XML 61 R47.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Condensed consolidating financial information - Statement of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
NET SALES |  |  |  |
Related parties | $ 305.3 | $ 299.2 | $ 884.2 | $ 876.1
Other customers | 176.5 | 101.4 | 522.1 | 279.1
Total net sales | 481.8 | 400.6 | 1,406.3 | 1,155.2
Cost of goods sold | 493.6 | 359.2 | 1,369.9 | 1,074.5
Gross profit (loss) | (11.8) | 41.4 | 36.4 | 80.7
Selling, general and administrative expenses | 8.8 | 14.0 | 31.5 | 34.0
Ravenswood (gains) losses | 0.0 | (5.5) | 0.0 | (5.5)
Helguvik (gains) losses | (4.5) | 0.0 | (4.5) | 0.0
Other operating (income) expense - net | (0.5) | 0.4 | 0.0 | 1.6
Operating income (loss) | (15.6) | 32.5 | 9.4 | 50.6
Interest expense | (5.6) | (5.5) | (16.7) | (16.6)
Intercompany interest | 0.0 | 0.0 | 0.0 | 0.0
Interest income | 0.4 | 0.4 | 1.3 | 0.9
Net gain (loss) on forward and derivative contracts | 0.8 | (3.9) | 2.8 | (17.1)
Other income (expense) - net | 0.7 | 0.4 | 1.8 | (1.0)
Income (loss) before income taxes and equity in earnings of joint ventures | (19.3) | 23.9 | (1.4) | 16.8
Income tax (expense) benefit | (1.7) | (3.3) | (3.0) | (4.5)
Income (loss) before equity in earnings of joint ventures | (21.0) | 20.6 | (4.4) | 12.3
Equity in earnings (loss) of joint ventures | 0.7 | 0.2 | 3.2 | 0.5
Net income (loss) | (20.3) | 20.8 | (1.2) | 12.8
Other comprehensive income (loss) before income tax effect | 0.5 | 1.4 | 4.2 | 3.1
Income tax effect | (0.4) | (0.4) | (1.1) | (1.2)
Other comprehensive income | 0.1 | 1.0 | 3.1 | 1.9
Total comprehensive income (loss) | (20.2) | 21.8 | 1.9 | 14.7
Consolidating Adjustments [Member] |  |  |  |
NET SALES |  |  |  |
Related parties | 0.0 | 0.0 | 0.0 | 0.0
Other customers | 0.0 | 0.0 | 0.0 | 0.0
Total net sales | 0.0 | 0.0 | 0.0 | 0.0
Cost of goods sold | 0.0 | 0.0 | 0.0 | 0.0
Gross profit (loss) | 0.0 | 0.0 | 0.0 | 0.0
Selling, general and administrative expenses | 0.0 | 0.0 | 0.0 | 0.0
Ravenswood (gains) losses |  | 0.0 |  | 0.0
Helguvik (gains) losses | 0.0 |  | 0.0 |
Other operating (income) expense - net | 0.0 | 0.0 | 0.0 | 0.0
Operating income (loss) | 0.0 | 0.0 | 0.0 | 0.0
Interest expense | 0.0 | 0.0 | 0.0 | 0.0
Intercompany interest | 0.0 | 0.0 | 0.0 | 0.0
Interest income | 0.0 | 0.0 | 0.0 | 0.0
Net gain (loss) on forward and derivative contracts | 0.0 | 0.0 | 0.0 | 0.0
Other income (expense) - net | 0.0 | 0.0 | 0.0 | 0.0
Income (loss) before income taxes and equity in earnings of joint ventures | 0.0 | 0.0 | 0.0 | 0.0
Income tax (expense) benefit | 0.0 | 0.0 | 0.0 | 0.0
Income (loss) before equity in earnings of joint ventures | 0.0 | 0.0 | 0.0 | 0.0
Equity in earnings (loss) of joint ventures | 13.8 | (31.9) | (14.9) | (35.6)
Net income (loss) | 13.8 | (31.9) | (14.9) | (35.6)
Other comprehensive income (loss) before income tax effect | (0.9) | (1.3) | (5.1) | (2.0)
Income tax effect | 0.0 | 0.0 | 0.0 | 0.0
Other comprehensive income | (0.9) | (1.3) | (5.1) | (2.0)
Total comprehensive income (loss) | 12.9 | (33.2) | (20.0) | (37.6)
The Company [Member] | Reportable Legal Entities [Member] |  |  |  |
NET SALES |  |  |  |
Related parties | 0.0 | 0.0 | 0.0 | 0.0
Other customers | 0.0 | 0.0 | 0.0 | 0.0
Total net sales | 0.0 | 0.0 | 0.0 | 0.0
Cost of goods sold | 0.0 | 0.0 | 0.0 | 0.0
Gross profit (loss) | 0.0 | 0.0 | 0.0 | 0.0
Selling, general and administrative expenses | 8.4 | 13.7 | 29.8 | 32.8
Ravenswood (gains) losses |  | 0.0 |  | 0.0
Helguvik (gains) losses | 0.0 |  | 0.0 |
Other operating (income) expense - net | 0.0 | 0.0 | 0.0 | 0.0
Operating income (loss) | (8.4) | (13.7) | (29.8) | (32.8)
Interest expense | (5.0) | (5.1) | (15.4) | (15.3)
Intercompany interest | 9.3 | 8.9 | 27.4 | 27.1
Interest income | 0.1 | 0.2 | 0.3 | 0.3
Net gain (loss) on forward and derivative contracts | (0.2) | 0.0 | (0.2) | 0.0
Other income (expense) - net | 0.0 | 0.0 | 0.6 | 0.7
Income (loss) before income taxes and equity in earnings of joint ventures | (4.2) | (9.7) | (17.1) | (20.0)
Income tax (expense) benefit | 0.5 | 0.0 | 0.7 | 1.1
Income (loss) before equity in earnings of joint ventures | (3.7) | (9.7) | (16.4) | (18.9)
Equity in earnings (loss) of joint ventures | (16.6) | 30.5 | 15.2 | 31.7
Net income (loss) | (20.3) | 20.8 | (1.2) | 12.8
Other comprehensive income (loss) before income tax effect | 0.5 | 1.4 | 4.2 | 3.1
Income tax effect | (0.4) | (0.4) | (1.1) | (1.2)
Other comprehensive income | 0.1 | 1.0 | 3.1 | 1.9
