v3.20.2

Debt 144A due 2028 and Credit Agreement (Details) - USD ($) |  |  |  |  |  |  | 9 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
May 13, 2020 | Apr. 02, 2020 | Apr. 01, 2020 | Mar. 25, 2020 | Feb. 07, 2020 | Feb. 05, 2020 | Sep. 30, 2020 | Sep. 30, 2019 | Mar. 31, 2020 | Aug. 01, 2012
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  | $ 1,200,000,000 |  |  |  |
Proceeds from debt issuance |  |  |  |  |  | $ 1,168,000,000 | $ 2,400,000,000 | $ 0 |  |
Cash |  |  | $ 500,000,000 |  |  |  |  |  | $ 60,000,000 |
Separation payment to former parent company (A) |  |  | $ 728,000,000 |  |  |  | 728,000,000 |  |  |
Senior Secured Notes | Second-Lien Notes due 2028, 6.125% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | $ 600,000,000 |  |  |  |  |
Fixed interest rate |  |  |  |  | 6.125% |  |  |  |  |
Proceeds from debt issuance |  |  |  |  | $ 593,000,000 |  |  |  |  |
Debt, carrying value |  |  |  |  |  |  | 1,277,000,000 |  |  |
Senior Secured Notes | First-Lien Notes due 2025, 6.000% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount | $ 700,000,000 |  |  |  |  |  |  |  |  |
Fixed interest rate | 6.00% |  |  |  |  |  |  |  |  |
Proceeds from debt issuance | $ 691,000,000 |  |  |  |  |  |  |  |  |
Debt Issuance Costs, Net |  |  |  |  |  |  | 15,000,000 |  |  |
Unamortized Debt Issuance Expense |  |  |  |  |  |  | 12,000,000 |  |  |
Interest Expense, Other Long-term Debt |  |  |  |  |  |  | 19,000,000 |  |  |
Write off of Deferred Debt Issuance Cost |  |  |  |  |  |  | 3,000,000 |  |  |
Debt, carrying value |  |  |  |  |  |  | 1,365,000,000 |  |  |
Senior Secured Loans | First-Lien Term B Loan Facility |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount | 600,000,000 |  |  | $ 600,000,000 |  |  |  |  |  |
Debt instrument, term |  |  |  | 7 years |  |  |  |  |  |
Proceeds from debt issuance |  |  |  | $ 575,000,000 |  |  |  |  |  |
Debt Issuance Costs, Net |  |  |  |  |  |  | 30,000,000 |  |  |
Unamortized Debt Issuance Expense |  |  |  |  |  |  | 14,000,000 |  |  |
Interest Expense, Other Long-term Debt |  |  |  |  |  |  | 19,000,000 |  |  |
Write off of Deferred Debt Issuance Cost |  |  |  |  |  |  | 16,000,000 |  |  |
Senior Secured Credit Facility | First-Lien Revolving Credit Facility | Revolving Credit Facility |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  | $ 1,000 |  |  |  |  |  |
Debt instrument, term |  |  |  | 5 years |  |  |  |  |  |
Basis spread on variable rate |  | 2.00% |  |  |  |  |  |  |  |
Proceeds from revolving credit facility | $ 500,000,000 | $ 500,000,000 |  |  |  |  |  |  |  |
Debt Issuance Costs, Net |  |  |  |  |  |  | 30,000,000 |  |  |
Unamortized Debt Issuance Expense |  |  |  |  |  |  | 14,000,000 |  |  |
Interest Expense, Other Long-term Debt |  |  |  |  |  |  | 19,000,000 |  |  |
Write off of Deferred Debt Issuance Cost |  |  |  |  |  |  | 16,000,000 |  |  |
Senior Secured Credit Facility | ABL Credit Agreement | Revolving Credit Facility | Deutsche Bank AG New York Branch |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Issuance Costs, Net |  |  |  |  |  |  | 15,000,000 |  |  |
Unamortized Debt Issuance Expense |  |  |  |  |  |  | 12,000,000 |  |  |
Interest Expense, Other Long-term Debt |  |  |  |  |  |  | 19,000,000 |  |  |
Write off of Deferred Debt Issuance Cost |  |  |  |  |  |  | 3,000,000 |  |  |
Revolving credit facility, current borrowing capacity |  |  |  |  |  |  | 681,000,000 |  |  |
Required fixed charge coverage ratio | 1.00 |  |  |  |  |  |  |  |  |
Senior Secured Credit Facility | ABL Credit Agreement | Revolving Credit Facility | LIBOR | Deutsche Bank AG New York Branch |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Basis spread on variable rate | 1.00% |  |  |  |  |  |  |  |  |
Bonds [Member] | Midwestern Disaster Area Revenue Bonds Series 2012 [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  | $ 250,000,000
Secured Debt and Line of Credit [Member] | First-Lien Revolving Credit Facility and Second-Lien Notes due 2028, 6.125% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Issuance Costs, Net |  |  |  |  |  |  | $ 42,000,000 |  |  |
Minimum | Senior Secured Notes | Second-Lien Notes due 2028, 6.125% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Required prior notice for debt redemption, term |  |  |  |  | 10 days |  |  |  |  |
Minimum | Senior Secured Notes | First-Lien Notes due 2025, 6.000% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Required prior notice for debt redemption, term | 10 days |  |  |  |  |  |  |  |  |
Minimum | Senior Secured Credit Facility | ABL Credit Agreement | Revolving Credit Facility | LIBOR | Deutsche Bank AG New York Branch |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Fixed interest rate | 0.75% |  |  |  |  |  |  |  |  |
Maximum | Senior Secured Notes | Second-Lien Notes due 2028, 6.125% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Required prior notice for debt redemption, term |  |  |  |  | 60 days |  |  |  |  |
Maximum | Senior Secured Notes | First-Lien Notes due 2025, 6.000% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Required prior notice for debt redemption, term | 60 days |  |  |  |  |  |  |  |  |
Redemption prior to February 15, 2023 | Senior Secured Notes | Second-Lien Notes due 2028, 6.125% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt redemption percentage |  |  |  |  | 100.00% |  |  |  |  |
Debt redemption, basis spread on discount rate | 5000.00% |  |  |  |  |  |  |  |  |
Debt redemption, additional make-whole charge |  |  |  |  | 1.00% |  |  |  |  |
Redemption prior to February 15, 2023 | Senior Secured Notes | First-Lien Notes due 2025, 6.000% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt redemption percentage | 100.00% |  |  |  |  |  |  |  |  |
Debt redemption, basis spread on discount rate |  |  |  |  | 5000.00% |  |  |  |  |
Debt redemption, additional make-whole charge | 1.00% |  |  |  |  |  |  |  |  |
