Condensed Consolidating Balance Sheet (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
ASSETS
Current assets	$ 1,254.9	$ 1,254.3
Property, plant and equipment net of accumulated depreciation	469.4	483.4
Other noncurrent assets	216.2	226.5
Total assets	1,940.5	1,964.2
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	488.1	456.0
Noncurrent liabilities	1,734.6	1,788.7
Redeemable noncontrolling interest	1.5	1.7
Ryerson Inc. stockholders' equity	(282.9)	(284.9)
Noncontrolling interest	(0.8)	2.7
Total Liabilities and Equity	1,940.5	1,964.2
Parent
ASSETS
Current assets	14.6	381.7
Property, plant and equipment net of accumulated depreciation
Other noncurrent assets	966.3	944.2
Total assets	980.9	1,325.9
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	258.7	16.5
Noncurrent liabilities	1,005.1	1,594.3
Redeemable noncontrolling interest
Ryerson Inc. stockholders' equity	(282.9)	(284.9)
Noncontrolling interest
Total Liabilities and Equity	980.9	1,325.9
Joseph T. Ryerson
ASSETS
Current assets	1,173.4	2,215.9
Property, plant and equipment net of accumulated depreciation	400.0	410.8
Other noncurrent assets	898.8	319.2
Total assets	2,472.2	2,945.9
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	265.1	254.3
Noncurrent liabilities	1,351.3	1,872.2
Redeemable noncontrolling interest
Ryerson Inc. stockholders' equity	855.8	819.4
Noncontrolling interest
Total Liabilities and Equity	2,472.2	2,945.9
Guarantor Subsidiaries
ASSETS
Current assets	126.8	63.0
Property, plant and equipment net of accumulated depreciation	3.2	3.1
Other noncurrent assets	355.0	1,818.6
Total assets	485.0	1,884.7
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	155.1	1,738.3
Noncurrent liabilities	0.8	0.8
Redeemable noncontrolling interest
Ryerson Inc. stockholders' equity	329.1	145.6
Noncontrolling interest
Total Liabilities and Equity	485.0	1,884.7
Non-Guarantor Subsidiaries
ASSETS
Current assets	235.4	214.5
Property, plant and equipment net of accumulated depreciation	66.2	69.5
Other noncurrent assets	7.4	14.4
Total assets	309.0	298.4
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	104.8	67.7
Noncurrent liabilities	30.1	32.8
Redeemable noncontrolling interest	1.5	1.7
Ryerson Inc. stockholders' equity	173.4	193.5
Noncontrolling interest	(0.8)	2.7
Total Liabilities and Equity	309.0	298.4
Eliminations
ASSETS
Current assets	(295.3)	(1,620.8)
Property, plant and equipment net of accumulated depreciation
Other noncurrent assets	(2,011.3)	(2,869.9)
Total assets	(2,306.6)	(4,490.7)
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	(295.6)	(1,620.8)
Noncurrent liabilities	(652.7)	(1,711.4)
Redeemable noncontrolling interest
Ryerson Inc. stockholders' equity	(1,358.3)	(1,158.5)
Noncontrolling interest
Total Liabilities and Equity	$ (2,306.6)	$ (4,490.7)