $ 20.0 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) 45.0 4.0 Debt classified as non-current liabilities: Iceland Revolving Credit Facility (4) 45.0 — 7.5% senior secured notes due June 2021, net of debt discount of $0.5 million and $0.8 million, respectively, interest payable semiannually (5) 249.5 249.2 Hawesville Term Loan - less current portion (1) , principal and interest payable monthly 10.0 20.0 Total $ 377.3 $ 301.0 (1) See "Hawesville Term Loan" below. At June 30, 2020, the applicable interest rate was LIBOR of 0.4% plus margin of 5.375% and there is no interest payable outstanding. As of June 30, 2020, we have made $10.0 million of principal payments and $1.2 million of interest payments. (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 June 30, 2020 was 0.39%. (3) We have elected to incur interest at LIBOR plus applicable margin as defined within the agreement. The interest rate at June 30, 2020 was 2.5%. (4) We have elected to incur interest at a base rate plus applicable margin as defined within the agreement. The interest rate at June 30, 2020 was 3.8%. (5) Due to the refinancing with the 2025 Notes noted below, the 2021 Notes is presented as non-current liability on the Consolidated Balance Sheets. 7.5% Notes due 2021 General. In June 2013, we issued $250.0 million of 7.5% Notes due June 2021 (the "2021 Notes") in a private offering exempt from the registration requirements of the Securities Act of 1933, as amended. The 2021 Notes accrued interest at a 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 the 2021 Notes, based on the available trading data, was $250.5 million and $244.2 million, as of June 30, 2020 and December 31, 2019, 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. As disclosed in N ote 15 . Subsequent E vents , on July 1, 2020, we issued $250.0 million in aggregate principal amount of senior secured notes due 2025 (the "2025 Notes"). The 2025 Notes bear interest semi-annually in arrears on January 1 and July 1 of each year, beginning on January 1, 2021, at a rate of (i) 10.00% per annum in cash and (ii) 2.00% per annum in the form of additional notes or in cash, at Century's option. In connection with the offering of the 2025 Notes, we also commenced a cash tender offer to purchase at par any and all of our outstanding 2021 Notes. Hawesville Term Loan On April 29, 2019, we entered into a loan agreement with Glencore Ltd. pursuant to which the Company borrowed $40.0 million. Borrowings under the Hawesville Term Loan were 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, at a floating rate equal to LIBOR plus 5.375% per annum. The Hawesville Term Loan is not secured by any collateral. U.S. Revolving Credit Facility We and certain of our direct and indirect domestic subsidiaries ("the Borrowers") 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. In connection with the offering of the 2025 Notes, on June 17, 2020, we entered into Amendment No.1 to our U.S. revolving credit facility extending the maturity date of the U.S. revolving credit facility to May 16, 2023. Amendment No.1 became effective on July 1, 2020, upon the closing of the offering of the 2025 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 June 30, 2020, there were $45.0 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 and may be prepaid without penalty. The U.S revolving credit facility contains a springing financial covenant that requires us to maintain a fixed charge coverage ratio of at least 1.0 to 1.0 any time availability under the U.S revolving credit facility is less than or equal to the lower of $17.5 million or 10% of the borrowing base but not less than $12.5 million. As of June 30, 2020, we were in compliance with all such covenants or maintained availability above such covenant triggers. Status of our U.S. revolving credit facility: June 30, 2020 Credit facility maximum amount $ 175.0 Borrowing availability 106.2 Outstanding letters of credit issued 42.9 Outstanding borrowings 45.0 Borrowing availability, net of outstanding letters of credit and borrowings 18.3 Iceland Revolving Credit Facility Our wholly-owned subsidiary, Nordural Grundartangi ehf ("Grundartangi"), has entered into a $50.0 million revolving credit facility agreement with Landsbankinn hf., dated November 2013, as amended (the "Iceland revolving credit facility"). At June 30, 2020, there were $45.0 million in outstanding borrowings under our Iceland revolving credit facility. The Iceland revolving credit facility has a term through November 2022. Principal payments, if any, are due upon maturity of the Iceland revolving credit facility and may be prepaid without penalty. Status of our Iceland revolving credit facility: June 30, 2020 Credit facility maximum amount $ 50.0 Borrowing availability 50.0 Outstanding letters of credit issued — Outstanding borrowings 45.0 Borrowing availability, net of borrowings 5.0

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and Contingencies We have pending against us or may be subject to various lawsuits, claims and proceedings related primarily to employment, commercial, stockholder, environmental, safety and health matters and are involved in other matters that may give rise to contingent liabilities. While the results of such matters and claims cannot be predicted with certainty, we believe that the ultimate outcome of any such matters and claims 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 and estimating liabilities, should the resolution or 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 or environmental 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. While we regularly review the status of, and our estimates of potential liability associated with, contingencies to determine the adequacy of any associated accruals and related disclosures, the ultimate amount of loss may differ from our estimates. Legal Contingencies 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. Trial was bifurcated and moved from March 2020 to November 2020 for Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA") issues and to February 2021 for questions of fact. At this stage, we cannot predict the ultimate outcome of this action or estimate a range of reasonably possible losses related to this matter. Ravenswood Retiree Medical Benefits 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 ten 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 $12.5 million. CAWV has agreed to pay the remaining amounts under the settlement agreement in annual increments of $2.0 million for nine 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 six month periods ended June 30, 2020 and 2019. 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. Environmental Contingencies 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. 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 2021. Each of these agreements provide for automatic extension on a year-to-year basis unless a one 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 2021. Each of these agreements provides for automatic extension on a year-to-year basis unless a one 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 can 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 rates linked to the Nord Pool power market. 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 67% of our total workforce. Approximately 87% of Grundartangi’s work force is represented by five labor unions, governed by a labor agreement that establishes wages and work rules for covered employees. This agreement expired on December 31, 2019. Since such time we have been operating under the terms of the expired agreement while we engage in negotiations with the unions regarding the terms of a new agreement. 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, 2021. 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	6 Months Ended
	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Components of Accumulated Other Comprehensive Loss	Components of Accumulated Other Comprehensive Loss Components of AOCL: June 30, 2020 December 31, 2019 Defined benefit plan liabilities $ (113.1) $ (115.9) Unrealized gain (loss) on financial instruments 2.2 2.3 Other comprehensive loss before income tax effect (110.9) (113.6) Income tax effect (1) 3.3 3.8 Accumulated other comprehensive loss $ (107.6) $ (109.8) (1) The allocation of the income tax effect to the components of other comprehensive loss is as follows: June 30, 2020 December 31, 2019 Defined benefit plan liabilities $ 3.7 $ 4.3 Unrealized loss on financial instruments (0.4) (0.4) 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, April 1, 2020 $ (110.3) $ 1.9 $ (108.4) Net amount reclassified to net income (loss) 0.8 — 0.8 Balance, June 30, 2020 $ (109.5) $ 1.9 $ (107.6) Balance, April 1, 2019 $ (101.7) $ 2.0 $ (99.7) Net amount reclassified to net income 1.0 0.0 1.0 Balance, June 30, 2019 $ (100.7) $ 2.0 $ (98.7) Balance, December 31, 2019 $ (111.7) $ 1.9 $ (109.8) Net amount reclassified to net loss 2.2 0.0 2.2 Balance, June 30, 2020 $ (109.5) $ 1.9 $ (107.6) Balance, December 31, 2018 $ (100.7) $ 2.0 $ (98.7) Impact of ASU 2018-02 (1) (1.3) — (1.3) Net amount reclassified to net income (loss) 1.3 (0.1) 1.3 Balance, June 30, 2019 $ (100.7) $ 2.0 $ (98.7) (1) ASU 2018-02. See Note 7. 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 June 30, Six months ended June 30, AOCL Components Location 2020 2019 2020 2019 Defined benefit plan and other postretirement liabilities Cost of goods sold $ 0.4 $ 0.3 $ 1.5 $ 0.9 Selling, general and administrative expenses 0.2 (0.2) 0.4 (0.6) Other operating expense, net 0.5 1.2 0.9 1.5 Income tax effect (0.3) (0.3) (0.6) (0.5) Net of tax $ 0.8 $ 1.0 $ 2.2 $ 1.3 Unrealized loss on financial instruments Cost of goods sold $ 0.0 $ 0.0 $ 0.0 $ (0.1) Income tax effect 0.0 0.0 0.0 0.0 Net of tax $ 0.0 $ 0.0 $ 0.0 $ (0.1)

Components of Net Periodic Bene

Components of Net Periodic Benefit Cost	6 Months Ended
	Jun. 30, 2020
Components of net periodic benefit cost [Abstract]
Components of Net Periodic Benefit Cost	Components of Net Periodic Benefit Cost Pension Benefits Three months ended June 30, Six months ended June 30, 2020 2019 2020 2019 Service cost $ 1.1 $ 0.5 $ 2.4 $ 1.5 Interest cost 2.8 3.4 5.6 6.7 Expected return on plan assets (5.2) (4.3) (10.3) (9.1) Amortization of prior service costs 0.0 0.5 0.0 0.5 Amortization of net loss 1.8 2.2 3.3 3.3 Net periodic benefit cost $ 0.5 $ 2.3 $ 1.0 $ 2.9 Other Postretirement Benefits ("OPEB") Three months ended June 30, Six months ended June 30, 2020 2019 2020 2019 Service cost $ 0.1 $ 0.7 $ 0.2 $ 0.7 Interest cost 0.7 1.2 1.5 2.3 Amortization of prior service cost (0.8) (1.8) (1.6) (3.1) Amortization of net loss 0.1 0.4 1.1 1.1 Net periodic benefit cost $ 0.1 $ 0.5 $ 1.2 $ 1.0

Derivatives

Derivatives	6 Months Ended
	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DerivativesAs of June 30, 2020, we had an open position of 104,740 tonnes related to LME forward financial sales contracts to fix the forward LME aluminum price. These contracts are expected to settle monthly through December 2024. We also had an open position of 151,500 tonnes related to Midwest Premium ("MWP") forward financial sales contracts to fix the forward MWP price. These contracts are expected to settle through December 2021. We have also entered into LME and MWP 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 aluminum prices. As of June 30, 2020, we had an open position related to such arrangements of 14,596 tonnes that will settle at various dates through October 2021. We have 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"). As of June 30, 2020, we had an open position of 395,280 MWh. The Hawesville L4 power price swaps are expected to settle monthly through December 2020. We have entered into financial contracts to hedge a portion of our exposure at our U.S operations to the MISO Indiana Hub (“MISO Indiana Hub power price swaps”) and the NYMEX Henry Hub (“NYMEX Henry Hub natural gas price swaps”). The natural gas volume is measured per million British Thermal Units ("mmBTU"). As of June 30, 2020, we had an open position of 1,170,000 mmBTU related to the NYMEX Henry Hub natural gas price swaps and an open position of 735,660 MWh related to the MISO Indiana Hub power price swaps. Both the NYMEX Henry Hub natural gas price swaps and MISO Indiana power price swaps are expected to settle monthly through September 2020. We have entered into financial contracts to hedge a portion of Grundartangi's exposure to the Nord Pool power market (“Nord Pool power price swaps”). As of June 30, 2020, we had an open position of 1,340,992 MWh related to the Nord Pool power price swaps. The Nord Pool power price swaps are expected to settle monthly through December 2021. Because the Nord Pool power price swaps are settled in Euros, we have entered into financial contracts to hedge the risk of fluctuations associated with the Euro ("FX swaps"). As of June 30, 2020, we had an open position related to the FX swaps of €35.6 million that will settle monthly through December 2021. The following table sets forth the Company's derivative assets and liabilities that were accounted for at fair value and not designated as cash flow hedges as of June 30, 2020 and December 31, 2019, respectively: Asset Fair Value June 30, 2020 December 31, 2019 Commodity contracts (1) $ 34.6 $ 19.7 Foreign exchange contracts (2) — — Total $ 34.6 $ 19.7 Liability Fair Value June 30, 2020 December 31, 2019 Commodity contracts (1) $ 15.3 $ 3.6 Foreign exchange contracts (2) 0.4 0.6 Total $ 15.7 $ 4.2 (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, NYMEX Henry Hub natural gas price swaps, MISO Indiana Hub power price swaps, and Nord Pool power price swaps. At June 30, 2020 and December 31, 2019, $1.5 million and $0.2 million of Due from affiliates and $3.9 million and $0.5 million of Due from affiliates - less current portion, respectively, is related to commodity contract assets with Glencore. (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 June 30, Six months ended June 30, 2020 2019 2020 2019 Commodity contracts (3) $ 2.9 $ 6.1 $ 11.8 $ 0.6 Foreign exchange contracts 0.8 0.0 (4.3) (0.2) Total $ 3.7 $ 6.1 $ 7.5 $ 0.4 (3) For the three months ended June 30, 2020 and 2019, $(7.9) million and $1.8 million of the net (loss) gain, respectively, was with Glencore. For the six months ended June 30, 2020 and 2019, $4.7 million and $0.8 million of net (loss) gain, respectively, was with Glencore.