Total comprehensive income (loss) | (20.2) | 21.8 | 1.9 | 14.7
Combined Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member] |  |  |  |
NET SALES |  |  |  |
Related parties | 110.8 | 138.2 | 315.1 | 404.1
Other customers | 175.8 | 101.4 | 519.1 | 279.1
Total net sales | 286.6 | 239.6 | 834.2 | 683.2
Cost of goods sold | 301.5 | 220.7 | 821.1 | 655.0
Gross profit (loss) | (14.9) | 18.9 | 13.1 | 28.2
Selling, general and administrative expenses | 0.0 | 0.0 | 0.0 | 0.0
Ravenswood (gains) losses |  | 0.0 |  | 0.0
Helguvik (gains) losses | 0.0 |  | 0.0 |
Other operating (income) expense - net | 0.0 | 0.0 | 0.0 | 0.0
Operating income (loss) | (14.9) | 18.9 | 13.1 | 28.2
Interest expense | (0.4) | (0.4) | (1.2) | (1.2)
Intercompany interest | 2.4 | 2.2 | 7.0 | 6.4
Interest income | 0.0 | 0.0 | 0.0 | 0.0
Net gain (loss) on forward and derivative contracts | 0.4 | (3.9) | 1.1 | (17.1)
Other income (expense) - net | 0.0 | 0.0 | (0.2) | 0.2
Income (loss) before income taxes and equity in earnings of joint ventures | (12.5) | 16.8 | 19.8 | 16.5
Income tax (expense) benefit | 0.0 | 0.0 | 0.0 | 0.0
Income (loss) before equity in earnings of joint ventures | (12.5) | 16.8 | 19.8 | 16.5
Equity in earnings (loss) of joint ventures | 2.8 | 1.4 | (0.3) | 3.9
Net income (loss) | (9.7) | 18.2 | 19.5 | 20.4
Other comprehensive income (loss) before income tax effect | 0.5 | 1.0 | 3.9 | 0.8
Income tax effect | 0.0 | 0.0 | 0.0 | 0.0
Other comprehensive income | 0.5 | 1.0 | 3.9 | 0.8
Total comprehensive income (loss) | (9.2) | 19.2 | 23.4 | 21.2
Combined Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member] |  |  |  |
NET SALES |  |  |  |
Related parties | 194.5 | 161.0 | 569.1 | 472.0
Other customers | 0.7 | 0.0 | 3.0 | 0.0
Total net sales | 195.2 | 161.0 | 572.1 | 472.0
Cost of goods sold | 192.1 | 138.5 | 548.8 | 419.5
Gross profit (loss) | 3.1 | 22.5 | 23.3 | 52.5
Selling, general and administrative expenses | 0.4 | 0.3 | 1.7 | 1.2
Ravenswood (gains) losses |  | (5.5) |  | (5.5)
Helguvik (gains) losses | (4.5) |  | (4.5) |
Other operating (income) expense - net | (0.5) | 0.4 | 0.0 | 1.6
Operating income (loss) | 7.7 | 27.3 | 26.1 | 55.2
Interest expense | (0.2) | 0.0 | (0.1) | (0.1)
Intercompany interest | (11.7) | (11.1) | (34.4) | (33.5)
Interest income | 0.3 | 0.2 | 1.0 | 0.6
Net gain (loss) on forward and derivative contracts | 0.6 | 0.0 | 1.9 | 0.0
Other income (expense) - net | 0.7 | 0.4 | 1.4 | (1.9)
Income (loss) before income taxes and equity in earnings of joint ventures | (2.6) | 16.8 | (4.1) | 20.3
Income tax (expense) benefit | (2.2) | (3.3) | (3.7) | (5.6)
Income (loss) before equity in earnings of joint ventures | (4.8) | 13.5 | (7.8) | 14.7
Equity in earnings (loss) of joint ventures | 0.7 | 0.2 | 3.2 | 0.5
Net income (loss) | (4.1) | 13.7 | (4.6) | 15.2
Other comprehensive income (loss) before income tax effect | 0.4 | 0.3 | 1.2 | 1.2
Income tax effect | 0.0 | 0.0 | 0.0 | 0.0
Other comprehensive income | 0.4 | 0.3 | 1.2 | 1.2
Total comprehensive income (loss) | $ (3.7) | $ 14.0 | $ (3.4) | $ 16.4
Century Aluminum [Member] | Combined Guarantor Subsidiaries [Member] |  |  |  |
Condensed Statement of Income Captions [Line Items] |  |  |  |
Ownership percentage | 100.00% |  | 100.00% |

X
- Definition Gain Loss Related Project Termination Including Asset Impairment + References No definition available. + Details
Name: | cenx_GainLossRelatedProjectTerminationIncludingAssetImpairment
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Gain (Loss) Related to Litigation Settlement And Litigation Expenses + References No definition available. + Details
Name: | cenx_GainLossRelatedtoLitigationSettlementAndLitigationExpenses
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Sum of operating profit and nonoperating income or expense, net of income taxes, before Income or Loss from equity method investments, extraordinary items, and noncontrolling interest. + References No definition available. + Details
Name: | cenx_IncomeLossAfterIncomeTaxesBeforeIncomeLossFromEquityMethodInvestments
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | srt_CondensedStatementOfIncomeCaptionsLineItems
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4K -URI http://asc.fasb.org/extlink&oid=84234705&loc=SL4591552-111686 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669619-108580 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669625-108580 + Details
