Global Brass & Copper (BRSS) S-1 26 Nov 13 IPO registration Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013
Document And Entity Information [Abstract]	'
Document Type	'S-1
Amendment Flag	'false
Document Period End Date	30-Sep-13
Trading Symbol	'BRSS
Entity Registrant Name	'GLOBAL BRASS & COPPER HOLDINGS, INC.
Entity Central Index Key	'0001533526
Entity Filer Category	'Non-accelerated Filer

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Jan. 01, 2010
In Thousands, unless otherwise specified
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	$18,088	$13,862	$13,018	'	'	$49,537	'	'	'	$15,523	$7,832
Accounts receivable, net of allowance	198,473	164,317	211,638	193,310	203,740	161,715	'	'	'	'	'
Inventories	208,778	174,378	'	180,004	172,677	185,947	163,492	168,735	202,515	192,623	'
Prepaid expenses and other current assets	26,591	12,141	'	'	'	19,912	25,746	22,201	31,101	38,441	'
Deferred income taxes	32,122	33,465	26,361	29,343	28,119	29,027	27,716	27,053	28,394	29,312	'
Income tax receivable, net	625	1,300	474	4,520	1,405	5,046	3,260	1,804	2,993	2,276	'
Total current assets	484,677	399,463	447,298	430,404	497,339	451,184	464,098	473,231	510,401	439,564	'
Property, plant and equipment, net	78,137	71,127	'	'	'	57,556	52,067	47,780	42,587	'	'
Investment in joint venture	2,184	2,972	'	'	'	3,507	'	'	'	'	'
Goodwill	4,399	4,399	'	'	'	4,399	'	'	'	'	'
Intangible assets, net	762	839	'	'	'	951	'	'	'	'	'
Deferred income taxes	5,736	6,138	17,040	19,657	19,798	19,970	31,257	31,921	32,520	34,254	'
Other noncurrent assets	16,620	17,755	'	'	'	11,173	'	'	'	'	'
Total assets	592,515	502,693	555,669	539,223	594,905	548,740	566,963	573,975	610,402	537,721	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Current maturities of long-term debt	'	'	'	'	'	31,880	'	'	'	'	'
Accounts payable	105,311	81,577	'	104,585	111,425	77,888	107,959	'	'	'	'
Accrued liabilities	59,639	48,424	59,604	40,574	48,364	48,604	59,291	63,314	72,592	84,992	'
Accrued interest	12,448	3,287	'	'	'	4,069	'	'	'	'	'
Income tax payable	156	248	'	'	'	300	'	'	'	'	'
Total current liabilities	177,554	133,536	180,595	148,507	195,457	162,741	175,044	183,986	201,326	170,999	'
Long-term debt	397,500	389,522	'	'	'	271,698	'	'	'	'	'
Other noncurrent liabilities	26,312	27,436	'	'	'	31,641	'	'	'	'	'
Total liabilities	601,366	550,494	610,727	605,174	498,419	466,080	507,408	521,497	567,463	509,252	'
Commitments and contingencies	'	'	'	'	'	'	'	'	'	'	'
Global Brass and Copper Holdings, Inc. stockholders' (deficit)/equity:	'	'	'	'	'	'	'	'	'	'	'
Common stock, value	211	211	'	'	'	211	'	'	'	'	'
Additional paid-in capital	30,260	'	'	'	'	11,091	'	'	'	'	'
(Accumulated deficit)/Retained earnings	-43,948	-48,153	-55,654	-66,686	82,711	68,718	45,128	37,845	27,644	13,586	'
Accumulated other comprehensive income	761	1,466	'	'	'	1,923	'	'	'	'	'
Receivable from stockholder	'	-4,875	'	'	'	-2,451	'	'	'	'	'
Total Global Brass and Copper Holdings, Inc. stockholders' (deficit)/equity	-12,716	-51,351	-58,499	-69,309	93,247	79,492	56,382	49,347	39,907	25,564	'
Noncontrolling interest	3,865	3,550	'	'	'	3,168	'	'	'	'	'
Total (deficit) / equity	-8,851	-47,801	-55,058	-65,951	96,486	82,660	59,555	52,478	42,940	28,469	24,859
Total liabilities and (deficit) / equity	$592,515	$502,693	$555,669	$539,223	$594,905	$548,740	$566,963	$573,975	$610,402	$537,721	'

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, except Share data, unless otherwise specified
Statement Of Financial Position [Abstract]	'	'	'
Accounts receivable, allowance	$1,506	$1,408	$2,067
Common stock, par value	$0.01	$0.01	$0.01
Common stock, shares authorized	80,000,000	80,000,000	80,000,000
Common stock, shares issued	21,110,000	21,110,000	21,110,000
Common stock, shares outstanding	21,110,000	21,110,000	21,110,000

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended																6 Months Ended		9 Months Ended			12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Statement [Abstract]	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Net sales	$396,173		$393,977	[1]	$416,979	[1]	$443,391	[1]	$373,477	[1]	$439,500	[1]	$473,251	[1]	$492,915	[1]	'	'	$1,345,678	$1,254,347	'	$1,650,520	$1,779,143	$1,658,729
Cost of sales	'		349,580		369,858		393,437		310,141		401,423		429,020		442,889		763,295	871,909	1,201,815	1,112,875	1,273,332	1,467,334	1,583,473	1,496,695
Gross profit	41,714	[2]	44,397	[1]	47,121	[1]	49,954	[1]	63,336	[1],[3]	38,077	[1]	44,231	[1]	50,026	[1]	97,075	94,257	143,863	141,472	132,334	183,186	195,670	162,034
Selling, general and administrative expenses (including non-cash profits interest expense)	'		'		'		'		'		'		'		'		'	'	92,622	73,241	'	92,641	69,391	68,857
Operating income	'		27,044		9,156		32,031		46,386		20,979		27,748		31,166		41,187	58,914	51,241	68,231	79,893	90,545	126,279	93,177
Interest expense	'		'		'		'		9,618		9,954		10,988		9,450		'	20,438	29,938	29,894	30,392	39,727	40,010	25,076
Third party interest expense	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	22,613
Related party interest expense	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	2,463
Loss on extinguishment of debt	'		'		19,612		'		'		'		'		'		'	'	'	19,612	'	19,612	'	'
Other expense, net	'		'		'		'		'		'		'		'		'	'	256	172	'	121	432	810
Income (loss) before provision for (benefit from) income taxes and equity income	12,532		17,645	[1]	-21,063	[1],[4]	21,971	[1]	35,848	[1]	10,779	[1]	17,498	[1]	21,712	[1]	908	39,210	21,047	18,553	49,989	31,085	85,837	67,291
Provision for income taxes	'		6,769		-971		8,198		12,613		3,726		7,258		7,840		7,227	15,098	17,762	13,996	18,824	19,185	31,437	26,676
Income (loss) before equity income	'		10,876		-20,092		13,773		23,235		7,053		10,240		13,872		-6,319	24,112	3,285	4,557	31,165	11,900	54,400	40,615
Equity income, net of tax	'		'		'		'		'		'		'		'		'	'	1,148	736	'	995	888	1,530
Net income (loss)	7,602		11,137	[1]	-19,891	[1]	14,047	[1]	23,570	[1]	7,280	[1]	10,268	[1]	14,170	[1]	-5,844	24,438	4,433	5,293	31,718	12,895	55,288	42,145
Less: Net income attributable to noncontrolling interest	'		'		'		'		'		'		'		'		'	'	228	273	'	374	156	512
Net income (loss) attributable to Global Brass and Copper Holdings, Inc.	$7,501		$11,032	[1]	($20,005)	[1]	$13,993	[1]	$23,590	[1]	$7,283	[1]	$10,201	[1]	$14,058	[1]	($6,012)	$24,259	$4,205	$5,020	$31,542	$12,521	$55,132	$41,633
Net income (loss) attributable to Global Brass and Copper Holdings, Inc. per common share:	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Basic	$0.36		$0.52	[1]	($0.95)	[1]	$0.66	[1]	$1.12	[1]	$0.35	[1]	$0.48	[1]	$0.67	[1]	($0.28)	$1.15	$0.20	$0.24	$1.49	$0.59	$2.61	$1.97
Diluted	'		'		'		'		'		'		'		'		'	'	$0.20	$0.24	'	'	'	'
Weighted average common shares outstanding:	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Basic	'		'		'		'		'		'		'		'		'	'	21,110,000	21,110,000	'	21,110,000	21,110,000	21,110,000
Diluted	'		'		'		'		'		'		'		'		'	'	21,134,169	21,110,000	'	'	'	'
[1]	The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".
[2]	Includes $4,775 gain from liquidation of LIFO inventory layers.
[3]	Includes $15,236 gain from liquidation of LIFO inventory layers.
[4]	Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.

Consolidated_Statements_of_Ope1

Consolidated Statements of Operations (Parenthetical) (USD $)	3 Months Ended	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Statement [Abstract]	'	'	'	'	'	'
Non-cash profits interest expense	$19,517	$29,271	$19,517	$19,517	$885	$3,452

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement Of Income And Comprehensive Income [Abstract]	'	'	'	'	'
Net income (loss)	$4,433	$5,293	$12,895	$55,288	$42,145
Other comprehensive income (loss):	'	'	'	'	'
Foreign currency translation adjustment	-1,095	-199	-512	522	793
Less: Income tax expense (benefit) on other comprehensive income (loss)	-477	-69	-63	53	280
Comprehensive income (loss)	3,815	5,163	12,446	55,757	42,658
Less: Comprehensive income attributable to noncontrolling interest	315	273	382	263	583
Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.	$3,500	$4,890	$12,064	$55,494	$42,075

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in (Deficit)/Equity (USD $)	Total	Common stock [Member]	Additional paid-in capital [Member]	(Accumulated deficit)/ Retained Earnings [Member]	Accumulated other comprehensive income [Member]	Receivables from stockholder [Member]	Total Global Brass and Copper Holdings, Inc. stockholder's equity [Member]	Noncontrolling interest [Member]
In Thousands
Stockholders' Equity, Beginning Balance at Jan. 01, 2010	$24,859	$211	$20,000	$1,207	$1,119	'	$22,537	$2,322
Profits interest compensation	3,452	'	3,452	'	'	'	3,452	'
Distribution to shareholder	-42,500	'	-13,246	-29,254	'	'	-42,500	'
Net income (loss)	42,145	'	'	41,633	'	'	41,633	512
Other comprehensive (loss) income, net of tax	513	'	'	'	442	'	442	71
Stockholders' Equity, Ending Balance at Dec. 31, 2010	28,469	211	10,206	13,586	1,561	'	25,564	2,905
Profits interest compensation	885	'	885	'	'	'	885	'
(Amounts due) \ payments from stockholder	-2,451	'	'	'	'	-2,451	-2,451	'
Net income (loss)	55,288	'	'	55,132	'	'	55,132	156
Other comprehensive (loss) income, net of tax	469	'	'	'	362	'	362	107
Stockholders' Equity, Ending Balance at Dec. 31, 2011	82,660	211	11,091	68,718	1,923	-2,451	79,492	3,168
Profits interest compensation	19,517	'	19,517	'	'	'	19,517	'
Distribution to shareholder	-160,000	'	-30,608	-129,392	'	'	-160,000	'
(Amounts due) \ payments from stockholder	-2,398	'	'	'	'	-2,398	-2,398	'
Net income (loss)	5,293	'	'	5,020	'	'	5,020	273
Other comprehensive (loss) income, net of tax	-130	'	'	'	-130	'	-130	'
Stockholders' Equity, Ending Balance at Sep. 30, 2012	-55,058	211	'	-55,654	1,793	-4,849	-58,499	3,441
Stockholders' Equity, Beginning Balance at Dec. 31, 2011	82,660	'	11,091	68,718	1,923	-2,451	79,492	3,168
Profits interest compensation	19,517	'	19,517	'	'	'	19,517	'
Distribution to shareholder	-160,000	'	-30,608	-129,392	'	'	-160,000	'
(Amounts due) \ payments from stockholder	-2,424	'	'	'	'	-2,424	-2,424	'
Net income (loss)	12,895	'	'	12,521	'	'	12,521	374
Other comprehensive (loss) income, net of tax	-449	'	'	'	-457	'	-457	8
Stockholders' Equity, Ending Balance at Dec. 31, 2012	-47,801	211	'	-48,153	1,466	-4,875	-51,351	3,550
Profits interest compensation	29,271	'	29,271	'	'	'	29,271	'
Share-based compensation	989	'	989	'	'	'	989	'
(Amounts due) \ payments from stockholder	4,875	'	'	'	'	4,875	4,875	'
Net income (loss)	4,433	'	'	4,205	'	'	4,205	228
Other comprehensive (loss) income, net of tax	-618	'	'	'	-705	'	-705	87
Stockholders' Equity, Ending Balance at Sep. 30, 2013	($8,851)	$211	$30,260	($43,948)	$761	'	($12,716)	$3,865

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities	'	'	'	'	'
Net income (loss)	$4,433	$5,293	$12,895	$55,288	$42,145
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:	'	'	'	'	'
Lower of cost or market adjustment to inventory	318	302	302	'	'
Mark to market on commodity contracts	1,062	-1,473	-1,588	1,095	11,984
Mark to market on interest rate cap agreements	1	156	156	1,851	-800
Depreciation	6,023	4,805	6,822	4,560	2,772
Amortization of intangible assets	78	86	112	199	199
Amortization of debt discount and issuance costs	1,857	3,961	4,564	4,701	2,299
Term loan call premium	'	'	-6,394	'	'
Loss on debt extinguishment	'	19,612	19,612	'	'
Profits interest compensation expense	29,271	19,517	19,517	885	3,452
Share-based compensation expense	989	'	'	'	'
Provision for bad debts, net of reductions	73	-627	-814	-4,171	1,324
Deferred income taxes	691	2,273	5,248	10,491	6,041
(Gain) loss on sale of property, plant and equipment	3	-9	-17	-69	-39
Equity income, net of tax	-1,148	-736	-995	-888	-1,530
Distributions from equity method investment	452	500	1,000	500	566
Change in assets and liabilities:	'	'	'	'	'
Accounts receivable	-33,959	-48,917	-1,540	3,848	-20,241
Inventories	-34,610	1,343	11,512	6,592	8,656
Prepaid expenses and other current assets	-14,988	5,440	4,676	18,264	-8,308
Accounts payable	23,893	30,787	3,682	-50	14,856
Accrued liabilities	10,676	12,083	850	-36,988	341
Accrued interest	9,160	8,127	-782	-151	2,507
Income taxes, net	574	2,702	3,685	-2,674	855
Other, net	-317	-6,973	-589	1,565	2,335
Net cash (used in) provided by operating activities	4,532	58,252	81,914	64,848	69,414
Cash flows from investing activities	'	'	'	'	'
Capital expenditures	-13,205	-11,360	-20,408	-22,440	-11,927
Proceeds from sale of property, plant and equipment	174	25	32	97	39
Net cash used in investing activities	-13,031	-11,335	-20,376	-22,343	-11,888
Cash flows from financing activities	'	'	'	'	'
Deferred financing fees	'	-12,981	-12,981	-1,675	-15,131
Proceeds from senior secured notes	'	375,000	375,000	'	'
Proceeds from term loan, net of discount	'	'	'	'	305,550
Payments on term loan	'	-310,875	-310,875	-3,300	-825
Borrowings on ABL Facility	337,236	142,400	204,275	168,021	1,096,578
Payments on ABL Facility	-329,258	-113,900	-189,753	-168,021	-1,272,197
Principal payments under capital lease obligation	'	'	'	-916	-52
Payments on related party debt	'	'	'	'	-119,805
Distribution to shareholder	'	-160,000	-160,000	'	-42,500
Net payment (amounts due) from stockholder	4,875	-2,398	-2,424	-2,451	'
Cash overdrafts	'	'	'	'	-1,228
Net cash provided by (used in) financing activities	12,853	-82,754	-96,758	-8,342	-49,610
Effect of foreign currency exchange rates	-128	-682	-455	-149	-225
Net (decrease) increase in cash	4,226	-36,519	-35,675	34,014	7,691
Cash at beginning of period	13,862	49,537	49,537	15,523	7,832
Cash at end of period	18,088	13,018	13,862	49,537	15,523
Cash paid during the period for:	'	'	'	'	'
Interest, net of amount capitalized	'	'	35,788	33,580	19,626
Income taxes, net of refunds	'	'	10,235	24,017	19,657
Noncash investing activities	'	'	'	'	'
Capital lease obligations	'	'	'	'	$968

Basis_of_Presentation_and_Prin

Basis of Presentation and Principles of Consolidation	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Basis of Presentation and Principles of Consolidation	'
		1		Basis of Presentation and Principles of Consolidation
	Global Brass and Copper Holdings, Inc. (“Holdings” or the “Company”) was incorporated in Delaware, on October 10, 2007. Holdings, through its wholly-owned principal operating subsidiary, Global Brass and Copper, Inc. (“GBC”), commenced commercial operations on November 19, 2007 through the acquisition of the metals business from Olin Corporation. GBC is a leading, value-added converter, fabricator, distributor and processor of specialized copper and brass products in North America. On May 29, 2013, the Company completed its initial public offering of 8,050,000 shares of its common stock (the “initial public offering” or “IPO”). The shares began trading on the New York Stock Exchange on May 23, 2013 under the ticker symbol “BRSS”. Halkos Holdings, LLC (“Halkos”), the sole stockholder of the Company prior to the IPO, sold all of the shares in the initial public offering and received all of the net proceeds from the offering. After giving effect to the IPO, Halkos beneficially owned approximately 61.5% of the outstanding common stock of the Company. Halkos’s beneficial ownership percentage remained approximately the same as of September 30, 2013. On October 1, 2013, the Company completed its follow-on public offering of 5,750,000 shares of its common stock (the “follow-on public offering”). Halkos sold all of the shares in the follow-on public offering and received all of the net proceeds from the offering. After giving effect to the follow-on public offering, Halkos beneficially owns approximately 34.4% of the outstanding common stock of the Company. KPS Capital Partners, L.P. and its affiliates (“KPS”) are the majority shareholders of Halkos.
	The Company is operated and managed through three distinct divisions which are also the Company’s reportable segments: Olin Brass, Chase Brass (“Chase”) and A.J. Oster (“Oster”).
	These consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries and its majority-owned subsidiaries in which the Company has a controlling interest. All significant intercompany accounts and transactions relative to wholly- and majority-owned subsidiaries have been eliminated. The equity method is used to account for investments in affiliated companies, that are 20% to 50% owned where the Company does not hold a controlling voting interest and does not direct the matters that most significantly impact the investee’s operations.
	The accompanying unaudited interim financial statements include all normal recurring adjustments which are, in the opinion of management, necessary to a fair statement of the results for the interim periods presented. The December 31, 2012 consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S. GAAP”). Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with U.S. GAAP have been condensed or omitted.
	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. In addition, it requires management to make estimates and assumptions that affect the reported amount of net sales and expenses during the reporting periods. Actual amounts could differ from those estimates.
	Results of operations for the interim periods presented are not necessarily indicative of results which may be expected for any other interim period or for the year as a whole. There have been no significant changes to the Company’s significant accounting policies during the nine months ended September 30, 2013. These interim financial statements should be read in conjunction with the December 31, 2012 audited financial statements of the Company.
	Revision of Prior Period Financial Statements
	During 2012, the Company identified immaterial errors in previously issued consolidated financial statements related to the three and nine months ended September 30, 2012, which were corrected in the period identified, including:
		1	An error in the accounting for raw material in-transit was identified, which resulted in an overstatement of cost of sales of $811 and $423 for the three months and nine months ended September 30, 2012, respectively.
		2	Duplicate accruals for the receipt of raw material were identified, which resulted in an understatement of cost of sales of $1,396 and $389 for the three and nine months ended September 30, 2012, respectively.
	The Company assessed the materiality of all errors, individually and in the aggregate, on previously issued consolidated financial statements and concluded that the errors were not material to any of the Company’s previously issued financial statements.
	A summary of the revisions to the consolidated financial statements as of September 30, 2012 and for the three and nine months ended September 30, 2012 is as follows:
			As			Adjustment			As Revised
			Previously
			Reported
	Consolidated Statement of Operations
			Three Months Ended September 30, 2012
	Cost of sales		$	348,995		$	585		$	349,580
	Gross profit			44,982			(585	)		44,397
	Operating income			27,629			(585	)		27,044
	Income before provision for income taxes and equity income			18,230			(585	)		17,645
	Provision for income taxes			6,670			99			6,769
	Income before equity income			11,560			(684	)		10,876
	Net income			11,821			(684	)		11,137
	Net income attributable to Global Brass and Copper Holdings, Inc.			11,716			(684	)		11,032
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic		$	0.55		$	(0.03	)	$	0.52
	Consolidated Statement of Operations
			Nine Months Ended September 30, 2012
	Cost of sales		$	1,112,909		$	(34	)	$	1,112,875
	Gross profit			141,438			34			141,472
	Operating income			68,197			34			68,231
	Income before provision for income taxes and equity income			18,519			34			18,553
	Provision for income taxes			13,891			105			13,996
	Income before equity income			4,628			(71	)		4,557
	Net income			5,364			(71	)		5,293
	Net income attributable to Global Brass and Copper Holdings, Inc.			5,091			(71	)		5,020
	Net income attributable to Global Brass and
	Copper Holdings, Inc. per common share:
	Basic		$	0.24		$	—		$	0.24
	Consolidated Statement of Comprehensive Income
			Three Months Ended September 30, 2012
	Net income		$	11,821		$	(684	)	$	11,137
	Comprehensive income			11,814			(684	)		11,130
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			11,731			(684	)		11,047
	Consolidated Statement of Comprehensive Income
			Nine Months Ended September 30, 2012
	Net income		$	5,364		$	(71	)	$	5,293
	Comprehensive income			5,234			(71	)		5,163
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			4,961			(71	)		4,890
	Consolidated Statement of Changes in Deficit
			Nine Months Ended September 30, 2012
	Net income		$	5,364		$	(71	)	$	5,293
	Net income attributable to Global Brass and Copper Holdings, Inc.			5,091			(71	)		5,020
	Accumulated deficit—Balance, September 30, 2012			(56,083	)		429			(55,654	)
	Total Global Brass and Copper Holdings, Inc. stockholders’ deficit—Balance, September 30, 2012			(58,928	)		429			(58,499	)
	Total deficit—Balance, September 30, 2012			(55,487	)		429			(55,058	)
	Recently Issued and Recently Adopted Accounting Pronouncements
	In February 2013, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income. This guidance requires entities to provide disclosures about items that are required by U.S. GAAP to be reclassified from accumulated other comprehensive income (“AOCI”) to net income in their entirety in the same reporting period. The disclosure includes the amount of the reclassification and identifies the line item on the statement where net income is presented that is affected by the reclassification. For other items reclassified from AOCI, the disclosure cross-references to other disclosures where additional details about their effects are disclosed. This guidance is effective for reporting periods beginning after December 15, 2012. The adoption of this guidance in the first quarter of 2013 did not have a material effect on the Company’s consolidated financial statements and disclosures.
	In December 2011, the FASB issued ASU 2011-11, Disclosures about Offsetting Assets and Liabilities. This guidance requires entities to disclose both gross and net information about both instruments and transactions eligible for offset in the statement of financial position and instruments and transactions subject to an agreement similar to a master netting arrangement. This guidance does not amend existing guidance on when it is appropriate to offset. In January 2013, the FASB issued ASU 2013-01, Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities, which limits the scope of ASU 2011-11 to derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and lending arrangements. The guidance is effective for annual periods beginning January 1, 2013 and interim periods within those annual periods. The Company adopted this guidance in the first quarter of 2013 and has included the required disclosures in note 10, “Derivative Contracts”.

Inventories

Inventories	9 Months Ended						12 Months Ended
	Sep. 30, 2013						Dec. 31, 2012
Inventory Disclosure [Abstract]	'						'
Inventories	'						'
		2		Inventories				3		Inventories
	The Company’s inventories were as follows:						The Company’s inventories are as follows:
			As of						As of December 31,
			September 30,		December 31,				2012		2011
			2013		2012		Raw materials and supplies		$	37,766	$	21,320
	Raw materials and supplies		$	34,646	$	37,766	Work-in-process			69,286		93,555
	Work-in-process			99,119		69,286	Finished goods			67,326		71,072
	Finished goods			75,013		67,326
							Total inventories		$	174,378	$	185,947
	Total inventories		$	208,778	$	174,378
							During 2012, 2011 and 2010, inventory quantities were reduced resulting in a liquidation of LIFO inventory layers carried at lower costs prevailing in prior years as compared with current costs. In 2012, the effect of this reduction of inventory decreased cost of sales by $4,775 and increased net income attributable to Global Brass and Copper Holdings, Inc. by $2,908. In 2011, the effect of this reduction of inventory decreased cost of sales by $15,236 and increased net income attributable to Global Brass and Copper Holdings, Inc. by $9,291. In 2010, the effect of this reduction of inventory decreased cost of sales by $21,009 and increased net income by $12,862. If all inventories had been valued at period-end market values, inventories would have been approximately $319,282 and $347,840 at December 31, 2012 and December 31, 2011, respectively.
	Inventories include costs attributable to direct labor and manufacturing overhead but are primarily comprised of raw material costs. The material component of inventories that is valued on a last-in, first-out (“LIFO”) basis comprises approximately 73% and 70% of total inventory at September 30, 2013 and December 31, 2012, respectively. Other manufactured inventories, including the non-material components and certain non-U.S. inventories, are valued on a first-in, first-out (“FIFO”) basis. During the nine months ended September 30, 2013, the Company reduced the recorded value of inventory by $318. This non-cash, lower of cost or market adjustment was recorded in cost of sales in the accompanying consolidated statement of operations for the nine months ended September 30, 2013.						During 2012, the Company reduced the recorded value of inventory by $302. This non-cash, lower of cost or market adjustment was recorded in cost of sales in the accompanying consolidated statement of operations.
	If all inventories had been valued at period-end market values, inventories would have been approximately $331,213 and $319,282 at September 30, 2013 and December 31, 2012, respectively.