Condensed Consolidating Financi

Condensed Consolidating Financial Information	6 Months Ended
	Jun. 30, 2020
Condensed Financial Information Disclosure [Abstract]
Condensed Consolidating Financial Information	Condensed Consolidating Financial Information The Company has filed a Registration Statement on Form S-3 (the "Universal Shelf Registration Statement") with the Securities and Exchange Commission pursuant to which the Company may, from time to time, offer an indeterminate amount of securities, which may include securities that are guaranteed by certain of the Company's subsidiaries. The condensed consolidated financial information below is presented herein pursuant to the Universal Shelf Registration Statement. We have not issued any debt securities pursuant to the Universal Shelf Registration Statement. "Guarantor Subsidiaries" refers to all of our material domestic 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 will be full and unconditional; all guarantees will be joint and several. Our foreign subsidiaries, together with Nordural US LLC, Century Aluminum Development LLC and Century Aluminum of West Virginia, Inc., are collectively referred to as 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 six months ended June 30, 2020 and 2019, condensed consolidating balance sheets as of June 30, 2020 and December 31, 2019 and the condensed consolidating statements of cash flows for the six months ended June 30, 2020 and 2019 present separate results for Century, the Guarantor Subsidiaries, the Non-Guarantor Subsidiaries, consolidating adjustments and total consolidated amounts. Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended June 30, 2020 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 156.2 $ 129.4 $ — $ 285.6 Other customers — 91.5 24.8 — 116.3 Total net sales — 247.7 154.2 — 401.9 Cost of goods sold — 266.3 148.6 — 414.9 Gross profit (loss) — (18.6) 5.6 — (13.0) Selling, general and administrative expenses 11.5 — 0.3 — 11.8 Other operating (income) expense - net — — 0.2 — 0.2 Operating income (loss) (11.5) (18.6) 5.1 — (25.0) Interest expense - term loan (0.5) — — — (0.5) Interest expense (5.4) (0.4) (0.1) — (5.9) Intercompany interest 8.1 2.7 (10.8) — — Interest income 0.3 — 0.1 — 0.4 Net gain (loss) on forward and derivative contracts (1.9) 0.3 5.3 — 3.7 Other income (expense) - net (0.2) 0.8 0.7 — 1.3 Income (loss) before income taxes and equity in earnings of joint ventures (11.1) (15.2) 0.3 — (26.0) Income tax benefit (expense) 0.5 — (1.4) — (0.9) Income (loss) before equity in earnings of joint ventures (10.6) (15.2) (1.1) — (26.9) Equity in earnings (loss) of joint ventures (16.3) 1.9 — 14.4 0.0 Net income (loss) (26.9) (13.3) (1.1) 14.4 (26.9) Other comprehensive income before income tax effect 1.0 0.4 0.5 (0.9) 1.0 Income tax effect (0.3) — — — (0.3) Other comprehensive income 0.7 0.4 0.5 (0.9) 0.7 Total comprehensive income (loss) $ (26.2) $ (12.9) $ (0.6) $ 13.5 $ (26.2) Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended June 30, 2019 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 147.4 $ 157.6 $ — $ 305.0 Other customers — 162.2 5.9 — 168.1 Total net sales — 309.6 163.5 — 473.1 Cost of goods sold — 306.0 171.2 — 477.2 Gross profit (loss) — 3.6 (7.7) — (4.1) Selling, general and administrative expenses 11.5 — 0.4 — 11.9 Other operating (income) expense - net — — 0.3 — 0.3 Operating income (loss) (11.5) 3.6 (8.4) — (16.3) Interest expense - term loan (0.6) — — — (0.6) Interest expense (5.3) (0.4) (0.1) — (5.8) Intercompany interest 8.7 2.5 (11.2) — — Interest income 0.1 — 0.1 — 0.2 Net gain (loss) on forward and derivative contracts 4.8 0.3 1.0 — 6.1 Other income (expense) - net — (1.3) (0.4) — (1.7) Income (loss) before income taxes and equity in earnings of joint ventures (3.8) 4.7 (19.0) — (18.1) Income tax (expense) benefit (0.1) — 1.7 — 1.6 Income (loss) before equity in earnings of joint ventures (3.9) 4.7 (17.3) — (16.5) Loss on Sale of BHH — — (4.3) (4.3) Equity in earnings (loss) of joint ventures (16.8) (0.6) 0.1 17.4 0.1 Net income (loss) (20.7) 4.1 (21.5) 17.4 (20.7) Other comprehensive income (loss) before income tax effect 1.2 0.3 1.2 (1.5) 1.2 Income tax effect (0.2) — — — (0.2) Other comprehensive income 1.0 0.3 1.2 (1.5) 1.0 Total comprehensive income (loss) $ (19.7) $ 4.4 $ (20.3) $ 15.9 $ (19.7) Condensed Consolidating Statements of Comprehensive Income (Loss) For the six months ended June 30, 2020 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 304.1 $ 252.5 $ — $ 556.6 Other customers — 217.8 48.7 — 266.5 Total net sales — 521.9 301.2 — 823.1 Cost of goods sold — 547.3 284.0 — 831.3 Gross profit (loss) — (25.4) 17.2 — (8.2) Selling, general and administrative expenses 19.9 — 0.8 — 20.7 Other operating (income) expense - net — — 0.5 — 0.5 Operating income (loss) (19.9) (25.4) 15.9 — (29.4) Interest expense - term loan (1.2) — — — (1.2) Interest expense (10.5) (0.8) (0.6) — (11.9) Intercompany interest 16.5 5.4 (21.9) — — Interest income 0.3 — 0.2 — 0.5 Net gain (loss) on forward and derivative contracts 30.7 0.7 (23.9) — 7.5 Other income (expense) - net 0.2 0.6 2.2 — 3.0 Income (loss) before income taxes and equity in earnings of joint ventures 16.1 (19.5) (28.1) — (31.5) Income tax benefit (expense) 1.0 — 0.9 — 1.9 Income (loss) before equity in earnings of joint ventures 17.1 (19.5) (27.2) — (29.6) Equity in earnings (loss) of joint ventures (46.7) 2.4 — 44.3 0.0 Net income (loss) (29.6) (17.1) (27.2) 44.3 (29.6) Other comprehensive income before income tax effect 2.7 1.5 0.9 (2.4) 2.7 Income tax effect (0.6) — — — (0.6) Other comprehensive income 2.1 1.5 0.9 (2.4) 2.1 Total comprehensive income (loss) $ (27.5) $ (15.6) $ (26.3) $ 41.9 $ (27.5) Condensed Consolidating Statements of Comprehensive Income (Loss) For the six months ended June 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 299.9 $ 316.5 $ — $ 616.4 Other customers — 334.9 11.9 — 346.8 Total net sales — 634.8 328.4 — 963.2 Cost of goods sold — 633.2 346.9 — 980.1 Gross profit (loss) — 1.6 (18.5) — (16.9) Selling, general and administrative expenses 25.6 — 1.0 — 26.6 Other operating (income) expense - net — — 0.6 — 0.6 Operating income (loss) (25.6) 1.6 (20.1) — (44.1) Interest expense - term loan (0.6) — — — (0.6) Interest expense (10.8) (0.8) (0.1) — (11.7) Intercompany interest 17.4 5.0 (22.4) — — Interest income 0.1 — 0.3 — 0.4 Net gain (loss) on forward and derivative contracts 0.1 0.7 (0.4) — 0.4 Other income (expense) - net 0.9 (1.9) 0.5 — (0.5) Income (loss) before income taxes and equity in earnings of joint ventures (18.5) 4.6 (42.2) — (56.1) Income tax benefit (expense) 0.9 — 3.5 — 4.4 Income (loss) before equity in earnings of joint ventures (17.6) 4.6 (38.7) — (51.7) Loss on sale of BHH — — (4.3) — (4.3) Equity in earnings (loss) of joint ventures (37.7) (0.3) 0.7 38.0 0.7 Net income (loss) (55.3) 4.3 (42.3) 38.0 (55.3) Other comprehensive income before income tax effect 1.8 0.9 1.5 (2.4) 1.8 Income tax effect (0.5) — — — (0.5) Other comprehensive income 1.3 0.9 1.5 (2.4) 1.3 Total comprehensive income (loss) $ (54.0) $ 5.2 $ (40.8) $ 35.6 $ (54.0) Condensed Consolidating Balance Sheets As of June 30, 2020 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 103.7 $ 0.2 $ 70.2 $ — $ 174.1 Restricted cash — 1.8 1.9 — 3.7 Accounts receivable - net 3.6 31.4 0.9 — 35.9 Due from affiliates 1.9 7.5 0.4 — 9.8 Inventories — 168.7 106.3 — 275.0 Derivative Assets 18.3 — — — 18.3 Prepaid and other current assets 4.5 1.0 9.1 — 14.6 Total current assets 132.0 210.6 188.8 — 531.4 Property, plant and equipment - net 15.7 327.7 575.6 — 919.0 Investment in subsidiaries 568.3 65.1 — (633.4) — Due from affiliates - less current portion 736.2 599.6 5.3 (1,337.2) 3.9 Other assets 48.1 3.7 17.9 — 69.7 TOTAL $ 1,500.3 $ 1,206.7 $ 787.6 $ (1,970.6) $ 1,524.0 Accounts payable, trade $ 2.5 $ 62.2 $ 23.0 $ — $ 87.7 Due to affiliates — 1.8 — — 1.8 Accrued and other current liabilities 26.2 22.6 28.1 — 76.9 Accrued employee benefits costs 1.9 7.7 0.8 — 10.4 Term loan - current 20.0 — — — 20.0 U.S revolving credit facility 45.0 — — — 45.0 Industrial revenue bonds — 7.8 — — 7.8 Total current liabilities 95.6 102.1 51.9 — 249.6 Senior notes payable 249.5 — — — 249.5 Term loan - less current portion 10.0 — — — 10.0 Iceland revolving credit facility — — 45.0 — 45.0 Accrued pension benefits costs - less current portion 24.4 26.0 7.3 — 57.7 Accrued postretirement benefits costs - less current portion 1.0 96.5 1.8 — 99.3 Due to affiliates - long term 459.5 320.0 557.7 (1,337.2) — Other liabilities 6.3 23.9 17.6 — 47.8 Leases - right of use liabilities 5.3 0.0 16.4 — 21.7 Deferred taxes — 0.3 94.4 — 94.7 Total noncurrent liabilities 756.0 466.7 740.2 (1,337.2) 625.7 Preferred stock 0.0 — — — 0.0 Common stock 1.0 — — — 1.0 Other shareholders' equity 647.7 637.9 (4.5) (633.4) 647.7 Total shareholders' equity 648.7 637.9 (4.5) (633.4) 648.7 TOTAL $ 1,500.3 $ 1,206.7 $ 787.6 $ (1,970.6) $ 1,524.0 Condensed Consolidating Balance Sheets As of December 31, 2019 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 0.3 $ 0.1 $ 38.5 $ — $ 38.9 Restricted cash — 0.8 — — 0.8 Accounts receivable - net 0.7 64.1 5.3 — 70.1 Due from affiliates — 10.9 19.2 — 30.1 Inventories — 205.5 115.1 — 320.6 Derivative Assets 12.2 — 2.4 — 14.6 Prepaid and other current assets 3.0 2.8 6.4 — 12.2 Total current assets 16.2 284.2 186.9 — 487.3 Property, plant and equipment - net 17.2 334.8 597.2 — 949.2 Investment in subsidiaries 609.5 62.7 — (672.2) — Due from affiliates - long term 749.5 537.9 5.1 (1,292.0) 0.5 Other assets 38.1 5.7 18.9 — 62.7 TOTAL $ 1,430.5 $ 1,225.3 $ 808.1 $ (1,964.2) $ 1,499.7 Accounts payable, trade $ 2.3 $ 66.2 $ 28.6 $ — $ 97.1 Due to affiliates — 2.2 30.7 — 32.9 Accrued and other current liabilities 23.5 27.3 14.7 — 65.5 Accrued employee benefits costs 1.9 7.7 0.8 — 10.4 Hawesville term loan 20.0 — — — 20.0 Industrial revenue bonds — 7.8 — — 7.8 Total current liabilities 47.7 111.2 74.8 — 233.7 Senior notes payable 249.2 — — — 249.2 Hawesville term loan - less current portion 20.0 — — — 20.0 Accrued pension benefits costs - less current portion 25.1 27.3 8.4 — 60.8 Accrued postretirement benefits costs - less current portion 1.1 97.8 1.8 — 100.7 Leases - right of use liabilities 5.5 0.4 16.9 — 22.8 Other liabilities 3.5 22.2 16.7 — 42.4 Due to affiliates - long term 403.4 315.9 572.7 (1,292.0) — Deferred taxes — 0.4 94.7 — 95.1 Total noncurrent liabilities 707.8 464.0 711.2 (1,292.0) 591.0 Preferred stock 0.0 — — — 0.0 Common stock 1.0 0.0 0.1 (0.1) 1.0 Other shareholders' equity 674.0 650.1 22.0 (672.1) 674.0 Total shareholders' equity 675.0 650.1 22.1 (672.2) 675.0 TOTAL $ 1,430.5 $ 1,225.3 $ 808.1 $ (1,964.2) $ 1,499.7 Condensed Consolidating Statements of Cash Flows For the six months ended June 30, 2020 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (21.6) $ 66.8 $ 26.4 $ — $ 71.6 Purchase of property, plant and equipment (0.5) (8.3) (0.8) — (9.6) Proceeds from sale of property, plant, and equipment — — 0.1 — 0.1 Intercompany transactions 38.4 (56.3) (0.2) 18.1 — Net cash provided by (used in) investing activities 37.9 (64.6) (0.9) 18.1 (9.5) Repayments on term loan (10.0) — — — (10.0) Borrowings under revolving credit facilities 77.4 — 45.0 — 122.4 Repayments under revolving credit facilities (36.4) — — — (36.4) Intercompany transactions 56.1 (1.1) (36.9) (18.1) — Net cash provided by (used in) financing activities 87.1 (1.1) 8.1 (18.1) 76.0 CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH 103.4 1.1 33.6 — 138.1 Cash, cash equivalents and restricted cash, beginning of period 0.3 0.9 38.5 — 39.7 Cash, cash equivalents and restricted cash, end of period $ 103.7 $ 2.0 $ 72.1 $ — $ 177.8 Condensed Consolidating Statements of Cash Flows For the six months ended June 30, 2019 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (35.6) $ (1.1) $ 11.1 $ — $ (25.6) Purchase of property, plant and equipment (0.6) (12.2) (10.5) — (23.3) Proceeds from sale of joint venture — — 10.5 — 10.5 Intercompany transactions (22.2) (33.6) 0.2 55.6 — Net cash provided by (used in) investing activities (22.8) (45.8) 0.2 55.6 (12.8) Borrowing under term loan 40.0 — — — 40.0 Borrowings under revolving credit facilities 288.2 — — — 288.2 Repayments under revolving credit facilities (303.3) — — — (303.3) 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 33.7 46.8 (24.9) (55.6) — Net cash provided by (used in) financing activities 58.9 46.8 (24.9) (55.6) 25.2 CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH 0.5 (0.1) (13.6) — (13.2) 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 $ 0.6 $ 0.7 $ 25.2 $ — $ 26.5

