Condensed Consolidating Guarantor Financial Statements - Condensed Consolidating Statement Of Comprehensive Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	$ 859.8	$ 962.2	$ 2,657.8	$ 3,174.4
Cost of materials sold	704.7	781.7	2,188.4	2,619.1
Gross profit	155.1	180.5	469.4	555.3
Warehousing, delivery, selling, general and administrative	119.6	127.1	362.7	390.0
Restructuring and other charges			2.1
Impairment charges on fixed assets and goodwill	1.1		8.8	0.9
Operating profit (loss)	34.4	53.4	95.8	164.4
Other income and (expense), net	(1.1)	(1.5)	2.1	(1.0)
Interest and other expense on debt	(27.1)	(19.8)	(83.3)	(58.9)
Interest expense on intercompany loans
Interest income on intercompany loans
Income before income taxes	6.2	32.1	14.6	104.5
Provision (benefit) for income taxes	2.9	0.5	6.2	6.4
Equity in (earnings) loss of subsidiaries
Net income	3.3	31.6	8.4	98.1
Less: Net loss attributable to noncontrolling interest	(1.0)	(1.9)	(4.9)	(4.2)
Net income (loss) attributable to Ryerson Inc.	4.3	33.5	13.3	102.3
Comprehensive income (loss)	8.6	42.5	6.9	110.4
Less: Comprehensive loss attributable to noncontrolling interest	(1.2)	(2.1)	(4.9)	(4.8)
Comprehensive income (loss) attributable to Ryerson Inc.	9.8	44.6	11.8	115.2
Parent [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales
Cost of materials sold
Gross profit
Warehousing, delivery, selling, general and administrative	1.3	1.0	3.8	3.5
Restructuring and other charges
Impairment charges on fixed assets and goodwill
Operating profit (loss)	(1.3)	(1.0)	(3.8)	(3.5)
Other income and (expense), net				0.3
Interest and other expense on debt	(3.3)	(19.0)	(11.9)	(56.4)
Interest expense on intercompany loans	(7.4)	(13.9)	(19.4)	(38.5)
Interest income on intercompany loans
Income before income taxes	(12.0)	(33.9)	(35.1)	(98.1)
Provision (benefit) for income taxes	(8.6)		(13.0)
Equity in (earnings) loss of subsidiaries	(7.7)	(67.4)	(35.4)	(200.4)
Net income	4.3	33.5	13.3	102.3
Less: Net loss attributable to noncontrolling interest
Net income (loss) attributable to Ryerson Inc.	4.3	33.5	13.3	102.3
Comprehensive income (loss)	9.8	44.6	11.8	115.2
Less: Comprehensive loss attributable to noncontrolling interest
Comprehensive income (loss) attributable to Ryerson Inc.	9.8	44.6	11.8	115.2
Joseph T. Ryerson [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	726.2	811.5	2,241.9	2,684.6
Cost of materials sold	599.2	661.7	1,857.4	2,235.3
Gross profit	127.0	149.8	384.5	449.3
Warehousing, delivery, selling, general and administrative	91.3	98.2	278.9	305.6
Restructuring and other charges
Impairment charges on fixed assets and goodwill	1.1		2.0	0.9
Operating profit (loss)	34.6	51.6	103.6	142.8
Other income and (expense), net		0.1	0.2	0.2
Interest and other expense on debt	(23.1)	(0.1)	(69.2)	(0.1)
Interest expense on intercompany loans		(10.3)		(30.1)
Interest income on intercompany loans	5.5		13.6
Income before income taxes	17.0	41.3	48.2	112.8
Provision (benefit) for income taxes	12.2	0.4	18.3	4.0
Equity in (earnings) loss of subsidiaries	(4.7)	(8.7)	(14.3)	(38.0)
Net income	9.5	49.6	44.2	146.8
Less: Net loss attributable to noncontrolling interest
Net income (loss) attributable to Ryerson Inc.	9.5	49.6	44.2	146.8
Comprehensive income (loss)	10.3	49.8	46.7	147.5
Less: Comprehensive loss attributable to noncontrolling interest