Name: | us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(a),(d)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_CostOfGoodsAndServicesSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
Name: | us-gaap_GainLossOnDerivativeInstrumentsNetPretax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1,2) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_GrossProfit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(1)(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(12)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(10)) -URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(f)) -URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 + Details
Name: | us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e38679-109324 + Details
Name: | us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of the cost of borrowed funds accounted for as interest expense. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (210.5-03(11)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.9) -URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260 + Details
Name: | us-gaap_InterestExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of interest expense incurred on a debt or other obligation to related party. + References No definition available. + Details
Name: | us-gaap_InterestExpenseRelatedParty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of interest income earned from interest bearing assets classified as other. + References No definition available. + Details
Name: | us-gaap_InterestIncomeOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669619-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(22)) -URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669625-108580 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(18)) -URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(20)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
Name: | us-gaap_NetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The net result for the period of deducting operating expenses from operating revenues. + References No definition available. + Details
Name: | us-gaap_OperatingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount before tax, after reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33775-111570 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax and reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669619-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=109228884&loc=d3e1436-108581 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669625-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of tax expense (benefit) allocated to other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 11 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e39076-109324 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e38679-109324 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e640-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of income (expense) related to nonoperating activities, classified as other. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.9) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_OtherNonoperatingIncomeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The total amount of other operating income, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_OtherOperatingIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations. + References No definition available. + Details
Name: | us-gaap_OtherOperatingIncomeExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-07.1(c)) -URI http://asc.fasb.org/extlink&oid=114873854&loc=SL114874292-224272 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1(e)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_RevenueFromRelatedParties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 + Details
Name: | us-gaap_Revenues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_RevenuesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=68048583&loc=d3e3636-108311 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_SellingGeneralAndAdministrativeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_ConsolidationItemsAxis=srt_ConsolidationEliminationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidationItemsAxis=srt_ReportableLegalEntitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_GuarantorSubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_NonGuarantorSubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=cenx_CenturyAluminumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |