Derivative Asset Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag

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- Definition

Derivative Liability, Statement Of Financial Position, Extensible Enumeration, Not Disclosed Flag

+ References

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- Definition

Fair value portion 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. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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- Definition

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

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- 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.

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Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jul. 02, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	Assets
Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	Liabilities
ATI Convertible Senior Notes, 3.5%, Due 2025 [Member] \| Convertible Debt [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Equity component of convertible debt			$ 46.8	$ 51.4
Fair Value Measurements at Reporting Date Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 584.0	$ 687.7
Derivative financial instruments: Assets	0.0	0.0
Derivative financial instruments: Liabilities	0.0	0.0
Debt	1,665.7	1,690.1
Fair Value Measurements at Reporting Date Using Significant Observable Inputs (Level 2)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	0.0	0.0
Derivative financial instruments: Assets	18.0	7.6
Derivative financial instruments: Liabilities	4.6	2.7
Debt	298.8	313.1
Total Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	584.0	687.7
Derivative financial instruments: Assets	18.0	7.6
Derivative financial instruments: Liabilities	4.6	2.7
Debt	1,765.2	1,863.7
Fair Value Measurements at Reporting Date Using Total Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	584.0	687.7
Derivative financial instruments: Assets	18.0	7.6
Derivative financial instruments: Liabilities	4.6	2.7
Debt	1,964.5	2,003.2
Fair Value Measurements at Reporting Date Using Total Estimated Fair Value \| Fair Value Measurements at Reporting Date Using Quoted Prices in Active Markets for Identical Assets (Level 1) \| ATI Convertible Senior Notes, 3.5%, Due 2025 [Member] \| Convertible Debt [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt	$ 590.0	$ 379.0