Condensed Consolidating Guarantor Financial Statements - Condensed Consolidating Statement of Comprehensive Income (Unaudited) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	$ 931.5	$ 906.9	$ 1,805.9	$ 1,798.0
Cost of materials sold	777.1	748.4	1,503.8	1,483.7
Gross profit	154.4	158.5	302.1	314.3
Warehousing, delivery, selling, general and administrative	120.4	121.4	238.2	243.1
Restructuring and other charges		2.1		2.1
Impairment charge on goodwill		6.8		7.7
Operating profit (loss)	34.0	28.2	63.9	61.4
Other income and (expense), net	(1.7)	2.0	0.3	3.2
Interest and other expense on debt	(27.5)	(27.8)	(54.9)	(56.2)
Income (loss) before income taxes	4.8	2.4	9.3	8.4
Provision (benefit) for income taxes	2.1	2.2	5.6	3.3
Net income (loss)	2.7	0.2	3.7	5.1
Less: Net loss attributable to noncontrolling interest	(0.9)	(1.7)	(1.8)	(3.9)
Net income (loss) attributable to Ryerson Inc.	3.6	1.9	5.5	9.0
Comprehensive income (loss)	6.2	(7.8)		(1.7)
Less: Comprehensive loss attributable to noncontrolling interest	(0.8)	(1.6)	(1.9)	(3.7)
Comprehensive income (loss) attributable to Ryerson Inc.	7.0	(6.2)	1.9	2.0
Parent [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Warehousing, delivery, selling, general and administrative	1.4	1.2	2.7	2.5
Operating profit (loss)	(1.4)	(1.2)	(2.7)	(2.5)
Interest and other expense on debt	(3.7)	(4.0)	(7.5)	(8.6)
Interest expense on intercompany loans	(7.5)	(6.6)	(15.0)	(12.0)
Income (loss) before income taxes	(12.6)	(11.8)	(25.2)	(23.1)
Provision (benefit) for income taxes	(5.0)	(2.7)	(15.0)	(4.4)
Equity in (earnings) loss of subsidiaries	(11.2)	(11.0)	(15.7)	(27.7)
Net income (loss)	3.6	1.9	5.5	9.0
Net income (loss) attributable to Ryerson Inc.	3.6	1.9	5.5	9.0
Comprehensive income (loss)	7.0	(6.2)	1.9	2.0
Comprehensive income (loss) attributable to Ryerson Inc.	7.0	(6.2)	1.9	2.0
Joseph T. Ryerson [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	793.0	766.0	1,535.8	1,515.7
Cost of materials sold	670.3	636.3	1,295.1	1,258.2
Gross profit	122.7	129.7	240.7	257.5
Warehousing, delivery, selling, general and administrative	95.9	93.3	188.5	187.6
Impairment charge on goodwill				0.9
Operating profit (loss)	26.8	36.4	52.2	69.0
Other income and (expense), net	0.1	0.1	0.1	0.2
Interest and other expense on debt	(23.0)	(23.0)	(46.0)	(46.1)
Interest income on intercompany loans	5.6	4.7	11.1	8.1
Income (loss) before income taxes	9.5	18.2	17.4	31.2
Provision (benefit) for income taxes	4.1	4.0	10.3	6.1
Equity in (earnings) loss of subsidiaries	(8.6)	(1.6)	(18.3)	(9.6)
Net income (loss)	14.0	15.8	25.4	34.7
Net income (loss) attributable to Ryerson Inc.	14.0	15.8	25.4	34.7
Comprehensive income (loss)	13.9	16.6	25.3	36.4
Comprehensive income (loss) attributable to Ryerson Inc.	13.9	16.6	25.3	36.4
Guarantor [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	669.8	598.7	1,238.4	1,203.5
Cost of materials sold	656.8	587.1	1,213.5	1,180.5
Gross profit	13.0	11.6	24.9	23.0
Warehousing, delivery, selling, general and administrative	6.0	5.7	12.1	11.2
Operating profit (loss)	7.0	5.9	12.8	11.8
Interest income on intercompany loans	1.9	1.9	3.9	3.9
Income (loss) before income taxes	8.9	7.8	16.7	15.7
Provision (benefit) for income taxes	4.3	1.8	10.0	3.0
Equity in (earnings) loss of subsidiaries	(1.3)	3.0	(0.1)	3.9
Net income (loss)	5.9	3.0	6.8	8.8
Net income (loss) attributable to Ryerson Inc.	5.9	3.0	6.8	8.8
Comprehensive income (loss)	2.7	0.6	3.5	10.1
Comprehensive income (loss) attributable to Ryerson Inc.	2.7	0.6	3.5	10.1
Non-Guarantor [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	116.8	121.7	228.7	244.4
Cost of materials sold	98.1	104.5	192.2	210.6
Gross profit	18.7	17.2	36.5	33.8
Warehousing, delivery, selling, general and administrative	17.1	21.2	34.9	41.8
Restructuring and other charges		2.1		2.1
Impairment charge on goodwill		6.8		6.8
Operating profit (loss)	1.6	(12.9)	1.6	(16.9)
Other income and (expense), net	(1.8)	1.9	0.2	3.0
Interest and other expense on debt	(0.8)	(0.8)	(1.4)	(1.5)
Income (loss) before income taxes	(1.0)	(11.8)	0.4	(15.4)
Provision (benefit) for income taxes	(1.3)	(0.9)	0.3	(1.4)
Net income (loss)	0.3	(10.9)	0.1	(14.0)
Less: Net loss attributable to noncontrolling interest	(0.9)	(1.7)	(1.8)	(3.9)
Net income (loss) attributable to Ryerson Inc.	1.2	(9.2)	1.9	(10.1)
Comprehensive income (loss)	7.2	(17.2)	(0.1)	(23.8)
Less: Comprehensive loss attributable to noncontrolling interest	(0.8)	(1.6)	(1.9)	(3.7)
Comprehensive income (loss) attributable to Ryerson Inc.	8.0	(15.6)	1.8	(20.1)
Eliminations [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	(648.1)	(579.5)	(1,197.0)	(1,165.6)
Cost of materials sold	(648.1)	(579.5)	(1,197.0)	(1,165.6)
Interest expense on intercompany loans	7.5	6.6	12.0	12.0
Interest income on intercompany loans	(7.5)	(6.6)	(12.0)	(12.0)
Equity in (earnings) loss of subsidiaries	21.1	9.6	34.1	33.4
Net income (loss)	(21.1)	(9.6)	(34.1)	(33.4)
Net income (loss) attributable to Ryerson Inc.	(21.1)	(9.6)	(34.1)	(33.4)
Comprehensive income (loss)	(24.6)	(1.6)	(30.6)	(26.4)
Comprehensive income (loss) attributable to Ryerson Inc.	$ (24.6)	$ (1.6)	$ (30.6)	$ (26.4)