Redemption prior to February 15, 2023; limited to 40% of aggregate principal | Senior Secured Notes | Second-Lien Notes due 2028, 6.125% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt redemption percentage |  |  |  |  | 106.125% |  |  |  |  |
Redemption limitation based on aggregate principal |  |  |  |  | 40.00% |  |  |  |  |
Minimum aggregate principal following redemption |  |  |  |  | 60.00% |  |  |  |  |
Maximum term allowed for redemption following offering |  |  |  |  | 120 days |  |  |  |  |
Redemption prior to February 15, 2023; limited to 40% of aggregate principal | Senior Secured Notes | First-Lien Notes due 2025, 6.000% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt redemption percentage | 106.00% |  |  |  |  |  |  |  |  |
Redemption limitation based on aggregate principal | 40.00% |  |  |  |  |  |  |  |  |
Minimum aggregate principal following redemption | 60.00% |  |  |  |  |  |  |  |  |
Maximum term allowed for redemption following offering | 120 days |  |  |  |  |  |  |  |  |
Redemption after February 14, 2023 | Senior Secured Notes | Second-Lien Notes due 2028, 6.125% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt redemption percentage |  |  |  |  | 103.063% |  |  |  |  |
Redemption after February 14, 2023 | Senior Secured Notes | First-Lien Notes due 2025, 6.000% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt redemption percentage | 103.00% |  |  |  |  |  |  |  |  |
Redemption upon change in control | Senior Secured Notes | Second-Lien Notes due 2028, 6.125% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt redemption percentage |  |  |  |  | 101.00% |  |  |  |  |
Redemption upon change in control | Senior Secured Notes | First-Lien Notes due 2025, 6.000% |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt redemption percentage | 101.00% |  |  |  |  |  |  |  |  |

X
- Definition Debt Instrument, Notice for Debt Redemption, Term + References No definition available. + Details
Name: | arnc_DebtInstrumentNoticeforDebtRedemptionTerm
Namespace Prefix: | arnc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt Instrument, Redemption, Additional Make-Whole Redemption Charge + References No definition available. + Details
Name: | arnc_DebtInstrumentRedemptionAdditionalMakeWholeRedemptionCharge
Namespace Prefix: | arnc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt Instrument, Redemption, Basis Spread on Discount Rate + References No definition available. + Details
Name: | arnc_DebtInstrumentRedemptionBasisSpreadonDiscountRate
Namespace Prefix: | arnc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt Instrument, Redemption, Limitation Based on Aggregate Principal + References No definition available. + Details
Name: | arnc_DebtInstrumentRedemptionLimitationBasedonAggregatePrincipal
Namespace Prefix: | arnc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt Instrument, Redemption, Maximum Term Following Offering + References No definition available. + Details
Name: | arnc_DebtInstrumentRedemptionMaximumTermFollowingOffering
Namespace Prefix: | arnc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt Instrument, Redemption, Minimum Aggregate Principal Following Redemption + References No definition available. + Details
Name: | arnc_DebtInstrumentRedemptionMinimumAggregatePrincipalFollowingRedemption
Namespace Prefix: | arnc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fixed Charge Coverage Ratio + References No definition available. + Details
Name: | arnc_FixedChargeCoverageRatio
Namespace Prefix: | arnc_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Payments for Separation Transaction + References No definition available. + Details
Name: | arnc_PaymentsForSeparationTransaction
Namespace Prefix: | arnc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=118262064&loc=SL116631418-115840 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 45 -Paragraph 21 -URI http://asc.fasb.org/extlink&oid=118262064&loc=SL116631419-115840 + Details
Name: | us-gaap_Cash
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage price of original principal amount of debt at which debt can be redeemed by the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph e -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 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=119993939&loc=d3e28555-108399 + Details
Name: | us-gaap_DeferredFinanceCostsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of interest expense incurred on long-term debt classified as other, including, but not limited to, interest on long-term notes and amortization of issuance costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.8) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details
Name: | us-gaap_InterestExpenseOtherLongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromLongTermLinesOfCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt. + 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 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
Name: | us-gaap_WriteOffOfDeferredDebtIssuanceCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=arnc_SecondLienNotesdue20286.125Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=arnc_FirstLienNotesdue20256.000Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=arnc_FirstLienTermBLoanFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=arnc_FirstLienRevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=arnc_ABLCreditAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LineOfCreditFacilityAxis=arnc_DeutscheBankAGNewYorkBranchMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_BondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=arnc_MidwesternDisasterAreaRevenueBondsSeries2012Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=arnc_SecuredDebtAndLineOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=arnc_FirstLienRevolvingCreditFacilityAndSecondLienNotesDue20286125Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |