v3.26.1
Long-Term Debt - Foreign Debt - Additional Information (Detail) - Foreign Debt [Member] - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Debt Instrument [Line Items]    
Foreign debt $ 2.6 $ 1.9
Available credit facility $ 47.0 $ 47.0
Ryerson China [Member]    
Debt Instrument [Line Items]    
Debt instrument initiation fee rate 0.15% 0.15%
Ryerson China [Member] | Secured With Ryerson China's Accounts Receivables [Member]    
Debt Instrument [Line Items]    
Debt instrument initiation fee rate 0.05% 0.05%
Letter of Credit Drawdowns [Member] | Ryerson China [Member]    
Debt Instrument [Line Items]    
Foreign debt $ 1.5 $ 1.3
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