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On July 1, 2020, we completed our offering of $250 million aggregate principal amount of the 2025 Notes. The 2025 Notes bear interest semi-annually in arrears on January 1 and July 1 of each year, beginning on January 1, 2021, at a rate of (i) 10.00% per annum in cash and (ii) 2.00% per annum in the form of additional notes or in cash, at our option. Concurrently with the closing of the issuance of the 2025 Notes, on July 1, 2020, (i) the maturity date of our U.S. revolving credit facility was extended to May 16, 2023; (ii) we purchased at par $243,690,000 in aggregate principal amount of the 2021 Notes pursuant to a tender offer commenced in connection with the offering; and (iii) we notified the holders of all outstanding 2021 Notes that were not purchased in the tender offer of our election to redeem all such remaining 2021 Notes on July 31, 2020, and deposited with the trustee under the indenture governing the 2021 Notes an amount sufficient to fund the full redemption of the remaining 2021 Notes and discharge our obligations with respect thereto. We applied the net proceeds from the offering of the 2025 Notes described above, together with cash on hand, toward payment of the total consideration amount to holders whose 2021 Notes were accepted and purchased in the tender offer and to fund the redemption of any remaining 2021 Notes, which were redeemed on July 31, 2020. Based on the characteristics of the 2021 Notes and the 2025 Notes that were issued, the tender and redemption of the 2021 Notes would be accounted for as an extinguishment of the debt. Accordingly, we expect to record a loss on early extinguishment of debt in the third quarter of 2020, consisting of the write-off of deferred financing costs and the debt discount associated with the 2021 Notes, as well as the tender fees paid as part of the tender offer.

General (Policies)

General (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Recently Issued Accounting Standards	Recently Issued Accounting Standards In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes." Amendments include the removal of certain exceptions to the general principles of ASC 740 and to improve and simplify accounting for income taxes by clarifying and amending existing guidance. Updates are related to intraperiod tax allocation, interim period tax calculations, tax laws or rate changes in interim periods, and income taxes related to employee stock ownership plans. The ASU is effective for fiscal years beginning after December 15, 2020, including interim periods therein and early adoption is permitted. The Company is currently evaluating the impacts of ASU 2019-12 and we do not expect the adoption to have a material effect on the consolidated financial statements. In March 2020, the Securities and Exchange Commission (“SEC”) issued a final rule that amends the disclosure requirements related issuers and guarantors of certain registered securities under SEC Regulation S-X Rule 3-10. The final rule allows registrants to provide alternative financial disclosures in either the registrant’s MD&A or financial statements, rather than the previous requirement under Rule 3-10, which required condensed consolidating financial information within the financial statements. It also simplifies the requirements in Rule 3-10 that currently must be met for a parent company to qualify for exceptions allowing it to provide alternative disclosures rather than full audited financial statements. The ruling also reduces the periods for which summarized financial information is required to be presented to the most recent (1) annual period and (2) year-to-date interim period. The final rule applies to annual reports on Form 10-K for fiscal years ending after January 4, 2021 and quarterly reports on Form 10-Q for quarterly periods ending after January 4, 2021 and registrants may voluntarily comply with the final rule before the effective date. The Company does not expect the future adoption, which is limited to disclosures only, to have a material effect on the Company’s consolidated financial statements.

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2020
Related Party Transactions [Abstract]
Schedule of related party transactions	A summary of the aforementioned significant related party transactions is as follows: Three months ended June 30, Six months ended June 30, 2020 2019 2020 2019 Net sales to Glencore $ 285.6 $ 305.0 $ 556.6 $ 616.4 Purchases from Glencore 33.4 115.6 73.6 206.3 Purchases from BHH (1) — 8.5 — 14.6 (1) We previously owned a 40% interest in Baise Haohai Carbon Co. Ltd. ("BHH") and purchased carbon anodes from them for use in our operations. Purchases represented herein were prior to the divestiture of our interest in BHH in May 2019.

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Jun. 30, 2020
Revenue Recognition and Deferred Revenue [Abstract]
Disaggregation of revenue	We disaggregate our revenue by geographical region as follows: Net Sales Three months ended June 30, Six months ended June 30, 2020 2019 2020 2019 United States $ 247.9 $ 309.5 $ 522.0 $ 634.8 Iceland 154.0 163.6 301.1 328.4 Total $ 401.9 $ 473.1 $ 823.1 $ 963.2

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Financial assets and liabilities at fair value on a recurring basis	Recurring Fair Value Measurements As of June 30, 2020 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 162.2 $ — $ — $ 162.2 Trust assets (1) 0.8 — — 0.8 Derivative instruments — 28.5 6.1 34.6 TOTAL $ 163.0 $ 28.5 $ 6.1 $ 197.6 LIABILITIES: Contingent obligation – net $ — $ — $ — $ — Derivative instruments — 14.2 1.5 15.7 TOTAL $ — $ 14.2 $ 1.5 $ 15.7 (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. (2) Surety bonds were invested in U.S. treasury bills and represent collateral against our workers' compensation insurance policy. Recurring Fair Value Measurements As of December 31, 2019 Level 1 Level 2 Level 3 Total ASSETS: Cash equivalents $ 23.3 $ — $ — $ 23.3 Trust assets (1) 0.2 — — 0.2 Surety bonds (2) 1.8 — — 1.8 Derivative instruments — 9.1 10.6 19.7 TOTAL $ 25.3 $ 9.1 $ 10.6 $ 45.0 LIABILITIES: Contingent obligation – net $ — $ — $ — $ — Derivative instruments — 1.3 2.9 4.2 TOTAL $ — $ 1.3 $ 2.9 $ 4.2 (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	We use the following valuation techniques and inputs for fair value measurements categorized within Level 2 of the fair value hierarchy: Level 2 Fair Value Measurements: Asset / Liability Level Valuation Techniques Inputs LME forward financial sales contracts 2 Discounted cash flows Quoted LME forward market 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 NYMEX Henry Hub natural gas price swaps 2 Discounted cash flows Quoted Henry Hub forward market MISO Indiana Hub power price swaps 2 Discounted cash flows Quoted Indy Hub forward market FX swaps 2 Discounted cash flows Euro/USD forward exchange rate When valuing Level 3 assets and liabilities, we use certain significant unobservable inputs. Management incorporates various inputs and assumptions including forward commodity prices, commodity price volatility, and macroeconomic conditions, including interest rates and discount rates. Our estimates of significant unobservable inputs are ultimately based on our estimates of risks that market participants would consider when valuing our assets and liabilities. The following table presents the inputs for fair value measurements categorized within Level 3 of the fair value hierarchy, along with information regarding significant unobservable inputs used to value Level 3 assets and liabilities: Level 3 Fair Value Measurements: Asset / Liability Fair Value at June 30, 2020 Valuation Technique Observable Inputs Significant Unobservable Input Value/Range of Unobservable Input LME forward financial sales contracts $ 6.1 Discounted cash flows Quoted LME forward market prices Discount rate (1) 10.00% Contingent obligation $ — Discounted cash flows Quoted LME forward market prices Management's estimates of the LME forward market price beyond the quoted periods (2) $1,594/T-$2,179/T Hawesville L4 power price swaps $ (1.5) Discounted cash flows Quoted Indy Hub forward market prices Estimates of locational margin prices during contract term in megawatt hours (MWh) (3) $0.52/MWh (1) Represents risk adjusted discount rate. (2) Represents the range of estimated forward LME prices of primary aluminum through the term of the agreement in December 2028. (3) Represents historical average of locational margin prices in the past three years.
Schedule of fair value reconciliation of Level 3 assets and liabilities measured at fair value	The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis. Level 3 Assets Level 3 Liabilities For the three months ended June 30, 2020 LME forward financial sales contracts Hawesville L4 power price swaps Balance as of April 1, 2020 $ 7.8 $ (3.2) Total realized/unrealized gains (losses) Included in net income (loss) (1) (1.7) 0.0 Purchases, sales, settlements Purchases — — Sales — — Settlements — 1.7 Transfers into Level 3 — — Transfers out of Level 3 — — Balance as of June 30, 2020 $ 6.1 $ (1.5) Change in unrealized gains (losses) (1) $ (1.7) $ 1.7 (1) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts." For the three months ended June 30, 2019 Level 3 Assets Level 3 Liabilities Nord Pool power price swaps U.S. LME forward financial sales contracts Hawesville L4 Power Price Swaps Iceland LME forward financial sales contracts MWP forward financial sales contracts FX Swaps Balance as of April 1, 2019 $ 3.7 $ (1.8) $ — $ (0.3) $ (0.9) $ (0.6) Total realized/unrealized gains (losses) Included in Net Income (2) — 8.7 — — — — Purchases, sales, settlements Purchases — — — — — — Sales — — — — — — Settlements — — — — — — Transfers into Level 3 (1) — — (2.7) — — — Transfers out of Level 3 (3.7) — — 0.3 0.9 0.6 Balance as of June 30, 2019 $ — $ 6.9 $ (2.7) $ — $ — $ — Change in unrealized gains (losses) (2) $ — $ 8.7 $ (2.7) $ — $ — $ — (1) Transfer into Level 3 resulting from derivative contracts entered into during the second quarter of 2019. (2) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts." Level 3 Assets Level 3 Liabilities For the six months ended June 30, 2020 LME forward financial sales contracts Hawesville L4 power price swaps Balance as of January 1, 2020 $ 10.6 $ (2.9) Total realized/unrealized gains (losses) Included in net income (loss) (2) 5.0 (1.4) Purchases, sales, settlements Purchases — — Sales — — Settlements — 2.8 Transfers into Level 3 — — Transfers out of Level 3 (1) (9.5) — Balance as of June 30, 2020 $ 6.1 $ (1.5) Change in unrealized gains (losses) (2) $ 5.0 $ 1.4 (1) Transfer out of Level 3 due to period of time remaining in derivative contract. (2) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts." For the six months ended June 30, 2019 Level 3 Assets Level 3 Liabilities Nord Pool power price swaps US LME forward financial sales contracts Hawesville L4 Power Price Swaps Iceland LME forward financial sales contracts FX Swaps Balance as of January 1, 2019 $ 4.7 $ 0.3 $ — $ (0.2) $ (0.3) Total realized/unrealized gains (losses) Included in Net Income (2) (1.0) 6.8 — (0.1) (0.3) Purchases, sales, settlements Purchases — — — — — Sales — — — — — Settlements — — — — — Transfers into Level 3 (1) — (0.2) (2.7) — — Transfers out of Level 3 (3.7) — — 0.3 0.6 Balance as of June 30, 2019 $ — $ 6.9 $ (2.7) $ — $ — Change in unrealized gains (losses) (2) $ (1.0) $ 6.6 $ (2.7) $ (0.1) $ (0.3) (1) Transfer into Level 3 resulting from derivative contracts entered into during the first six months of 2019. (2) Gains and losses are presented in the Consolidated Statement of Operations within the line item "Net gain (loss) on forward and derivative contracts".

Earnings (Loss) Per Share (Tabl

Earnings (Loss) Per Share (Tables)	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Basic and diluted earnings (loss) per share	The following table shows the basic and diluted earnings (loss) per share: For the three months ended June 30, 2020 2019 Net Income (Loss) Shares (in millions) Per Share Net Income (Loss) Shares (in millions) Per Share Net income (loss) $ (26.9) $ (20.7) Amount allocated to common stockholders 100.0 % 100.0 % Basic and diluted EPS (1) $ (26.9) 89.5 $ (0.30) $ (20.7) 88.8 $ (0.23) For the six months ended June 30, 2020 2019 Net Income (Loss) Shares (in millions) Per Share Net Income (Loss) Shares (in millions) Per Share Net income (loss) $ (29.6) $ (55.3) Amount allocated to common stockholders 100.0 % 100.0 % Basic and diluted EPS (1) $ (29.6) 89.4 $ (0.33) $ (55.3) 88.5 $ (0.63) (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.
Securities excluded from the calculation of diluted EPS	Three months ended June 30, Six months ended June 30, Securities excluded from the calculation of diluted EPS (in millions) (1) : 2020 2019 2020 2019 Share-based compensation 0.6 0.7 0.7 0.6 (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)	6 Months Ended
	Jun. 30, 2020
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 six months ended June 30, 2020 and 2019. Preferred stock Common stock Common and Preferred Stock Activity (in shares): Series A Convertible Treasury Outstanding Beginning balance as of December 31, 2019 67,323 7,186,521 89,185,661 Conversion of convertible preferred stock (1,284) — 128,389 Issuance for share-based compensation plans — — 170,784 Ending balance as of June 30, 2020 66,039 7,186,521 89,484,834 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 June 30, 2019 68,575 7,186,521 88,893,767

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2020
Inventory, Net [Abstract]
Schedule of Inventories	Inventories consist of the following: June 30, 2020 December 31, 2019 Raw materials $ 81.8 $ 101.3 Work-in-process 32.2 44.1 Finished goods 26.1 34.3 Operating and other supplies 134.9 140.9 Total inventories $ 275.0 $ 320.6

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Schedule of Debt	June 30, 2020 December 31, 2019 Debt classified as current liabilities: Hawesville Term Loan - current portion (1) $ 20.0 $ 20.0 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) 45.0 4.0 Debt classified as non-current liabilities: Iceland Revolving Credit Facility (4) 45.0 — 7.5% senior secured notes due June 2021, net of debt discount of $0.5 million and $0.8 million, respectively, interest payable semiannually (5) 249.5 249.2 Hawesville Term Loan - less current portion (1) , principal and interest payable monthly 10.0 20.0 Total $ 377.3 $ 301.0 (1) See "Hawesville Term Loan" below. At June 30, 2020, the applicable interest rate was LIBOR of 0.4% plus margin of 5.375% and there is no interest payable outstanding. As of June 30, 2020, we have made $10.0 million of principal payments and $1.2 million of interest payments. (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 June 30, 2020 was 0.39%. (3) We have elected to incur interest at LIBOR plus applicable margin as defined within the agreement. The interest rate at June 30, 2020 was 2.5%. (4) We have elected to incur interest at a base rate plus applicable margin as defined within the agreement. The interest rate at June 30, 2020 was 3.8%. (5) Due to the refinancing with the 2025 Notes noted below, the 2021 Notes is presented as non-current liability on the Consolidated Balance Sheets.
Schedule of Line of Credit Facilities	Status of our U.S. revolving credit facility: June 30, 2020 Credit facility maximum amount $ 175.0 Borrowing availability 106.2 Outstanding letters of credit issued 42.9 Outstanding borrowings 45.0 Borrowing availability, net of outstanding letters of credit and borrowings 18.3 Status of our Iceland revolving credit facility: June 30, 2020 Credit facility maximum amount $ 50.0 Borrowing availability 50.0 Outstanding letters of credit issued — Outstanding borrowings 45.0 Borrowing availability, net of borrowings 5.0

Components of Accumulated Oth_2

Components of Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated balances for each component of AOCI	Components of AOCL: June 30, 2020 December 31, 2019 Defined benefit plan liabilities $ (113.1) $ (115.9) Unrealized gain (loss) on financial instruments 2.2 2.3 Other comprehensive loss before income tax effect (110.9) (113.6) Income tax effect (1) 3.3 3.8 Accumulated other comprehensive loss $ (107.6) $ (109.8) (1) The allocation of the income tax effect to the components of other comprehensive loss is as follows: June 30, 2020 December 31, 2019 Defined benefit plan liabilities $ 3.7 $ 4.3 Unrealized loss on financial instruments (0.4) (0.4) 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, April 1, 2020 $ (110.3) $ 1.9 $ (108.4) Net amount reclassified to net income (loss) 0.8 — 0.8 Balance, June 30, 2020 $ (109.5) $ 1.9 $ (107.6) Balance, April 1, 2019 $ (101.7) $ 2.0 $ (99.7) Net amount reclassified to net income 1.0 0.0 1.0 Balance, June 30, 2019 $ (100.7) $ 2.0 $ (98.7) Balance, December 31, 2019 $ (111.7) $ 1.9 $ (109.8) Net amount reclassified to net loss 2.2 0.0 2.2 Balance, June 30, 2020 $ (109.5) $ 1.9 $ (107.6) Balance, December 31, 2018 $ (100.7) $ 2.0 $ (98.7) Impact of ASU 2018-02 (1) (1.3) — (1.3) Net amount reclassified to net income (loss) 1.3 (0.1) 1.3 Balance, June 30, 2019 $ (100.7) $ 2.0 $ (98.7) (1) ASU 2018-02. See Note 7. 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 June 30, Six months ended June 30, AOCL Components Location 2020 2019 2020 2019 Defined benefit plan and other postretirement liabilities Cost of goods sold $ 0.4 $ 0.3 $ 1.5 $ 0.9 Selling, general and administrative expenses 0.2 (0.2) 0.4 (0.6) Other operating expense, net 0.5 1.2 0.9 1.5 Income tax effect (0.3) (0.3) (0.6) (0.5) Net of tax $ 0.8 $ 1.0 $ 2.2 $ 1.3 Unrealized loss on financial instruments Cost of goods sold $ 0.0 $ 0.0 $ 0.0 $ (0.1) Income tax effect 0.0 0.0 0.0 0.0 Net of tax $ 0.0 $ 0.0 $ 0.0 $ (0.1)

Components of Net Periodic Be_2

Components of Net Periodic Benefit Cost (Tables)	6 Months Ended
	Jun. 30, 2020
Components of net periodic benefit cost [Abstract]
Schedule of net periodic benefit cost	Pension Benefits Three months ended June 30, Six months ended June 30, 2020 2019 2020 2019 Service cost $ 1.1 $ 0.5 $ 2.4 $ 1.5 Interest cost 2.8 3.4 5.6 6.7 Expected return on plan assets (5.2) (4.3) (10.3) (9.1) Amortization of prior service costs 0.0 0.5 0.0 0.5 Amortization of net loss 1.8 2.2 3.3 3.3 Net periodic benefit cost $ 0.5 $ 2.3 $ 1.0 $ 2.9 Other Postretirement Benefits ("OPEB") Three months ended June 30, Six months ended June 30, 2020 2019 2020 2019 Service cost $ 0.1 $ 0.7 $ 0.2 $ 0.7 Interest cost 0.7 1.2 1.5 2.3 Amortization of prior service cost (0.8) (1.8) (1.6) (3.1) Amortization of net loss 0.1 0.4 1.1 1.1 Net periodic benefit cost $ 0.1 $ 0.5 $ 1.2 $ 1.0

Derivatives (Tables)

Derivatives (Tables)	6 Months Ended
	Jun. 30, 2020
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 cash flow hedges as of June 30, 2020 and December 31, 2019, respectively: Asset Fair Value June 30, 2020 December 31, 2019 Commodity contracts (1) $ 34.6 $ 19.7 Foreign exchange contracts (2) — — Total $ 34.6 $ 19.7 Liability Fair Value June 30, 2020 December 31, 2019 Commodity contracts (1) $ 15.3 $ 3.6 Foreign exchange contracts (2) 0.4 0.6 Total $ 15.7 $ 4.2 (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, NYMEX Henry Hub natural gas price swaps, MISO Indiana Hub power price swaps, and Nord Pool power price swaps. At June 30, 2020 and December 31, 2019, $1.5 million and $0.2 million of Due from affiliates and $3.9 million and $0.5 million of Due from affiliates - less current portion, respectively, is related to commodity contract assets with Glencore. (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 June 30, Six months ended June 30, 2020 2019 2020 2019 Commodity contracts (3) $ 2.9 $ 6.1 $ 11.8 $ 0.6 Foreign exchange contracts 0.8 0.0 (4.3) (0.2) Total $ 3.7 $ 6.1 $ 7.5 $ 0.4 (3) For the three months ended June 30, 2020 and 2019, $(7.9) million and $1.8 million of the net (loss) gain, respectively, was with Glencore. For the six months ended June 30, 2020 and 2019, $4.7 million and $0.8 million of net (loss) gain, respectively, was with Glencore.

Condensed Consolidating Finan_2

Condensed Consolidating Financial Information (Tables)	6 Months Ended
	Jun. 30, 2020
Condensed Financial Information Disclosure [Abstract]
Condensed Consolidating Statements of Comprehensive Income (Loss)	Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended June 30, 2020 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 156.2 $ 129.4 $ — $ 285.6 Other customers — 91.5 24.8 — 116.3 Total net sales — 247.7 154.2 — 401.9 Cost of goods sold — 266.3 148.6 — 414.9 Gross profit (loss) — (18.6) 5.6 — (13.0) Selling, general and administrative expenses 11.5 — 0.3 — 11.8 Other operating (income) expense - net — — 0.2 — 0.2 Operating income (loss) (11.5) (18.6) 5.1 — (25.0) Interest expense - term loan (0.5) — — — (0.5) Interest expense (5.4) (0.4) (0.1) — (5.9) Intercompany interest 8.1 2.7 (10.8) — — Interest income 0.3 — 0.1 — 0.4 Net gain (loss) on forward and derivative contracts (1.9) 0.3 5.3 — 3.7 Other income (expense) - net (0.2) 0.8 0.7 — 1.3 Income (loss) before income taxes and equity in earnings of joint ventures (11.1) (15.2) 0.3 — (26.0) Income tax benefit (expense) 0.5 — (1.4) — (0.9) Income (loss) before equity in earnings of joint ventures (10.6) (15.2) (1.1) — (26.9) Equity in earnings (loss) of joint ventures (16.3) 1.9 — 14.4 0.0 Net income (loss) (26.9) (13.3) (1.1) 14.4 (26.9) Other comprehensive income before income tax effect 1.0 0.4 0.5 (0.9) 1.0 Income tax effect (0.3) — — — (0.3) Other comprehensive income 0.7 0.4 0.5 (0.9) 0.7 Total comprehensive income (loss) $ (26.2) $ (12.9) $ (0.6) $ 13.5 $ (26.2) Condensed Consolidating Statements of Comprehensive Income (Loss) For the three months ended June 30, 2019 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 147.4 $ 157.6 $ — $ 305.0 Other customers — 162.2 5.9 — 168.1 Total net sales — 309.6 163.5 — 473.1 Cost of goods sold — 306.0 171.2 — 477.2 Gross profit (loss) — 3.6 (7.7) — (4.1) Selling, general and administrative expenses 11.5 — 0.4 — 11.9 Other operating (income) expense - net — — 0.3 — 0.3 Operating income (loss) (11.5) 3.6 (8.4) — (16.3) Interest expense - term loan (0.6) — — — (0.6) Interest expense (5.3) (0.4) (0.1) — (5.8) Intercompany interest 8.7 2.5 (11.2) — — Interest income 0.1 — 0.1 — 0.2 Net gain (loss) on forward and derivative contracts 4.8 0.3 1.0 — 6.1 Other income (expense) - net — (1.3) (0.4) — (1.7) Income (loss) before income taxes and equity in earnings of joint ventures (3.8) 4.7 (19.0) — (18.1) Income tax (expense) benefit (0.1) — 1.7 — 1.6 Income (loss) before equity in earnings of joint ventures (3.9) 4.7 (17.3) — (16.5) Loss on Sale of BHH — — (4.3) (4.3) Equity in earnings (loss) of joint ventures (16.8) (0.6) 0.1 17.4 0.1 Net income (loss) (20.7) 4.1 (21.5) 17.4 (20.7) Other comprehensive income (loss) before income tax effect 1.2 0.3 1.2 (1.5) 1.2 Income tax effect (0.2) — — — (0.2) Other comprehensive income 1.0 0.3 1.2 (1.5) 1.0 Total comprehensive income (loss) $ (19.7) $ 4.4 $ (20.3) $ 15.9 $ (19.7) Condensed Consolidating Statements of Comprehensive Income (Loss) For the six months ended June 30, 2020 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 304.1 $ 252.5 $ — $ 556.6 Other customers — 217.8 48.7 — 266.5 Total net sales — 521.9 301.2 — 823.1 Cost of goods sold — 547.3 284.0 — 831.3 Gross profit (loss) — (25.4) 17.2 — (8.2) Selling, general and administrative expenses 19.9 — 0.8 — 20.7 Other operating (income) expense - net — — 0.5 — 0.5 Operating income (loss) (19.9) (25.4) 15.9 — (29.4) Interest expense - term loan (1.2) — — — (1.2) Interest expense (10.5) (0.8) (0.6) — (11.9) Intercompany interest 16.5 5.4 (21.9) — — Interest income 0.3 — 0.2 — 0.5 Net gain (loss) on forward and derivative contracts 30.7 0.7 (23.9) — 7.5 Other income (expense) - net 0.2 0.6 2.2 — 3.0 Income (loss) before income taxes and equity in earnings of joint ventures 16.1 (19.5) (28.1) — (31.5) Income tax benefit (expense) 1.0 — 0.9 — 1.9 Income (loss) before equity in earnings of joint ventures 17.1 (19.5) (27.2) — (29.6) Equity in earnings (loss) of joint ventures (46.7) 2.4 — 44.3 0.0 Net income (loss) (29.6) (17.1) (27.2) 44.3 (29.6) Other comprehensive income before income tax effect 2.7 1.5 0.9 (2.4) 2.7 Income tax effect (0.6) — — — (0.6) Other comprehensive income 2.1 1.5 0.9 (2.4) 2.1 Total comprehensive income (loss) $ (27.5) $ (15.6) $ (26.3) $ 41.9 $ (27.5) Condensed Consolidating Statements of Comprehensive Income (Loss) For the six months ended June 30, 2019 The Company Combined Guarantor Subsidiaries Combined Non-Guarantor Subsidiaries Consolidating Adjustments Total Consolidated NET SALES: Related parties $ — $ 299.9 $ 316.5 $ — $ 616.4 Other customers — 334.9 11.9 — 346.8 Total net sales — 634.8 328.4 — 963.2 Cost of goods sold — 633.2 346.9 — 980.1 Gross profit (loss) — 1.6 (18.5) — (16.9) Selling, general and administrative expenses 25.6 — 1.0 — 26.6 Other operating (income) expense - net — — 0.6 — 0.6 Operating income (loss) (25.6) 1.6 (20.1) — (44.1) Interest expense - term loan (0.6) — — — (0.6) Interest expense (10.8) (0.8) (0.1) — (11.7) Intercompany interest 17.4 5.0 (22.4) — — Interest income 0.1 — 0.3 — 0.4 Net gain (loss) on forward and derivative contracts 0.1 0.7 (0.4) — 0.4 Other income (expense) - net 0.9 (1.9) 0.5 — (0.5) Income (loss) before income taxes and equity in earnings of joint ventures (18.5) 4.6 (42.2) — (56.1) Income tax benefit (expense) 0.9 — 3.5 — 4.4 Income (loss) before equity in earnings of joint ventures (17.6) 4.6 (38.7) — (51.7) Loss on sale of BHH — — (4.3) — (4.3) Equity in earnings (loss) of joint ventures (37.7) (0.3) 0.7 38.0 0.7 Net income (loss) (55.3) 4.3 (42.3) 38.0 (55.3) Other comprehensive income before income tax effect 1.8 0.9 1.5 (2.4) 1.8 Income tax effect (0.5) — — — (0.5) Other comprehensive income 1.3 0.9 1.5 (2.4) 1.3 Total comprehensive income (loss) $ (54.0) $ 5.2 $ (40.8) $ 35.6 $ (54.0)
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets As of June 30, 2020 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 103.7 $ 0.2 $ 70.2 $ — $ 174.1 Restricted cash — 1.8 1.9 — 3.7 Accounts receivable - net 3.6 31.4 0.9 — 35.9 Due from affiliates 1.9 7.5 0.4 — 9.8 Inventories — 168.7 106.3 — 275.0 Derivative Assets 18.3 — — — 18.3 Prepaid and other current assets 4.5 1.0 9.1 — 14.6 Total current assets 132.0 210.6 188.8 — 531.4 Property, plant and equipment - net 15.7 327.7 575.6 — 919.0 Investment in subsidiaries 568.3 65.1 — (633.4) — Due from affiliates - less current portion 736.2 599.6 5.3 (1,337.2) 3.9 Other assets 48.1 3.7 17.9 — 69.7 TOTAL $ 1,500.3 $ 1,206.7 $ 787.6 $ (1,970.6) $ 1,524.0 Accounts payable, trade $ 2.5 $ 62.2 $ 23.0 $ — $ 87.7 Due to affiliates — 1.8 — — 1.8 Accrued and other current liabilities 26.2 22.6 28.1 — 76.9 Accrued employee benefits costs 1.9 7.7 0.8 — 10.4 Term loan - current 20.0 — — — 20.0 U.S revolving credit facility 45.0 — — — 45.0 Industrial revenue bonds — 7.8 — — 7.8 Total current liabilities 95.6 102.1 51.9 — 249.6 Senior notes payable 249.5 — — — 249.5 Term loan - less current portion 10.0 — — — 10.0 Iceland revolving credit facility — — 45.0 — 45.0 Accrued pension benefits costs - less current portion 24.4 26.0 7.3 — 57.7 Accrued postretirement benefits costs - less current portion 1.0 96.5 1.8 — 99.3 Due to affiliates - long term 459.5 320.0 557.7 (1,337.2) — Other liabilities 6.3 23.9 17.6 — 47.8 Leases - right of use liabilities 5.3 0.0 16.4 — 21.7 Deferred taxes — 0.3 94.4 — 94.7 Total noncurrent liabilities 756.0 466.7 740.2 (1,337.2) 625.7 Preferred stock 0.0 — — — 0.0 Common stock 1.0 — — — 1.0 Other shareholders' equity 647.7 637.9 (4.5) (633.4) 647.7 Total shareholders' equity 648.7 637.9 (4.5) (633.4) 648.7 TOTAL $ 1,500.3 $ 1,206.7 $ 787.6 $ (1,970.6) $ 1,524.0 Condensed Consolidating Balance Sheets As of December 31, 2019 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated Cash & cash equivalents $ 0.3 $ 0.1 $ 38.5 $ — $ 38.9 Restricted cash — 0.8 — — 0.8 Accounts receivable - net 0.7 64.1 5.3 — 70.1 Due from affiliates — 10.9 19.2 — 30.1 Inventories — 205.5 115.1 — 320.6 Derivative Assets 12.2 — 2.4 — 14.6 Prepaid and other current assets 3.0 2.8 6.4 — 12.2 Total current assets 16.2 284.2 186.9 — 487.3 Property, plant and equipment - net 17.2 334.8 597.2 — 949.2 Investment in subsidiaries 609.5 62.7 — (672.2) — Due from affiliates - long term 749.5 537.9 5.1 (1,292.0) 0.5 Other assets 38.1 5.7 18.9 — 62.7 TOTAL $ 1,430.5 $ 1,225.3 $ 808.1 $ (1,964.2) $ 1,499.7 Accounts payable, trade $ 2.3 $ 66.2 $ 28.6 $ — $ 97.1 Due to affiliates — 2.2 30.7 — 32.9 Accrued and other current liabilities 23.5 27.3 14.7 — 65.5 Accrued employee benefits costs 1.9 7.7 0.8 — 10.4 Hawesville term loan 20.0 — — — 20.0 Industrial revenue bonds — 7.8 — — 7.8 Total current liabilities 47.7 111.2 74.8 — 233.7 Senior notes payable 249.2 — — — 249.2 Hawesville term loan - less current portion 20.0 — — — 20.0 Accrued pension benefits costs - less current portion 25.1 27.3 8.4 — 60.8 Accrued postretirement benefits costs - less current portion 1.1 97.8 1.8 — 100.7 Leases - right of use liabilities 5.5 0.4 16.9 — 22.8 Other liabilities 3.5 22.2 16.7 — 42.4 Due to affiliates - long term 403.4 315.9 572.7 (1,292.0) — Deferred taxes — 0.4 94.7 — 95.1 Total noncurrent liabilities 707.8 464.0 711.2 (1,292.0) 591.0 Preferred stock 0.0 — — — 0.0 Common stock 1.0 0.0 0.1 (0.1) 1.0 Other shareholders' equity 674.0 650.1 22.0 (672.1) 674.0 Total shareholders' equity 675.0 650.1 22.1 (672.2) 675.0 TOTAL $ 1,430.5 $ 1,225.3 $ 808.1 $ (1,964.2) $ 1,499.7
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows For the six months ended June 30, 2020 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (21.6) $ 66.8 $ 26.4 $ — $ 71.6 Purchase of property, plant and equipment (0.5) (8.3) (0.8) — (9.6) Proceeds from sale of property, plant, and equipment — — 0.1 — 0.1 Intercompany transactions 38.4 (56.3) (0.2) 18.1 — Net cash provided by (used in) investing activities 37.9 (64.6) (0.9) 18.1 (9.5) Repayments on term loan (10.0) — — — (10.0) Borrowings under revolving credit facilities 77.4 — 45.0 — 122.4 Repayments under revolving credit facilities (36.4) — — — (36.4) Intercompany transactions 56.1 (1.1) (36.9) (18.1) — Net cash provided by (used in) financing activities 87.1 (1.1) 8.1 (18.1) 76.0 CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH 103.4 1.1 33.6 — 138.1 Cash, cash equivalents and restricted cash, beginning of period 0.3 0.9 38.5 — 39.7 Cash, cash equivalents and restricted cash, end of period $ 103.7 $ 2.0 $ 72.1 $ — $ 177.8 Condensed Consolidating Statements of Cash Flows For the six months ended June 30, 2019 The Company Combined Guarantor Subsidiaries Combined Consolidating Adjustments Total Consolidated Net cash provided by (used in) operating activities $ (35.6) $ (1.1) $ 11.1 $ — $ (25.6) Purchase of property, plant and equipment (0.6) (12.2) (10.5) — (23.3) Proceeds from sale of joint venture — — 10.5 — 10.5 Intercompany transactions (22.2) (33.6) 0.2 55.6 — Net cash provided by (used in) investing activities (22.8) (45.8) 0.2 55.6 (12.8) Borrowing under term loan 40.0 — — — 40.0 Borrowings under revolving credit facilities 288.2 — — — 288.2 Repayments under revolving credit facilities (303.3) — — — (303.3) 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 33.7 46.8 (24.9) (55.6) — Net cash provided by (used in) financing activities 58.9 46.8 (24.9) (55.6) 25.2 CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH 0.5 (0.1) (13.6) — (13.2) 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 $ 0.6 $ 0.7 $ 25.2 $ — $ 26.5

