Income Taxes - Reconciliation of Income Taxes with Amounts Computed by Applying Federal Tax Rate (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation Of Effective Income Tax Rate [Line Items]
Statutory tax rate	35.00%	35.00%	35.00%
Deferred tax benefit	$ (65.3)	$ (10.2)	$ (12.7)
U.S. federal and state net operating loss carryforwards		22.0
Turret Steel [Member]
Reconciliation Of Effective Income Tax Rate [Line Items]
Deferred tax benefit		$ (8.5)