Condensed Consolidating Guarantor Financial Statements - Condensed Consolidating Balance Sheet (Unaudited) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
ASSETS
Current assets	$ 1,291.3	$ 1,241.9
Property, plant and equipment net of accumulated depreciation	447.7	452.7
Other noncurrent assets	217.4	223.4
Total assets	1,956.4	1,918.0
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	534.6	461.1
Noncurrent liabilities	1,571.2	1,600.1
Redeemable noncontrolling interest	1.2	1.3
Ryerson Inc. stockholders' equity	(147.1)	(142.0)
Noncontrolling interest	(3.5)	(2.5)
Total liabilities and equity	1,956.4	1,918.0
Parent [Member]
ASSETS
Current assets	24.5	3.5
Other noncurrent assets	1,118.3	1,113.0
Total assets	1,142.8	1,116.5
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	252.7	259.3
Noncurrent liabilities	1,037.2	999.2
Ryerson Inc. stockholders' equity	(147.1)	(142.0)
Total liabilities and equity	1,142.8	1,116.5
Joseph T. Ryerson [Member]
ASSETS
Current assets	1,256.3	1,173.7
Property, plant and equipment net of accumulated depreciation	386.6	387.8
Other noncurrent assets	827.2	870.6
Total assets	2,470.1	2,432.1
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	274.2	239.7
Noncurrent liabilities	1,192.1	1,200.0
Ryerson Inc. stockholders' equity	1,003.8	992.4
Total liabilities and equity	2,470.1	2,432.1
Guarantor [Member]
ASSETS
Current assets	61.0	113.0
Property, plant and equipment net of accumulated depreciation	3.2	3.1
Other noncurrent assets	422.6	321.8
Total assets	486.8	437.9
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	177.2	135.0
Noncurrent liabilities	11.3	5.3
Ryerson Inc. stockholders' equity	298.3	297.6
Total liabilities and equity	486.8	437.9
Non-Guarantor [Member]
ASSETS
Current assets	245.5	235.4
Property, plant and equipment net of accumulated depreciation	57.9	61.8
Other noncurrent assets	5.0	5.8
Total assets	308.4	303.0
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	124.8	110.8
Noncurrent liabilities	26.4	27.7
Redeemable noncontrolling interest	1.2	1.3
Ryerson Inc. stockholders' equity	159.5	165.7
Noncontrolling interest	(3.5)	(2.5)
Total liabilities and equity	308.4	303.0
Eliminations [Member]
ASSETS
Current assets	(296.0)	(283.7)
Other noncurrent assets	(2,155.7)	(2,087.8)
Total assets	(2,451.7)	(2,371.5)
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	(294.3)	(283.7)
Noncurrent liabilities	(695.8)	(632.1)
Ryerson Inc. stockholders' equity	(1,461.6)	(1,455.7)
Total liabilities and equity	$ (2,451.7)	$ (2,371.5)