Condensed Consolidating Financial Statements - Condensed Consolidating Statement of Comprehensive Income (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Condensed Consolidating Statement of Income and Comprehensive Income [Line Items]
Comprehensive income (loss)	$ 143.9	$ 66.0	$ (41.4)
Less: Comprehensive loss attributable to noncontrolling interest	(5.6)	(5.9)	(7.0)
Comprehensive income (loss) attributable to Ryerson Inc.	149.5	71.9	(34.4)
Parent [Member]
Schedule of Condensed Consolidating Statement of Income and Comprehensive Income [Line Items]
Comprehensive income (loss)	149.5	71.9	(34.4)
Comprehensive income (loss) attributable to Ryerson Inc.	149.5	71.9	(34.4)
Joseph T. Ryerson [Member]
Schedule of Condensed Consolidating Statement of Income and Comprehensive Income [Line Items]
Comprehensive income (loss)	199.9	136.1	67.5
Comprehensive income (loss) attributable to Ryerson Inc.	199.9	136.1	67.5
Guarantor Subsidiaries [Member]
Schedule of Condensed Consolidating Statement of Income and Comprehensive Income [Line Items]
Comprehensive income (loss)	5.7	79.6	59.8
Comprehensive income (loss) attributable to Ryerson Inc.	5.7	79.6	59.8
Non-Guarantor Subsidiaries [Member]
Schedule of Condensed Consolidating Statement of Income and Comprehensive Income [Line Items]
Comprehensive income (loss)	(31.7)	(5.0)	(16.7)
Less: Comprehensive loss attributable to noncontrolling interest	(5.6)	(5.9)	(7.0)
Comprehensive income (loss) attributable to Ryerson Inc.	(26.1)	0.9	(9.7)
Eliminations [Member]
Schedule of Condensed Consolidating Statement of Income and Comprehensive Income [Line Items]
Comprehensive income (loss)	(179.5)	(216.6)	(117.6)
Comprehensive income (loss) attributable to Ryerson Inc.	$ (179.5)	$ (216.6)	$ (117.6)