Segment Information - Reconciliation of Segment Adjusted EBITDA to Income Before Provision for Income Taxes and Equity Income (Parenthetical) (Detail) (Olin Brass [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Olin Brass [Member]
Segment Information [Line Items]
Accretion income	$ 181	$ 181	$ 362	$ 362