Comprehensive income (loss) attributable to Ryerson Inc.	10.3	49.8	46.7	147.5
Guarantor Subsidiaries [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	596.5	639.9	1,800.0	2,249.9
Cost of materials sold	585.7	628.0	1,766.2	2,206.2
Gross profit	10.8	11.9	33.8	43.7
Warehousing, delivery, selling, general and administrative	6.3	6.6	17.5	19.3
Restructuring and other charges
Impairment charges on fixed assets and goodwill
Operating profit (loss)	4.5	5.3	16.3	24.4
Other income and (expense), net
Interest and other expense on debt
Interest expense on intercompany loans
Interest income on intercompany loans	1.9	24.2	5.8	68.6
Income before income taxes	6.4	29.5	22.1	93.0
Provision (benefit) for income taxes	5.3		8.3	2.0
Equity in (earnings) loss of subsidiaries	(4.1)	1.6	(0.2)	1.0
Net income	5.2	27.9	14.0	90.0
Less: Net loss attributable to noncontrolling interest
Net income (loss) attributable to Ryerson Inc.	5.2	27.9	14.0	90.0
Comprehensive income (loss)	5.7	31.2	15.8	94.6
Less: Comprehensive loss attributable to noncontrolling interest
Comprehensive income (loss) attributable to Ryerson Inc.	5.7	31.2	15.8	94.6
Non-Guarantor Subsidiaries [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	116.3	131.9	360.7	420.5
Cost of materials sold	99.0	113.1	309.6	358.2
Gross profit	17.3	18.8	51.1	62.3
Warehousing, delivery, selling, general and administrative	20.7	21.3	62.5	61.6
Restructuring and other charges			2.1
Impairment charges on fixed assets and goodwill			6.8
Operating profit (loss)	(3.4)	(2.5)	(20.3)	0.7
Other income and (expense), net	(1.1)	(1.6)	1.9	(1.5)
Interest and other expense on debt	(0.7)	(0.7)	(2.2)	(2.4)
Interest expense on intercompany loans
Interest income on intercompany loans
Income before income taxes	(5.2)	(4.8)	(20.6)	(3.2)
Provision (benefit) for income taxes	(6.0)	0.1	(7.4)	0.4
Equity in (earnings) loss of subsidiaries
Net income	0.8	(4.9)	(13.2)	(3.6)
Less: Net loss attributable to noncontrolling interest	(1.0)	(1.9)	(4.9)	(4.2)
Net income (loss) attributable to Ryerson Inc.	1.8	(3.0)	(8.3)	0.6
Comprehensive income (loss)	4.7	2.3	(19.1)	2.9
Less: Comprehensive loss attributable to noncontrolling interest	(1.2)	(2.1)	(4.9)	(4.8)
Comprehensive income (loss) attributable to Ryerson Inc.	5.9	4.4	(14.2)	7.7
Eliminations [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	(579.2)	(621.1)	(1,744.8)	(2,180.6)
Cost of materials sold	(579.2)	(621.1)	(1,744.8)	(2,180.6)
Gross profit
Warehousing, delivery, selling, general and administrative
Restructuring and other charges
Impairment charges on fixed assets and goodwill
Operating profit (loss)
Other income and (expense), net
Interest and other expense on debt
Interest expense on intercompany loans	7.4	24.2	19.4	68.6
Interest income on intercompany loans	(7.4)	(24.2)	(19.4)	(68.6)
Income before income taxes
Provision (benefit) for income taxes
Equity in (earnings) loss of subsidiaries	16.5	74.5	49.9	237.4
Net income	(16.5)	(74.5)	(49.9)	(237.4)
Less: Net loss attributable to noncontrolling interest
Net income (loss) attributable to Ryerson Inc.	(16.5)	(74.5)	(49.9)	(237.4)
Comprehensive income (loss)	(21.9)	(85.4)	(48.3)	(249.8)
Less: Comprehensive loss attributable to noncontrolling interest
Comprehensive income (loss) attributable to Ryerson Inc.	$ (21.9)	$ (85.4)	$ (48.3)	$ (249.8)