Income from Tariff Refunds

No definition available.

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- 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. 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. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

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-Publisher FASB
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- Definition

For an unclassified balance sheet, amount of receivables due from an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

+ References

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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-Publisher FASB
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- Definition

Amount of income (loss) for proportionate share of equity method investee's income (loss).

+ References

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- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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- Definition

Amount of cash inflow from a noncontrolling interest. Includes, but is not limited to, purchase of additional shares or other increase in noncontrolling interest ownership.

+ References

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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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Joint Ventures (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		10 Months Ended	57 Months Ended
Joint Ventures (Details) - USD ($) $ in Millions	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2018	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Cash and cash equivalents	$ 329.1			$ 329.1				$ 687.7
Sale of noncontrolling interests				0.9	$ 0.0
Income (loss) from equity investments	0.8		$ 0.4	11.2	0.4
Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Income from tariff refunds		$ 19.7
Allegheny & Tsingshan Stainless \| Import Duties
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity investments				9.9
Next Gen Alloys LLC
Schedule of Equity Method Investments [Line Items]
Cash and cash equivalents	$ 1.5			1.5
Sale of noncontrolling interests				$ 0.9
Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage	50.00%			50.00%
Sale of noncontrolling interests						$ 12.0
Allegheny & Tsingshan Stainless \| Forecast
Schedule of Equity Method Investments [Line Items]
Sale of noncontrolling interests							$ 17.5
Uniti
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage	50.00%			50.00%
Tsingshan Group \| Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Due from Affiliates	$ 5.5			$ 5.5
Advanced Alloys & Solutions \| Shanghai STAL Precision Stainless Steel Co Ltd
Schedule of Equity Method Investments [Line Items]
Cash and cash equivalents	65.3			65.3
Advanced Alloys & Solutions \| Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity investments	(0.5)		0.3	8.7	(0.6)
Due from Affiliates	2.9			2.9				2.9
Advanced Alloys & Solutions \| Uniti
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity investments	1.3		$ 0.1	2.5	$ 1.0
Prepaid expenses and other current assets \| Advanced Alloys & Solutions \| Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Due from Affiliates	0.5			0.5				0.7
Other Noncurrent Assets [Member] \| Advanced Alloys & Solutions \| Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Due from Affiliates	$ 2.4			$ 2.4				$ 2.2
China Baowu Steel Group Corporation Limited \| Advanced Alloys & Solutions \| China Baowu Steel Group Corporation Limited \| Shanghai STAL Precision Stainless Steel Co Ltd
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage by unaffiliated entity	40.00%			40.00%
Tsingshan Group \| Tsingshan Group \| Allegheny & Tsingshan Stainless
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage by unaffiliated entity	50.00%			50.00%
VSMPO \| VSMPO \| Uniti
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage by unaffiliated entity	50.00%			50.00%
ATI Inc. \| Next Gen Alloys LLC
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage	51.00%			51.00%
ATI Inc. \| Advanced Alloys & Solutions \| Shanghai STAL Precision Stainless Steel Co Ltd
Schedule of Equity Method Investments [Line Items]
Joint venture ownership percentage	60.00%			60.00%