Prepaid_Expenses_and_Other_Cur

Prepaid Expenses and Other Current Assets	9 Months Ended					12 Months Ended
	Sep. 30, 2013					Dec. 31, 2012
Text Block [Abstract]	'					'
Prepaid Expenses and Other Current Assets	'					'
	3	Prepaid Expenses and Other Current Assets					4		Prepaid Expenses and Other Current Assets
	The Company’s prepaid expenses and other current assets were as follows:					The Company’s prepaid expenses and other current assets are as follows:
		As of						As of December 31,
		September 30,		December 31,				2012		2011
		2013		2012		Collateral on deposit—commodity derivative contracts		$	767	$	4,622
	Collateral on deposit—commodity derivative contracts	$	1,861	$	767	Commodity derivative contracts			548		—
	Commodity derivative contracts		5		548	Deferred financing fees, net			—		3,646
	Deferred expense		13,018		—	Loss fund payments—workers’ compensation			6,968		7,538
	Loss fund payments—workers’ compensation		6,466		6,968	Prepaid insurance			1,261		1,974
	Prepaid insurance		1,705		1,261	Other			2,597		2,132
	Prepaid tooling		1,926		764
	Other		1,610		1,833	Total prepaid expenses and other current assets		$	12,141	$	19,912
	Total prepaid expenses and other current assets	$	26,591	$	12,141

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Goodwill	'
		4	Goodwill
	On January 31, 2008, the Company, through its Chase reportable segment, acquired certain assets of the brass business of Bolton Metals Product Company (“Bolton”). As of September 30, 2013 and December 31, 2012, the carrying value of goodwill was $4,399. All goodwill is assigned to Chase, which is the Company’s applicable reporting unit for purposes of testing goodwill impairment. The Bolton acquisition is treated as an asset acquisition for tax purposes. As of September 30, 2013, $1,973 of goodwill is expected to be deductible for tax purposes.

Investment_in_Joint_Venture

Investment in Joint Venture	9 Months Ended			12 Months Ended
	Sep. 30, 2013			Dec. 31, 2012
Equity Method Investments And Joint Ventures [Abstract]	'			'
Investment in Joint Venture	'			'
		5	Investment in Joint Venture		7	Investment in Joint Venture
	The Company owns a 50% interest in Dowa—Olin Metal Corporation (“Dowa”), a joint venture based in Japan. The Company accounts for Dowa under the equity method of accounting. Due to the timing of the receipt of available financial information, the results of Dowa are recorded on a one-month lag basis.			In November 2007, the equity investment in Dowa, which was purchased as part of the metals business acquired from Olin Corporation, was recorded at a carrying value of zero as a result of the bargain purchase event recognized under the purchase method of accounting for the acquisition, creating a negative basis difference of $9,416. Based on management’s estimate as to the underlying commercial utility of the alloys that Dowa manufactured and sold at the date of acquisition, the negative basis difference is being accreted on a straight-line basis over a 13-year period as an increase to equity earnings. Accretion of the negative basis difference of $724 was reflected in equity income, net of tax in the accompanying consolidated statements of operations for each of the years ended December 31, 2012, 2011 and 2010. At December 31, 2012 and 2011, the remaining negative basis difference was $5,735 and $6,459, respectively.
	In November 2007, the equity investment in Dowa, which was purchased as part of the metals business acquired from Olin Corporation, was recorded at a carrying value of zero as a result of the bargain purchase event recognized under the purchase method of accounting for the acquisition, creating a negative basis difference of $9,416. Based on management’s estimate as to the underlying commercial utility of the alloys that Dowa manufactured and sold at the date of acquisition, the negative basis difference is being accreted on a straight-line basis over a 13-year period as an increase to equity earnings. Accretion of the negative basis difference of $543 was reflected in equity income, net of tax in the accompanying consolidated statements of operations for each of the nine months ended September 30, 2013 and 2012. At September 30, 2013 and December 31, 2012, the remaining negative basis difference was $5,192 and $5,735, respectively.			During the years ended December 31, 2012, 2011 and 2010, the Company received cash dividends from Dowa of $1,000, $500 and $566, respectively, which were recorded as reductions in the Company’s investment in Dowa. During the years ended December 31, 2012, 2011 and 2010, the Company recorded $995, $888 and $1,530, respectively, of equity income, net of tax, including $724 of accretion of the negative basis difference in each year. The undistributed earnings of Dowa in GBC’s retained earnings as of December 31, 2012 and 2011 totaled $62 and $67, respectively.
	During the nine months ended September 30, 2013 and 2012, the Company received cash dividends from Dowa of $452 and $500, respectively, which were recorded as a reduction in the Company’s investment in Dowa. During the nine months ended September 30, 2013 and 2012, the Company recorded equity income, net of tax of $1,148 and $736, respectively, including $543
	of accretion of the negative basis difference in each period. The undistributed earnings of Dowa in GBC’s retained earnings as of September 30, 2013 and December 31, 2012 totaled $758 and $62, respectively.

Other_Noncurrent_Assets

Other Noncurrent Assets	9 Months Ended						12 Months Ended
	Sep. 30, 2013						Dec. 31, 2012
Text Block [Abstract]	'						'
Other Noncurrent Assets	'						'
		6		Other Noncurrent Assets				8		Other Noncurrent Assets
	Other noncurrent assets consisted of the following:						Other noncurrent assets consisted of the following:
			As of						As of December 31,
			September 30,		December 31,				2012		2011
			2013		2012		Deferred financing fees, net		$	17,082	$	9,779
	Deferred financing fees, net		$	15,225	$	17,082	Utility and other deposits			668		1,060
	Utility and other deposits			1,395		668	Interest rate cap agreements			1		157
	Interest rate cap agreements			—		1	Other			4		177
	Other			—		4
							Total other noncurrent assets		$	17,755	$	11,173
	Total other noncurrent assets		$	16,620	$	17,755
							As described in note 10, “Financing,” on June 1, 2012, GBC (i) issued $375,000 in aggregate principal amount of 9.50% senior secured notes due 2019 (the “Senior Secured Notes”), (ii) amended the agreement governing its asset-based revolving loan facility (the “2010 ABL Facility”, and, as currently amended, the “ABL Facility”), and (iii) repaid and retired its senior secured term loan credit facility (the “Term Loan Facility”) under the Credit and Guaranty Agreement dated August 18, 2010, as amended. The Company refers to these transactions as the “Term Loan Refinancing”.
							As a result of the Term Loan Refinancing described above, the Company incurred and deferred debt issuance costs of $12,981, of which $10,196 was related to the Senior Secured Notes and $2,785 was for the ABL Facility. Additionally, $1,783 of unamortized debt issuance costs and $1,234 of unamortized issuance discount relating to the retired Term Loan Facility is being amortized over the term of the Senior Secured Notes in accordance with ASC 470-50, Modifications and Extinguishments.

Accrued_Liabilities

Accrued Liabilities	9 Months Ended						12 Months Ended
	Sep. 30, 2013						Dec. 31, 2012
Payables And Accruals [Abstract]	'						'
Accrued Liabilities	'						'
		7		Accrued Liabilities				9		Accrued Liabilities
	Accrued liabilities consisted of the following:						Accrued liabilities consisted of the following:
			As of						As of December 31,
			September 30,		December 31,				2012		2011
			2013		2012		Commodity derivative contracts		$	—	$	1,825
	Personnel expense		$	20,685	$	20,872	Personnel expense			20,872		20,548
	Workers’ compensation			14,383		15,754	Workers’ compensation			15,754		15,653
	Deferred revenue			13,018		—	Professional fees			2,145		2,623
	Professional fees			1,826		2,145	Insurance			2,253		1,689
	Insurance			2,358		2,253	Utilities			1,844		1,531
	Utilities			1,877		1,844	Taxes			1,745		1,471
	Taxes			1,371		1,745	Other			3,811		3,264
	Tooling			737		686
	Commodity derivative contracts			357		—	Total accrued liabilities		$	48,424	$	48,604
	Other			3,027		3,125
	Total accrued liabilities		$	59,639	$	48,424

Financing

Financing

9 Months Ended

12 Months Ended

Sep. 30, 2013

Dec. 31, 2012

Debt Disclosure [Abstract]

'

'

Financing

'

'

8

Financing

10

Financing

Long-term debt consisted of the following:

Long-term debt consisted of the following:

As of

As of December 31,

September 30,

December 31,

2012

2011

2013

2012

ABL Facility

$

14,522

$

—

ABL Facility

$

22,500

$

14,522

Senior Secured Notes

375,000

—

Senior Secured Notes

375,000

375,000

Term Loan Facility

—

310,875

Discount, net of amortization

—

(7,297

)

Total long-term debt

$

397,500

$

389,522

389,522

303,578

Senior Secured Notes

Less: Current maturities of long-term debt

—

31,880

On June 1, 2012, GBC issued $375,000 in aggregate principal amount of 9.50% Senior Secured Notes due 2019 (the “Senior Secured Notes”), which are guaranteed by Holdings. The Senior Secured Notes mature on June 1, 2019. Interest on the Senior Secured Notes accrues at the rate of 9.50% per annum and is payable semiannually in arrears on June 1 and December 1, commencing on December 1, 2012.

The credit agreement governing the ABL Facility (hereinafter defined) and the indenture governing the Senior Secured Notes (the “Indenture”) limit the ability of GBC and its subsidiaries to dividend or distribute cash to Holdings and to its equityholders, although ordinary course dividends and distributions to meet the limited holding company expenses and related obligations at Holdings of up to $5 million per year are permitted under those agreements. Under the terms of the Indenture, GBC is also permitted to dividend or distribute to Holdings and its equityholders up to 50% of its “Consolidated Net Income” (as such term is used in the Indenture) from April 1, 2012 to the end of GBC’s most recently ended fiscal quarter. As of September 30, 2013, all of the net assets of the subsidiaries are restricted except for $34,957, which are permitted for dividend distributions under the Indenture. As of September 30, 2013, GBC was in compliance with all of its covenants relating to the Senior Secured Notes.

Total long-term debt

$

389,522

$

271,698

Pursuant to a registration rights agreement, on October 7, 2013, GBC completed an exchange offer to issue registered new notes (with substantially the same terms as the Senior Secured Notes) in exchange for the Senior Secured Notes that GBC issued in a private offering on June 1, 2012.

ABL Facility

Senior Secured Notes

Concurrent with the issuance of the Senior Secured Notes in 2012, the Company amended the agreement governing its asset-based revolving loan facility (the “ABL Facility”).

On June 1, 2012, GBC issued $375,000 in aggregate principal amount of 9.50% Senior Secured Notes due 2019. The Senior Secured Notes are guaranteed by Holdings and substantially all of the existing 100%-owned U.S. subsidiaries. The Senior Secured Notes are secured by a senior-priority security interest in the Company’s fixed assets (which secure the ABL Facility on a junior-priority basis) and by a junior-priority security interest in the Company’s accounts receivable and inventory (which secure the Company’s ABL Facility on a senior-priority basis).

The unused portion of the ABL Facility was $177,000 and $184,978 as of September 30, 2013 and December 31, 2012, respectively. As of September 30, 2013 and December 31, 2012, amounts outstanding under the ABL Facility accrued interest at a rate of 3.33% and 4.50%, respectively.

The proceeds from the issuance of the Senior Secured Notes were used to repay the Term Loan Facility under the Credit and Guaranty Agreement and to fund a cash distribution of $160,000 to Halkos. The indenture governing the Senior Secured Notes contains covenants that limit GBC’s ability and the ability of restricted subsidiaries to, among other things: incur or guarantee additional debt or issue preferred stock; pay dividends; repurchase equity interests; repay subordinated indebtedness; make investments; create restrictions on the payment of dividends or other amounts to GBC from restricted subsidiaries; sell assets, including collateral; enter into transactions with affiliates; merge or consolidate with another person, or sell or otherwise dispose of all or substantially all of GBC’s assets; and create liens on GBC’s or the restricted subsidiaries’ assets to secure debt. The credit agreement governing the ABL Facility and the indenture governing the Senior Secured Notes do, however, limit the ability of Global Brass and Copper, Inc. and its subsidiaries to dividend or distribute cash to Global Brass and Copper Holdings and to its equityholders, although ordinary course dividends and distributions to meet the limited holding company expenses and related obligations at Global Brass and Copper Holdings of up to $5 million per year are permitted under those agreements. Under the terms of the indenture governing the Senior Secured Notes, Global Brass and Copper, Inc. is also permitted to dividend or distribute to Global Brass and Copper Holdings and its equityholders up to 50% of its Consolidated Net Income (as defined in the indenture governing the Senior Secured Notes) from April 1, 2012 to the end of Global Brass and Copper’s most recently ended fiscal quarter. All of the net assets of the subsidiaries are restricted except for $16,432, which are permitted dividend distributions under the Company’s indenture governing the Senior Secured Notes. As of December 31, 2012, the Company was in compliance with all of its covenants relating to the Senior Secured Notes.

The ABL Facility has an expiration date of June 1, 2017 and contains various debt covenants to which the Company is subject on an ongoing basis. As of September 30, 2013, the Company was in compliance with all of its covenants under the ABL Facility.

The Senior Secured Notes mature on June 1, 2019. Interest on the Senior Secured Notes accrues at the rate of 9.50% per annum and is payable semiannually in arrears on June 1 and December 1, commencing on December 1, 2012.

The Company is required to offer to redeem the Senior Secured Notes at a purchase price of 101% of their principal amount (plus accrued and unpaid interest) upon the occurrence of certain change of control events. In addition, upon the completion of certain asset dispositions, the Company may be required to offer to redeem the Senior Secured Notes at a purchase price of 100% of their principal amount (plus accrued and unpaid interest) if it does not apply the proceeds of such asset dispositions in accordance with the indenture by certain specified deadlines.

Pursuant to a registration rights agreement, dated as of June 1, 2012, the Company is required to effect a registered offer to issue registered new notes (with substantially the same terms as the Senior Secured Notes) in exchange for the Senior Secured Notes that the Company issued in a private offering on June 1, 2012. If the Company does not cause the registration statement for the exchange offer to go effective within 365 days after June 1, 2012, or otherwise fails to comply with the other deadlines in the registration rights agreement, it will be required to pay additional interest on the Senior Secured Notes equal to 0.25% per annum for each 90 days it is in default, up to a maximum of 0.50% per annum.

ABL Facility

Concurrent with the issuance of the Senior Secured Notes, the Company amended the ABL Facility to, among other things:

•

increase the commitments under the facility from $150,000 to $200,000;

•

extend the maturity of the ABL Facility to June 1, 2017;

•

lower the applicable margin and unused line fee under the ABL Facility;

•

permit additional acquisitions, investments, restricted payments, asset sales and debt incurrences if certain conditions are satisfied;

•

increase the inventory loan limit for the borrowing base;

•

adjust certain reporting requirements and collateral audit requirements to make them less restrictive; and

•

reduce the excess availability threshold which requires testing of the fixed charge coverage ratio covenant.

The Company refers to these amendments collectively as the “ABL Credit Facility Amendment”.

The ABL Facility provides for borrowings of up to the lesser of $200,000 or the Borrowing Base less outstanding loans and letters of credit. The Borrowing Base is defined as 85% of Eligible Accounts; plus the lesser of 80% of Eligible Inventory, 90% of the Net Recovery Percentage for the Eligible Inventory or the Inventory Loan Limit; minus Reserves. The maximum availability was $200,000 at December 31, 2012 and the Company had outstanding letters of credit of approximately $500 at December 31, 2012. In the event of increased commodity prices as indicated by the terms of the agreement, the Company may request, but the lenders are not obligated to, increase the maximum borrowings up to $250,000. At any time, if the amount outstanding under the ABL Facility exceeds the maximum allowable borrowings, the Company may be required to make a mandatory prepayment for the amount of the excess borrowings. At any time after the occurrence and during the continuance of a Trigger Event (as defined in the agreement governing the ABL Facility), subject to certain thresholds, reinvestment rights and other exceptions, proceeds received from asset sales, equity issuances or other specified events will be required to be applied (as mandatory prepayments) in whole or in part towards the extinguishment of outstanding amounts due under the ABL Facility.

The Company may elect to receive advances under the ABL Facility in the form of either prime rate advances or LIBOR rate advances, as defined by the agreement governing the ABL Facility. The unused portion under the ABL Facility determines the applicable spread added to the prime rate or LIBOR rate. The unused portion of the ABL Facility was $184,978 and $149,300 as of December 31, 2012 and 2011, respectively. Effective with the amendment described above, unused amounts under the ABL Facility incur an unused line fee at a rate of 0.50% per annum, payable in full on a quarterly basis (subject to certain possible adjustments on and after January 1, 2013). Also effective with the amendment described above, outstanding borrowings under the ABL Facility bear interest at a rate equal to either (i) for prime rate loans, a prime rate plus a spread between 1.0% and 1.5%, depending on excess availability levels or (ii) for LIBOR rate loans, LIBOR plus a spread of 2.0% to 2.5% depending on excess availability levels. As of December 31, 2012 and 2011, amounts outstanding under the ABL Facility accrued interest at a rate of 4.50% and 5.25%, respectively.

The ABL Facility has an expiration date of June 1, 2017 and contains various debt covenants to which the Company is subject on an ongoing basis. The ABL Facility restricts the Company’s ability to, among other things, incur indebtedness, grant liens, repurchase stock, issue cash dividends, make investments and acquisitions and sell assets, in each case subject to certain designated exceptions. Outstanding borrowings under the ABL Facility are secured by a senior-priority security interest in the Company’s accounts receivable and inventory (which secure the Senior Secured Notes on a junior-priority basis) and by a junior-priority security interest in the Company’s fixed assets (which secure the Senior Secured Notes on a senior-priority basis). As of December 31, 2012, the Company was in compliance with all of its covenants under the ABL Facility.

The ABL Facility contains customary events of default including, among others, failure to make payment when due, materially incorrect representations and warranties, breach of covenants, events of bankruptcy, or a change in control. In the case of an event of default occurring, the applicable interest rate spread increases by 2.0% and the lenders would have the option to call the outstanding amount due.

Term Loan Facility

On June 1, 2012, the Company repaid and retired its senior secured term loan credit facility under the Credit and Guaranty Agreement dated August 18, 2010, as amended, with proceeds received from the issuance of the Senior Secured Notes offering.

In connection with the termination prior to maturity of the Term Loan Facility, the Company recognized $19,612 as loss from extinguishment of debt for the fiscal year ended December 31, 2012 on the Company’s consolidated statements of operations. The loss on extinguishment of debt includes the write-off of $7,126 of unamortized debt issuance costs and $4,932 of unamortized debt discount as well as the payment of $6,394 of call premium and $21 of professional services fees related to the termination.

Furthermore, in accordance with ASC 470-50, Modifications and Extinguishments, $1,139 of costs associated with the issuance of the Senior Secured Notes was expensed as incurred and reflected in the loss from extinguishment of debt.

Income_Taxes

Income Taxes	9 Months Ended								12 Months Ended
	Sep. 30, 2013								Dec. 31, 2012
Income Tax Disclosure [Abstract]	'								'
Income Taxes	'								'
		9		Income Taxes						11		Income Taxes
	The effective income tax rate, which is provision for income taxes as a percentage of income before provision for income taxes and equity income, differs from the amount determined by applying the applicable U.S. statutory federal income tax rate to pretax results primarily as a result of the following:								Income before provision for income taxes and equity income is comprised of the following:
			Nine Months Ended								Year Ended December 31,
			September  30,								2012			2011			2010
			2013			2012			Domestic		$	24,583		$	81,534		$	61,903
	Statutory provision rate			35	%		35	%	Foreign			6,502			4,303			5,388
	Permanent differences and other items
	State tax provision			7.9	%		3.6	%	Total		$	31,085		$	85,837		$	67,291
	Section 199 manufacturing credit			(6.9	%)		(2.8	%)
	Return to provision adjustments / Uncertain tax positions			(1.4	%)		(3.1	%)	The provision for income taxes is summarized as follows:
	Non-deductible non-cash compensation			48.7	%		41.2	%
	Other			1.1	%		1.5	%
											Year Ended December 31,
	Effective income tax rate			84.4	%		75.4	%			2012			2011			2010
									Current tax provision
	The “Non-deductible non-cash compensation” expense as described further in note 14, “Profits Interest Awards,” is not deductible in the Company’s tax returns and has been reflected as a permanent difference in the effective tax rate reconciliations above.								U.S. federal		$	10,329		$	16,518		$	13,663
	As of September 30, 2013 and December 31, 2012, the Company had $25,841 and $27,401 respectively, of unrecognized tax benefits, none of which would impact the effective tax rate, if recognized. Estimated interest and penalties expense related to the underpayment of income taxes were $29 for nine months ended September 30, 2013. During the nine months ended September 30, 2012, the Company revised its estimate of interest and penalties expense related to the underpayment of income taxes, which resulted in a $138 reduction of the accrual. Estimated interest and penalties expense are classified as a component of income tax expense in the accompanying consolidated statements of operations. Accrued interest and penalties as of September 30, 2013 and December 31, 2012 were $64 and $35, respectively, inclusive of the estimated interest and penalties mentioned above. The Company’s liability for uncertain tax positions of $25,905 and $27,436 at September 30, 2013 and December 31, 2012, respectively, are presented in other noncurrent liabilities.								State and local			1,923			3,347			5,660
	The Company is subject to income taxation in several jurisdictions around the world. Management believes that an adequate provision has been made for any adjustments that may result from tax examinations. However, the outcome of tax audits cannot be predicted with certainty. If any issues addressed in the Company’s tax audits are resolved in a manner not consistent with management’s expectations, the Company could be required to adjust its provision for income tax in the period such resolution occurs. Although timing of the resolution and/or closure of audits is not certain, the Company believes it has adequately reserved for any potential tax exposures at September 30, 2013. The Internal Revenue Service completed its examination of the Corporation’s income tax returns through the period ended December 31, 2010. The Company’s U.S. federal returns for the period ended December 31, 2011 and all subsequent periods remain open for audit. The majority of state returns for the period ended September 30, 2010 and all subsequent periods remain open for audit.								Foreign			1,685			1,081			1,312
									Total current			13,937			20,946			20,635
									Deferred tax provision
									U.S. federal			4,389			10,209			5,760
									State and local			571			188			372
									Foreign			288			94			(91	)
									Total deferred			5,248			10,491			6,041
									Total provision		$	19,185		$	31,437		$	26,676
									The effective income tax rate differs from the amount determined by applying the applicable U.S. statutory federal income tax rate to pretax results primarily as a result of the following:
											Year Ended December 31,
											2012			2011			2010
									Statutory provision rate			35	%		35	%		35	%
									Permanent differences and other items
									State tax provision			6.7	%		3.9	%		6	%
									Section 199 manufacturing credit			(3.2	%)		(2.3	%)		(1.5	%)
									Incremental tax effects of foreign earnings			1.8	%		0.2	%		0.3	%
									Return to provision adjustments			1.2	%		(0.7	%)		(2.2	%)
									Re-rate of deferred taxes			(0.8	%)		(0.3	%)		(0.2	%)
									Non-deductible non-cash compensation			22	%		0.4	%		1.8	%
									Other			(1.0	%)		0.4	%		0.4	%
									Effective income tax rate			61.7	%		36.6	%		39.6	%
									The “Non-deductible non-cash compensation” expense as described further in note 17, “Profits Interest Awards,” is not deductible in the Company’s tax returns and has been reflected as a permanent difference in the effective tax rate reconciliations above.
									Deferred tax assets and liabilities are comprised of the following:
											As of December 31,
											2012			2011
									Deferred tax assets
									Inventory		$	48,932		$	50,936
									Accruals and other reserves			7,721			8,376
									Financing fees			—			731
									Accounts receivable			1,082			939
									UNICAP adjustment			1,278			1,319
									Derivative contracts			487			1,104
									Other			680			—
									Gross deferred tax assets		$	60,180		$	63,405
									Deferred tax liabilities
									Investments in foreign entities		$	7,310		$	6,507
									Fixed assets and intangibles			11,122			7,139
									Financing fees			2,145			—
									Other			—			762
									Gross deferred tax liability			20,577			14,408
									Net deferred tax asset		$	39,603		$	48,997
									Net current deferred tax asset		$	33,465		$	29,027
									Net long-term deferred tax asset			6,138			19,970
									Net deferred tax asset		$	39,603		$	48,997
									At December 31, 2012, the inventory deferred tax asset includes $25,521 related to the impact of the November 19, 2007 purchase price allocations to LIFO inventories for tax purposes, which resulted in a bargain purchase gain. There is a corresponding liability recorded in the Company’s other noncurrent liabilities in accordance with the provisions of ASC 740, Income Taxes.
									The net deferred tax assets do not require a valuation allowance at December 31, 2012 and 2011 as it is more likely than not that the tax benefit will be realized.
								The Company does not assert permanent reinvestment on the excess of its financial reporting over tax basis of its foreign investments. As a result, deferred tax liabilities of $7,310 and $6,507 have been established on the U.S. federal and state income taxes, net of applicable credits, on the excess financial reporting over tax basis of its foreign entities at December 31, 2012 and 2011, respectively. The Company plans foreign remittance amounts based on projected cash flow needs as well as the working capital and long-term investment requirements of its foreign subsidiaries and its domestic operations.
								At December 31, 2012, the Company has a foreign tax credit carryforward of $514 which will expire by 2022.
								Uncertain Tax Positions
								The Company accounts for its income tax positions under the provisions of ASC 740, which was initially adopted on November 19, 2007. ASC 740 prescribes a minimum threshold a tax position is required to meet before being recognized in these consolidated financial statements. ASC 740 requires the Company to recognize in its consolidated financial statements tax positions determined more likely than not to be sustained upon examination, based on the technical merits of the position.
								The Company is subject to income taxation in several jurisdictions around the world. Resolution of the related tax positions through negotiations with relevant tax authorities or through litigation may take years to complete. Therefore, it is difficult to predict the timing for resolution of tax positions. However, the Company does not anticipate that the total amount of unrecognized tax benefits will increase or decrease significantly in the next twelve months. The Company’s U.S. federal returns and the majority of state returns for the period ended September 30, 2009 and all subsequent periods remain open for audit. The Company’s federal returns are currently under examination by the Internal Revenue Service for the periods ended September 30, 2009 through December 31, 2010. The Company believes it has adequately reserved for any potential tax exposures at December 31, 2012.
								At December 31, 2012 and 2011, the Company had $27,401 and $31,340, respectively, of unrecognized tax benefits, none of which would impact the effective tax rate, if recognized. Estimated interest and penalties related to the underpayment of income taxes are classified as a component of income tax expense in the accompanying consolidated statements of operations. Accrued interest and penalties as of December 31, 2012 and 2011 were $35 and $301, respectively. The Company’s liability for uncertain tax positions, including accrued interest and penalties, of $27,436 and $31,641 at December 31, 2012 and 2011, respectively, are presented in other noncurrent liabilities.
								A reconciliation of the summary of activity of the Company’s uncertain tax positions is summarized as follows:
								Balance at January 1, 2011		$	35,483
								Additions for tax positions related to prior years			207
								Reductions for tax positions related to prior years			(4,350	)
								Balance at December 31, 2011		$	31,340
								Additions for tax positions related to prior years			—
								Reductions for tax positions related to prior years			(1,963	)
								Reductions due to tax settlements			(1,515	)
								Reductions due to tax statute of limitations			(461	)
								Balance at December 31, 2012		$	27,401
								From 2007 through 2009, the Company’s tax year end was September 30 and its fiscal year end was December 31. During 2010, the Company filed a request to change its tax year end to December 31. The effective date of this request was December 31, 2010. Accordingly, the Company filed a stub year income tax return for the period from October 1, 2010 through December 31, 2010.

