Summary of Significant Accounting Policies - Principles of Consolidation (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Uniti [Member]
Noncontrolling Interest [Line Items]
Equity method investment ownership percentage	50.00%
Related party accounts receivable	$ 4.5	$ 6.1
Allegheny & Tsingshan Stainless
Noncontrolling Interest [Line Items]
Equity method investment ownership percentage	50.00%
Shanghai STAL Precision Stainless Steel Co Ltd [Member] \| Allegheny Technologies Inc
Noncontrolling Interest [Line Items]
Joint venture ownership percentage	60.00%

Amount of receivables arising from transactions with related parties due within one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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