Long-Term Debt - Foreign Debt - Additional Information (Detail) - Foreign Debt [Member] - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Foreign debt	$ 1.4	$ 0.7
Available credit facility	47.0	47.0
Letters of credit issued by our foreign subsidiaries	$ 1.0	$ 1.0
Ryerson China [Member]
Debt Instrument [Line Items]
Debt instrument initiation fee rate	0.05%	0.004%
Ryerson China [Member] \| Secured With Ryerson China's Accounts Receivables [Member]
Debt Instrument [Line Items]
Debt instrument initiation fee rate		0.05%
Ryerson China [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument initiation fee rate	0.05%
Ryerson China [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt instrument initiation fee rate	0.15%
Letter of Credit Drawdowns [Member] \| Ryerson China [Member]
Debt Instrument [Line Items]
Foreign debt	$ 0.3	$ 0.1
Letter of Credit Drawdowns [Member] \| Ryerson China [Member] \| Secured With Ryerson China's Accounts Receivables [Member]
Debt Instrument [Line Items]
Foreign debt	$ 1.1	$ 0.6

Debt instrument initiation fee rate.

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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.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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