Derivative_Contracts

Derivative Contracts	9 Months Ended																12 Months Ended
	Sep. 30, 2013																Dec. 31, 2012
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'																'
Derivative Contracts	'																'
		10		Derivative Contracts														13		Derivative Contracts
	The Company maintains a metal, natural gas and electricity pricing risk-management strategy that uses commodity derivative contracts to minimize significant, unanticipated gains or losses that may arise from volatility of the commodity indices.																The Company maintains a metal, natural gas and electricity pricing risk-management strategy that uses commodity derivative contracts to minimize significant, unanticipated gains or losses and cash fluctuations that may arise from volatility of the commodity indices.
	The Company’s commodity derivative contracts consist of delivery contracts matched in quantity, price and maturity to firm price sales orders in order to protect sales margins from metal price fluctuations between the firm price sale order date and shipment date.																The Company’s commodity derivative contracts consist of delivery contracts matched in quantity, price and maturity to firm price sales orders, in circumstances where physical firm price metal is unavailable, in order to protect sales margins from metal price fluctuations between the firm price sale order date and shipment date.
	The prices of natural gas and electricity can be particularly volatile. The Company attempts to mitigate short-term volatility in natural gas and electricity costs through the use of derivatives contracts in an effort to offset the effect of increasing costs.																The prices of natural gas and electricity can be particularly volatile. As a result, our natural gas and electricity costs may fluctuate dramatically. The Company attempts to mitigate short-term volatility in natural gas and electricity costs through the use of derivatives contracts in an effort to offset the effect of increasing costs.
	The Company also utilized interest rate cap agreements in compliance with the requirement under its prior senior secured term loan credit facility (the “Term Loan Facility”) to provide that at least 50% of the Term Loan Facility be subject to a fixed rate or interest rate protection for a period of not less than three years. These interest rate cap agreements were not designated as an accounting hedge and changes in the fair value of the interest rate cap agreements have been recorded as non-cash interest expense. The agreements expired in August 2013.																The Company also utilized interest rate cap agreements in compliance with the requirement under the Term Loan Facility to provide that at least 50% of the term loan be subject to a fixed rate or interest rate protection for a period of not less than three years. During 2010, the Company entered into three-year interest rate cap agreements that capped the interest rate on $300,000 of the aggregate principal outstanding. The interest rate cap agreements are not designated as an accounting hedge and changes in the fair value of the interest rate cap agreements are recorded as non-cash interest expense.
	By using derivative contracts to limit exposures to fluctuations in metal, natural gas and electricity prices and interest rate movements, the Company exposes itself to credit risk and market risk. Credit risk is the risk that the counterparty might fail to fulfill its performance obligations under the terms of the derivative contract. Market risk is the risk that the value of a derivative instrument might be adversely affected by a change in commodity price or interest rates. The Company manages the market risk associated with derivative contracts by establishing and monitoring parameters that limit the types and degree of market risk that may be undertaken.																By using derivative contracts to limit exposures to fluctuations in metal, natural gas and electricity prices and interest rate movements, the Company exposes itself to credit risk and market risk. Credit risk is the risk that the counterparty might fail to fulfill its performance obligations under the terms of the derivative contract. Market risk is the risk that the value of a derivative instrument might be adversely affected by a change in commodity price or interest rates. The Company manages the market risk associated with derivative contracts by establishing and monitoring parameters that limit the types and degree of market risk that may be undertaken.
	The Company manages credit risk associated with derivative contracts by only executing derivative instruments with counterparties with investment-grade credit ratings. The amount of such credit risk is limited to the fair value of the derivative contract plus the unpaid portion of amounts due to the Company pursuant to terms of the derivative contracts, if any. If a downgrade in the credit rating of these counterparties occurs, management believes that this exposure is mitigated by provisions in the derivative arrangements which allow for the legal right of offset of any amounts due to the Company from the counterparties with any amounts payable to the counterparties by the Company.																The Company primarily executes derivative contracts with major financial institutions. These counterparties expose the Company to credit risk in the event of non-performance. The amount of such exposure is limited to the fair value of the derivative contract plus the unpaid portion of amounts due to the Company pursuant to terms of the derivative contracts, if any. If a downgrade in the credit rating of these counterparties occurs, management believes that this exposure is mitigated by provisions in the derivative arrangements which allow for the legal right of offset of any amounts due to the Company from the counterparties with any amounts payable to the counterparties by the Company.
																	The fair values of derivative contracts in the consolidated balance sheet include the impact of netting derivative assets and liabilities when a legally enforceable master netting arrangement exists. The following tables summarize the gross amounts of recognized derivative assets and liabilities, the net amounts presented in the consolidated balance sheet, and the net amounts after deducting collateral that has been deposited with counterparties:
	The fair values of derivative contracts in the consolidated balance sheet include the impact of netting derivative assets and liabilities when a legally enforceable master netting arrangement exists. The following tables summarize the gross amounts of recognized derivative assets and liabilities, the net amounts presented in the consolidated balance sheet, and the net amounts after deducting collateral that has been deposited with counterparties:
																			As of December 31, 2012
			As of September 30, 2013																								Amounts Not Offset in
											Amounts Not Offset in																the Consolidated
											the Consolidated																Balance Sheet
											Balance Sheet								Gross		Gross			Net Amounts			Financial		Cash			Net
			Gross			Gross			Net Amounts		Financial		Cash		Net				Amounts of		Amounts			of Assets			Instruments		Collateral			Amount
			Amounts of			Amounts			of Assets		Instruments		Collateral		Amount				Recognized		Offset in			Presented in					Received
			Recognized			Offset in			Presented in				Received						Assets		Consolidated			Consolidated
			Assets			Consolidated			Consolidated												Balance			Balance
						Balance			Balance												Sheet			Sheet
						Sheet			Sheet								Open metals contracts		$	603	$	(224	)	$	379		$	—	$	—		$	379
	Open metal contracts		$	722		$	(722	)	$	—	$	—	$	—	$	—	(208 contracts)
	(361 contracts)																Open natural gas contracts			2		—			2			—		—			2
	Open electricity contracts			56			(51	)		5		—		—		5	(6 contracts)
	(10 contracts)																Open electricity contracts			169		(2	)		167			—		—			167
																	(17 contracts)
	Total		$	778		$	(773	)	$	5	$	—	$	—	$	5	Interest rate cap agreements			1		—			1			—		—			1
																	(2 contracts)
	Consolidated balance sheet location:
	Prepaid expenses and other current assets					$	5										Total		$	775	$	(226	)	$	549		$	—	$	—		$	549
	Total					$	5										Consolidated balance sheet location:
																	Prepaid expenses and other current assets				$	548
																	Other noncurrent assets					1
											Amounts Not Offset in
											the Consolidated						Total				$	549
											Balance Sheet
			Gross			Gross			Net Amounts		Financial		Cash		Net
			Amounts of			Amounts			of Liabilities		Instruments		Collateral		Amount												Amounts Not Offset in
			Recognized			Offset in			Presented in				Deposited														the Consolidated
			Liabilities			Consolidated			Consolidated																		Balance Sheet
						Balance			Balance										Gross		Gross			Net Amounts			Financial		Cash			Net
						Sheet			Sheet										Amounts of		Amounts			of Liabilities			Instruments		Collateral			Amount
	Open metal contracts		$	1,074		$	(722	)	$	352	$	—	$	352	$	—			Recognized		Offset in			Presented in					Deposited
	(406 contracts)																		Liabilities		Consolidated			Consolidated
	Open natural gas contracts			5			—			5		—		5		—					Balance			Balance
	(4 contracts)																				Sheet			Sheet
	Open electricity contracts			51			(51	)		—		—		—		—	Open metals contracts		$	224	$	(224	)	$	—		$	—	$	—		$	—
	(14 contract)																(85 contracts)
																	Open electricity contracts			2		(2	)		—			—		—			—
	Total		$	1,130		$	(773	)	$	357	$	—	$	357	$	—	(1 contract)
	Consolidated balance sheet location:																Total		$	226	$	(226	)	$	—		$	—	$	—		$	—
	Accrued liabilities					$	357
	Total					$	357										Not included in the table above is $767 of collateral included in Prepaid Expenses and Other Current Assets, which is because collateral is limited to the net amounts of assets or liabilities presented in the consolidated balance sheet.
	Not included in the above table is $1,504 of collateral included in prepaid expenses and other current assets, which is because collateral is limited to the net amounts of assets or liabilities presented in the consolidated balance sheet.																		As of December 31, 2011
																											Gross Amounts Not
																											Offset in the
			As of December 31, 2012																								Consolidated Balance
											Amounts Not Offset in																Sheet
											the Consolidated						(dollars in thousands)		Gross		Gross			Net Amounts			Financial		Cash			Net
											Balance Sheet								Amounts of		Amounts			of Assets			Instruments		Collateral			Amount
			Gross			Gross			Net Amounts		Financial		Cash		Net				Recognized		Offset in			Presented in					Received
			Amounts of			Amounts			of Assets		Instruments		Collateral		Amount				Assets		Consolidated			Consolidated
			Recognized			Offset in			Presented in				Received								Balance			Balance
			Assets			Consolidated			Consolidated												Sheet			Sheet
			Balance			Balance									Open metals contracts (88 contracts)		$	294	$	(294	)	$	—		$	—	$	—		$	—
			Sheet			Sheet									Open electricity contracts (6 contracts)			43		(43	)		—			—		—			—
Open metals contracts		$	603		$	(224	)	$	379	$	—	$	—	$	379	Interest rate cap agreements (2 contracts)			157		—			157			—		—			157
(208 contracts)
Open natural gas contracts			2			—			2		—		—		2	Total		$	494	$	(337	)	$	157		$	—	$	—		$	157
(6 contracts)
Open electricity contracts			169			(2	)		167		—		—		167	Consolidated balance sheet location:
(17 contracts)																Other noncurrent assets							$	157
Interest rate cap agreements			1			—			1		—		—		1
(2 contracts)
																										Gross Amounts Not
Total		$	775		$	(226	)	$	549	$	—	$	—	$	549											Offset in the
																										Consolidated Balance
Consolidated balance sheet location:																										Sheet
Prepaid expenses and other current assets					$	548										(dollars in thousands)		Gross		Gross			Net Amounts			Financial		Cash			Net
Other noncurrent assets						1												Amounts of		Amounts			of Liabilities			Instruments		Collateral			Amount
																		Recognized		Offset in			Presented in					Deposited
Total					$	549												Liabilities		Consolidated			Consolidated
																				Balance			Balance
																				Sheet			Sheet
										Amounts Not Offset in						Open metals contracts (151 contracts)		$	1,647	$	(294	)	$	1,353		$	—	$	(1,353	)	$	—
										the Consolidated						Open natural gas contracts (31 contracts)			384		—			384			—		(384	)		—
										Balance Sheet						Open electricity contracts (8 contracts)			131		(43	)		88			—		—			88
		Gross			Gross			Net Amounts		Financial		Cash		Net
		Amounts of			Amounts			of Liabilities		Instruments		Collateral		Amount		Total		$	2,162	$	(337	)	$	1,825		$	—	$	(1,737	)	$	88
		Recognized			Offset in			Presented in				Deposited
		Liabilities			Consolidated			Consolidated								Consolidated balance sheet location:
					Balance			Balance								Accrued liabilities							$	1,825
					Sheet			Sheet
Open metals contracts		$	224		$	(224	)	$	—	$	—	$	—	$	—
(85 contracts)																Not included in the table above is $2,885 of collateral included in Prepaid Expenses and Other Current Assets, which is because collateral is limited to the net amounts of assets or liabilities presented in the consolidated balance sheet.
Open electricity contracts			2			(2	)		—		—		—		—	The following table summarizes the effects of derivative contracts in the consolidated statements of operations:
(1 contract)
Total		$	226		$	(226	)	$	—	$	—	$	—	$	—			Year Ended December 31,
																		2012		2011			2010
																Cost of sales
Not included in the above table is $767 of collateral included in prepaid expenses and other current assets, which is because collateral is limited to the net amounts of assets or liabilities presented in the consolidated balance sheet.																Realized and unrealized loss—metal contracts		$	1,339	$	3,884		$	7,605
The following table summarizes the effects of derivative contracts in the consolidated statements of operations:																Realized and unrealized loss—natural gas contracts			76		517			1,825
																Realized and unrealized loss—electricity contracts			243		57			—
		Nine Months Ended														Total		$	1,658	$	4,458		$	9,430
		September 30,
		2013			2012											Interest expense
Cost of sales																Unrealized loss (gain)—interest rate cap agreements		$	156	$	1,851		$	(800	)
Realized and unrealized (loss) gain—metal contracts		$	(143	)	$	614
Realized and unrealized (loss) gain—natural gas contracts			(12	)		113
Realized and unrealized (loss) gain—electricity contracts			(193	)		222
Total		$	(348	)	$	949
Interest expense
Unrealized loss—interest rate cap agreements		$	(1	)	$	(156	)

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended										12 Months Ended
	Sep. 30, 2013										Dec. 31, 2012
Fair Value Disclosures [Abstract]	'										'
Fair Value Measurements	'										'
		11		Fair Value Measurements								14		Fair Value Measurements
	ASC 820 defines fair value, establishes a framework for measuring fair value and enhances disclosures about fair value measures required under other accounting pronouncements but does not change existing guidance as to whether or not an instrument is carried at fair value. This guidance also specifies a fair value hierarchy based upon the observability of inputs used in valuation techniques. In accordance with this guidance, fair value measurements are classified under the following hierarchy:										ASC 820 defines fair value, establishes a framework for measuring fair value and enhances disclosures about fair value measures required under other accounting pronouncements but does not change existing guidance as to whether or not an instrument is carried at fair value. This guidance also specifies a fair value hierarchy based upon the observability of inputs used in valuation techniques. In accordance with this guidance, fair value measurements are classified under the following hierarchy:
		•		Level 1—Quoted prices for identical instruments in active markets.								•		Level 1—Quoted prices for identical instruments in active markets.
		•		Level 2—Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active and model-derived valuations in which all significant inputs or significant value-drivers are observable in active markets.								•		Level 2—Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active and model-derived valuations in which all significant inputs or significant value-drivers are observable in active markets.
		•		Level 3—Model-derived valuations in which one or more significant inputs or significant value-drivers are unobservable.								•		Level 3—Model-derived valuations in which one or more significant inputs or significant value-drivers are unobservable.
	The following tables provide the hierarchy of inputs used to derive the fair value of the Company’s assets and liabilities at fair value on a recurring basis as of September 30, 2013 and December 31, 2012:										The following tables provide the hierarchy of inputs used to derive the fair value of the Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2012 and December 31, 2011:
			As of September 30, 2013										As of December 31, 2012
			Level 1		Level 2		Level 3		Total				Level 1		Level 2		Level 3		Total
	Open electricity contracts		$	—	$	5	$	—	$	5	Open metal contracts		$	—	$	379	$	—	$	379
											Open natural gas contracts			—		2		—		2
	Total assets		$	—	$	5	$	—	$	5	Open electricity contracts			—		167		—		167
											Interest rate cap agreements			—		1		—		1
	Open metal contracts		$	—	$	352	$	—	$	352
	Open natural gas contracts			—		5		—		5	Total assets		$	—	$	549	$	—	$	549
	Total liabilities		$	—	$	357	$	—	$	357
													As of December 31, 2011
													Level 1		Level 2		Level 3		Total
											Interest rate cap agreements		$	—	$	157	$	—	$	157
			As of December 31, 2012
			Level 1		Level 2		Level 3		Total		Total assets		$	—	$	157	$	—	$	157
	Open metal contracts		$	—	$	379	$	—	$	379
	Open natural gas contracts			—		2		—		2	Open metal contracts		$	—	$	1,353	$	—	$	1,353
	Open electricity contracts			—		167		—		167	Open natural gas contracts			—		384		—		384
	Interest rate cap agreements			—		1		—		1	Open electricity contracts			—		88		—		88
	Total assets		$	—	$	549	$	—	$	549	Total liabilities		$	—	$	1,825	$	—	$	1,825
	In accordance with ASC 820, the Company determines the fair value of its interest rate agreement and commodity derivative contracts using Level 2 inputs.										In accordance with ASC 820, the Company determines the fair value of its interest rate agreement and commodity derivative contracts using Level 2 inputs.
	The Company’s metal, natural gas and electricity commodity derivative contracts are considered Level 2 as fair value measurements consist of both quoted price inputs and inputs provided by a third party that are derived principally from or corroborated by observable market data by correlation. These assumptions include, but are not limited to, those concerning interest rates, credit rates, discount rates, default rates and other factors. All derivative commodity contracts have a set term of 24 months or less.										The Company’s metal, natural gas and electricity commodity derivative contracts are considered Level 2 as fair value measurements consist of both quoted price inputs and inputs provided by a third party that are derived principally from or corroborated by observable market data by correlation. These assumptions include, but are not limited to, those concerning interest rates, credit rates, discount rates, default rates and other factors. All derivative commodity contracts have a set term of 24 months or less.
	The Company’s interest rate cap agreements are considered Level 2 fair value measurements as the pricing is derived from discounting the future expected cash flows that would occur if variable interest rates rise above the strike rates of the caps. The variable interest rates used in the calculation of projected cash flows on the caps are based on an expectation of future interest rates derived from observable market interest rate curves (LIBOR forward curves) and volatilities that are observable at commonly quoted intervals.										The Company’s interest rate cap agreements are considered Level 2 fair value measurements as the pricing is derived from discounting the future expected cash flows that would occur if variable interest rates rise above the strike rates of the caps. The variable interest rates used in the calculation of projected cash flows on the caps are based on an expectation of future interest rates derived from observable market interest rate curves (LIBOR forward curves) and volatilities that are observable at commonly quoted intervals.
	The Company does not hold assets or liabilities requiring a Level 3 measurement and there have not been any transfers between the hierarchy levels during 2013 or 2012.										The Company does not hold assets or liabilities requiring a Level 3 measurement and there have not been any transfers between the hierarchy levels during 2012 or 2011.
	For purposes of financial reporting, the Company has determined that the carrying value of cash, accounts receivable, accounts payable, and accrued expenses approximates fair value due to the short maturities of these instruments. Additionally, given the revolving nature and the variable interest rates, the Company has determined that the carrying value of the ABL Facility also approximates fair value. As of September 30, 2013, the fair value of the Company’s Senior Secured Notes approximated $415,781. The fair value of the Senior Secured Notes was based upon quotes from financial institutions (Level 2 in the fair value hierarchy as defined by ASC 820).										For purposes of financial reporting, the Company has determined that the carrying value of cash, accounts receivable, accounts payable, and accrued expenses approximates fair value due to the short maturities of these instruments. Additionally, given the revolving nature and the variable interest rates, the Company has determined that the carrying value of the ABL Facility also approximates fair value. As of December 31, 2012, the fair value of the Company’s Senior Secured Notes approximated $406,875. The fair value of the Senior Secured Notes was based upon quotes from financial institutions (Level 2 in the fair value hierarchy as defined by ASC 820).

Related_Parties

Related Parties	9 Months Ended			12 Months Ended
	Sep. 30, 2013			Dec. 31, 2012
Related Party Transactions [Abstract]	'			'
Related Parties	'			'
		12	Related Parties		15	Related Parties
	KPS Special Situations Fund II, L.P., KPS Special Situations Fund II (A), L.P., KPS Special Situations Fund III, L.P. and KPS Special Situations Fund III (A), L.P. (together, “KPS Funds”) are majority shareholders of Halkos. As of September 30, 2013, Halkos beneficially owned 61.5% of the outstanding shares of Holdings. On October 1, 2013, the Company completed its follow-on public offering of 5,750,000 shares of its common stock. Halkos sold all of the shares in the follow-on public offering and received all of the net proceeds from the offering. After giving effect to the follow-on public offering, Halkos beneficially owns approximately 34.4% of the outstanding common stock of the Company.			KPS Special Situations Fund II, L.P., KPS Special Situations Fund II (A), L.P., KPS Special Situations Fund III, L.P. and KPS Special Situations Fund III (A), L.P. (together, “KPS Funds”) are majority shareholders of Halkos. Halkos owns all of the outstanding shares of Holdings. On June 1, 2012, the Company distributed $160,000 to Halkos (see note 10, “Financing”).
	The Company and affiliates of KPS Funds entered into an agreement whereby affiliates of KPS Funds charged the Company for services of their personnel engaged in line or staff functions relating specifically to the operations of the Company (the “Management Services Agreement”). In May 2013, in connection with the IPO, the Company terminated the Management Services Agreement prior to the expiration of the initial term and was required to pay the affiliates of KPS Funds an early termination fee equal to the value of the advisory fee that would have otherwise been payable to the affiliates of KPS Funds through the end of the Management Services Agreement. The Company paid $4,500 to the affiliates of KPS Funds related to the Company’s early termination and all unpaid management advisory fees. The total charges, which are included in selling, general and administrative expenses, were $4,750 for the nine months ended September 30, 2013, all of which were recorded in the first six months of 2013, and $750 for the nine months ended September 30, 2012. As of December 31, 2012, $250 of these charges were accrued for in accrued liabilities. Additionally, pursuant to the Management Services Agreement, the Company was required to reimburse the affiliates of KPS Funds for all reasonable costs and expenses incurred in connection with the services provided. These costs were $24 and $62 for the nine months ended September 30, 2013 and 2012, respectively.			The Company and affiliates of KPS Funds have entered into an agreement whereby affiliates of KPS Funds charge the Company for services of their personnel engaged in line or staff functions relating specifically to the operations of the Company (the “Management Services Agreement”). The charges, which are included in selling, general and administrative expenses, were $1,000 for each of the years ended December 31, 2012, 2011 and 2010, of which $250 is included in accrued liabilities at December 31, 2012 and 2011. Additionally, pursuant to the Management Services Agreement, the Company is required to reimburse the affiliates of KPS Funds for all reasonable costs and expenses incurred in connection with the services provided. These costs were $77, $167 and $102 for the year ended December 31, 2012, 2011 and 2010, respectively.
	The Company and KPS Funds entered into an agreement dated October 18, 2011 whereby the KPS Funds agreed to reimburse the Company for specific incremental costs directly attributable to the offering of equity securities (the “KPS Reimbursement Obligation”). Pursuant to the completion of the offering that occurred on May 29, 2013, KPS Funds reimbursed the Company all amounts owed in connection with the KPS Reimbursement Obligation. As of December 31, 2012, the Company had recorded $4,875 as a receivable from stockholder pertaining to the KPS Reimbursement Obligation.			The Company and KPS Funds entered into an agreement dated October 18, 2011 whereby the KPS Funds agreed to reimburse the Company for specific incremental costs directly attributable to an offering of equity securities (the “KPS Reimbursement Obligation”). As of December 31, 2012 and 2011, the Company has recorded $4,875 and $2,451, respectively, as a receivable from stockholder pertaining to the KPS Reimbursement Obligation.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended			12 Months Ended
	Sep. 30, 2013			Dec. 31, 2012
Commitments And Contingencies Disclosure [Abstract]	'			'
Commitments and Contingencies	'			'
		13	Commitments and Contingencies		16		Commitments and Contingencies
	Environmental Considerations			Environmental Considerations
	The Company is subject to a variety of environmental laws and regulations governing discharges to air and water, the handling, storage and disposal of hazardous or solid waste materials and the remediation of contamination associated with releases of hazardous substances. Although the Company believes it is in material compliance with all of the various regulations applicable to its business, there can be no assurance that requirements will not change in the future or that the Company will not incur significant costs to comply with such requirements. The Company employs responsible personnel at each facility, along with various environmental engineering consultants from time to time to assist with ongoing management of environmental, health and safety requirements. Management expenses environmental costs related to existing conditions resulting from past or current operations and from which no current or future benefit is discernible. Expenditures that extend the life of the related property are capitalized. The Company determines its liability on a location by location basis and records a liability at the time it is deemed probable and can be reasonably estimated. The Company is currently not aware of any environmental matters which may have a material impact on the Company’s financial position, results of operations, or liquidity.			The Company is subject to a variety of environmental laws and regulations governing discharges to air and water, the handling, storage and disposal of hazardous or solid waste materials and the remediation of contamination associated with releases of hazardous substances. Although the Company believes it is in material compliance with all of the various regulations applicable to its business, there can be no assurance that requirements will not change in the future or that the Company will not incur significant cost to comply with such requirements. The Company employs responsible personnel at each facility, along with various environmental engineering consultants from time to time to assist with ongoing management of environmental, health and safety requirements. Management expenses environmental costs related to existing conditions resulting from past or current operations and from which no current or future benefit is discernible. Expenditures that extend the life of the related property are capitalized. The Company determines its liability on a location by location basis and records a liability at the time it is deemed probable and can be reasonably estimated. The Company is currently not aware of any environmental matters which may have a material impact on the Company’s financial position, results of operations, or liquidity.
	On November 19, 2007 (the date of inception of GBC), the Company acquired the assets and operations relating to the worldwide metals business of Olin Corporation. Olin Corporation agreed to retain liability arising out of the existing conditions on certain of our properties for any remedial actions required by environmental laws, and agreed to indemnify the Company for all or part of a number of other environmental liabilities. Since 2007, Olin Corporation has been performing remedial actions at the facilities in East Alton, Illinois and Waterbury, Connecticut, and has been participating in remedial actions at certain other properties as well. If Olin Corporation were to stop its environmental remedial activities at the Company’s properties, the Company could be required to assume responsibility for these activities, the cost of which could be material.			On November 19, 2007 (the date of inception of GBC), the Company acquired the assets and operations relating to the worldwide metals business of Olin Corporation. Olin Corporation agreed to retain liability arising out of the existing conditions on certain of our properties for any remedial actions required by environmental laws, and agreed to indemnify the Company for all or part of a number of other environmental liabilities. Since 2007, Olin Corporation has been performing remedial actions at the facilities in East Alton, Illinois and Waterbury, Connecticut, and has been participating in remedial actions at certain other properties as well. If Olin Corporation were to stop its environmental remedial activities at the Company’s properties, the Company could be required to assume responsibility for these activities, the cost of which could be material.
	Insurance Coverage			Insurance Coverage
	The Company maintains Comprehensive Medical Plans for employees of GBC and its subsidiaries (the “Plans”) to provide health insurance for eligible employees on a self-insured basis. The Plans are covered by a stop loss policy for those benefits provided on a self-insured basis with a deductible of $275 per occurrence for all GBC employees, except for employees of our Chase Brass division, which has a deductible of $100 per occurrence. The policy for our Chase Brass division also has a specific stop loss maximum resulting in the Company being responsible for paying the amount in excess of $2,000 per occurrence.			The Company maintains Comprehensive Medical Plans for employees of GBC and its subsidiaries (the “Plans”) to provide health insurance for eligible employees on a self-insured basis. The Plans are covered by a stop loss policy for those benefits provided on a self-insured basis with a deductible of $275 per occurrence for all GBC employees, except for employees of our Chase Brass division, which has a deductible of $100 per occurrence and a specific stop loss maximum of $2,000.
	The Company is self-insured for workers’ compensation claims assumed from its predecessor company for activity prior to November 19, 2007. Workers’ compensation claims relating to activity after November 19, 2007 are covered by a loss funding insurance arrangement whereby the Company makes a fixed payment to the insurer which is used to pay submitted claims. The Company is self-insured for annual workers’ compensation costs relating to activity after November 19, 2007 of up to $500 per occurrence.			The Company is self-insured for workers’ compensation claims assumed from its predecessor company for activity prior to November 19, 2007 and benefits paid under employee health care programs. Workers’ compensation claims relating to activity after November 19, 2007 are covered by a loss funding insurance arrangement whereby the Company makes a fixed payment to the insurer which is used to pay submitted claims. The Company is self-insured for annual workers’ compensation costs relating to activity after November 19, 2007 of up to $500 per occurrence.
	Legal Considerations			Legal Considerations
	The Company is party to various legal proceedings arising in the ordinary course of business. The Company believes that none of its lawsuits are individually material or that the aggregate exposure of all of its lawsuits, including those that are probable and those that are only reasonably possible, is material to its financial condition, results of operations or cash flows.			The Company is party to various legal proceedings arising in the ordinary course of business. The Company believes that none of its lawsuits are individually material or that the aggregate exposure of all of its lawsuits, including those that are probable and those that are only reasonably possible, is material to its financial condition, results of operations or cash flows.
				Operating Leases
				The Company has operating leases covering certain of its facilities and equipment under non-cancelable lease agreements.
				Future minimum lease payments under non-cancelable leases in effect are as follows:
				Year		Payment
				2013		$	2,654
				2014			1,621
				2015			956
				2016			612
				2017			122
				Thereafter			—
				Total minimum lease payments		$	5,965
				Rental expense under all operating leases was approximately $3,606, $3,603 and $3,543 for the years ended December 31, 2012, 2011 and 2010, respectively, and is recorded in cost of sales or selling, general and administrative costs depending on the nature and use of the underlying asset being leased.

Profits_Interest_Awards

Profits Interest Awards	9 Months Ended			12 Months Ended
	Sep. 30, 2013			Dec. 31, 2012
Text Block [Abstract]	'			'
Profits Interest Awards	'			'
		14	Profits Interest Awards		17	Profits Interest Awards
	Halkos granted, pursuant to the Halkos Equity Plan, non-voting membership interests to select members of the Company’s management titled “Class B Shares.” The Class B Shares are profits interests in Halkos.			Halkos has granted, pursuant to the Halkos Equity Plan, non-voting membership interests to select members of the Company’s management titled Class B, C and D Shares. The Class B, C and D Shares are profits interests in Halkos.
	Certain members of the Company’s management receive distributions from Halkos to the extent their Class B Shares are vested. During the nine months ended September 30, 2013 and 2012, GBC executives received $8,902 and $19,517, respectively. These distributions were accounted for by GBC as non-cash compensation expense with a corresponding increase in additional paid-in capital in the period in which the distributions were determined to be probable.			Class B Shares
	In June 2013, Halkos modified the Halkos LLC Agreement to eliminate its right to acquire all or a portion of the Class B Shares. This modification to the Halkos LLC Agreement triggered the recognition of additional non-cash compensation expense reflecting the fair value of vested Class B Shares as of the date of modification. The observable market price of the Company’s publicly traded shares was used to determine the fair value of the Class B Shares. In June 2013, the Company recognized $20,369 of incremental non-cash compensation expense as a result of the modification.			In 2007, in connection with the issuance of Class C and D Shares, Halkos issued Class B Shares to certain members of the Company’s management. Halkos issued additional Class B Shares in 2010 and 2011 to certain members of the Company’s management. Class B Shares generally vest over a period of three years. Despite the fact that these Shares are in the form of equity, the Class B Shares are considered a profit sharing plan due to certain aspects of the plan, primarily the ability of Halkos to repurchase the Shares at no cost from the employee holding such shares. Award recipients substantively derive economic value in the instrument through profit sharing distributions. Accordingly, the Class B Shares are a compensation liability award accounted for as a profit sharing arrangement by Halkos. Because the awards were granted by Halkos, an economic interest holder of the Company, to employees of the Company, distributions are accounted for by the Company as non-cash compensation expense with a corresponding increase in additional paid-in capital to reflect the deemed capital contribution by Halkos. Expense on the Class B Shares is recorded in the period in which distributions to Class B award holders are determined to be probable.
				During the years ended December 31, 2012, 2011 and 2010, certain members of the Company’s management received distributions from Halkos in the amount of $20,110, $292 and $3,452, respectively. The Company recorded the distributions as non-cash compensation expense with a corresponding increase in additional paid in capital in the period in which these distributions were determined to be probable. Non-cash compensation expense of $19,517, $885 and $3,452 is included as a component of selling, general and administrative expenses in the consolidated statements of operations for the years ended December 31, 2012, 2011 and 2010, respectively.
				Class C and D Shares
				In June 2011, the Halkos limited liability company agreement was amended and the Class C and D Shares were converted to Class B Shares at fair value. No expense relative to these awards is reflected in the accompanying consolidated financial statements. The conversion was in effect a liability to liability modification and the achievement of the Class C and D Shares performance condition was not probable nor were there any probable distributions payable for Class B Shares at the time of conversion.

Segment_Information

Segment Information	9 Months Ended								12 Months Ended
	Sep. 30, 2013								Dec. 31, 2012
Segment Reporting [Abstract]	'								'
Segment Information	'								'
		15		Segment Information					18		Segment Information
	The Company’s Chief Operating Decision Maker allocates resources and evaluates performance at the divisional level. As such, the Company has determined that it has three reportable segments: Olin Brass, Chase and Oster.								The Company’s Chief Operating Decision Maker allocates resources and evaluates performance at the divisional level. As such, the Company has determined that it has three reportable segments: Olin Brass, Chase and Oster.
	Olin Brass is a leading manufacturer and converter of copper and brass sheet, strip and fabricated products. Olin Brass also rerolls and forms other alloys such as stainless, carbon steel and aluminum. Olin Brass’s products are used in five primary end markets: building and housing,								The Olin Brass segment is the leading manufacturer and converter of copper and copper-alloy sheet, strip, foil, and fabricated components in North America. While primarily processing copper and copper-alloys, the segment also rerolls and forms other metals such as stainless and carbon steel. Olin Brass’s products are used in five primary end markets: building and housing, munitions, automotive, coinage, and electronics/electrical components.
	munitions, automotive, coinage, and electronics/electrical components.								Chase is a leading North American manufacturer of brass rod. The segment principally produces brass rod in sizes ranging from 1/4 inch to 4.5 inches in diameter. The key attributes of brass rod include its machinability, corrosion resistance and moderate strength, making it ideal for forging and machining products such as valves and fittings. Chase produces brass rod used in production applications which can be grouped into four end markets: building and housing, transportation, electronics/electrical components and industrial machinery and equipment.
	Chase is a leading manufacturer of brass rod in North America. Chase primarily manufactures brass rod, including round and other shapes, ranging from 1/4 inch to 4.5 inches in diameter. The key attributes of brass rod include its machinability, corrosion resistance and moderate strength, making it especially suitable for forging and machining products such as valves and fittings. Brass rod is generally manufactured from copper or copper-alloy scrap. Chase produces brass rod used in production applications which can be grouped into four primary end markets: building and housing, transportation, electronics/electrical components and industrial machinery and equipment.
	Oster is a processing distributor of copper and copper-alloy sheet, strip and foil. Oster operates six strategically-located service centers in the United States, Puerto Rico and Mexico. Each Oster service center reliably provides a broad range of high quality products at quick lead-times in small quantities. These capabilities, combined with Oster’s operations of precision slitting, hot tinning, traverse winding, cutting, edging and special packaging, provide value to a broad customer base. Oster’s products are used in three primary end markets: building and housing, automotive and electronics/electrical components.								Oster is a leading copper-alloy distributor and processor. The segment, through its family of metal service centers, is strategically focused on satisfying its customers’ needs for brass and copper parts and other products, with a high level of service, quality and flexibility by offering customization and just-in-time delivery. Value-added processing services include precision slitting and traverse winding to provide greater customer press up-time, hot air level tinning for superior corrosion resistance and product enhancement such as edging and cutting. Important Oster end markets include building and housing, automotive, transportation, and electronics/electrical components (primarily for housing and commercial construction).
	The Chief Operating Decision Maker evaluates performance and determines resource allocations based on a number of factors, the primary performance measure being Segment Adjusted EBITDA.								The Chief Operating Decision Maker evaluates performance and determines resource allocations based on a number of factors, the primary performance measure being Segment Adjusted EBITDA.
	Segment Adjusted EBITDA is an EBITDA-based measure of operating performance, with EBITDA being defined by the Company as net income before depreciation and amortization, interest expense, and income taxes. The Company defines Segment Adjusted EBITDA as EBITDA further adjusted to exclude unrealized gains and losses on derivative contracts, lower of cost or market adjustments to inventory, LIFO-based gains and losses, non-cash compensation expense, share-based compensation expense, loss on extinguishment of debt and non-cash income accretion related to the Company’s joint venture investment, each of which are excluded because management believes they are not indicative of the ongoing performance of the Company’s core operations. Corporate and Other includes compensation for corporate executives and officers, corporate office and administrative salaries, and professional fees for accounting, tax and legal services. Corporate and Other also includes interest expense, state and Federal income taxes, overhead costs that management has not allocated to our operating segments and the elimination of intercompany balances.								Segment Adjusted EBITDA is an EBITDA based measure of operating performance, with EBITDA being defined by the Company as net income before depreciation and amortization, interest expense, and income taxes. The Company defines Segment Adjusted EBITDA as EBITDA further adjusted to remove the impacts of inventory values for LIFO and lower of cost or market charges, the cost of terminating certain collateral hedges, unrealized mark to market gains and losses on derivative instruments, non-cash compensation expense, loss on extinguishment of debt and non-cash income accretion related to the Company’s joint venture investment, each of which are excluded because management believes they are not indicative of the ongoing performance of the Company’s core operations. Corporate and Eliminations include corporate amounts, primarily compensation, tax and overhead costs unrelated to a specific segment, and elimination of intercompany balances. The Chief Operating Decision Maker is not provided with nor reviews assets by segment for purposes of allocating resources.
	Below is a reconciliation of the Company’s Segment Adjusted EBITDA to income before provision for income taxes and equity income:								Below is a reconciliation of the Company’s Segment Adjusted EBITDA to income before provision for income taxes and equity income:
			Nine Months Ended											Year Ended December 31,
			September 30,											2012			2011			2010
			2013			2012			Net Sales, External Customers
	Net Sales, External Customers								Olin Brass					$	676,563		$	718,244		$	710,271
	Olin Brass		$	613,926		$	496,786		Chase						647,711			704,968			611,870
	Chase			488,475			505,951		Oster						326,246			355,931			336,588
	Oster			243,277			251,610
									Total net sales, external customers					$	1,650,520		$	1,779,143		$	1,658,729
	Total net sales, external customers		$	1,345,678		$	1,254,347
									Intersegment Net Sales
	Intersegment Net Sales								Olin Brass					$	46,287		$	48,312		$	57,919
	Olin Brass		$	40,539		$	36,315		Chase						305			626			765
	Chase			7			302		Oster						167			285			928
	Oster			173			81
									Total intersegment net sales					$	46,759		$	49,223		$	59,612
	Total intersegment net sales		$	40,719		$	36,698
									Segment Adjusted EBITDA
	Segment Adjusted EBITDA								Olin Brass					$	45,115		$	45,320		$	23,291
	Olin Brass		$	41,209		$	37,432		Chase						66,641			73,658			61,158
	Chase			53,831			53,311		Oster						19,517			17,898			21,324
	Oster			13,164			15,137
									Total segment adjusted EBITDA						131,273			136,876			105,773
	Total segment adjusted EBITDA			108,204			105,880		Corporate and Eliminations						(20,562	)		(19,518	)		(15,714	)
	Corporate and Other			(19,101	)		(14,664	)	Loss on extinguishment of debt						(19,612	)		—			—
	Loss on extinguishment of debt			—			(19,612	)	Depreciation and amortization						(6,934	)		(4,759	)		(2,971	)
	Depreciation and amortization			(6,101	)		(4,891	)	Interest expense						(39,727	)		(40,010	)		(25,076	)
	Interest expense			(29,938	)		(29,894	)	Equity method investment income			(A	)		(271	)		(164	)		(806	)
	Equity method investment income(A)			(605	)		(193	)	Net income attributable to noncontrolling interest						374			156			512
	Net income attributable to noncontrolling interest			228			273		LIFO liquidation gain						4,775			15,236			21,009
	Lower of cost or market adjustment to inventory			(318	)		(302	)	Lower of cost or market adjustment to inventory						(302	)		—			—
	(Loss) gain on derivative contracts			(1,062	)		1,473		Gain (loss) on derivative contracts						1,588			(1,095	)		(11,984	)
	Share-based compensation expense			(989	)		—		Compensation expense—profits interest awards						(19,517	)		(885	)		(3,452	)
	Compensation expense—profits interest awards			(29,271	)		(19,517	)
									Income before provision for income taxes and equity income					$	31,085		$	85,837		$	67,291
	Income before provision for income taxes and equity income		$	21,047		$	18,553
										(A)	Excludes accretion income of $724 in each of the years ended December 31, 2012, 2011 and 2010. Equity method investment income is exclusive to Olin Brass.
		(A)	Excludes accretion income of $543 in both the nine months ended September 30, 2013 and 2012. Equity method investment income is exclusive to Olin Brass.
											Year Ended December 31,
											2012			2011			2010
									Depreciation and amortization
									Olin Brass		$	3,849		$	2,622		$	1,624
									Chase			2,521			1,921			1,200
									Oster			247			196			147
									Corporate and Eliminations			317			20			—
									Total depreciation and amortization		$	6,934		$	4,759		$	2,971
									LIFO liquidation gain/(loss)
									Olin Brass		$	175		$	8,401		$	23,253
									Chase			1,623			—			75
									Oster			4,478			7,050			(48	)
									Corporate and Eliminations			(1,501	)		(215	)		(2,271	)
									Total LIFO liquidation gain		$	4,775		$	15,236		$	21,009
									Capital expenditures
									Olin Brass		$	12,455		$	10,818		$	3,999
									Chase			6,846			10,171			7,377
								Oster			558			505			551
								Corporate and Eliminations			549			946			—
								Total capital expenditures		$	20,408		$	22,440		$	11,927
								Summarized geographic information is shown in the following table. Net sales are attributed to individual countries based on the location from which the products are shipped. No customer represented 10 percent or more of consolidated revenues in 2012, 2011 or 2010.
										Year Ended December 31,
										2012			2011			2010
								Net sales:
								United States		$	1,556,865		$	1,691,007		$	1,567,472
								Asia Pacific			53,668			54,638			62,358
								Mexico			39,987			33,498			28,899
								Total net sales		$	1,650,520		$	1,779,143		$	1,658,729
								Substantially all long-lived assets are maintained in the United States.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Earnings Per Share	'
		16		Earnings Per Share
	Basic earnings per share is computed based on the weighted-average number of common shares outstanding and diluted earnings per share is computed based on the weighted-average number of common shares outstanding adjusted by the number of additional shares that would have been outstanding had potentially dilutive common shares been issued. Potentially dilutive securities include stock options and nonvested share awards. Nonvested performance-based share awards are included in the average diluted shares outstanding for each period if established performance criteria have been met at the end of the respective periods.
	The following table sets forth the computation of basic and diluted earnings per share attributable to the Company:
			Nine Months Ended
			September 30,
			2013		2012
	Numerator
	Net income attributable to Global Brass and Copper Holdings, Inc.		$	4,205	$	5,020
	Denominator
	Weighted-average common shares outstanding			21,110,000		21,110,000
	Effect of potentially dilutive securities:
	Stock options and nonvested share awards			24,169		—
	Weighted-average common shares outstanding, assuming dilution			21,134,169		21,110,000
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic		$	0.2	$	0.24
	Diluted		$	0.2	$	0.24
	During the nine months ended September 30, 2013, the Company granted 107,895 options to purchase shares of common stock, 141,486 nonvested shares of restricted stock, and 101,754 nonvested performance-based shares to certain members of the Company’s management and its Board of Directors. The computation of weighted-average common shares outstanding, assuming dilution, for the nine months ended September 30, 2013, includes the average common shares outstanding that would result from the assumed exercise of outstanding stock options and vesting of restricted stock awards. Nonvested performance-based shares are excluded from the computation because the established performance criterion was not met at September 30, 2013.

Stock_Split

Stock Split	9 Months Ended			12 Months Ended
	Sep. 30, 2013			Dec. 31, 2012
Text Block [Abstract]	'			'
Stock Split	'			'
		17	Stock Split		20	Stock Split
	On April 10, 2013 the Company’s Board of Directors authorized a 211,100-to-1 stock split to be effected after the effective date of the Company’s Form S-1 Registration Statement and prior to the completion of the Company’s initial public offering. On May 29, 2013, the Company completed its initial public offering of 8,050,000 shares of its common stock at a price of $11.00 per share. The share numbers and per share amounts disclosed in the consolidated financial statements and notes to consolidated financial statements have been retroactively adjusted to give effect to the stock split.			On April 10, 2013 the Company’s Board of Directors authorized a 211,100-to-1 stock split to be effected after the effective date of the Company’s Form S-1 Registration Statement and prior to the completion of the Company’s IPO. On May 29, 2013, the Company completed its IPO. The share numbers and per share amounts disclosed in the consolidated financial statements and notes to consolidated financial statements have been retroactively adjusted to give effect to the stock split.
	The balance sheets have been retroactively adjusted for the impact of the stock split by an increase to common stock of $211 with an offsetting charge to accumulated deficit.			The balance sheets have been retroactively adjusted for the impact of the stock split by an increase to common stock of $211 with an offsetting charge to accumulated deficit.

