Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (17,071)	$ (19,891)	$ (5,585)	$ (5,844)
Other comprehensive loss :
Foreign currency translation adjustment	(753)	(221)	(1,395)	(198)
Less: Income tax benefit on other comprehensive loss	(313)	(78)	(583)	(75)
Comprehensive income (loss)	(17,511)	(20,034)	(6,397)	(5,967)
Less: Comprehensive income attributable to noncontrolling interest	110	119	226	190
Comprehensive loss attributable to Global Brass and Copper Holdings, Inc.	$ (17,621)	$ (20,153)	$ (6,623)	$ (6,157)