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Apr. 29, 2019
Related Party Transaction [Line Items]
Related parties	$ 285.6	$ 305	$ 556.6	$ 616.4
Glencore [Member]
Related Party Transaction [Line Items]
Related parties	285.6	305	556.6	616.4
Hawesville [Member]
Related Party Transaction [Line Items]
Term loan - less current portion					$ 40
Aluminum [Member] | Glencore [Member]
Related Party Transaction [Line Items]
Related parties	$ 0.9	$ 13.6	$ 1.2	$ 21.7
Consolidated Sales [Member] | Customer Concentration Risk [Member] | Glencore [Member]
Related Party Transaction [Line Items]
Major customer, percentage of revenue, net (percent)	71.00%	64.50%	67.60%	64.00%
Glencore [Member]
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	42.90%		42.90%
Economic ownership percentage by related party	46.80%		46.80%

Related Party Transactions - Su

Related Party Transactions - Summary of related party transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	May 22, 2019
Related Party Transaction [Line Items]
Net sales to Glencore	$ 285.6	$ 305	$ 556.6	$ 616.4
Glencore [Member]
Related Party Transaction [Line Items]
Net sales to Glencore	285.6	305	556.6	616.4
Purchases from Glencore	33.4	115.6	73.6	206.3
BHH [Member]
Related Party Transaction [Line Items]
Purchases from Glencore	$ 0	$ 8.5	$ 0	$ 14.6
Percentage of voting interests sold					40.00%

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 401.9	$ 473.1	$ 823.1	$ 963.2
Decrease in accounts receivable			(34.1)	(0.7)
United States [Member]
Disaggregation of Revenue [Line Items]
Revenue	247.9	309.5	522	634.8
Iceland [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 154	$ 163.6	301.1	$ 328.4
Trade Accounts Receivable [Member]
Disaggregation of Revenue [Line Items]
Decrease in accounts receivable			$ 34.2

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Recurring [Member] - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
ASSETS:
Cash equivalents	$ 162.2	$ 23.3
Trust assets	0.8	0.2
Surety bonds		1.8
Derivative instruments	34.6	19.7
TOTAL	197.6	45
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Contingent obligation – net	0	0
Derivative instruments	15.7	4.2
TOTAL	15.7	4.2
Level 1 [Member]
ASSETS:
Cash equivalents	162.2	23.3
Trust assets	0.8	0.2
Surety bonds		1.8
Derivative instruments	0	0
TOTAL	163	25.3
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Contingent obligation – net	0	0
Derivative instruments	0	0
TOTAL	0	0
Level 2 [Member]
ASSETS:
Cash equivalents	0	0
Trust assets	0	0
Surety bonds		0
Derivative instruments	28.5	9.1
TOTAL	28.5	9.1
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Contingent obligation – net	0	0
Derivative instruments	14.2	1.3
TOTAL	14.2	1.3
Level 3 [Member]
ASSETS:
Cash equivalents	0	0
Trust assets	0	0
Surety bonds		0
Derivative instruments	6.1	10.6
TOTAL	6.1	10.6
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Contingent obligation – net	0	0
Derivative instruments	1.5	2.9
TOTAL	$ 1.5	$ 2.9

Fair Value Measurements - Signi

Fair Value Measurements - Significant Unobservable Inputs (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)MWhT	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Locational margin price average term	3 years
LME Swap [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 6.1	$ 7.8	$ 10.6
LME Swap [Member] | Discounted Cash Flow [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, percentage	0.1000
Contingent obligation [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 0
Contingent obligation [Member] | Minimum [Member] | Discounted Cash Flow [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset (in tones) | T	1,594
Contingent obligation [Member] | Maximum [Member] | Discounted Cash Flow [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset (in tones) | T	2,179
Hawesville L4 Power Price Swaps [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ (1.5)	$ (3.2)	$ (2.9)	$ (2.7)	$ 0	$ 0
Hawesville L4 Power Price Swaps [Member] | Discounted Cash Flow [Member] | Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative liability (in MwH) | MWh	0.52

Fair Value Measurements - Level

Fair Value Measurements - Level 3 Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Nordpool Power Price Swap [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning		$ 3.7		$ 4.7
Total realized/unrealized gains (losses)
Included in net income (loss)		0		(1)
Purchases, sales, settlements
Purchases		0		0
Sales		0		0
Settlements		0		0
Transfers into Level 3		0		0
Transfers out of Level 3		(3.7)		(3.7)
Balance, ending		0		0
Change in unrealized gains (losses)		0		(1)
LME Swap [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning	$ 7.8		$ 10.6
Total realized/unrealized gains (losses)
Included in net income (loss)	(1.7)		5
Purchases, sales, settlements
Purchases	0		0
Sales	0		0
Settlements	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	0		(9.5)
Balance, ending	6.1		6.1
Change in unrealized gains (losses)	(1.7)		5
Hawesville L4 Power Price Swaps [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning	(3.2)	0	(2.9)	0
Total realized/unrealized gains (losses)
Included in net income (loss)	0	0	(1.4)	0
Purchases, sales, settlements
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	1.7	0	2.8	0
Transfers into Level 3	0	(2.7)	0	(2.7)
Transfers out of Level 3	0	0	0	0
Balance, ending	(1.5)	(2.7)	(1.5)	(2.7)
Change in unrealized gains (losses)	$ 1.7	(2.7)	$ 1.4	(2.7)
Midwest Premium (MWP) [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning		(0.9)
Total realized/unrealized gains (losses)
Included in net income (loss)		0
Purchases, sales, settlements
Purchases		0
Sales		0
Settlements		0
Transfers into Level 3		0
Transfers out of Level 3		0.9
Balance, ending		0		0
Change in unrealized gains (losses)		0
FX Swap [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning		(0.6)		(0.3)
Total realized/unrealized gains (losses)
Included in net income (loss)		0		(0.3)
Purchases, sales, settlements
Purchases		0		0
Sales		0		0
Settlements		0		0
Transfers into Level 3		0		0
Transfers out of Level 3		0.6		0.6
Balance, ending		0		0
Change in unrealized gains (losses)		0		(0.3)
United States [Member] | LME Swap [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning		(1.8)		0.3
Total realized/unrealized gains (losses)
Included in net income (loss)		8.7		6.8
Purchases, sales, settlements
Purchases		0		0
Sales		0		0
Settlements		0		0
Transfers into Level 3		0		(0.2)
Transfers out of Level 3		0		0
Balance, ending		6.9		6.9
Change in unrealized gains (losses)		8.7		6.6
Iceland [Member] | LME Swap [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning		(0.3)		(0.2)
Total realized/unrealized gains (losses)
Included in net income (loss)		0		(0.1)
Purchases, sales, settlements
Purchases		0		0
Sales		0		0
Settlements		0		0
Transfers into Level 3		0		0
Transfers out of Level 3		0.3		0.3
Balance, ending		0		0
Change in unrealized gains (losses)		$ 0		$ (0.1)

Earnings (Loss) Per Share (Deta

Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income (loss)	$ (26.9)	$ (20.7)	$ (29.6)	$ (55.3)
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 (shares)	89.5	88.8	89.4	88.5
Basic and diluted (USD per share)	$ (0.30)	$ (0.23)	$ (0.33)	$ (0.63)
Securities excluded from calculation of diluted EPS (shares)	0.6	0.7	0.7	0.6

Shareholders_ Equity (Details)

Shareholders’ Equity (Details) - USD ($)	3 Months Ended	6 Months Ended		63 Months Ended	114 Months Ended
	Mar. 31, 2015	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	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)		96,671,355		96,671,355	96,671,355	96,372,182
Common stock, shares, outstanding (in shares)		89,484,834		89,484,834	89,484,834	89,185,661
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						$ 60,000,000
Stock repurchase program, authorized, increase amount	$ 70,000,000
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)		66,039		66,039	66,039	67,323
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)		67,323	71,967
Conversion of convertible preferred stock (in shares)		(1,284)	(3,392)
Issuance for stock compensation plans (in shares)		0	0
Ending balance (in shares)		66,039	68,575	66,039	66,039
Treasury [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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
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]
Beginning balance (in shares)		89,185,661	88,103,440
Conversion of convertible preferred stock (in shares)		128,389	339,166
Issuance for stock compensation plans (in shares)		170,784	451,161
Ending balance (in shares)		89,484,834	88,893,767	89,484,834	89,484,834

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income tax benefit (expense)	$ (0.9)	$ 1.6	$ 1.9	$ 4.4
Impact of ASU 2018-02				$ 1.3

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Inventory, Net [Abstract]
Raw materials	$ 81.8	$ 101.3
Work-in-process	32.2	44.1
Finished goods	26.1	34.3
Operating and other supplies	134.9	140.9
Total inventories	$ 275	$ 320.6

Debt (Details)

Debt (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Jun. 30, 2013
Debt Instrument [Line Items]
Hawesville term loan - current portion	$ 20,000,000	$ 20,000,000
Hancock County industrial revenue bonds (IRBs) due April 1, 2028, interest payable quarterly (variable interest rates (not to exceed 12%))	7,800,000	7,800,000
Hawesville term loan - less current portion, interest payable monthly	10,000,000	20,000,000
Total debt	377,300,000	301,000,000
Hawesville [Member]
Debt Instrument [Line Items]
Hawesville term loan - current portion	20,000,000	20,000,000
Hawesville term loan - less current portion, interest payable monthly	10,000,000	20,000,000
Long-term Debt [Member] | Senior secured notes due June 01, 2021 [Member]
Debt Instrument [Line Items]
7.5% senior secured notes due June 2021, net of debt discount of $0.5 million and $0.8 million, respectively, interest payable semiannually (5)	249,500,000	249,200,000
Stated interest rate, percentage				7.50%
Debt discount	500,000	800,000
Short-term Debt [Member] | Industrial revenue bonds due April 1, 2028 [Member]
Debt Instrument [Line Items]
Hancock County industrial revenue bonds (IRBs) due April 1, 2028, interest payable quarterly (variable interest rates (not to exceed 12%))	$ 7,800,000	7,800,000
Stated interest rate, percentage	0.39%
Short-term Debt [Member] | Industrial revenue bonds due April 1, 2028 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Effective interest rate, maximum	12.00%
Short-term Debt [Member] | Revolving credit facility [Member]
Debt Instrument [Line Items]
Stated interest rate, percentage	5.375%
Interest payable outstanding	$ 0
Principal payment	10,000,000
Interest payable	$ 1,200,000
Short-term Debt [Member] | Revolving credit facility [Member] | Revolving Credit Facility, Portion Subject To LIBOR Rate [Member]
Debt Instrument [Line Items]
Stated interest rate, percentage	0.40%
U.S. revolving credit facility [Member] | Short-term Debt [Member] | Revolving credit facility [Member]
Debt Instrument [Line Items]
Revolving credit facility	$ 45,000,000		$ 4,000,000
Stated interest rate, percentage	2.50%
Iceland revolving line of credit [Member] | Long-term Debt [Member] | Revolving credit facility [Member]
Debt Instrument [Line Items]
Revolving credit facility	$ 45,000,000	$ 0
Stated interest rate, percentage	3.80%