Condensed_Consolidating_Financ

Condensed Consolidating Financial Information	9 Months Ended																				12 Months Ended
	Sep. 30, 2013																				Dec. 31, 2012
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'																				'
Condensed Consolidating Financial Information	'																				'
		18		Condensed Consolidating Financial Information																		19		Condensed Consolidating Financial Information
	In June 2012, Holdings (presented as “Parent” in the following tables), through its wholly-owned principal operating subsidiary, GBC (presented as “Issuer” in the following tables), issued Senior Secured Notes as further described in note 8, “Financing”. The Senior Secured Notes are jointly and severally guaranteed on a senior secured basis by Holdings and substantially all existing																				In June 2012, Holdings (presented as “Parent” in the following tables), through its wholly-owned principal operating subsidiary, GBC (presented as “Issuer” in the following tables), issued Senior Secured Notes as further described in note 10. The Senior Secured Notes are jointly and severally guaranteed on a senior secured basis by Holdings and substantially all existing 100%-owned U.S. subsidiaries of GBC (collectively, the “Guarantors”). The guarantees are full and unconditional, except that a Guarantor can be automatically released and relieved of its obligations under certain customary provisions contained in the indenture governing the Senior Secured Notes. Under these customary provisions, a Guarantor is automatically released from its obligations as a guarantor upon the sale of the Guarantor or substantially all of its assets to a third party, the designation of the Guarantor as an unrestricted subsidiary in accordance with the terms of the indenture, the release or discharge of all guarantees by such Guarantor and the repayment of all indebtedness, or upon the Issuer’s exercise of its legal defeasance option or covenant defeasance option or if the obligations under the indenture are discharged in accordance with the terms of the indenture. All other subsidiaries of GBC, whether direct or indirect, do not guarantee the Senior Secured Notes (collectively, the “Non-Guarantors”).
																					Holdings is also a guarantor of the asset-based revolving loan facility (the “ABL Facility”) and substantially all of its 100%-owned U.S. subsidiaries are borrowers under, or guarantors of, the ABL Facility on a senior secured basis.
	100%-owned U.S. subsidiaries of GBC and any future restricted subsidiaries who guarantee or incur certain types of Permitted Debt under the Indenture (collectively, the “Guarantors”). The guarantees are full and unconditional, except that a Guarantor can be automatically released and relieved of its obligations under certain customary provisions contained in the Indenture. Under these customary provisions, a Guarantor is automatically released from its obligations as a guarantor upon the sale of the Guarantor or substantially all of its assets to a third party, the designation of the Guarantor as an unrestricted subsidiary in accordance with the terms of the Indenture, the release or discharge of all guarantees by such Guarantor and the repayment of all indebtedness, or upon the Issuer’s exercise of its legal defeasance option or covenant defeasance option or if the obligations under the Indenture are discharged in accordance with the terms of the Indenture. All other subsidiaries of GBC, whether direct or indirect, do not guarantee the Senior Secured Notes (collectively, the “Non-Guarantors”).																				The following condensed consolidating financial information presents the financial position, results of operations, comprehensive income and cash flows of (1) the Parent, (2) the Issuer, (3) the Guarantors, (4) the Non-Guarantors and (5) eliminations to arrive at the information for Holdings on a consolidated basis. The condensed consolidating financial information presented below is not necessarily indicative of the financial position, results of operations, comprehensive income or cash flows of the Parent, the Issuer, the Guarantors or the Non-Guarantors on a stand-alone basis.
	Holdings is also a guarantor of the ABL Facility and substantially all of its 100%-owned U.S. subsidiaries are borrowers under, or guarantors of, the ABL Facility on a senior secured basis.
	The following condensed consolidating financial information presents the financial position, results of operations, comprehensive income and cash flows of (1) the Parent, (2) the Issuer, (3) the Guarantors, (4) the Non-Guarantors and (5) eliminations to arrive at the information for the Company on a consolidated basis. The condensed consolidating financial information presented below is not necessarily indicative of the financial position, results of operations, comprehensive income or cash flows of the Parent, the Issuer, the Guarantors or the Non-Guarantors on a stand-alone basis.																				Global Brass and Copper Holdings, Inc.
																					Condensed Consolidating Balance Sheet
																					31-Dec-12
			Condensed Consolidating Balance Sheet
			As of September 30, 2013
			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated					Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
									Subsidiaries			Subsidiaries																	Subsidiaries			Subsidiaries
	Assets																				Assets
	Current assets:																				Current assets:
	Cash		$	—		$	11,164		$	2,633		$	4,291		$	—		$	18,088		Cash		$	—		$	8,537		$	—		$	5,446		$	(121	)	$	13,862
	Accounts receivable, net of allowance			—			4,914			176,272			17,287			—			198,473		Accounts receivable, net of allowance			—			4,630			144,533			15,154			—			164,317
	Inventories			—			—			193,825			15,363			(410	)		208,778		Inventories			—			343			158,713			15,885			(563	)		174,378
	Prepaid expenses and other current assets			—			10,064			16,441			86			—			26,591		Prepaid expenses and other current assets			—			9,229			2,600			312			—			12,141
	Deferred income taxes			—			32,122			—			—			—			32,122		Deferred income taxes			—			33,465			—			—			—			33,465
	Income tax receivable, net			—			799			—			—			(174	)		625		Income tax receivable, net			—			1,656			—			—			(356	)		1,300
	Total current assets			—			59,063			389,171			37,027			(584	)		484,677		Total current assets			—			57,860			305,846			36,797			(1,040	)		399,463
	Property, plant and equipment, net			—			976			76,810			351			—			78,137		Property, plant and equipment, net			—			1,154			69,646			327			—			71,127
	Investment in joint venture			—			—			2,184			—			—			2,184		Investment in joint venture			—			—			2,972			—			—			2,972
	Investment in subsidiaries			—			623,442			19,974			—			(643,416	)		—		Investment in subsidiaries			—			522,912			19,850			—			(542,762	)		—
	Intercompany accounts			—			—			270,599			—			(270,599	)		—		Intercompany accounts			—			—			223,081			—			(223,081	)		—
	Goodwill			—			—			4,399			—			—			4,399		Goodwill			—			—			4,399			—			—			4,399
	Intangible assets, net			—			—			762			—			—			762		Intangible assets, net			—			—			839			—			—			839
	Deferred income taxes			—			5,736			—			—			—			5,736		Deferred income taxes			—			6,138			—			—			—			6,138
	Other noncurrent assets			—			15,705			915			—			—			16,620		Other noncurrent assets			—			17,115			640			—			—			17,755
	Total assets		$	—		$	704,922		$	764,814		$	37,378		$	(914,599	)	$	592,515		Total assets		$	—		$	605,179		$	627,273		$	37,124		$	(766,883	)	$	502,693
	Liabilities and (deficit) / equity																				Liabilities and (deficit) / equity
	Current liabilities:																				Current liabilities:
	Accounts payable		$	—		$	2,455		$	101,105		$	2,161		$	(410	)	$	105,311		Accounts payable		$	—		$	1,398		$	77,390		$	2,910		$	(121	)	$	81,577
	Accrued liabilities			—			18,710			40,232			697			—			59,639		Accrued liabilities			—			20,592			26,971			861			—			48,424
	Accrued interest			—			12,448			—			—			—			12,448		Accrued interest			—			3,287			—			—			—			3,287
	Income tax payable			—			—			35			295			(174	)		156		Income taxes payable			—			248			—			356			(356	)		248
	Total current liabilities			—			33,613			141,372			3,153			(584	)		177,554		Total current liabilities			—			25,525			104,361			4,127			(477	)		133,536
	Long-term debt			—			397,500			—			—			—			397,500		Long-term debt			—			389,522			—			—			—			389,522
	Other noncurrent liabilities			—			26,312			—			—			—			26,312		Other noncurrent liabilities			—			27,436			—			—			—			27,436
	Obligations and advances in excess of investment in subsidiary			5,447			—			—			—			(5,447	)		—		Obligations and advances in excess of investment in subsidiary			42,522			—			—			—			(42,522	)		—
	Intercompany accounts			7,269			252,944			—			10,386			(270,599	)		—		Intercompany accounts			8,829			205,218			—			9,597			(223,644	)		—
	Total liabilities			12,716			710,369			141,372			13,539			(276,630	)		601,366		Total liabilities			51,351			647,701			104,361			13,724			(266,643	)		550,494
	Commitments and contingencies			—			—			—			—			—			—		Commitments and contingencies			—			—			—			—			—			—
	Global Brass and Copper Holdings, Inc. stockholders’ (deficit) / equity			(12,716	)		(5,447	)		623,442			19,974			(637,969	)		(12,716	)	Global Brass and Copper Holdings, Inc. stockholder’s (deficit) / equity			(51,351	)		(42,522	)		522,912			19,850			(500,240	)		(51,351	)
	Noncontrolling interest			—			—			—			3,865			—			3,865		Noncontrolling interest			—			—			—			3,550			—			3,550
	Total (deficit) / equity			(12,716	)		(5,447	)		623,442			23,839			(637,969	)		(8,851	)	Total (deficit) / equity			(51,351	)		(42,522	)		522,912			23,400			(500,240	)		(47,801	)
	Total liabilities and (deficit) / equity		$	—		$	704,922		$	764,814		$	37,378		$	(914,599	)	$	592,515		Total liabilities and (deficit) / equity		$	—		$	605,179		$	627,273		$	37,124		$	(766,883	)	$	502,693
																					Global Brass and Copper Holdings, Inc.
			Condensed Consolidating Balance Sheet																		Condensed Consolidating Balance Sheet
			As of December 31, 2012																		31-Dec-11
			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
									Subsidiaries			Subsidiaries
	Assets																						Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
	Current assets:																												Subsidiaries			Subsidiaries
	Cash		$	—		$	8,537		$	—		$	5,446		$	(121	)	$	13,862		Assets
	Accounts receivable, net of allowance			—			4,630			144,533			15,154			—			164,317		Current assets:
	Inventories			—			343			158,713			15,885			(563	)		174,378		Cash		$	—		$	45,302		$	—		$	4,648		$	(413	)	$	49,537
	Prepaid expenses and other current assets			—			9,229			2,600			312			—			12,141		Accounts receivable, net of allowance			—			4,184			145,083			12,448			—			161,715
	Deferred income taxes			—			33,465			—			—			—			33,465		Inventories			—			218			174,429			11,921			(621	)		185,947
	Income tax receivable, net			—			1,656			—			—			(356	)		1,300		Prepaid expenses and other current assets			—			17,916			2,245			135			(384	)		19,912
																					Deferred income taxes			—			29,027			—			—			—			29,027
	Total current assets			—			57,860			305,846			36,797			(1,040	)		399,463		Income tax receivable, net			—			5,204			128			—			(286	)		5,046
	Property, plant and equipment, net			—			1,154			69,646			327			—			71,127
Investment in joint venture			—			—			2,972			—			—			2,972		Total current assets			—			101,851			321,885			29,152			(1,704	)		451,184
Investment in subsidiaries			—			522,912			19,850			—			(542,762	)		—		Property, plant and equipment, net			—			923			56,322			311			—			57,556
Intercompany accounts			—			—			223,081			—			(223,081	)		—		Investment in joint venture			—			—			3,507			—			—			3,507
Goodwill			—			—			4,399			—			—			4,399		Investment in subsidiaries			85,020			393,708			13,351			—			(492,079	)		—
Intangible assets, net			—			—			839			—			—			839		Intercompany accounts			—			—			92,889			—			(92,889	)		—
Deferred income taxes			—			6,138			—			—			—			6,138		Goodwill			—			—			4,399			—			—			4,399
Other noncurrent assets			—			17,115			640			—			—			17,755		Intangible assets, net			—			—			951			—			—			951
																				Deferred income taxes			—			19,970			—			—			—			19,970
Total assets		$	—		$	605,179		$	627,273		$	37,124		$	(766,883	)	$	502,693		Other noncurrent assets			—			9,963			1,210			—			—			11,173
Liabilities and (deficit) / equity																				Total assets		$	85,020		$	526,415		$	494,514		$	29,463		$	(586,672	)	$	548,740
Current liabilities:
Accounts payable		$	—		$	1,398		$	77,390		$	2,910		$	(121	)	$	81,577		Liabilities and (deficit) / equity
Accrued liabilities			—			20,592			26,971			861			—			48,424		Current liabilities:
Accrued interest			—			3,287			—			—			—			3,287		Current maturities of long-term debt		$	—		$	31,880		$	—		$	—		$	—		$	31,880
Income tax payable			—			248			—			356			(356	)		248		Accounts payable			—			—			76,190			2,495			(797	)		77,888
																				Accrued liabilities			—			23,202			24,616			786			—			48,604
Total current liabilities			—			25,525			104,361			4,127			(477	)		133,536		Accrued interest			—			4,069			—			—			—			4,069
Long-term debt			—			389,522			—			—			—			389,522		Income taxes payable			—			300			—			286			(286	)		300
Other noncurrent liabilities			—			27,436			—			—			—			27,436
Obligations and advances in excess of investment in subsidiary			42,522			—			—			—			(42,522	)		—		Total current liabilities			—			59,451			100,806			3,567			(1,083	)		162,741
Intercompany accounts			8,829			205,218			—			9,597			(223,644	)		—		Long-term debt			—			271,698			—			—			—			271,698
																				Other noncurrent liabilities			—			31,641			—			—			—			31,641
Total liabilities			51,351			647,701			104,361			13,724			(266,643	)		550,494		Intercompany accounts			5,528			78,605			—			9,377			(93,510	)		—
Commitments and contingencies			—			—			—			—			—			—		Total liabilities			5,528			441,395			100,806			12,944			(94,593	)		466,080
Global Brass and Copper Holdings, Inc. stockholders’ (deficit) / equity			(51,351	)		(42,522	)		522,912			19,850			(500,240	)		(51,351	)
Noncontrolling interest			—			—			—			3,550			—			3,550		Commitments and contingencies			—			—			—			—			—			—
																				Global Brass and Copper Holdings, Inc. stockholder’s (deficit) / equity			79,492			85,020			393,708			13,351			(492,079	)		79,492
Total (deficit) / equity			(51,351	)		(42,522	)		522,912			23,400			(500,240	)		(47,801	)	Noncontrolling interest			—			—			—			3,168			—			3,168
Total liabilities and (deficit) / equity		$	—		$	605,179		$	627,273		$	37,124		$	(766,883	)	$	502,693		Total (deficit) / equity			79,492			85,020			393,708			16,519			(492,079	)		82,660
																				Total liabilities and (deficit) / equity		$	85,020		$	526,415		$	494,514		$	29,463		$	(586,672	)	$	548,740
		Condensed Consolidating Statement of Operations
		Nine Months Ended September 30, 2013																		Global Brass and Copper Holdings, Inc.
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated			Condensed Consolidating Statement of Operations
								Subsidiaries			Subsidiaries									Year Ended December 31, 2012
Net sales		$	—		$	—		$	1,294,809		$	73,586		$	(22,717	)	$	1,345,678
Cost of sales			—			1,208			1,155,186			68,138			(22,717	)		1,201,815
																						Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
Gross profit (loss)			—			(1,208	)		139,623			5,448			—			143,863										Subsidiaries			Subsidiaries
Selling, general and administrative expenses			5,390			33,569			51,444			2,219			—			92,622		Net sales		$	—		$	—		$	1,584,301		$	93,655		$	(27,436	)	$	1,650,520
																				Cost of sales			—			83			1,409,588			85,099			(27,436	)		1,467,334
Operating income (loss)			(5,390	)		(34,777	)		88,179			3,229			—			51,241
Interest expense			—			29,938			—			—			—			29,938		Gross profit (loss)			—			(83	)		174,713			8,556			—			183,186
Other (income) expense, net			—			264			(134	)		126			—			256		Selling, general and administrative expenses			1,427			30,756			57,879			2,579			—			92,641
Income (loss) before provision for (benefit from) income taxes and equity income			(5,390	)		(64,979	)		88,313			3,103			—			21,047		Operating income (loss)			(1,427	)		(30,839	)		116,834			5,977			—			90,545
Provision for (benefit from) income taxes			(2,075	)		(15,753	)		34,676			914			—			17,762		Interest expense			—			39,730			(3	)		—			—			39,727
																				Loss on extinguishment of debt			—			19,612			—			—			—			19,612
Income (loss) before equity income			(3,315	)		(49,226	)		53,637			2,189			—			3,285		Other (income) expense, net			—			766			(120	)		(525	)		—			121
Equity income, net of tax			7,520			56,746			3,109			—			(66,227	)		1,148
																				Income (loss) before provision for income taxes and equity income			(1,427	)		(90,947	)		116,957			6,502			—			31,085
Net income			4,205			7,520			56,746			2,189			(66,227	)		4,433		Provision for (benefit from) income taxes			(550	)		(30,066	)		47,828			1,973			—			19,185
Less: Net income attributable to noncontrolling interest			—			—			—			228			—			228
																				Income (loss) before equity income			(877	)		(60,881	)		69,129			4,529			—			11,900
Net income attributable to Global Brass and Copper Holdings, Inc.		$	4,205		$	7,520		$	56,746		$	1,961		$	(66,227	)	$	4,205		Equity income, net of tax			13,398			74,279			5,150			—			(91,832	)		995
																				Net income			12,521			13,398			74,279			4,529			(91,832	)		12,895
																				Less: Net income attributable to noncontrolling interest			—			—			—			374			—			374
		Condensed Consolidating Statement of Operations
		Nine Months Ended September 30, 2012																		Net income attributable to Global Brass and Copper Holdings, Inc.		$	12,521		$	13,398		$	74,279		$	4,155		$	(91,832	)	$	12,521
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
								Subsidiaries			Subsidiaries
Net sales		$	—		$	—		$	1,204,470		$	69,679		$	(19,802	)	$	1,254,347		Global Brass and Copper Holdings, Inc.
Cost of sales			—			(1,896	)		1,071,405			63,168			(19,802	)		1,112,875		Condensed Consolidating Statement of Operations
																				Year Ended December 31, 2011
Gross profit			—			1,896			133,065			6,511			—			141,472
Selling, general and administrative expenses			1,086			26,223			43,969			1,963			—			73,241
																						Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
Operating income (loss)			(1,086	)		(24,327	)		89,096			4,548			—			68,231										Subsidiaries			Subsidiaries
Interest expense (income)			—			29,896			(2	)		—			—			29,894		Net sales		$	—		$	—		$	1,713,367		$	88,136		$	(22,360	)	$	1,779,143
Loss on extinguishment of debt			—			19,612			—			—			—			19,612		Cost of sales			—			735			1,523,655			81,443			(22,360	)		1,583,473
Other (income) expense, net			—			689			2			(519	)		—			172
																				Gross profit (loss)			—			(735	)		189,712			6,693			—			195,670
Income (loss) before provision for (benefit from) income taxes and equity income			(1,086	)		(74,524	)		89,096			5,067			—			18,553		Selling, general and administrative expenses			1,650			15,721			49,451			2,569			—			69,391
Provision for (benefit from) income taxes			(418	)		(24,813	)		38,710			517			—			13,996
																				Operating income (loss)			(1,650	)		(16,456	)		140,261			4,124			—			126,279
Income (loss) before equity income			(668	)		(49,711	)		50,386			4,550			—			4,557		Interest expense			—			39,950			60			—			—			40,010
Equity income, net of tax			5,688			55,399			5,013			—			(65,364	)		736		Other (income) expense, net			—			292			317			(177	)		—			432
Net income			5,020			5,688			55,399			4,550			(65,364	)		5,293		Income (loss) before provision for income taxes and equity income			(1,650	)		(56,698	)		139,884			4,301			—			85,837
Less: Net income attributable to noncontrolling interest			—			—			—			273			—			273		Provision for (benefit from) income taxes			(635	)		(20,765	)		51,662			1,175			—			31,437
Net income attributable to Global Brass and Copper Holdings, Inc.		$	5,020		$	5,688		$	55,399		$	4,277		$	(65,364	)	$	5,020		Income (loss) before equity income			(1,015	)		(35,933	)		88,222			3,126			—			54,400
																				Equity income, net of tax			56,147			92,080			3,858			—			(151,197	)		888
																				Net income			55,132			56,147			92,080			3,126			(151,197	)		55,288
		Condensed Consolidating Statement of Comprehensive Income																		Less: Net income attributable to noncontrolling interest			—			—			—			156			—			156
		Nine Months Ended September 30, 2013
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated			Net income attributable to Global Brass and Copper Holdings, Inc.		$	55,132		$	56,147		$	92,080		$	2,970		$	(151,197	)	$	55,132
								Subsidiaries			Subsidiaries
Net income		$	4,205		$	7,520		$	56,746		$	2,189		$	(66,227	)	$	4,433
Foreign currency translation adjustment, net of tax			(705	)		(705	)		(1,181	)		340			1,633			(618	)	Global Brass and Copper Holdings, Inc.
																				Condensed Consolidating Statement of Operations
Comprehensive income			3,500			6,815			55,565			2,529			(64,594	)		3,815		Year Ended December 31, 2010
Less: Comprehensive income attributable to noncontrolling interest			—			—			—			315			—			315
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		$	3,500		$	6,815		$	55,565		$	2,214		$	(64,594	)	$	3,500				Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
																												Subsidiaries			Subsidiaries
																				Net sales		$	—		$	—		$	1,599,714		$	91,256		$	(32,241	)	$	1,658,729
																				Cost of sales			—			16,759			1,428,661			83,516			(32,241	)		1,496,695
		Condensed Consolidating Statement of Comprehensive Income
		Nine Months Ended September 30, 2012																		Gross profit (loss)			—			(16,759	)		171,053			7,740			—			162,034
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated			Selling, general and administrative expenses			1,102			12,337			52,988			2,430			—			68,857
								Subsidiaries			Subsidiaries
Net income		$	5,020		$	5,688		$	55,399		$	4,550		$	(65,364	)	$	5,293		Operating income (loss)			(1,102	)		(29,096	)		118,065			5,310			—			93,177
Foreign currency translation adjustment, net of tax			(130	)		(130	)		(200	)		983			(653	)		(130	)	Interest expense			—			25,070			6			—			—			25,076
																				Other (income) expense, net			—			668			219			(77	)		—			810
Comprehensive income			4,890			5,558			55,199			5,533			(66,017	)		5,163
Less: Comprehensive income attributable to noncontrolling interest			—			—			—			273			—			273		Income (loss) before provision for income taxes and equity income			(1,102	)		(54,834	)		117,840			5,387			—			67,291
																				Provision for (benefit from) income taxes			(424	)		(20,214	)		46,093			1,221			—			26,676
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		$	4,890		$	5,558		$	55,199		$	5,260		$	(66,017	)	$	4,890
																				Income (loss) before equity income			(678	)		(34,620	)		71,747			4,166			—			40,615
																				Equity income, net of tax			42,311			76,931			5,184			—			(122,896	)		1,530
		Condensed Consolidating Statement of Cash Flows																		Net income			41,633			42,311			76,931			4,166			(122,896	)		42,145
		Nine Months Ended September 30, 2013																		Less: Net income attributable to noncontrolling interest			—			—			—			512			—			512
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
								Subsidiaries			Subsidiaries									Net income attributable to Global Brass and Copper Holdings, Inc.		$	41,633		$	42,311		$	76,931		$	3,654		$	(122,896	)	$	41,633
Cash flows from operating activities
Net cash provided by (used in) operating activities		$	—		$	(5,275	)	$	15,537		$	1,024		$	(6,754	)	$	4,532
Cash flows from investing activities																				Global Brass and Copper Holdings, Inc.
Capital expenditures			—			(76	)		(13,074	)		(55	)		—			(13,205	)	Condensed Consolidating Statement of Comprehensive Income
Payable to subsidiaries			(4,875	)		—			—			—			4,875			—		Year Ended December 31, 2012
Proceeds from sale of property, plant and equipment			—			—			170			4			—			174
Net cash used in investing activities			(4,875	)		(76	)		(12,904	)		(51	)		4,875			(13,031	)			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
Cash flows from financing activities																												Subsidiaries			Subsidiaries
Borrowings on ABL Facility			—			337,236			—			—			—			337,236		Net income		$	12,521		$	13,398		$	74,279		$	4,529		$	(91,832	)	$	12,895
Payments on ABL Facility			—			(329,258	)		—			—			—			(329,258	)	Other comprehensive income (loss):
Distribution to stockholder			—			—			—			(2,000	)		2,000			—		Foreign currency translation adjustment			(457	)		(457	)		(521	)		1,060			(74	)		(449	)
Net payments (amounts due) from stockholder			4,875			—			—			—			—			4,875
																				Comprehensive income			12,064			12,941			73,758			5,589			(91,906	)		12,446
Net cash provided by (used in) financing activities			4,875			7,978			—			(2,000	)		2,000			12,853		Less: Comprehensive income attributable to noncontrolling interest			—			—			—			382			—			382
Effect of foreign currency exchange rate changes			—			—			—			(128	)		—			(128	)
																				Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		$	12,064		$	12,941		$	73,758		$	5,207		$	(91,906	)	$	12,064
Net increase (decrease) in cash			—			2,627			2,633			(1,155	)		121			4,226
Cash at beginning of period			—			8,537			—			5,446			(121	)		13,862
																				Global Brass and Copper Holdings, Inc.
Cash at end of period		$	—		$	11,164		$	2,633		$	4,291		$	—		$	18,088		Condensed Consolidating Statement of Comprehensive Income
																				Year Ended December 31, 2011
		Condensed Consolidating Statement of Cash Flows																				Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
		Nine Months Ended September 30, 2012																										Subsidiaries			Subsidiaries
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated			Net income		$	55,132		$	56,147		$	92,080		$	3,126		$	(151,197	)	$	55,288
								Subsidiaries			Subsidiaries									Other comprehensive income (loss):
Cash flows from operating activities																				Foreign currency translation adjustment			362			362			415			(417	)		(253	)		469
Net cash provided by (used for) operating activities		$	73,624		$	49,063		$	10,765		$	(30	)	$	(75,170	)	$	58,252
Cash flows from investing activities																				Comprehensive income			55,494			56,509			92,495			2,709			(151,450	)		55,757
Capital expenditures			—			(549	)		(10,790	)		(21	)		—			(11,360	)	Less: Comprehensive income attributable to noncontrolling interest			—			—			—			263			—			263
Capital distributions from subsidiary			86,376			—			—						(86,376	)		—
Payable to subsidiaries			2,398			—			—			—			(2,398	)		—		Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		$	55,494		$	56,509		$	92,495		$	2,446		$	(151,450	)	$	55,494
Proceeds from sale of property, plant and equipment			—			—			25			—			—			25
Net cash provided by (used in) investing activities			88,774			(549	)		(10,765	)		(21	)		(88,774	)		(11,335	)	Global Brass and Copper Holdings, Inc.
Cash flows from financing activities																				Condensed Consolidating Statement of Comprehensive Income
Deferred financing fees			—			(12,981	)		—			—			—			(12,981	)	Year Ended December 31, 2010
Proceeds from senior secured notes			—			375,000			—			—			—			375,000
Payments on term loan			—			(310,875	)		—			—			—			(310,875	)
Borrowings on ABL Facility			—			142,400			—			—			—			142,400				Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
Payments on ABL Facility			—			(113,900	)		—			—			—			(113,900	)									Subsidiaries			Subsidiaries
Distribution to stockholder			(160,000	)		(160,000	)		—			—			160,000			(160,000	)	Net income		$	41,633		$	42,311		$	76,931		$	4,166		$	(122,896	)	$	42,145
Amounts due from stockholder			(2,398	)		—			—			—			—			(2,398	)	Other comprehensive income (loss):
																				Foreign currency translation adjustment			442			442			1,430			(1,741	)		(60	)		513
Net cash used in financing activities			(162,398	)		(80,356	)		—			—			160,000			(82,754	)
Effect of foreign currency exchange rate changes			—			—			—			(682	)		—			(682	)	Comprehensive income			42,075			42,753			78,361			2,425			(122,956	)		42,658
																				Less: Comprehensive income attributable to noncontrolling interest			—			—			—			583			—			583
Net decrease in cash			—			(31,842	)		—			(733	)		(3,944	)		(36,519	)
Cash at beginning of period			—			45,302			—			4,648			(413	)		49,537		Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		$	42,075		$	42,753		$	78,361		$	1,842		$	(122,956	)	$	42,075
Cash at end of period		$	—		$	13,460		$	—		$	3,915		$	(4,357	)	$	13,018
																				Global Brass and Copper Holdings, Inc.
																				Condensed Consolidating Statement of Cash Flows
																				Year Ended December 31, 2012
																						Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
																												Subsidiaries			Subsidiaries
																				Cash flows from operating activities
																				Net cash provided by operating activities		$	73,624		$	58,118		$	19,781		$	1,299		$	(70,908	)	$	81,914
																				Cash flows from investing activities
																				Capital expenditures			—			(549	)		(19,813	)		(46	)		—			(20,408	)
																				Capital distributions from subsidiary			86,376			—			—			—			(86,376	)		—
																				Payable to subsidiaries			2,424			—			—			—			(2,424	)		—
																				Other			—			—			32			—			—			32
																				Net cash provided by (used in) investing activities			88,800			(549	)		(19,781	)		(46	)		(88,800	)		(20,376	)
																				Cash flows from financing activities
																				Deferred financing fees			—			(12,981	)		—			—			—			(12,981	)
																				Proceeds from senior secured notes			—			375,000			—			—			—			375,000
																				Payments on term loan			—			(310,875	)		—			—			—			(310,875	)
																				Borrowings on ABL Facility			—			204,275			—			—			—			204,275
																				Payments on ABL Facility			—			(189,753	)		—			—			—			(189,753	)
																				Distributions to stockholder			(160,000	)		(160,000	)		—			—			160,000			(160,000	)
																				Amounts due from stockholder			(2,424	)		—			—			—			—			(2,424	)
																				Net cash used in financing activities			(162,424	)		(94,334	)		—			—			160,000			(96,758	)
																				Effect of foreign currency exchange rate changes			—			—			—			(455	)		—			(455	)
																				Net (decrease) increase in cash			—			(36,765	)		—			798			292			(35,675	)
																				Cash at beginning of year			—			45,302			—			4,648			(413	)		49,537
																				Cash at end of year		$	—		$	8,537		$	—		$	5,446		$	(121	)	$	13,862
																				Global Brass and Copper Holdings, Inc.
																				Condensed Consolidating Statement of Cash Flows
																				Year Ended December 31, 2011
																						Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
																												Subsidiaries			Subsidiaries
																				Cash flows from operating activities
																				Net cash provided by operating activities		$	—		$	37,381		$	22,250		$	2,687		$	2,530		$	64,848
																				Cash flows from investing activities
																				Capital expenditures			—			(946	)		(21,429	)		(65	)		—			(22,440	)
																				Payable to subsidiaries			2,451			—			—			—			(2,451	)		—
																				Other			—			—			95			2			—			97
																				Net cash provided by (used in) investing activities			2,451			(946	)		(21,334	)		(63	)		(2,451	)		(22,343	)
																				Cash flows from financing activities
																				Deferred financing fees			—			(1,675	)		—			—			—			(1,675	)
																				Payments on term loan			—			(3,300	)		—			—			—			(3,300	)
																				Borrowings on ABL Facility			—			168,021			—			—			—			168,021
																				Payments on ABL Facility			—			(168,021	)		—			—			—			(168,021	)
																				Principal payments under capital lease obligation			—			—			(916	)		—			—			(916	)
																				Amounts due from stockholder			(2,451	)		—			—			—			—			(2,451	)
																				Net cash used in financing activities			(2,451	)		(4,975	)		(916	)		—			—			(8,342	)
																				Effect of foreign currency exchange rate changes			—			—			—			(149	)		—			(149	)
																				Net increase in cash			—			31,460			—			2,475			79			34,014
																				Cash at beginning of year			—			13,842			—			2,173			(492	)		15,523
																				Cash at end of year		$	—		$	45,302		$	—		$	4,648		$	(413	)	$	49,537
																				Global Brass and Copper Holdings, Inc.
																				Condensed Consolidating Statement of Cash Flows
																				Year Ended December 31, 2010
																						Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
																												Subsidiaries			Subsidiaries
																				Cash flows from operating activities
																				Net cash provided by operating activities		$	42,500		$	60,079		$	9,237		$	590		$	(42,992	)	$	69,414
																				Cash flows from investing activities
																				Capital expenditures			—			—			(11,664	)		(263	)		—			(11,927	)
																				Other			—			—			39			—			—			39
																				Net cash provided by (used in) investing activities			—			—			(11,625	)		(263	)		—			(11,888	)
																				Cash flows from financing activities
																				Deferred financing fees			—			(15,131	)		—			—			—			(15,131	)
																				Proceeds from term loan			—			305,550			—			—			—			305,550
																				Payments on term loan			—			(825	)		—			—			—			(825	)
																				Borrowings on ABL Facility			—			1,096,578			—			—			—			1,096,578
																				Payments on ABL Facility			—			(1,272,197	)		—			—			—			(1,272,197	)
																				Principal payments under capital lease obligation			—			—			(52	)		—			—			(52	)
																				Payments on related party debt			—			(119,805	)		—			—			—			(119,805	)
																				Distribution to stockholder			(42,500	)		(42,500	)		—			—			42,500			(42,500	)
																				Cash overdrafts			—			(1,228	)		—			—			—			(1,228	)
																				Net cash used in financing activities			(42,500	)		(49,558	)		(52	)		—			42,500			(49,610	)
																				Effect of foreign currency exchange rate changes			—			—			—			(225	)		—			(225	)
																				Net increase (decrease) in cash			—			10,521			(2,440	)		102			(492	)		7,691
																				Cash at beginning of year			—			3,321			2,440			2,071			—			7,832
																				Cash at end of year		$	—		$	13,842		$	—		$	2,173		$	(492	)	$	15,523

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2013
Subsequent Events [Abstract]	'
Subsequent Events	'
		19	Subsequent Events
	On October 1, 2013, the Company completed its follow-on public offering. See further discussion in note 1, “Basis of Presentation and Principles of Consolidation” and note 12, “Related Parties”.

Organization_and_Formation_of_

Organization and Formation of the Company	12 Months Ended
	Dec. 31, 2012
Accounting Policies [Abstract]	'
Organization and Formation of the Company	'
		1	Organization and Formation of the Company
	Global Brass and Copper Holdings, Inc. (“Holdings” or the “Company”), an investee company of KPS Capital Partners, L.P. and its affiliates (“KPS”), was incorporated in Delaware, on October 10, 2007. KPS is the majority shareholder of Halkos Holdings, LLC (“Halkos”). Halkos owns 100% of Holdings. Holdings, through its wholly-owned principal operating subsidiary, Global Brass and Copper, Inc. (“GBC”), commenced commercial operations on November 19, 2007 through the acquisition of the metals business from Olin Corporation. GBC is a leading value added manufacturer, fabricator and distributor of specialty copper and brass products in North America.
	The Company is operated and managed through three distinct divisions which are also the Company’s reportable segments: GBC Metals, LLC (“Olin Brass”), Chase Brass and Copper Company, LLC (“Chase”) and A.J. Oster, LLC (“Oster”).
	Olin Brass
	The Olin Brass division manufactures sheet, strip and fabricated components by primarily processing copper and copper alloys. The division also rerolls and forms other alloys such as stainless and carbon steel.
	Olin Brass manufactures its products through four sites in North America. The strip mill in East Alton, IL is the main operating facility, which produces strip products. Strip products are processed further through the division’s downstream operations for specified uses. The division’s downstream operations include: a stamping operation located also in East Alton, IL; a rolling mill in Waterbury, CT with rolling, annealing, leveling, plating and slitting capabilities for various products; a rolling mill in Bryan, OH specializing in products sold in the automotive and electrical connectors end-market; and a manufacturing facility in Cuba, MO that produces high frequency welded copper-alloy tube for heat transfer, utility, decorative, automotive and plumbing applications.
	Olin Brass also has operations in Guangzhou, People’s Republic of China, or PRC, through a service center joint venture with Luoyang Copper. Olin Brass’s products are distributed either directly to customers or through Oster.
	Chase
	Chase manufactures round and hexagonal shaped brass rod. The main attributes of brass rod are its machinability, corrosion resistance and moderate strength, and it is used for forging and machining products such as valves and fittings.
	All of the division’s rod is manufactured at the facility located in Montpelier, OH. Chase distributes all of its products directly to customers.
	Oster
	Oster is a distributor of primarily copper and copper-alloy strip products as well as phosphor bronze, nickel, silver, stainless steel and aluminum products. Oster operates as an independent service center with Olin Brass as its primary supplier. Oster also conducts finishing operations on products it distributes, including slitting, traverse coil winding, edging and cutting that aim to enhance product quality and usefulness.
	Oster has six service centers in the U.S. and Mexico, which are strategically located with the objective to service customers throughout North America.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2012
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
		2		Summary of Significant Accounting Policies
	Principles of Consolidation
	The consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries and its majority-owned subsidiaries, in which the Company holds a controlling interest. All intercompany accounts and transactions are eliminated in consolidation. The equity method is used to account for investments in affiliated companies, 20% to 50% owned, where the Company does not hold a controlling voting interest and does not direct the matters that most significantly impact the investee’s operations.
	The Company owns an 80% interest in Olin Luotong (GZ) Corporation (“Luotong”), based in China, and Luotong’s financial information is consolidated herein, with the net results attributable to the 20% noncontrolling interest reflected in the consolidated financial statements.
	Use of Estimates and Assumptions
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. In addition, it requires management to make estimates and assumptions that affect the reported amount of net sales and expenses during the reporting period. Actual amounts could differ from those estimates.
	Revision of Prior Period Financial Statements
	During 2012, the Company identified the following errors:
		1	The Company historically had not recognized deferred tax assets or liabilities related to inside basis differences of its foreign subsidiaries. The unrecognized net deferred tax asset was $797, $888, and $794 as January 1, 2010, December 31, 2010 and December 31, 2011, respectively. The provision for income taxes was overstated by $91 and understated by $94 for the years ended December 31, 2010 and 2011, respectively.
		2	Duplicate accruals for the receipt of raw material were identified in the third quarter of fiscal 2012. The error had no impact on the year ended December 31, 2010. Accrued liabilities and cost of sales were overstated by $389 as of and for the year ended December 31, 2011.
		3	An error in the accounting for raw material in-transit was identified in the third quarter of fiscal 2012. Inventory was understated by $22 as of January 1, 2010 and overstated by $275 and $423 as of December 31, 2010 and 2011, respectively. Cost of sales was understated by $297 and $148 for the years ended December 31, 2010 and 2011, respectively.
	Additionally, the Company identified immaterial errors in previously issued consolidated financial statements which were corrected in the year identified, including:
		4	An error in accounting for workers’ compensation insurance that was corrected during the year ended December 31, 2011 by decreasing cost of sales by $44 and by increasing prepaid expenses and other current assets by $7,269 and increasing accrued liabilities by $7,225. Prepaid expenses and other current assets were understated by $5,036 and $7,269 as of January 1, 2010 and December 31, 2010, respectively. Accrued liabilities were understated by $5,725 and $7,225 as of January 1, 2010 and December 31, 2010, respectively. Cost of sales was overstated by $733 for the year ended December 31, 2010.
		5	An error in accounting for certain derivative contracts that was corrected during the year ended December 31, 2011 by increasing prepaid expenses and other current assets and decreasing cost of sales by $510. Prepaid expenses and other current assets were overstated by $303 as of January 1, 2010 and understated by $510 as of December 31, 2010. Cost of sales was overstated by $813 for the year ended December 31, 2010.
	The Company assessed the materiality of all errors, individually and in the aggregate, on previously issued consolidated financial statements and concluded that the errors were not material to any of the Company’s previously issued quarterly or annual financial statements. In assessing the effect of correcting previously unrecorded errors in 2012, the Company has concluded that correction of these errors in 2012 could be considered material to 2012 net income. Accordingly, the consolidated financial statements as of and for the year ended December 31, 2011 and as of and for the year ended December 31, 2010 have been revised to reflect the correction of all errors identified in their proper periods. To recognize the cumulative effect of all error corrections as of January 1, 2010, an adjustment of $482 was made to increase retained earnings.
	A summary of the revisions to the consolidated financial statements as of December 31, 2011 and 2010 and for the periods ended December 31, 2011 and 2010 is as follows:
			As Previously			Adjustment			As Revised
			Reported
	Consolidated Balance Sheet
			December 31, 2010
	Inventories		$	192,898		$	(275	)	$	192,623
	Prepaid expenses and other current assets			30,662			7,779			38,441
	Deferred income tax assets—current			28,433			879			29,312
	Income tax receivable			2,139			137			2,276
	Total current assets			431,044			8,520			439,564
	Deferred income tax assets—noncurrent			34,354			(100	)		34,254
	Total assets			529,301			8,420			537,721
	Accrued liabilities			78,002			6,990			84,992
	Income tax payable			—			199			199
	Total current liabilities			163,810			7,189			170,999
	Total liabilities			502,063			7,189			509,252
	Retained earnings			12,355			1,231			13,586
	Total Global Brass and Copper Holdings, Inc. stockholder’s equity			24,333			1,231			25,564
	Total equity			27,238			1,231			28,469
	Total liabilities and equity			529,301			8,420			537,721
	Consolidated Statement of Operations
			Year Ended December 31, 2010
	Cost of sales		$	1,497,944		$	(1,249	)	$	1,496,695
	Gross profit			160,785			1,249			162,034
	Operating income			91,928			1,249			93,177
	Income before provision for income taxes and equity income			66,042			1,249			67,291
	Provision for income taxes			26,176			500			26,676
	Income before equity income			39,866			749			40,615
	Net income			41,396			749			42,145
	Net income attributable to Global Brass and Copper Holdings, Inc.			40,884			749			41,633
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic		$	1.94		$	0.03		$	1.97
	Consolidated Statement of Comprehensive Income
			Year Ended December 31, 2010
	Net income		$	41,396		$	749		$	42,145
	Comprehensive income			41,909			749			42,658
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			41,326			749			42,075
	Consolidated Statement of Changes in Equity
			Year Ended December 31, 2010
	Net income		$	41,396		$	749		$	42,145
	Net income attributable to Global Brass and Copper Holdings, Inc.			40,884			749			41,633
	Retained earnings —Balance, December 31, 2010			12,355			1,231			13,586
	Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, December 31, 2010			24,333			1,231			25,564
	Total equity—Balance, December 31, 2010			27,238			1,231			28,469
			As			Adjustment			As Revised
			Previously
			Reported
	Consolidated Balance Sheet
		31-Dec-11
Accounts receivable, net of allowance		$	160,731		$	984		$	161,715
Inventories			186,370			(423	)		185,947
Deferred income tax assets—current			27,972			1,055			29,027
Income tax receivable			5,017			29			5,046
Total current assets			449,539			1,645			451,184
Deferred income tax assets—noncurrent			20,218			(248	)		19,970
Total assets			547,343			1,397			548,740
Accounts payable			78,276			(388	)		77,888
Accrued liabilities			47,619			985			48,604
Income tax payable			—			300			300
Total current liabilities			161,844			897			162,741
Total liabilities			465,183			897			466,080
Retained earnings			68,218			500			68,718
Total Global Brass and Copper Holdings, Inc. stockholder’s equity			78,992			500			79,492
Total equity			82,160			500			82,660
Total liabilities and equity			547,343			1,397			548,740
Consolidated Statement of Operations
		Year Ended December 31, 2011
Cost of sales		$	1,582,925		$	548		$	1,583,473
Gross profit			196,218			(548	)		195,670
Operating income			126,827			(548	)		126,279
Income before provision for income taxes and equity income			86,385			(548	)		85,837
Provision for income taxes			31,254			183			31,437
Income before equity income			55,131			(731	)		54,400
Net income			56,019			(731	)		55,288
Net income attributable to Global Brass and Copper Holdings, Inc.			55,863			(731	)		55,132
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	2.65		$	(0.04	)	$	2.61
Consolidated Statement of Comprehensive Income
		Year Ended December 31, 2011
Net income		$	56,019		$	(731	)	$	55,288
Comprehensive income			56,488			(731	)		55,757
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			56,225			(731	)		55,494
Consolidated Statement of Changes in Equity
		Year Ended December 31, 2011
Net income		$	56,019		$	(731	)	$	55,288
Net income attributable to Global Brass and Copper Holdings, Inc.			55,863			(731	)		55,132
Retained earnings —Balance, December 31, 2011			68,218			500			68,718
Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, December 31, 2011			78,992			500			79,492
Total equity—Balance, December 31, 2011			82,160			500			82,660
Accounts Receivable and Allowance for Doubtful Accounts
Accounts receivable primarily consists of trade receivables for amounts billed to customers for products sold and other receivables. The determination of collectability of the Company’s accounts receivable requires management to make frequent judgments and estimates in order to determine the appropriate amount of allowance needed for doubtful accounts. In circumstances where the Company is aware of a customer’s inability to meet its financial obligations (e.g., bankruptcy filings or substantial down-grading of credit ratings), it records an allowance for bad debts equal to the amount the Company does not believe to be collectible. For all other customers, the Company recognizes allowances for bad debts based on its historical collection experience. If circumstances change (e.g., greater than expected defaults or an unexpected material change in a major customer’s ability to meet its financial obligations), the Company’s estimate of the recoverability of amounts due could be changed by a material amount. Accounts are written off once deemed to be uncollectible. Any subsequent cash collections relating to accounts that have been previously written off are recorded as a reduction to the provision for bad debts in the period of collection.
The reconciliation of the activity in the allowance for doubtful accounts is summarized below:
		Year Ended December 31,
		2012			2011			2010
Balance at beginning of period		$	2,067		$	7,921		$	7,505
Provision for bad debts, net of reductions			(814	)		(4,171	)		1,324
Write-offs, net of recoveries			—			(1,683	)		(908	)
Recoveries, net of write-offs			155			—			—
Balance at end of period		$	1,408		$	2,067		$	7,921
Inventories
Inventories include costs attributable to direct labor and manufacturing overhead but are primarily comprised of raw material costs. The material component of inventories that is valued on a last-in, first-out (“LIFO”) basis comprises approximately 70% and 72% of total inventory at December 31, 2012 and 2011, respectively. Other manufactured inventories, including the non-material components and certain non-U.S. inventories, are valued on a first-in, first-out (“FIFO”) basis. Elements of cost in finished goods inventory in addition to the cost of material include depreciation, utilities, consumable production supplies, maintenance, production wages and transportation costs.
Inventories are stated at the lower of cost or market. The market price of metals used in production and related scrap is subject to volatility. We evaluate the need to record adjustments for inventory on a regular basis. During periods when open market prices decline below net book value, the Company records a provision to reduce the carrying value of its inventory. Additionally, the Company records an estimate for slow moving and obsolete inventory based upon product knowledge, physical inventory observation, future demand, market conditions and an aging analysis of the inventory on hand. Our policy is to evaluate all inventories including raw material, work-in-process, finished goods, and spare parts. Inventory in excess of our estimated usage requirements is written down to its estimated net realizable value. See note 3, “Inventories,” in these notes to the consolidated financial statements.
Prepaid Expenses and Other Current Assets
Prepaid expenses are stated at historical cost, net of any related amortization, and consist of amounts which are of continuing benefit to the Company. See note 4, “Prepaid Expenses and Other Current Assets,” in these notes to the consolidated financial statements.
Property, Plant and Equipment
Property, plant and equipment are recorded at cost. Depreciation of property, plant and equipment generally is computed using the straight-line method based on the estimated useful lives of the assets as they are placed into service. Depreciation expense is recorded in cost of sales or selling, general and administrative costs depending on the nature and use of the underlying asset.
Expenditures for repairs, maintenance and minor renewals are expensed as incurred. Expenditures which improve an asset or extend its estimated useful life are capitalized. Interest related to the construction of qualifying assets is capitalized as part of the construction costs. When assets are retired or otherwise disposed of, the related cost and accumulated depreciation are removed from the accounts and any gain or loss is included in the accompanying consolidated statement of operations.
The Company reviews property, plant and equipment for impairment when a change in events or circumstances indicates that the carrying value of the assets may not be recoverable. The Company has determined that its asset group for impairment testing is comprised of the assets and liabilities of each of its reporting units. Reporting units are businesses, for which discrete financial information is available and reviewed by segment management. The Company’s reporting units are one level below the operating segment, with the exception of one operating segment, for which the operating segment represents the lowest level of identifiable cash flows. The Company determines the fair value of its asset group through various valuation techniques, including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. See note 5, “Property, Plant and Equipment,” in these notes to the consolidated financial statements.
Investment in Joint Venture
The Company owns a 50% interest in Dowa-Olin Metal Corporation (“Dowa”), a joint venture based in Japan. The Company accounts for Dowa under the equity method of accounting. Due to the timing of the receipt of available financial information, the results of Dowa are recorded on a one-month lag basis.
As a result of the purchase method of accounting, a negative basis difference of $9,416 was created between the Company’s books and the Company’s share of Dowa’s equity as of November 19, 2007. ASC 323, Investments—Equity Method & Joint Ventures, provides that the basis difference between the investor cost and underlying equity in net assets of the investee at the date of investment requires recognition unless it is attributable to a non-amortizing asset such as goodwill. The negative basis difference was created due to the bargain purchase event associated with the metals business acquired from Olin Corporation and was not attributable to any specific element of the joint venture itself. As the difference was not attributable to any of the specific assets of Dowa, the equity investment as a whole was assessed to determine the appropriate accretion period for the basis difference. The purpose of the joint venture is to provide Olin Brass’s high performance alloy materials to the Asia market through the licensing of Olin Brass technology. Given consideration of this use, the negative basis difference is being accreted over a period of 13 years. See note 7, “Investment in Joint Venture,” in these notes to the consolidated financial statements.
The Company reviews its equity method investment for impairment using an other-than-temporary model when triggering events are identified. An impairment loss is recognized when the investment’s carrying amount exceeds its fair value and this decline in fair value is deemed to be other-than-temporary.
Acquisitions and Goodwill
All acquisitions are accounted for using the acquisition method as prescribed by ASC 805, Business Combinations. The purchase price paid is allocated to the assets acquired and liabilities assumed based on their estimated fair values. Any excess purchase price over the fair value of the net assets acquired is recorded as goodwill.
Pursuant to ASC 350, Intangibles—Goodwill and Other, the Company does not amortize goodwill and other intangible assets with indefinite useful lives. The Company reviews goodwill to determine potential impairment annually, or more frequently if events and circumstances indicate that the asset might be impaired, by comparing the carrying value of the asset with the anticipated present value of future cash flows.
In 2011, the Financial Accounting Standards Board (“FASB”) amended its guidance to simplify the testing of goodwill for impairment. The amended guidance provides an option to perform a qualitative assessment to determine whether further impairment testing is necessary. If the qualitative evaluation yields support that it is more likely than not that the fair value of a reporting unit exceeds its carrying value, the quantitative impairment test is not required. The Company adopted the qualitative goodwill evaluation model for its annual goodwill impairment test conducted as of October 31, 2012. Based on the results of that qualitative assessment, the Company believes it was more likely than not that the fair value of the reporting units significantly exceeded their carrying values as of October 31, 2012, indicating no impairment of goodwill. The $4,399 of goodwill was assigned to the Chase business segment and as of December 31, 2012, $2,131 of goodwill is expected to be deductible for tax purposes.
Intangible Assets
Definite-lived intangible assets are recorded at fair value under the purchase method of accounting as of the respective acquisition dates and are amortized using the straight-line method over the estimated useful lives of the assets. Amortization expense related to intangible assets is reflected in selling, general and administrative expenses. Identifiable definite-lived intangible assets are reviewed for impairment whenever events or circumstances indicate that the carrying value may not be recoverable. See note 6, “Intangible Assets,” in these notes to the consolidated financial statements.
Deferred Financing Fees
Deferred financing fees incurred in connection with the issuance of debt are amortized as non-cash interest expense over the terms of the debt agreements.
Deferred financing fees incurred in connection with the issuance of the Senior Secured Notes, as defined in note 8, “Other Noncurrent Assets,” are amortized using the effective interest method over the term of the Senior Secured Notes. Deferred financing fees incurred in connection with the issuance of the ABL Facility, as defined in note 8, “Other Noncurrent Assets,” in these notes to the consolidated financial statements, are amortized on a straight-line basis over the term of the ABL Facility.
Derivative Contracts
The Company’s operating activities expose it to a variety of market risks, including risks related to the effects of commodity prices and interest rates. These financial exposures are monitored and managed by the Company as an integral part of its overall risk-management program. The Company does not enter into derivative contracts for speculation purposes where the objective is to generate profits. The Company has not applied hedge accounting to its derivative contracts in any of the years ended December 31, 2012, 2011 or 2010. The Company includes the fair value of the derivative contracts as assets or liabilities in its balance sheet and recognizes all amounts paid and received and changes in fair value of derivative contracts, including unrealized gains and losses, as adjustments to income. See note 13, “Derivative Contracts,” in these notes to the consolidated financial statements.
Revenue Recognition
The Company recognizes revenue for both toll and non-toll basis sales only when risk of loss and title passes to the customer, which generally occurs upon shipment. For the years ended December 31, 2012, 2011 and 2010, non-toll net sales were $1,576,070, $1,710,595 and $1,577,771, respectively. For the years ended December 31, 2012, 2011 and 2010, toll net sales were $74,450, $68,548 and $80,958, respectively. Estimates for future rebates on certain product lines and product returns are recognized in the period in which the revenue is recorded. Such rebates were not material for the years ended December 31, 2012, 2011 and 2010. Billings to customers for shipping costs are included in net sales and the cost of shipping product to those customers is reflected in cost of sales in the consolidated statements of operations.
Research and Development
The Company conducts research and development primarily through the Olin Brass reportable segment, the costs for which are expensed as incurred. Research and development expenditures for the years ended December 31, 2012, 2011 and 2010 were $1,516, $1,540 and $1,740, respectively, and are included as a component of selling, general and administrative expenses in the consolidated statements of operations.
Income Taxes
The provision for income taxes is determined using the asset and liability approach. The current and deferred tax consequences are measured by applying the provisions of enacted tax laws to determine the amount of taxes payable currently or in future years. Deferred income taxes are provided for temporary differences between the income tax basis of assets and liabilities and their carrying amounts for financial reporting purposes. A valuation allowance is recorded to reduce deferred tax assets when management determines it is “more likely than not” that some portion or all of the deferred tax assets will not be realized.
Profits Interest Compensation
Halkos has granted, pursuant to the Halkos Holdings, LLC Executive Equity Incentive Plan (“Halkos Equity Plan”), non-voting membership interests to select members of the Company’s management in the form of shares. The shares are profits interests in Halkos. See note 17, “Profits Interest Awards,” in these notes to the consolidated financial statements.
The shares are accounted for as a profit sharing arrangement under ASC 710, Compensation—General. Expense is recorded in the period in which distributions to award holders are determined to be probable. These distributions are accounted for by the Company as non-cash compensation expense with a corresponding increase in additional paid-in capital.
Foreign Currency Translation
The financial statements of foreign subsidiaries are translated into United States dollars in accordance with ASC 830, Foreign Currency Matters. The functional currency of the Company’s foreign subsidiaries is the local currency. The consolidated statements of foreign operations are translated at weighted-average exchange rates for the periods. Assets and liabilities are translated at period-end exchange rates and equity transactions are translated at historical rates. Gains and losses resulting from the translation adjustment are reported as a component of other comprehensive income. The income tax effect of currency translation adjustments related to foreign subsidiaries and joint ventures that are not considered indefinitely reinvested are recorded as a component of deferred taxes with an offset to other comprehensive income.
Concentrations of Credit Risk and Certain Other Exposures
The Company sells and distributes its products to a wide range of companies primarily in the ammunition, automotive, electronics, housing and coinage industries. The Company performs ongoing credit evaluations of its customers and generally does not require collateral. For the years ended December 31, 2012, 2011 and 2010, sales to any one customer did not exceed 10% of consolidated net sales.
The Company uses various strategies to minimize the impact of changes in the base metal prices between the date of order and the date of sale. Generally, the Company prices a forward replacement purchase of an equivalent amount of copper and other metals under flexible pricing arrangements it maintains with its suppliers, at the same time it determines the forward selling price of finished products to its customers. The Company has various sources of raw materials and is not materially dependent on any one supplier.
There are nine unions at the Olin Brass division, two labor unions at the Oster division, and one labor union at the Chase division. In 2012, employees at an Olin Brass downstream operation elected a union representative which was subsequently certified. The relationship with these unions has been satisfactory. The collective bargaining agreements with the Olin Brass unions expire between November 2013 and September 2014, the collective bargaining agreements with Oster’s unions expire January 2014 and the other has an indeterminable term, and the collective bargaining agreement with Chase’s union expires in June 2013. Since the Company’s establishment in November 2007, the Company has not experienced any work stoppages at any of its facilities.
Self-Insurance Programs
The Company is self-insured for workers’ compensation claims and benefits paid under employee health care programs. Accruals for employee health care are primarily based on estimated undiscounted cost of claims, which includes incurred but not reported claims. Accruals for workers’ compensation benefits and related expenses for claims are estimated, in part, by considering historical claims experience and undiscounted claims estimates provided by insurance carriers, third-party administrators and actuaries. Self-insurance accruals are deemed to be sufficient to cover outstanding claims, including those incurred but not reported as of the estimation date.
Workers’ compensation claims relating to activity after November 19, 2007 are covered by a loss funding insurance arrangement whereby the Company makes a fixed payment to the insurer which is used to pay submitted claims. Loss fund payments to the insurer in excess of workers’ compensation claim payments are classified as prepaid expenses and other current assets. The amount of the loss fund payments to the insurer is based on a combination of claims experience and a contractually agreed upon loss development factor.
Environmental Reserves and Environmental Expenses
The Company recognizes an environmental liability when it is probable the liability exists and the amount is reasonably estimable. The Company estimates the duration and extent of its remediation obligations based upon internal analyses of clean-up costs, ongoing monitoring costs and estimated legal fees, communications with regulatory agencies and changes in environmental law. If the Company were to determine that its estimates of the duration or extent of its environmental obligations were no longer accurate, the Company would adjust its environmental liabilities accordingly in the period that such determination is made. Estimated future expenditures for environmental remediation are not discounted to their present value. Accrued environmental liabilities are not reduced by potential insurance reimbursements.
Environmental expenses that relate to ongoing operations are included as a component of cost of sales. See note 16, “Commitments and Contingencies,” in these notes to the consolidated financial statements.
Recent Accounting Pronouncements
In February 2013, the FASB issued Accounting Standards Update (“ASU”) 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income. This guidance requires entities to provide disclosures about items that are required by U.S. GAAP to be reclassified from accumulated other comprehensive income (“AOCI”) to net income in their entirety in the same reporting period. The disclosure would include the amount of the reclassification and identify the line item on the statement where net income is presented that is affected by the reclassification. For other items reclassified from AOCI, the disclosure would list cross-references to other disclosures where additional details about their effects are disclosed. This guidance is effective for reporting periods beginning after December 15, 2012. The Company does not expect that adoption of the guidance will have a material effect on its financial statements and disclosures.
In December 2011, the FASB issued ASU 2011-11, Disclosures about Offsetting Assets and Liabilities. This guidance requires entities to disclose both gross and net information about both instruments and transactions eligible for offset in the statement of financial position and instruments and transactions subject to an agreement similar to a master netting arrangement. This guidance does not amend existing guidance on when it is appropriate to offset. In January 2013, the FASB issued ASU 2013-01, Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities, which limits the scope of ASU 2011-11 to derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and lending arrangements. The guidance is effective for annual periods beginning January 1, 2013 and interim periods within those annual periods. Early adoption is not permitted, but retrospective application is required. Adoption of the guidance is not expected to have a material impact on the Company’s consolidated financial statements and disclosures.

