XML 65 R55.htm IDEA: XBRL DOCUMENT
v3.24.1.u1

Derivative Financial Instruments and Hedging (Details2) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2024 | Apr. 02, 2023 | Dec. 31, 2023
Cash Flow Hedging |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net | $ (1.3) | $ 4.2 |
Cash Flow Hedging | Other Comprehensive Income (Loss) [Member] |  |  |
Derivatives Fair Value [Line Items] |  |  |
Net derivative gain (loss) on hedge transactions | (1.4) | (11.4) |
Nickel and other raw material contracts | Cash Flow Hedging |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net | 0.0 | 5.3 |
Nickel and other raw material contracts | Cash Flow Hedging | Other Comprehensive Income (Loss) [Member] |  |  |
Derivatives Fair Value [Line Items] |  |  |
Net derivative gain (loss) on hedge transactions | (0.2) | (5.3) |
Interest Rate Swap | Cash Flow Hedging |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net | 0.3 | 0.2 |
Interest Rate Swap | Cash Flow Hedging | Other Comprehensive Income (Loss) [Member] |  |  |
Derivatives Fair Value [Line Items] |  |  |
Net derivative gain (loss) on hedge transactions | 0.0 | (0.1) |
Natural gas contracts | Cash Flow Hedging |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net | (1.8) | (1.4) |
Natural gas contracts | Cash Flow Hedging | Other Comprehensive Income (Loss) [Member] |  |  |
Derivatives Fair Value [Line Items] |  |  |
Net derivative gain (loss) on hedge transactions | (1.4) | (6.1) |
Foreign exchange contracts | Cash Flow Hedging |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net | 0.2 | 0.1 |
Foreign exchange contracts | Cash Flow Hedging | Other Comprehensive Income (Loss) [Member] |  |  |
Derivatives Fair Value [Line Items] |  |  |
Net derivative gain (loss) on hedge transactions | 0.2 | $ 0.1 |
Designated as Hedging Instrument |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Fair Value Of Derivative Asset | 0.5 |  | $ 0.9
Derivative Fair Value Of Derivative Liability | 10.7 |  | 14.2
Designated as Hedging Instrument | Nickel and other raw material contracts | Accrued liabilities |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Fair Value Of Derivative Liability | 4.5 |  | 7.5
Designated as Hedging Instrument | Interest Rate Swap | Prepaid expenses and other current assets |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Fair Value Of Derivative Asset | 0.4 |  | 0.7
Designated as Hedging Instrument | Natural gas contracts | Other assets |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Fair Value Of Derivative Asset | 0.0 |  | 0.1
Designated as Hedging Instrument | Natural gas contracts | Accrued liabilities |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Fair Value Of Derivative Liability | 5.4 |  | 5.6
Designated as Hedging Instrument | Natural gas contracts | Other long-term liabilities |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Fair Value Of Derivative Liability | 0.8 |  | 1.1
Designated as Hedging Instrument | Foreign exchange contracts | Prepaid expenses and other current assets |  |  |
Derivatives Fair Value [Line Items] |  |  |
Derivative Fair Value Of Derivative Asset | $ 0.1 |  | $ 0.1

X
- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 22 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-22 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-7 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (c)(2) -SubTopic 20 -Topic 860 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481326/860-20-50-4D + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 22 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-22 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483466/210-20-50-3 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483444/210-20-55-7 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (c)(2) -SubTopic 20 -Topic 860 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481326/860-20-50-4D + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (b) -SubTopic 10 -Topic 815 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4D Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4C + Details
Name: | us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet
Namespace Prefix: | us-gaap_
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: | us-gaap_DerivativesFairValueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after tax and before reclassification, of gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 11 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482790/220-10-45-11 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 10A -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482790/220-10-45-10A + Details
Name: | us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_OtherComprehensiveIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=ati_NickelAndOtherRawMaterialContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=ati_NaturalGasContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_AccruedLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |