Condensed Consolidating Financial Statements - Condensed Consolidating Statement of Operations (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended														12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales	$ 802.5	[1]	$ 859.8	[2]	$ 906.9	[3]	$ 891.1	[4]	$ 850.3	[5]	$ 962.2	$ 1,090.6	[6]	$ 1,121.6	$ 3,460.3	$ 4,024.7	$ 4,729.8
Cost of materials sold															2,843.7	3,315.1	4,071.0
Gross profit	147.2	[1]	155.1	[2]	158.5	[3]	155.8	[4]	154.3	[5]	180.5	184.0	[6]	190.8	616.6	709.6	658.8
Warehousing, delivery, selling, general and administrative expenses															479.5	508.2	539.8
Restructuring and other charges					2.1				1.1						1.9	1.1	11.1
Impairment charges on fixed assets and goodwill	1.2		1.1		6.8		0.9		0.1			0.9			10.0	1.0	9.3
Pension and other postretirement benefits curtailment gain																(1.7)
Operating profit (loss)															125.2	201.0	98.6
Other income and (expense), net															(0.2)	(18.0)	4.6
Interest and other expense on debt															(110.5)	(86.4)	(80.1)
Income (loss) before income taxes	(0.1)	[1]	6.2	[2]	2.4	[3]	6.0	[4]	(7.9)	[5]	32.1	32.6	[6]	39.8	14.5	96.6	23.1
Provision (benefit) for income taxes															(65.4)	(7.2)	(11.5)
Net income	71.5	[1]	3.3	[2]	0.2	[3]	4.9	[4]	5.7	[5]	31.6	29.4	[6]	37.1	79.9	103.8	34.6
Less: Net loss attributable to noncontrolling interest															(5.8)	(5.5)	(8.3)
Net income (loss) attributable to Ryerson Inc.	72.4	[1]	4.3	[2]	1.9	[3]	7.1	[4]	7.0	[5]	33.5	30.6	[6]	38.2	85.7	109.3	42.9
Parent [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Warehousing, delivery, selling, general and administrative expenses															5.1	4.7	5.2
Operating profit (loss)															(5.1)	(4.7)	(5.2)
Other income and (expense), net															(4.4)	(16.8)	(0.2)
Interest and other expense on debt															(15.3)	(62.4)	(76.6)
Interest expense on intercompany loans															(26.9)	(53.5)	(42.0)
Income (loss) before income taxes															(51.7)	(137.4)	(124.0)
Provision (benefit) for income taxes															(31.0)	(52.1)	(51.9)
Equity in (earnings) loss of subsidiaries															(106.4)	(194.6)	(115.0)
Net income															85.7	109.3	42.9
Net income (loss) attributable to Ryerson Inc.															85.7	109.3	42.9
Joseph T. Ryerson [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales															2,916.0	3,396.0	4,093.4
Cost of materials sold															2,412.8	2,819.0	3,560.9
Gross profit															503.2	577.0	532.5
Warehousing, delivery, selling, general and administrative expenses															368.2	395.5	442.8
Restructuring and other charges																(0.2)	10.0
Impairment charges on fixed assets and goodwill															3.2	1.0	7.8
Operating profit (loss)															131.8	180.7	71.9
Other income and (expense), net															0.3	0.2	6.0
Interest and other expense on debt															(92.2)	(20.9)	(0.1)
Interest expense on intercompany loans																(39.7)	(37.6)
Interest income on intercompany loans															19.0
Income (loss) before income taxes															58.9	120.3	40.2
Provision (benefit) for income taxes															(49.8)	(0.5)	1.1
Equity in (earnings) loss of subsidiaries															(16.4)	(46.0)	(65.5)
Net income															125.1	166.8	104.6
Net income (loss) attributable to Ryerson Inc.															125.1	166.8	104.6
Guarantor Subsidiaries [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales															2,387.0	2,827.4	3,326.1
Cost of materials sold															2,341.2	2,773.3	3,288.4
Gross profit															45.8	54.1	37.7
Warehousing, delivery, selling, general and administrative expenses															24.7	26.3	5.4
Operating profit (loss)															21.1	27.8	32.3
Interest income on intercompany loans															7.9	93.2	79.6
Income (loss) before income taxes															29.0	121.0	111.9
Provision (benefit) for income taxes															16.2	45.2	33.2
Equity in (earnings) loss of subsidiaries															7.1	4.0	8.7
Net income															5.7	71.8	70.0
Net income (loss) attributable to Ryerson Inc.															5.7	71.8	70.0
Non-Guarantor Subsidiaries [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales															471.4	543.7	645.0
Cost of materials sold															403.8	465.2	556.4
Gross profit															67.6	78.5	88.6
Warehousing, delivery, selling, general and administrative expenses															81.5	81.7	86.4
Restructuring and other charges															1.9	1.3	1.1
Impairment charges on fixed assets and goodwill															6.8		1.5
Pension and other postretirement benefits curtailment gain																(1.7)
Operating profit (loss)															(22.6)	(2.8)	(0.4)
Other income and (expense), net															3.9	(1.4)	(1.2)
Interest and other expense on debt															(3.0)	(3.1)	(3.4)
Income (loss) before income taxes															(21.7)	(7.3)	(5.0)
Provision (benefit) for income taxes															(0.8)	0.2	6.1
Net income															(20.9)	(7.5)	(11.1)
Less: Net loss attributable to noncontrolling interest															(5.8)	(5.5)	(8.3)
Net income (loss) attributable to Ryerson Inc.															(15.1)	(2.0)	(2.8)
Eliminations [Member]
Schedule of Condensed Consolidating Statement of Comprehensive Income [Line Items]
Net sales															(2,314.1)	(2,742.4)	(3,334.7)
Cost of materials sold															(2,314.1)	(2,742.4)	(3,334.7)
Interest expense on intercompany loans															26.9	93.2	79.6
Interest income on intercompany loans															(26.9)	(93.2)	(79.6)
Equity in (earnings) loss of subsidiaries															115.7	236.6	171.8
Net income															(115.7)	(236.6)	(171.8)
Net income (loss) attributable to Ryerson Inc.															$ (115.7)	$ (236.6)	$ (171.8)

[1] Included in the fourth quarter 2013 results is an impairment charge of $1.2 million related to certain assets held for sale to recognize the assets at their appraised fair value less cost to sell and an income tax benefit of $71.6 million, primarily related to a reduction in valuation allowance previously recorded against U.S. deferred tax assets.

[2] Included in the third quarter 2013 results is an impairment charge of $1.1 million related to certain assets held for sale to recognize the assets at their fair value less cost to sell.

[3] Included in the second quarter 2013 results is an impairment charge of $6.8 million to reduce the carrying value of goodwill at a reporting unit to its implied fair value. The second quarter also includes a $2.1 million restructuring charge related to the closure of a facility.

[4] Included in the first quarter 2013 results is an impairment charge of $0.9 million related to certain assets held for sale to recognize the assets at their fair value less cost to sell.

[5] Included in the fourth quarter 2012 results is an impairment charge of $0.1 million related to certain assets held for sale to recognize the assets at their fair value less cost to sell, $1.1 million restructuring charges primarily for employee-related costs resulting from a facility closure, a $17.2 million loss on the redemption of the Ryerson Notes, and a $1.7 million curtailment gain related to an amendment of a Canadian post-retirement medical and life insurance plan. The fourth quarter of 2012 also included an income tax benefit of $15.2 million related to the release of valuation allowance associated with certain state deferred tax assets.

[6] Included in the second quarter 2012 results is an impairment charge of $0.9 million related to certain assets held for sale to recognize the assets at their fair value less cost to sell.