Property_Plant_and_Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2012
Property Plant And Equipment [Abstract]	'
Property, Plant and Equipment	'
		5		Property, Plant and Equipment
	The Company’s property, plant and equipment balances are as follows:
			As of December 31,						Useful Life
			2012			2011			(in years)
	Land and land improvements		$	1,726		$	1,598
	Buildings			9,077			8,489		20
	Machinery and equipment			55,175			42,715		12
	Information technology			4,477			2,462		5
	Motor vehicles			2,521			1,403		5
	Leasehold improvements			1,083			127
	Construction-in-process			13,324			10,279
	Gross property, plant and equipment			87,383			67,073
	Accumulated depreciation			(16,256	)		(9,517	)
	Property, plant and equipment, net		$	71,127		$	57,556
	Leasehold improvements are amortized over the lesser of their useful lives or the remaining lease term.
	The Company capitalized interest relating to the construction of long-term assets in the amount of $557 in 2011. No interest was capitalized in 2012 or 2010.

Intangible_Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2012
Goodwill And Intangible Assets Disclosure [Abstract]	'
Intangible Assets	'
		6		Intangible Assets
	Intangible assets other than goodwill consisted of the following:
			As of						Amortization
			December 31,						Period (in  years)
			2012			2011
	Gross carrying amount:
	Customer relationships		$	1,350		$	1,350			13
	Non-compete agreement			380			380			4
	Total gross intangible assets			1,730			1,730
	Accumulated amortization:
	Customer relationships			(511	)		(407	)
	Non-compete agreement			(380	)		(372	)
	Total accumulated amortization			(891	)		(779	)
	Intangible assets, net		$	839		$	951
	Amortization expense is expected to be incurred in subsequent years as follows:
	Year		Amortization
	2013		$	104
	2014			104
	2015			104
	2016			104
	2017			104
	Thereafter			319
			$	839

Employee_Defined_Contribution_

Employee Defined Contribution Plans and Multi-Employer Pension Plans	12 Months Ended
	Dec. 31, 2012
Postemployment Benefits [Abstract]	'
Employee Defined Contribution Plans and Multi-Employer Pension Plans	'
		12		Employee Defined Contribution Plans and Multi-Employer Pension Plans
	The Company has a retirement savings plan (the “Plan”) for all of its domestic subsidiaries under section 401(k) of the Internal Revenue Code that covers all U.S. salaried and most hourly employees. Participants may elect to defer a percentage of their compensation to the Plan, subject to aggregate limits required by the Internal Revenue Code. The Plan provides for discretionary matching contributions under certain circumstances, for employees based on location, pay status and membership in a collective bargaining unit. In addition, the Company provides a retirement contribution to certain employees based on location and age. The Company contributed $7,439, $7,412 and $6,599 to the Plan for the years ended December 31, 2012, 2011 and 2010, respectively.
	Bargaining unit employees in East Alton, IL and Alliance, OH participate in the IAM National Pension Plan (“IAM Plan”). The IAM Plan is a multi-employer pension plan with negotiated fixed company costs per employee hour worked. The risks of participating in these multiemployer plans are different from single-employer plans, as the Company can be subject to additional risks if others do not meet their obligations. The Company recorded expense of $2,714, $2,669 and $2,779 for the years ended December 31, 2012, 2011 and 2010, respectively, which are included in cost of sales in the consolidated statement of operations. The Company’s participation in the IAM Plan for the annual period ended December 31, 2012, is outlined in the table below. There have been no significant changes that affect the comparability of 2012 and 2011 contributions. The IAM Plan reported $350,359 and $332,430 in employers’ contributions for the years ended December 31, 2012 and 2011, respectively.
	Pension Fund		IAM National Pension Fund
	EIN/ Pension Plan Number		51-6031295 / 002
	Pension Protection Act Zone Status (2011 and 2010)*		Green Zone
	FIP/RP Status Pending/Implemented		No
	Company Contributions (FY 2012)		$2,699
	Company Contributions (FY 2011)		$2,689
	Surcharge Imposed		No
	Expiration Date of Collective-Bargaining Agreement		3-Nov-13
		*	Plans in the green zone are at least 80 percent funded.
	At the date the financial statements were issued, Forms 5500 were not available for the plan year ended in 2012.

Quarterly_Financial_Informatio

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]	'
Quarterly Financial Information (Unaudited)	'
		21		Quarterly Financial Information (Unaudited)
			2012
			First		Second			Third		Fourth
			Quarter (A)		Quarter (A)			Quarter (A)		Quarter
	Net sales		$	443,391	$	416,979		$	393,977	$	396,173
	Gross profit			49,954		47,121			44,397		41,714	(C)
	Income (loss) before provision for (benefit from) income taxes and equity income			21,971		(21,063	) (B)		17,645		12,532
	Net income (loss)			14,047		(19,891	)		11,137		7,602
	Net income (loss) attributable to Global Brass and Copper Holdings, Inc.			13,993		(20,005	)		11,032		7,501
	Net income (loss) attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic			0.66		(0.95	)		0.52		0.36
			2011
			First		Second			Third		Fourth
			Quarter (A)		Quarter (A)			Quarter (A)		Quarter (A)
	Net sales		$	492,915	$	473,251		$	439,500	$	373,477
	Gross profit			50,026		44,231			38,077		63,336	(D)
	Income before provision for income taxes and equity income			21,712		17,498			10,779		35,848
	Net income			14,170		10,268			7,280		23,570
	Net income attributable to Global Brass and Copper Holdings, Inc.			14,058		10,201			7,283		23,590
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic			0.67		0.48			0.35		1.12
		(A)	The above data have been adjusted for prior period revisions discussed in note 2, “Summary of Significant Accounting Policies” and as illustrated in note 22, “Revision of Prior Period Financial Statements (Unaudited)”.
		(B)	Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.
		(C)	Includes $4,775 gain from liquidation of LIFO inventory layers.
		(D)	Includes $15,236 gain from liquidation of LIFO inventory layers.

Revision_of_Prior_Period_Finan

Revision of Prior Period Financial Statements (Unaudited)	12 Months Ended
	Dec. 31, 2012
Accounting Changes And Error Corrections [Abstract]	'
Revision of Prior Period Financial Statements (Unaudited)	'
		22		Revision of Prior Period Financial Statements (Unaudited)
	As discussed in note 2 “Summary of Significant Accounting Policies”, during 2012, the Company identified and corrected certain errors. A summary of the revisions to the consolidated financial statements during the interim periods is as follows:
			As			Adjustment			As Revised
			Previously
			Reported
	Consolidated Balance Sheet
			March 31, 2011
	Inventories		$	202,745		$	(230	)	$	202,515
	Prepaid expenses and other current assets			23,623			7,478			31,101
	Deferred income tax assets—current			27,143			1,251			28,394
	Income tax receivable			2,666			327			2,993
	Total current assets			501,575			8,826			510,401
	Property, plant and equipment, net			42,475			112			42,587
	Deferred income tax assets—noncurrent			32,867			(347	)		32,520
	Total assets			601,811			8,591			610,402
	Accrued liabilities			65,352			7,240			72,592
	Income tax payable			—			398			398
	Total current liabilities			193,688			7,638			201,326
	Total liabilities			559,825			7,638			567,463
	Retained earnings			26,691			953			27,644
	Total Global Brass and Copper Holdings, Inc. stockholder’s equity			38,954			953			39,907
	Total equity			41,987			953			42,940
	Total liabilities and equity			601,811			8,591			610,402
	Consolidated Statement of Operations
			Three Months Ended March 31, 2011
	Cost of sales		$	442,383		$	506		$	442,889
	Gross profit			50,532			(506	)		50,026
	Operating income			31,672			(506	)		31,166
	Third party interest expense			9,562			(112	)		9,450
	Income before provision for income taxes and equity income			22,106			(394	)		21,712
	Provision for income taxes			7,956			(116	)		7,840
	Income before equity income			14,150			(278	)		13,872
	Net income			14,448			(278	)		14,170
	Net income attributable to Global Brass and Copper Holdings, Inc.			14,336			(278	)		14,058
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic		$	0.68		$	(0.01	)	$	0.67
	Consolidated Statement of Comprehensive Income
			Three Months Ended March 31, 2011
	Net income		$	14,448		$	(278	)	$	14,170
	Comprehensive income			14,771			(278	)		14,493
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			14,643			(278	)		14,365
	Consolidated Statement of Changes in Equity
			Three Months Ended March 31, 2011
	Net income		$	14,448		$	(278	)	$	14,170
	Net income attributable to Global Brass and Copper Holdings, Inc.			14,336			(278	)		14,058
	Retained earnings—Balance, March 31, 2011			26,691			953			27,644
	Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, March 31, 2011			38,954			953			39,907
	Total equity—Balance, March 31, 2011			41,987			953			42,940
	Consolidated Statement of Cash Flows
			Three Months Ended March 31, 2011
	Cash flows from operating activities:
	Net cash used in operating activities		$	(22,494	)	$	112		$	(22,382	)
	Cash flows from investing activities:
	Capital expenditures			(3,476	)		(112	)		(3,588	)
	Net cash used in investing activities			(3,476	)		(112	)		(3,588	)
	Consolidated Balance Sheet
			June 30, 2011
	Inventories		$	169,137		$	(402	)	$	168,735
	Prepaid expenses and other current assets			13,989			8,212			22,201
	Deferred income tax assets—current			25,823			1,230			27,053
	Income tax receivable			2,147			(343	)		1,804
	Total current assets			464,534			8,697			473,231
	Property, plant and equipment, net			47,507			273			47,780
Deferred income tax assets—noncurrent			32,450			(529	)		31,921
Total assets			565,534			8,441			573,975
Accrued liabilities			55,849			7,465			63,314
Total current liabilities			176,521			7,465			183,986
Total liabilities			514,032			7,465			521,497
Retained earnings			36,869			976			37,845
Total Global Brass and Copper Holdings, Inc. stockholder’s equity			48,371			976			49,347
Total equity			51,502			976			52,478
Total liabilities and equity			565,534			8,441			573,975
Consolidated Statements of Operations
		Three Months Ended June 30, 2011
Cost of sales		$	429,357		$	(337	)	$	429,020
Gross profit			43,894			337			44,231
Operating income			27,411			337			27,748
Third party interest expense			11,149			(161	)		10,988
Income before provision for income taxes and equity income			17,000			498			17,498
Provision for income taxes			6,783			475			7,258
Income before equity income			10,217			23			10,240
Net income			10,245			23			10,268
Net income attributable to Global Brass and Copper Holdings, Inc.			10,178			23			10,201
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	0.48		$	—		$	0.48
		Six Months Ended June 30, 2011
Cost of sales		$	871,740		$	169		$	871,909
Gross profit			94,426			(169	)		94,257
Operating income			59,083			(169	)		58,914
Third party interest expense			20,711			(273	)		20,438
Income before provision for income taxes and equity income			39,106			104			39,210
Provision for income taxes			14,739			359			15,098
Income before equity income			24,367			(255	)		24,112
Net income			24,693			(255	)		24,438
Net income attributable to Global Brass and Copper Holdings, Inc.			24,514			(255	)		24,259
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	1.16		$	(0.01	)	$	1.15
Consolidated Statements of Comprehensive Income
		Three Months Ended June 30, 2011
Net income		$	10,245		$	23		$	10,268
Comprehensive income			10,452			23			10,475
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			10,354			23			10,377
		Six Months Ended June 30, 2011
Net income		$	24,693		$	(255	)	$	24,438
Comprehensive income			25,223			(255	)		24,968
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			24,997			(255	)		24,742
Consolidated Statement of Changes in Equity
		Six Months Ended June 30, 2011
Net income		$	24,693		$	(255	)	$	24,438
Net income attributable to Global Brass and Copper Holdings, Inc.			24,514			(255	)		24,259
Retained earnings—Balance, June 30, 2011			36,869			976			37,845
Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, June 30, 2011			48,371			976			49,347
Total equity—Balance, June 30, 2011			51,502			976			52,478
Consolidated Statement of Cash Flows
		Six Months Ended June 30, 2011
Cash flows from operating activities:
Net cash provided by operating activities		$	32,428		$	273		$	32,701
Cash flows from investing activities:
Capital expenditures			(9,709	)		(273	)		(9,982	)
Net cash used in investing activities			(9,683	)		(273	)		(9,956	)
Consolidated Balance Sheet
		September 30, 2011
Inventories		$	163,880		$	(388	)	$	163,492
Prepaid expenses and other current assets			24,752			994			25,746
Deferred income tax assets—current			26,658			1,058			27,716
Income tax receivable			3,612			(352	)		3,260
Total current assets			462,786			1,312			464,098
Property, plant and equipment, net			51,589			478			52,067
Deferred income tax assets—noncurrent			31,903			(646	)		31,257
Total assets			565,819			1,144			566,963
Accounts payable			107,971			(12	)		107,959
Accrued liabilities			59,526			(235	)		59,291
Total current liabilities			175,291			(247	)		175,044
Total liabilities			507,655			(247	)		507,408
Retained earnings			43,737			1,391			45,128
Total Global Brass and Copper Holdings, Inc. stockholder’s equity			54,991			1,391			56,382
Total equity			58,164			1,391			59,555
Total liabilities and equity			565,819			1,144			566,963
Consolidated Statements of Operations
		Three Months Ended September 30, 2011
Cost of sales		$	401,931		$	(508	)	$	401,423
Gross profit			37,569			508			38,077
Operating income			20,471			508			20,979
Third party interest expense			10,159			(205	)		9,954
Income before provision for income taxes and equity income			10,066			713			10,779
Provision for income taxes			3,428			298			3,726
Income before equity income			6,638			415			7,053
Net income			6,865			415			7,280
Net income attributable to Global Brass and Copper Holdings, Inc.			6,868			415			7,283
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	0.33		$	0.02		$	0.35
		Nine Months Ended September 30, 2011
Cost of sales		$	1,273,671		$	(339	)	$	1,273,332
Gross profit			131,995			339			132,334
Operating income			79,554			339			79,893
Third party interest expense			30,870			(478	)		30,392
Income before provision for income taxes and equity income			49,172			817			49,989
Provision for income taxes			18,167			657			18,824
Income before equity income			31,005			160			31,165
Net income			31,558			160			31,718
Net income attributable to Global Brass and Copper Holdings, Inc.			31,382			160			31,542
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	1.49		$	—		$	1.49
Consolidated Statements of Comprehensive Income
		Three Months Ended September 30, 2011
Net income		$	6,865		$	415		$	7,280
Comprehensive income			6,955			415			7,370
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			6,913			415			7,328
		Nine Months Ended September 30, 2011
Net income		$	31,558		$	160		$	31,718
Comprehensive income			32,178			160			32,338
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			31,910			160			32,070
Consolidated Statement of Changes in Equity
		Nine Months Ended September 30, 2011
Net income		$	31,558		$	160		$	31,718
Net income attributable to Global Brass and Copper Holdings, Inc.			31,382			160			31,542
Retained earnings—Balance, September 30, 2011			43,737			1,391			45,128
Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, September 30, 2011			54,991			1,391			56,382
Total equity—Balance, September 30, 2011			58,164			1,391			59,555
Consolidated Statement of Cash Flows
		Nine Months Ended September 30, 2011
Cash flows from operating activities:
Net cash provided by operating activities		$	44,367		$	478		$	44,845
Cash flows from investing activities:
Capital expenditures			(15,062	)		(478	)		(15,540	)
Net cash used in investing activities			(14,992	)		(478	)		(15,470	)
Consolidated Statement of Operations
		Three Months Ended December 31, 2011
Cost of sales		$	309,254		$	887		$	310,141
Gross profit			64,223			(887	)		63,336
Operating income			47,273			(887	)		46,386
Third party interest expense			9,140			478			9,618
Income before provision for income taxes and equity income			37,213			(1,365	)		35,848
Provision for income taxes			13,087			(474	)		12,613
Income before equity income			24,126			(891	)		23,235
Net income			24,461			(891	)		23,570
Net income attributable to Global Brass and Copper Holdings, Inc.			24,481			(891	)		23,590
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	1.16		$	(0.04	)	$	1.12
Consolidated Statement of Comprehensive Income
		Three Months Ended December 31, 2011
Net income		$	24,461		$	(891	)	$	23,570
Comprehensive income			24,310			(891	)		23,419
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			24,315			(891	)		23,424
Consolidated Balance Sheet
		March 31, 2012
Accounts receivable, net of allowance		$	202,756		$	984		$	203,740
Inventories			173,538			(861	)		172,677
Deferred income tax assets—current			26,793			1,326			28,119
Income tax receivable			1,567			(162	)		1,405
Total current assets			496,052			1,287			497,339
Deferred income tax assets—noncurrent			20,092			(294	)		19,798
Total assets			593,912			993			594,905
Accounts payable			111,814			(389	)		111,425
Income Tax payable			—			64			64
Accrued liabilities			47,080			1,284			48,364
Total current liabilities			194,498			959			195,457
Total liabilities			497,460			959			498,419
Retained earnings			82,677			34			82,711
Total Global Brass and Copper Holdings, Inc. stockholder’s equity			93,213			34			93,247
Total equity			96,452			34			96,486
Total liabilities and equity			593,912			993			594,905
Consolidated Statement of Operations
		Three Months Ended March 31, 2012
Cost of sales		$	392,701		$	736		$	393,437
Gross profit			50,690			(736	)		49,954
Operating income			32,767			(736	)		32,031
Income before provision for income taxes and equity income			22,707			(736	)		21,971
Provision for income taxes			8,468			(270	)		8,198
Income before equity income			14,239			(466	)		13,773
Net income			14,513			(466	)		14,047
Net income attributable to Global Brass and Copper Holdings, Inc.			14,459			(466	)		13,993
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	0.68		$	(0.02	)	$	0.66
Consolidated Statement of Comprehensive Income
		Three Months Ended March 31, 2012
Net income		$	14,513		$	(466	)	$	14,047
Comprehensive income			14,533			(466	)		14,067
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			14,462			(466	)		13,996
Consolidated Statement of Changes in Equity
		Three Months Ended March 31, 2012
Net income		$	14,513		$	(466	)	$	14,047
Net income attributable to Global Brass and Copper Holdings, Inc.			14,459			(466	)		13,993
Retained earnings—Balance, March 31, 2012			82,677			34			82,711
Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, March 31, 2012			93,213			34			93,247
Total equity—Balance, March 31, 2012			96,452			34			96,486
Consolidated Balance Sheet
		June 30, 2012
Accounts receivable, net of allowance		$	192,326		$	984		$	193,310
Inventories			180,815			(811	)		180,004
Deferred income tax assets—current			28,079			1,264			29,343
Income tax receivable			4,996			(476	)		4,520
Total current assets			429,443			961			430,404
Deferred income tax assets—noncurrent			19,917			(260	)		19,657
Total assets			538,522			701			539,223
Accounts payable			105,981			(1,396	)		104,585
Accrued liabilities			39,590			984			40,574
Total current liabilities			148,919			(412	)		148,507
Total liabilities			605,586			(412	)		605,174
Accumulated deficit			(67,799	)		1,113			(66,686	)
Total Global Brass and Copper Holdings, Inc. stockholder’s deficit			(70,422	)		1,113			(69,309	)
Total deficit			(67,064	)		1,113			(65,951	)
Total liabilities and deficit			538,522			701			539,223
Consolidated Statements of Operations
		Three Months Ended June 30, 2012
Cost of sales		$	371,213		$	(1,355	)	$	369,858
Gross profit			45,766			1,355			47,121
Operating income			7,801			1,355			9,156
Loss before provision for income taxes and equity income			(22,418	)		1,355			(21,063	)
Benefit from income taxes			(1,247	)		276			(971	)
Income before equity income			(21,171	)		1,079			(20,092	)
Net loss			(20,970	)		1,079			(19,891	)
Net loss attributable to Global Brass and Copper Holdings, Inc.			(21,084	)		1,079			(20,005	)
Net loss attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	(1.00	)	$	0.05		$	(0.95	)
		Six Months Ended June 30, 2012
Cost of sales		$	763,914		$	(619	)	$	763,295
Gross profit			96,456			619			97,075
Operating income			40,568			619			41,187
Income before provision for income taxes and equity income			289			619			908
Provision for income taxes			7,221			6			7,227
Loss before equity income			(6,932	)		613			(6,319	)
Net loss			(6,457	)		613			(5,844	)
Net loss attributable to Global Brass and Copper Holdings, Inc.			(6,625	)		613			(6,012	)
Net loss attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	(0.31	)	$	0.03		$	(0.28	)
Consolidated Statements of Comprehensive Loss
		Three Months Ended June 30, 2012
Net loss		$	(20,970	)	$	1,079		$	(19,891	)
Comprehensive loss			(21,113	)		1,079			(20,034	)
Comprehensive loss attributable to Global Brass and Copper Holdings, Inc.			(21,232	)		1,079			(20,153	)
		Six Months Ended June 30, 2012
Net loss		$	(6,457	)	$	613		$	(5,844	)
Comprehensive loss			(6,580	)		613			(5,967	)
Comprehensive loss attributable to Global Brass and Copper Holdings, Inc.			(6,770	)		613			(6,157	)
Consolidated Statement of Changes in Equity
		Six Months Ended June 30, 2012
Net loss		$	(6,457	)	$	613		$	(5,844	)
Net loss attributable to Global Brass and Copper Holdings, Inc.			(6,625	)		613			(6,012	)
Accumulated deficit—Balance, June 30, 2012			(67,799	)		1,113			(66,686	)
Total Global Brass and Copper Holdings, Inc. stockholder’s deficit—Balance, June 30, 2012			(70,422	)		1,113			(69,309	)
Total deficit—Balance, June 30, 2012			(67,064	)		1,113			(65,951	)
Consolidated Balance Sheet
		September 30, 2012
Accounts receivable, net of allowance		$	210,654		$	984		$	211,638
Deferred income tax assets—current			25,390			971			26,361
Income tax receivable			648			(174	)		474
Total current assets			445,517			1,781			447,298
Deferred income tax assets—noncurrent			17,350			(310	)		17,040
Total assets			554,198			1,471			555,669
Accrued liabilities			58,620			984			59,604
Income tax payable			—			58			58
Total current liabilities			179,553			1,042			180,595
Total liabilities			609,685			1,042			610,727
Accumulated deficit			(56,083	)		429			(55,654	)
Total Global Brass and Copper Holdings, Inc. stockholder’s deficit			(58,928	)		429			(58,499	)
Total deficit			(55,487	)		429			(55,058	)
Total liabilities and deficit			554,198			1,471			555,669
Consolidated Statements of Operations
		Three Months Ended September 30, 2012
Cost of sales		$	348,995		$	585		$	349,580
Gross profit			44,982			(585	)		44,397
Operating income			27,629			(585	)		27,044
Income before provision for income taxes and equity income			18,230			(585	)		17,645
Provision for income taxes			6,670			99			6,769
Income before equity income			11,560			(684	)		10,876
Net income			11,821			(684	)		11,137
Net income attributable to Global Brass and Copper Holdings, Inc.			11,716			(684	)		11,032
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	0.55		$	(0.03	)	$	0.52
		Nine Months Ended September 30, 2012
Cost of sales		$	1,112,909		$	(34	)	$	1,112,875
Gross profit			141,438			34			141,472
Operating income			68,197			34			68,231
Income before provision for income taxes and equity income			18,519			34			18,553
Provision for income taxes			13,891			105			13,996
Income before equity income			4,628			(71	)		4,557
Net income			5,364			(71	)		5,293
Net income attributable to Global Brass and Copper Holdings, Inc.			5,091			(71	)		5,020
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	0.24		$	—		$	0.24
Consolidated Statements of Comprehensive Income
		Three Months Ended September 30, 2012
Net income		$	11,821		$	(684	)	$	11,137
Comprehensive income			11,814			(684	)		11,130
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			11,731			(684	)		11,047
		Nine Months Ended September 30, 2012
Net income		$	5,364		$	(71	)	$	5,293
Comprehensive income			5,234			(71	)		5,163
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			4,961			(71	)		4,890
Consolidated Statement of Changes in Equity
		Nine Months Ended September 30, 2012
Net income		$	5,364		$	(71	)	$	5,293
Net income attributable to Global Brass and Copper Holdings, Inc.			5,091			(71	)		5,020
Accumulated deficit—Balance, September 30, 2012			(56,083	)		429			(55,654	)
Total Global Brass and Copper Holdings, Inc. stockholder’s deficit—Balance, September 30, 2012			(58,928	)		429			(58,499	)
Total deficit—Balance, September 30, 2012			(55,487	)		429			(55,058	)