Debt - Credit Facility (Details

Debt - Credit Facility (Details)	Apr. 29, 2019USD ($)payment	Jul. 01, 2020USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Jun. 30, 2013USD ($)
Line of Credit Facility [Line Items]
Fair value of debt instrument			$ 250,500,000	$ 244,200,000
U.S. revolving credit facility [Member]
Line of Credit Facility [Line Items]
Outstanding borrowings			45,000,000
Credit facility maximum amount			175,000,000
Borrowing availability			106,200,000
Borrowing availability, net of outstanding letters of credit and borrowings			42,900,000
Borrowing availability, net of borrowings			18,300,000
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] | 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]
Outstanding borrowings			45,000,000
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			$ 5,000,000
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%
Senior secured notes due 2025 [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Face amount		$ 250,000,000
Senior secured notes due 2025 [Member] | Long-term Debt [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Face amount		$ 250,000,000
Interest rate, cash percentage		10.00%
Interest rate, additional notes or cash percentage		2.00%
Revolving credit facility [Member] | Iceland revolving line of credit [Member] | Long-term Debt [Member]
Line of Credit Facility [Line Items]
Stated interest rate, percentage			3.80%
Revolving credit facility			$ 45,000,000	$ 0
Short-term Debt [Member] | Revolving credit facility [Member]
Line of Credit Facility [Line Items]
Stated interest rate, percentage			5.375%
Short-term Debt [Member] | Revolving credit facility [Member] | U.S. revolving credit facility [Member]
Line of Credit Facility [Line Items]
Stated interest rate, percentage			2.50%
Debt, financial covenant, fixed coverage ratio			1
Debt, financial covenant, amount			$ 17,500,000
Debt, financial covenant, borrowing base, percentage			10.00%
Debt, financial covenant, borrowing base, minimum			$ 12,500,000
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 ($)	Sep. 30, 2017USD ($)	Jun. 30, 2020USD ($)Labor_UnionMW	Jun. 30, 2019USD ($)	Dec. 31, 2013USD ($)
Labor Commitments [Abstract]
Percentage of total work force in union			67.00%
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 [Member]
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			$ 9,100,000

Components of Accumulated Oth_3

Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	$ (110.9)		$ (110.9)		$ (113.6)
Income tax effect	3.3		3.3		3.8
Accumulated other comprehensive loss	(107.6)		(107.6)		(109.8)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, start	673.8	$ 728.1	675	$ 762.2
Impact of ASU 2018-02				1.3
Balance, end	648.7	709.4	648.7	709.4
Defined benefit plan and other postretirement liabilities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	(113.1)		(113.1)		(115.9)
Income tax effect	(3.7)		(3.7)		(4.3)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, start	(110.3)	(101.7)	(111.7)	(100.7)
Impact of ASU 2018-02				(1.3)
Net amount reclassified to net income (loss)	0.8	1	2.2	1.3
Balance, end	(109.5)	(100.7)	(109.5)	(100.7)
Unrealized gain (loss) on financial instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive loss before income tax effect	2.2		2.2		2.3
Income tax effect	0.4		0.4		$ 0.4
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, start	1.9	2	1.9	2
Impact of ASU 2018-02				0
Net amount reclassified to net income (loss)	0	0	0	(0.1)
Balance, end	1.9	2	1.9	2
Accumulated other comprehensive loss [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, start	(108.4)	(99.7)	(109.8)	(98.7)
Impact of ASU 2018-02				(1.3)
Net amount reclassified to net income (loss)	0.8	1	2.2	1.3
Balance, end	$ (107.6)	$ (98.7)	$ (107.6)	$ (98.7)

Components of Accumulated Oth_4

Components of Accumulated Other Comprehensive Loss - Reclassifications out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of goods sold	$ 414.9	$ 477.2	$ 831.3	$ 980.1
Selling, general and administrative expenses	11.8	11.9	20.7	26.6
Other operating (income) expense - net	0.2	0.3	0.5	0.6
Income tax effect	0.9	(1.6)	(1.9)	(4.4)
Net of tax	26.9	20.7	29.6	55.3
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	0.4	0.3	1.5	0.9
Selling, general and administrative expenses	0.2	(0.2)	0.4	(0.6)
Other operating (income) expense - net	0.5	1.2	0.9	1.5
Income tax effect	(0.3)	(0.3)	(0.6)	(0.5)
Net of tax	0.8	1	2.2	1.3
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	(0.1)
Income tax effect	0	0	0	0
Net of tax	$ 0	$ 0	$ 0	$ (0.1)

Components of Net Periodic Be_3

Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1.1	$ 0.5	$ 2.4	$ 1.5
Interest cost	2.8	3.4	5.6	6.7
Expected return on plan assets	(5.2)	(4.3)	(10.3)	(9.1)
Amortization of prior service costs	0	0.5	0	0.5
Amortization of net loss	1.8	2.2	3.3	3.3
Net periodic benefit cost	0.5	2.3	1	2.9
Other Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.1	0.7	0.2	0.7
Interest cost	0.7	1.2	1.5	2.3
Amortization of prior service costs	(0.8)	(1.8)	(1.6)	(3.1)
Amortization of net loss	0.1	0.4	1.1	1.1
Net periodic benefit cost	$ 0.1	$ 0.5	$ 1.2	$ 1

Derivatives (Details)

Derivatives (Details) € in Millions	6 Months Ended
	Jun. 30, 2020EUR (€)MMBTUMWht
LME Swap [Member]
Derivative [Line Items]
Other forward delivery contracts to sell primary aluminum, open (in tonnes) | t	104,740
Midwest Premium (MWP) [Member]
Derivative [Line Items]
Open position to offset fixed prices | t	151,500
Fixed For Floating Swaps [Member]
Derivative [Line Items]
Open position to offset fixed prices | t	14,596
Hawesville L4 Power Price Swaps [Member]
Derivative [Line Items]
Power available | MWh	395,280
NYMEX Henry Hub Natural Gas Price Swaps [Member]
Derivative [Line Items]
Power available | MMBTU	1,170,000
MISO Indiana Hub Power Price Swaps [Member]
Derivative [Line Items]
Power available | MWh	735,660
Nordpool Power Price Swap [Member] | Grundartangi [Member]
Derivative [Line Items]
Power available | MWh	1,340,992
FX Swap [Member]
Derivative [Line Items]
Derivative asset | €	€ 35.6

Derivatives - Assets and Liabil

Derivatives - Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Due from affiliates	$ 9.8	$ 30.1
Due from affiliates, noncurrent	3.9	0.5
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative asset	34.6	19.7
Derivative liability	15.7	4.2
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Derivative asset	34.6	19.7
Derivative liability	15.3	3.6
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative asset	0	0
Derivative liability	0.4	0.6
Glencore [Member] | Commodity Contract [Member]
Derivative [Line Items]
Due from affiliates	1.5	0.2
Due from affiliates, noncurrent	$ 3.9	$ 0.5

Derivatives - Net Gain (Loss) (

Derivatives - Net Gain (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	$ 3.7	$ 6.1	$ 7.5	$ 0.4
Commodity Contract [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	2.9	6.1	11.8	0.6
Commodity Contract [Member] | Glencore [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	(7.9)	1.8	4.7	0.8
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, (loss) gain on derivative, net	$ 0.8	$ 0	$ (4.3)	$ (0.2)

