Condensed Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement [Abstract]
Net sales	$ 461,478	$ 416,979	$ 906,440	$ 860,370
Cost of sales	409,778	369,858	807,824	763,295
Gross profit	51,700	47,121	98,616	97,075
Selling, general and administrative expenses (including non-cash profits interest expense of $29,271, $19,517, $29,271 and $19,517, respectively)	52,855	37,965	72,533	55,888
Operating (loss) income	(1,155)	9,156	26,083	41,187
Interest expense	9,959	10,209	19,834	19,958
Loss on extinguishment of debt		19,612		19,612
Other expense, net	4	398	191	709
(Loss) income before provision for (benefit from) income taxes and equity income	(11,118)	(21,063)	6,058	908
Provision for (benefit from) income taxes	6,461	(971)	12,503	7,227
Loss before equity income	(17,579)	(20,092)	(6,445)	(6,319)
Equity income, net of tax	508	201	860	475
Net loss	(17,071)	(19,891)	(5,585)	(5,844)
Less: Net income attributable to noncontrolling interest	61	114	159	168
Net loss attributable to Global Brass and Copper Holdings, Inc.	$ (17,132)	$ (20,005)	$ (5,744)	$ (6,012)
Net loss attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$ (0.81)	$ (0.95)	$ (0.27)	$ (0.28)
Diluted	$ (0.81)	$ (0.95)	$ (0.27)	$ (0.28)
Weighted average common shares outstanding:
Basic	21,110,000	21,110,000	21,110,000	21,110,000
Diluted	21,110,000	21,110,000	21,110,000	21,110,000