Condensed Consolidating Finan_3

Condensed Consolidating Financial Information - Statement of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
NET SALES
Related parties	$ 285.6	$ 305	$ 556.6	$ 616.4
Other customers	116.3	168.1	266.5	346.8
Total net sales	401.9	473.1	823.1	963.2
Cost of goods sold	414.9	477.2	831.3	980.1
Gross profit (loss)	(13)	(4.1)	(8.2)	(16.9)
Selling, general and administrative expenses	11.8	11.9	20.7	26.6
Other operating (income) expense - net	0.2	0.3	0.5	0.6
Operating income (loss)	(25)	(16.3)	(29.4)	(44.1)
Interest expense - term loan	(0.5)	(0.6)	(1.2)	(0.6)
Interest expense	(5.9)	(5.8)	(11.9)	(11.7)
Intercompany interest	0	0	0	0
Interest income	0.4	0.2	0.5	0.4
Net gain (loss) on forward and derivative contracts	3.7	6.1	7.5	0.4
Other income (expense) - net	1.3	(1.7)	3	(0.5)
Income (loss) before income taxes and equity in earnings of joint ventures	(26)	(18.1)	(31.5)	(56.1)
Income tax benefit (expense)	(0.9)	1.6	1.9	4.4
Income (loss) before equity in earnings of joint ventures	(26.9)	(16.5)	(29.6)	(51.7)
Loss on sale of BHH	0	(4.3)	0	(4.3)
Equity in earnings of joint ventures	0	0.1	0	0.7
Net income (loss)	(26.9)	(20.7)	(29.6)	(55.3)
Other comprehensive income before income tax effect	1	1.2	2.7	1.8
Income tax effect	(0.3)	(0.2)	(0.6)	(0.5)
Other comprehensive income (loss)	0.7	1	2.1	1.3
Total comprehensive income (loss)	(26.2)	(19.7)	(27.5)	(54)
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
Other operating (income) expense - net	0	0	0	0
Operating income (loss)	0	0	0	0
Interest expense - term loan	0	0	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	14.4	17.4	44.3	38
Net income (loss)	14.4	17.4	44.3	38
Other comprehensive income before income tax effect	(0.9)	(1.5)	(2.4)	(2.4)
Income tax effect	0	0	0	0
Other comprehensive income (loss)	(0.9)	(1.5)	(2.4)	(2.4)
Total comprehensive income (loss)	13.5	15.9	41.9	35.6
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	11.5	11.5	19.9	25.6
Other operating (income) expense - net	0	0	0	0
Operating income (loss)	(11.5)	(11.5)	(19.9)	(25.6)
Interest expense - term loan	(0.5)	(0.6)	(1.2)	(0.6)
Interest expense	(5.4)	(5.3)	(10.5)	(10.8)
Intercompany interest	8.1	8.7	16.5	17.4
Interest income	0.3	0.1	0.3	0.1
Net gain (loss) on forward and derivative contracts	(1.9)	4.8	30.7	0.1
Other income (expense) - net	(0.2)	0	0.2	0.9
Income (loss) before income taxes and equity in earnings of joint ventures	(11.1)	(3.8)	16.1	(18.5)
Income tax benefit (expense)	0.5	(0.1)	1	0.9
Income (loss) before equity in earnings of joint ventures	(10.6)	(3.9)	17.1	(17.6)
Loss on sale of BHH		0		0
Equity in earnings of joint ventures	(16.3)	(16.8)	(46.7)	(37.7)
Net income (loss)	(26.9)	(20.7)	(29.6)	(55.3)
Other comprehensive income before income tax effect	1	1.2	2.7	1.8
Income tax effect	(0.3)	(0.2)	(0.6)	(0.5)
Other comprehensive income (loss)	0.7	1	2.1	1.3
Total comprehensive income (loss)	(26.2)	(19.7)	(27.5)	(54)
Combined Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
NET SALES
Related parties	156.2	147.4	304.1	299.9
Other customers	91.5	162.2	217.8	334.9
Total net sales	247.7	309.6	521.9	634.8
Cost of goods sold	266.3	306	547.3	633.2
Gross profit (loss)	(18.6)	3.6	(25.4)	1.6
Selling, general and administrative expenses	0	0	0	0
Other operating (income) expense - net	0	0	0	0
Operating income (loss)	(18.6)	3.6	(25.4)	1.6
Interest expense - term loan	0	0	0	0
Interest expense	(0.4)	(0.4)	(0.8)	(0.8)
Intercompany interest	2.7	2.5	5.4	5
Interest income	0	0	0	0
Net gain (loss) on forward and derivative contracts	0.3	0.3	0.7	0.7
Other income (expense) - net	0.8	(1.3)	0.6	(1.9)
Income (loss) before income taxes and equity in earnings of joint ventures	(15.2)	4.7	(19.5)	4.6
Income tax benefit (expense)	0	0	0	0
Income (loss) before equity in earnings of joint ventures	(15.2)	4.7	(19.5)	4.6
Loss on sale of BHH		0		0
Equity in earnings of joint ventures	1.9	(0.6)	2.4	(0.3)
Net income (loss)	(13.3)	4.1	(17.1)	4.3
Other comprehensive income before income tax effect	0.4	0.3	1.5	0.9
Income tax effect	0	0	0	0
Other comprehensive income (loss)	0.4	0.3	1.5	0.9
Total comprehensive income (loss)	(12.9)	4.4	(15.6)	5.2
Combined Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
NET SALES
Related parties	129.4	157.6	252.5	316.5
Other customers	24.8	5.9	48.7	11.9
Total net sales	154.2	163.5	301.2	328.4
Cost of goods sold	148.6	171.2	284	346.9
Gross profit (loss)	5.6	(7.7)	17.2	(18.5)
Selling, general and administrative expenses	0.3	0.4	0.8	1
Other operating (income) expense - net	0.2	0.3	0.5	0.6
Operating income (loss)	5.1	(8.4)	15.9	(20.1)
Interest expense - term loan	0	0	0	0
Interest expense	(0.1)	(0.1)	(0.6)	(0.1)
Intercompany interest	(10.8)	(11.2)	(21.9)	(22.4)
Interest income	0.1	0.1	0.2	0.3
Net gain (loss) on forward and derivative contracts	5.3	1	(23.9)	(0.4)
Other income (expense) - net	0.7	(0.4)	2.2	0.5
Income (loss) before income taxes and equity in earnings of joint ventures	0.3	(19)	(28.1)	(42.2)
Income tax benefit (expense)	(1.4)	1.7	0.9	3.5
Income (loss) before equity in earnings of joint ventures	(1.1)	(17.3)	(27.2)	(38.7)
Loss on sale of BHH		(4.3)		(4.3)
Equity in earnings of joint ventures	0	0.1	0	0.7
Net income (loss)	(1.1)	(21.5)	(27.2)	(42.3)
Other comprehensive income before income tax effect	0.5	1.2	0.9	1.5
Income tax effect	0	0	0	0
Other comprehensive income (loss)	0.5	1.2	0.9	1.5
Total comprehensive income (loss)	$ (0.6)	$ (20.3)	$ (26.3)	$ (40.8)
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 Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	$ 174.1		$ 38.9
Restricted cash	3.7		0.8
Accounts receivable - net	35.9		70.1
Due from affiliates	9.8		30.1
Inventories	275		320.6
Derivative assets	18.3		14.6
Prepaid and other current assets	14.6		12.2
Total current assets	531.4		487.3
Property, plant and equipment - net	919		949.2
Investment in subsidiaries	0		0
Due from affiliates - less current portion	3.9		0.5
Other assets	69.7		62.7
TOTAL	1,524		1,499.7
Accounts payable, trade	87.7		97.1
Due to affiliates	1.8		32.9
Accrued and other current liabilities	76.9		65.5
Accrued employee benefits costs	10.4		10.4
Hawesville term loan	20		20
U.S. revolving credit facility	45		4
Industrial revenue bonds	7.8		7.8
Total current liabilities	249.6		233.7
Senior notes payable	249.5		249.2
Hawesville term loan - less current portion	10		20
Iceland revolving credit facility	45		0
Accrued pension benefits costs - less current portion	57.7		60.8
Accrued postretirement benefits costs - less current portion	99.3		100.7
Due to affiliates - long term	0		0
Other liabilities	47.8		42.4
Leases - right of use liabilities	21.7		22.8
Deferred taxes	94.7		95.1
Total noncurrent liabilities	625.7		591
Preferred stock	0		0
Common stock	1		1
Other shareholders' equity	647.7		674
Total shareholders’ equity	648.7	$ 673.8	675	$ 709.4	$ 728.1	$ 762.2
TOTAL	1,524		1,499.7
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
Derivative assets	0		0
Prepaid and other current assets	0		0
Total current assets	0		0
Property, plant and equipment - net	0		0
Investment in subsidiaries	(633.4)		(672.2)
Due from affiliates - less current portion	(1,337.2)		(1,292)
Other assets	0		0
TOTAL	(1,970.6)		(1,964.2)
Accounts payable, trade	0		0
Due to affiliates	0		0
Accrued and other current liabilities	0		0
Accrued employee benefits costs	0		0
Hawesville term loan	0		0
U.S. revolving credit facility	0
Industrial revenue bonds	0		0
Total current liabilities	0		0
Senior notes payable	0		0
Hawesville term loan - less current portion	0		0
Iceland revolving credit facility	0
Accrued pension benefits costs - less current portion	0		0
Accrued postretirement benefits costs - less current portion	0		0
Due to affiliates - long term	(1,337.2)		(1,292)
Other liabilities	0		0
Leases - right of use liabilities	0		0
Deferred taxes	0		0
Total noncurrent liabilities	(1,337.2)		(1,292)
Preferred stock	0		0
Common stock	0		(0.1)
Other shareholders' equity	(633.4)		(672.1)
Total shareholders’ equity	(633.4)		(672.2)
TOTAL	(1,970.6)		(1,964.2)
The Company [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	103.7		0.3
Restricted cash	0		0
Accounts receivable - net	3.6		0.7
Due from affiliates	1.9		0
Inventories	0		0
Derivative assets	18.3		12.2
Prepaid and other current assets	4.5		3
Total current assets	132		16.2
Property, plant and equipment - net	15.7		17.2
Investment in subsidiaries	568.3		609.5
Due from affiliates - less current portion	736.2		749.5
Other assets	48.1		38.1
TOTAL	1,500.3		1,430.5
Accounts payable, trade	2.5		2.3
Due to affiliates	0		0
Accrued and other current liabilities	26.2		23.5
Accrued employee benefits costs	1.9		1.9
Hawesville term loan	20		20
U.S. revolving credit facility	45
Industrial revenue bonds	0		0
Total current liabilities	95.6		47.7
Senior notes payable	249.5		249.2
Hawesville term loan - less current portion	10		20
Iceland revolving credit facility	0
Accrued pension benefits costs - less current portion	24.4		25.1
Accrued postretirement benefits costs - less current portion	1		1.1
Due to affiliates - long term	459.5		403.4
Other liabilities	6.3		3.5
Leases - right of use liabilities	5.3		5.5
Deferred taxes	0		0
Total noncurrent liabilities	756		707.8
Preferred stock	0		0
Common stock	1		1
Other shareholders' equity	647.7		674
Total shareholders’ equity	648.7		675
TOTAL	1,500.3		1,430.5
Combined Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	0.2		0.1
Restricted cash	1.8		0.8
Accounts receivable - net	31.4		64.1
Due from affiliates	7.5		10.9
Inventories	168.7		205.5
Derivative assets	0		0
Prepaid and other current assets	1		2.8
Total current assets	210.6		284.2
Property, plant and equipment - net	327.7		334.8
Investment in subsidiaries	65.1		62.7
Due from affiliates - less current portion	599.6		537.9
Other assets	3.7		5.7
TOTAL	1,206.7		1,225.3
Accounts payable, trade	62.2		66.2
Due to affiliates	1.8		2.2
Accrued and other current liabilities	22.6		27.3
Accrued employee benefits costs	7.7		7.7
Hawesville term loan	0		0
U.S. revolving credit facility	0
Industrial revenue bonds	7.8		7.8
Total current liabilities	102.1		111.2
Senior notes payable	0		0
Hawesville term loan - less current portion	0		0
Iceland revolving credit facility	0
Accrued pension benefits costs - less current portion	26		27.3
Accrued postretirement benefits costs - less current portion	96.5		97.8
Due to affiliates - long term	320		315.9
Other liabilities	23.9		22.2
Leases - right of use liabilities	0		0.4
Deferred taxes	0.3		0.4
Total noncurrent liabilities	466.7		464
Preferred stock	0		0
Common stock	0		0
Other shareholders' equity	637.9		650.1
Total shareholders’ equity	637.9		650.1
TOTAL	1,206.7		1,225.3
Combined Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash & cash equivalents	70.2		38.5
Restricted cash	1.9		0
Accounts receivable - net	0.9		5.3
Due from affiliates	0.4		19.2
Inventories	106.3		115.1
Derivative assets	0		2.4
Prepaid and other current assets	9.1		6.4
Total current assets	188.8		186.9
Property, plant and equipment - net	575.6		597.2
Investment in subsidiaries	0		0
Due from affiliates - less current portion	5.3		5.1
Other assets	17.9		18.9
TOTAL	787.6		808.1
Accounts payable, trade	23		28.6
Due to affiliates	0		30.7
Accrued and other current liabilities	28.1		14.7
Accrued employee benefits costs	0.8		0.8
Hawesville term loan	0		0
U.S. revolving credit facility	0
Industrial revenue bonds	0		0
Total current liabilities	51.9		74.8
Senior notes payable	0		0
Hawesville term loan - less current portion	0		0
Iceland revolving credit facility	45
Accrued pension benefits costs - less current portion	7.3		8.4
Accrued postretirement benefits costs - less current portion	1.8		1.8
Due to affiliates - long term	557.7		572.7
Other liabilities	17.6		16.7
Leases - right of use liabilities	16.4		16.9
Deferred taxes	94.4		94.7
Total noncurrent liabilities	740.2		711.2
Preferred stock	0		0
Common stock	0		0.1
Other shareholders' equity	(4.5)		22
Total shareholders’ equity	(4.5)		22.1
TOTAL	$ 787.6		$ 808.1

Condensed Consolidating Finan_5

Condensed Consolidating Financial Information - Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	$ 71.6	$ (25.6)
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	(9.6)	(23.3)
Proceeds from sale of joint venture		10.5
Proceeds from sales of property, plant & equipment	0.1	0
Intercompany transactions	0	0
Net cash provided by (used in) investing activities	(9.5)	(12.8)
Net cash provided by (used in) financing activities
Repayments on term loan	(10)	0
Borrowing under term loan	0	40
Borrowings under revolving credit facilities	122.4	288.2
Repayments under revolving credit facilities	(36.4)	(303.3)
Other short term borrowings		3.4
Repayment on other short-term borrowings	0	(3.4)
Issuance of common stock	0	0.3
Intercompany transactions	0	0
Net cash provided by (used in) financing activities	76	25.2
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	138.1	(13.2)
Cash, cash equivalents and restricted cash, beginning of period	39.7	39.7
Cash, cash equivalents and restricted cash, end of period	177.8	26.5
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
Proceeds from sales of property, plant & equipment	0
Intercompany transactions	18.1	55.6
Net cash provided by (used in) investing activities	18.1	55.6
Net cash provided by (used in) financing activities
Repayments on term loan	0
Borrowing under term loan		0
Borrowings under revolving credit facilities	0	0
Repayments under revolving credit facilities	0	0
Other short term borrowings		0
Repayment on other short-term borrowings		0
Issuance of common stock		0
Intercompany transactions	(18.1)	(55.6)
Net cash provided by (used in) financing activities	(18.1)	(55.6)
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	(21.6)	(35.6)
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	(0.5)	(0.6)
Proceeds from sale of joint venture		0
Proceeds from sales of property, plant & equipment	0
Intercompany transactions	38.4	(22.2)
Net cash provided by (used in) investing activities	37.9	(22.8)
Net cash provided by (used in) financing activities
Repayments on term loan	(10)
Borrowing under term loan		40
Borrowings under revolving credit facilities	77.4	288.2
Repayments under revolving credit facilities	(36.4)	(303.3)
Other short term borrowings		3.4
Repayment on other short-term borrowings		(3.4)
Issuance of common stock		0.3
Intercompany transactions	56.1	33.7
Net cash provided by (used in) financing activities	87.1	58.9
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	103.4	0.5
Cash, cash equivalents and restricted cash, beginning of period	0.3	0.1
Cash, cash equivalents and restricted cash, end of period	103.7	0.6
Combined Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	66.8	(1.1)
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	(8.3)	(12.2)
Proceeds from sale of joint venture		0
Proceeds from sales of property, plant & equipment	0
Intercompany transactions	(56.3)	(33.6)
Net cash provided by (used in) investing activities	(64.6)	(45.8)
Net cash provided by (used in) financing activities
Repayments on term loan	0
Borrowing under term loan		0
Borrowings under revolving credit facilities	0	0
Repayments under revolving credit facilities	0	0
Other short term borrowings		0
Repayment on other short-term borrowings		0
Issuance of common stock		0
Intercompany transactions	(1.1)	46.8
Net cash provided by (used in) financing activities	(1.1)	46.8
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	1.1	(0.1)
Cash, cash equivalents and restricted cash, beginning of period	0.9	0.8
Cash, cash equivalents and restricted cash, end of period	2	0.7
Combined Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash provided by (used in) operating activities	26.4	11.1
Net cash provided by (used in) investing activities
Purchase of property, plant and equipment	(0.8)	(10.5)
Proceeds from sale of joint venture		10.5
Proceeds from sales of property, plant & equipment	0.1
Intercompany transactions	(0.2)	0.2
Net cash provided by (used in) investing activities	(0.9)	0.2
Net cash provided by (used in) financing activities
Repayments on term loan	0
Borrowing under term loan		0
Borrowings under revolving credit facilities	45	0
Repayments under revolving credit facilities	0	0
Other short term borrowings		0
Repayment on other short-term borrowings		0
Issuance of common stock		0
Intercompany transactions	(36.9)	(24.9)
Net cash provided by (used in) financing activities	8.1	(24.9)
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	33.6	(13.6)
Cash, cash equivalents and restricted cash, beginning of period	38.5	38.8
Cash, cash equivalents and restricted cash, end of period	$ 72.1	$ 25.2

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event [Member]	Jul. 01, 2020USD ($)
Senior secured notes due 2025 [Member]
Subsequent Event [Line Items]
Face amount	$ 250,000,000
Senior secured notes due June 01, 2021 [Member]
Subsequent Event [Line Items]
Debt instrument, repurchased face amount	$ 243,690,000