Schedule_I_Condensed_Financial

Schedule I - Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2012
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]	'
Schedule I - Condensed Financial Information of Registrant	'
	Schedule I – Condensed Financial Information of Registrant
	Global Brass and Copper Holdings, Inc. (Parent Company Only)
	Condensed Balance Sheets
			As of December 31,
	(In thousands, except share data)		2012			2011
	Assets
	Current assets:
	Cash		$	—		$	—
	Total current assets			—			—
	Investment in subsidiary			—			85,020
	Total assets		$	—		$	85,020
	Liabilities and stockholder’s (deficit)/equity
	Current liabilities:
	Accounts payable		$	—		$	—
	Total current liabilities			—			—
	Payable to subsidiary			8,829			5,528
	Obligations and advances in excess of investment in subsidiary			42,522			—
	Total liabilities			51,351			5,528
	Stockholder’s (deficit)/equity:
	Common stock—$.01 par value; 80,000,000 shares authorized; 21,110,000 shares issued and outstanding at December 31, 2012 and 2011			211			211
	Additional paid-in capital			—			11,091
	(Accumulated deficit)/retained earnings			(48,153	)		68,718
	Accumulated other comprehensive income			1,466			1,923
	Receivable from stockholder			(4,875	)		(2,451	)
	Total stockholder’s (deficit)/equity			(51,351	)		79,492
	Total liabilities and stockholder’s (deficit)/equity		$	—		$	85,020
	See accompanying notes to condensed financial statements.
	Schedule I – Condensed Financial Information of Registrant
	Global Brass and Copper Holdings, Inc. (Parent Company Only)
	Condensed Statements of Operations
			Year Ended December 31,
	(In thousands)		2012			2011			2010
	Net sales		$	—		$	—		$	—
	Cost of sales			—			—			—
	Gross profit			—			—			—
	Selling, general and administrative expenses			1,427			1,650			1,102
	Loss before income taxes and equity income			(1,427	)		(1,650	)		(1,102	)
	Benefit from income taxes			(550	)		(635	)		(424	)
	Loss before equity income			(877	)		(1,015	)		(678	)
	Equity income, net of tax			13,398			56,147			42,311
	Net income		$	12,521		$	55,132		$	41,633
	See accompanying notes to condensed financial statements.
	Schedule I – Condensed Financial Information of Registrant
	Global Brass and Copper Holdings, Inc. (Parent Company Only)
	Condensed Statements of Comprehensive Income
			Year Ended December 31,
	(In thousands)		2012			2011			2010
	Net income		$	12,521		$	55,132		$	41,633
	Other comprehensive income:
	Foreign currency translation adjustment, net of tax			(457	)		362			442
	Comprehensive income		$	12,064		$	55,494		$	42,075
	See accompanying notes to condensed financial statements.
	Schedule I – Condensed Financial Information of Registrant
	Global Brass and Copper Holdings, Inc. (Parent Company Only)
	Condensed Statements of Cash Flows
			Year Ended December 31,
	(In thousands)		2012			2011			2010
	Net cash provided by operating activities		$	73,624		$	—		$	42,500
	Cash flows from investing activities
	Capital distributions from subsidiary			86,376			—			—
	Payable to subsidiary			2,424			2,451			—
	Net cash provided by investing activities			88,800			2,451			—
	Cash flows from financing activities
Distributions to stockholder			(160,000	)		—			(42,500	)
Amounts due from stockholder			(2,424	)		(2,451	)		—
Net cash used in financing activities			(162,424	)		(2,451	)		(42,500	)
Net increase (decrease) in cash			—			—			—
Cash at beginning of year			—			—			—
Cash at end of year		$	—		$	—		$	—
See accompanying notes to condensed financial statements.
Schedule I – Condensed Financial Information of Registrant
Global Brass and Copper Holdings, Inc. (Parent Company Only)
Notes to Condensed Financial Statements
31-Dec-12
(All dollar amounts in thousands)
1	Basis of Presentation
Global Brass and Copper, Inc. (“GBC”) is a direct subsidiary of Global Brass and Copper Holdings, Inc. (the “Company”). Under the terms of the agreements governing the 9.50% Senior Secured Notes issued by GBC and the asset-based revolving loan facility entered into by GBC and certain of its subsidiaries (the “ABL Facility”), GBC and substantially all of its existing 100%-owned U.S. subsidiaries are significantly restricted from making dividend payments, loans or advances to the Company. These restrictions have resulted in the restricted net assets (as defined in Rule 4-08(e)(3) of Regulation S-X) of the Company’s subsidiaries exceeding 25% of the consolidated net assets of the Company and its subsidiaries. These condensed financial statements should be read in conjunction with the consolidated financial statements and related notes thereto included in this filing.
2	Guarantees
The Senior Secured Notes and the ABL Facility are guaranteed by the Company and substantially all of GBC’s existing 100%-owned U.S. subsidiaries. The Senior Secured Notes, the ABL Facility and the related guarantees are secured by the fixed assets, accounts receivable and inventory of GBC and the guarantors.
3	Distributions from Subsidiary
Cash distributions received by the Company from GBC were $160,000 and $42,500 for the years ended December 31, 2012 and 2010, respectively. Of the $160,000 received during the year ended December 31, 2012, $73,624 represented a return on capital and $86,376 represented a return of capital. The $42,500 received during the year ended December 31, 2010 represented a return on capital. The Company did not receive any cash distributions for the year ended December 31, 2011.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2012
Accounting Policies [Abstract]	'
Principles of Consolidation	'
	Principles of Consolidation
	The consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries and its majority-owned subsidiaries, in which the Company holds a controlling interest. All intercompany accounts and transactions are eliminated in consolidation. The equity method is used to account for investments in affiliated companies, 20% to 50% owned, where the Company does not hold a controlling voting interest and does not direct the matters that most significantly impact the investee’s operations.
	The Company owns an 80% interest in Olin Luotong (GZ) Corporation (“Luotong”), based in China, and Luotong’s financial information is consolidated herein, with the net results attributable to the 20% noncontrolling interest reflected in the consolidated financial statements.
Use of Estimates and Assumptions	'
	Use of Estimates and Assumptions
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. In addition, it requires management to make estimates and assumptions that affect the reported amount of net sales and expenses during the reporting period. Actual amounts could differ from those estimates.
Revision of Prior Period Financial Statements	'
	Revision of Prior Period Financial Statements
	During 2012, the Company identified the following errors:
		1	The Company historically had not recognized deferred tax assets or liabilities related to inside basis differences of its foreign subsidiaries. The unrecognized net deferred tax asset was $797, $888, and $794 as January 1, 2010, December 31, 2010 and December 31, 2011, respectively. The provision for income taxes was overstated by $91 and understated by $94 for the years ended December 31, 2010 and 2011, respectively.
		2	Duplicate accruals for the receipt of raw material were identified in the third quarter of fiscal 2012. The error had no impact on the year ended December 31, 2010. Accrued liabilities and cost of sales were overstated by $389 as of and for the year ended December 31, 2011.
		3	An error in the accounting for raw material in-transit was identified in the third quarter of fiscal 2012. Inventory was understated by $22 as of January 1, 2010 and overstated by $275 and $423 as of December 31, 2010 and 2011, respectively. Cost of sales was understated by $297 and $148 for the years ended December 31, 2010 and 2011, respectively.
	Additionally, the Company identified immaterial errors in previously issued consolidated financial statements which were corrected in the year identified, including:
		4	An error in accounting for workers’ compensation insurance that was corrected during the year ended December 31, 2011 by decreasing cost of sales by $44 and by increasing prepaid expenses and other current assets by $7,269 and increasing accrued liabilities by $7,225. Prepaid expenses and other current assets were understated by $5,036 and $7,269 as of January 1, 2010 and December 31, 2010, respectively. Accrued liabilities were understated by $5,725 and $7,225 as of January 1, 2010 and December 31, 2010, respectively. Cost of sales was overstated by $733 for the year ended December 31, 2010.
		5	An error in accounting for certain derivative contracts that was corrected during the year ended December 31, 2011 by increasing prepaid expenses and other current assets and decreasing cost of sales by $510. Prepaid expenses and other current assets were overstated by $303 as of January 1, 2010 and understated by $510 as of December 31, 2010. Cost of sales was overstated by $813 for the year ended December 31, 2010.
	The Company assessed the materiality of all errors, individually and in the aggregate, on previously issued consolidated financial statements and concluded that the errors were not material to any of the Company’s previously issued quarterly or annual financial statements. In assessing the effect of correcting previously unrecorded errors in 2012, the Company has concluded that correction of these errors in 2012 could be considered material to 2012 net income. Accordingly, the consolidated financial statements as of and for the year ended December 31, 2011 and as of and for the year ended December 31, 2010 have been revised to reflect the correction of all errors identified in their proper periods. To recognize the cumulative effect of all error corrections as of January 1, 2010, an adjustment of $482 was made to increase retained earnings.
	A summary of the revisions to the consolidated financial statements as of December 31, 2011 and 2010 and for the periods ended December 31, 2011 and 2010 is as follows:
			As Previously			Adjustment			As Revised
			Reported
	Consolidated Balance Sheet
			December 31, 2010
	Inventories		$	192,898		$	(275	)	$	192,623
	Prepaid expenses and other current assets			30,662			7,779			38,441
	Deferred income tax assets—current			28,433			879			29,312
	Income tax receivable			2,139			137			2,276
	Total current assets			431,044			8,520			439,564
	Deferred income tax assets—noncurrent			34,354			(100	)		34,254
	Total assets			529,301			8,420			537,721
	Accrued liabilities			78,002			6,990			84,992
	Income tax payable			—			199			199
	Total current liabilities			163,810			7,189			170,999
	Total liabilities			502,063			7,189			509,252
	Retained earnings			12,355			1,231			13,586
	Total Global Brass and Copper Holdings, Inc. stockholder’s equity			24,333			1,231			25,564
	Total equity			27,238			1,231			28,469
	Total liabilities and equity			529,301			8,420			537,721
	Consolidated Statement of Operations
			Year Ended December 31, 2010
	Cost of sales		$	1,497,944		$	(1,249	)	$	1,496,695
	Gross profit			160,785			1,249			162,034
	Operating income			91,928			1,249			93,177
	Income before provision for income taxes and equity income			66,042			1,249			67,291
	Provision for income taxes			26,176			500			26,676
	Income before equity income			39,866			749			40,615
	Net income			41,396			749			42,145
	Net income attributable to Global Brass and Copper Holdings, Inc.			40,884			749			41,633
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic		$	1.94		$	0.03		$	1.97
	Consolidated Statement of Comprehensive Income
			Year Ended December 31, 2010
	Net income		$	41,396		$	749		$	42,145
	Comprehensive income			41,909			749			42,658
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			41,326			749			42,075
	Consolidated Statement of Changes in Equity
			Year Ended December 31, 2010
	Net income		$	41,396		$	749		$	42,145
	Net income attributable to Global Brass and Copper Holdings, Inc.			40,884			749			41,633
	Retained earnings —Balance, December 31, 2010			12,355			1,231			13,586
	Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, December 31, 2010			24,333			1,231			25,564
	Total equity—Balance, December 31, 2010			27,238			1,231			28,469
			As			Adjustment			As Revised
			Previously
			Reported
	Consolidated Balance Sheet
			31-Dec-11
	Accounts receivable, net of allowance		$	160,731		$	984		$	161,715
	Inventories			186,370			(423	)		185,947
	Deferred income tax assets—current			27,972			1,055			29,027
	Income tax receivable			5,017			29			5,046
	Total current assets			449,539			1,645			451,184
Deferred income tax assets—noncurrent			20,218			(248	)		19,970
Total assets			547,343			1,397			548,740
Accounts payable			78,276			(388	)		77,888
Accrued liabilities			47,619			985			48,604
Income tax payable			—			300			300
Total current liabilities			161,844			897			162,741
Total liabilities			465,183			897			466,080
Retained earnings			68,218			500			68,718
Total Global Brass and Copper Holdings, Inc. stockholder’s equity			78,992			500			79,492
Total equity			82,160			500			82,660
Total liabilities and equity			547,343			1,397			548,740
Consolidated Statement of Operations
		Year Ended December 31, 2011
Cost of sales		$	1,582,925		$	548		$	1,583,473
Gross profit			196,218			(548	)		195,670
Operating income			126,827			(548	)		126,279
Income before provision for income taxes and equity income			86,385			(548	)		85,837
Provision for income taxes			31,254			183			31,437
Income before equity income			55,131			(731	)		54,400
Net income			56,019			(731	)		55,288
Net income attributable to Global Brass and Copper Holdings, Inc.			55,863			(731	)		55,132
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic		$	2.65		$	(0.04	)	$	2.61
Consolidated Statement of Comprehensive Income
		Year Ended December 31, 2011
Net income		$	56,019		$	(731	)	$	55,288
Comprehensive income			56,488			(731	)		55,757
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.			56,225			(731	)		55,494
Consolidated Statement of Changes in Equity
		Year Ended December 31, 2011
Net income		$	56,019		$	(731	)	$	55,288
Net income attributable to Global Brass and Copper Holdings, Inc.			55,863			(731	)		55,132
Retained earnings —Balance, December 31, 2011			68,218			500			68,718
Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, December 31, 2011			78,992			500			79,492
Total equity—Balance, December 31, 2011			82,160			500			82,660
Accounts Receivable and Allowance for Doubtful Accounts	'
	Accounts Receivable and Allowance for Doubtful Accounts
	Accounts receivable primarily consists of trade receivables for amounts billed to customers for products sold and other receivables. The determination of collectability of the Company’s accounts receivable requires management to make frequent judgments and estimates in order to determine the appropriate amount of allowance needed for doubtful accounts. In circumstances where the Company is aware of a customer’s inability to meet its financial obligations (e.g., bankruptcy filings or substantial down-grading of credit ratings), it records an allowance for bad debts equal to the amount the Company does not believe to be collectible. For all other customers, the Company recognizes allowances for bad debts based on its historical collection experience. If circumstances change (e.g., greater than expected defaults or an unexpected material change in a major customer’s ability to meet its financial obligations), the Company’s estimate of the recoverability of amounts due could be changed by a material amount. Accounts are written off once deemed to be uncollectible. Any subsequent cash collections relating to accounts that have been previously written off are recorded as a reduction to the provision for bad debts in the period of collection.
	The reconciliation of the activity in the allowance for doubtful accounts is summarized below:
			Year Ended December 31,
			2012			2011			2010
	Balance at beginning of period		$	2,067		$	7,921		$	7,505
	Provision for bad debts, net of reductions			(814	)		(4,171	)		1,324
	Write-offs, net of recoveries			—			(1,683	)		(908	)
	Recoveries, net of write-offs			155			—			—
	Balance at end of period		$	1,408		$	2,067		$	7,921
Inventories	'
	Inventories
	Inventories include costs attributable to direct labor and manufacturing overhead but are primarily comprised of raw material costs. The material component of inventories that is valued on a last-in, first-out (“LIFO”) basis comprises approximately 70% and 72% of total inventory at December 31, 2012 and 2011, respectively. Other manufactured inventories, including the non-material components and certain non-U.S. inventories, are valued on a first-in, first-out (“FIFO”) basis. Elements of cost in finished goods inventory in addition to the cost of material include depreciation, utilities, consumable production supplies, maintenance, production wages and transportation costs.
	Inventories are stated at the lower of cost or market. The market price of metals used in production and related scrap is subject to volatility. We evaluate the need to record adjustments for inventory on a regular basis. During periods when open market prices decline below net book value, the Company records a provision to reduce the carrying value of its inventory. Additionally, the Company records an estimate for slow moving and obsolete inventory based upon product knowledge, physical inventory observation, future demand, market conditions and an aging analysis of the inventory on hand. Our policy is to evaluate all inventories including raw material, work-in-process, finished goods, and spare parts. Inventory in excess of our estimated usage requirements is written down to its estimated net realizable value. See note 3, “Inventories,” in these notes to the consolidated financial statements.
Prepaid Expenses and Other Current Assets	'
	Prepaid Expenses and Other Current Assets
	Prepaid expenses are stated at historical cost, net of any related amortization, and consist of amounts which are of continuing benefit to the Company. See note 4, “Prepaid Expenses and Other Current Assets,” in these notes to the consolidated financial statements.
Property, Plant and Equipment	'
	Property, Plant and Equipment
	Property, plant and equipment are recorded at cost. Depreciation of property, plant and equipment generally is computed using the straight-line method based on the estimated useful lives of the assets as they are placed into service. Depreciation expense is recorded in cost of sales or selling, general and administrative costs depending on the nature and use of the underlying asset.
	Expenditures for repairs, maintenance and minor renewals are expensed as incurred. Expenditures which improve an asset or extend its estimated useful life are capitalized. Interest related to the construction of qualifying assets is capitalized as part of the construction costs. When assets are retired or otherwise disposed of, the related cost and accumulated depreciation are removed from the accounts and any gain or loss is included in the accompanying consolidated statement of operations.
	The Company reviews property, plant and equipment for impairment when a change in events or circumstances indicates that the carrying value of the assets may not be recoverable. The Company has determined that its asset group for impairment testing is comprised of the assets and liabilities of each of its reporting units. Reporting units are businesses, for which discrete financial information is available and reviewed by segment management. The Company’s reporting units are one level below the operating segment, with the exception of one operating segment, for which the operating segment represents the lowest level of identifiable cash flows. The Company determines the fair value of its asset group through various valuation techniques, including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. See note 5, “Property, Plant and Equipment,” in these notes to the consolidated financial statements.
Investment in Joint Venture	'
	Investment in Joint Venture
	The Company owns a 50% interest in Dowa-Olin Metal Corporation (“Dowa”), a joint venture based in Japan. The Company accounts for Dowa under the equity method of accounting. Due to the timing of the receipt of available financial information, the results of Dowa are recorded on a one-month lag basis.
	As a result of the purchase method of accounting, a negative basis difference of $9,416 was created between the Company’s books and the Company’s share of Dowa’s equity as of November 19, 2007. ASC 323, Investments—Equity Method & Joint Ventures, provides that the basis difference between the investor cost and underlying equity in net assets of the investee at the date of investment requires recognition unless it is attributable to a non-amortizing asset such as goodwill. The negative basis difference was created due to the bargain purchase event associated with the metals business acquired from Olin Corporation and was not attributable to any specific element of the joint venture itself. As the difference was not attributable to any of the specific assets of Dowa, the equity investment as a whole was assessed to determine the appropriate accretion period for the basis difference. The purpose of the joint venture is to provide Olin Brass’s high performance alloy materials to the Asia market through the licensing of Olin Brass technology. Given consideration of this use, the negative basis difference is being accreted over a period of 13 years. See note 7, “Investment in Joint Venture,” in these notes to the consolidated financial statements.
	The Company reviews its equity method investment for impairment using an other-than-temporary model when triggering events are identified. An impairment loss is recognized when the investment’s carrying amount exceeds its fair value and this decline in fair value is deemed to be other-than-temporary.
Acquisitions and Goodwill	'
	Acquisitions and Goodwill
	All acquisitions are accounted for using the acquisition method as prescribed by ASC 805, Business Combinations. The purchase price paid is allocated to the assets acquired and liabilities assumed based on their estimated fair values. Any excess purchase price over the fair value of the net assets acquired is recorded as goodwill.
Intangibles-Goodwill and Other	'
	Pursuant to ASC 350, Intangibles—Goodwill and Other, the Company does not amortize goodwill and other intangible assets with indefinite useful lives. The Company reviews goodwill to determine potential impairment annually, or more frequently if events and circumstances indicate that the asset might be impaired, by comparing the carrying value of the asset with the anticipated present value of future cash flows.
	In 2011, the Financial Accounting Standards Board (“FASB”) amended its guidance to simplify the testing of goodwill for impairment. The amended guidance provides an option to perform a qualitative assessment to determine whether further impairment testing is necessary. If the qualitative evaluation yields support that it is more likely than not that the fair value of a reporting unit exceeds its carrying value, the quantitative impairment test is not required. The Company adopted the qualitative goodwill evaluation model for its annual goodwill impairment test conducted as of October 31, 2012. Based on the results of that qualitative assessment, the Company believes it was more likely than not that the fair value of the reporting units significantly exceeded their carrying values as of October 31, 2012, indicating no impairment of goodwill. The $4,399 of goodwill was assigned to the Chase business segment and as of December 31, 2012, $2,131 of goodwill is expected to be deductible for tax purposes.
Intangible Assets	'
	Intangible Assets
	Definite-lived intangible assets are recorded at fair value under the purchase method of accounting as of the respective acquisition dates and are amortized using the straight-line method over the estimated useful lives of the assets. Amortization expense related to intangible assets is reflected in selling, general and administrative expenses. Identifiable definite-lived intangible assets are reviewed for impairment whenever events or circumstances indicate that the carrying value may not be recoverable. See note 6, “Intangible Assets,” in these notes to the consolidated financial statements.
Deferred Financing Fees	'
	Deferred Financing Fees
	Deferred financing fees incurred in connection with the issuance of debt are amortized as non-cash interest expense over the terms of the debt agreements.
	Deferred financing fees incurred in connection with the issuance of the Senior Secured Notes, as defined in note 8, “Other Noncurrent Assets,” are amortized using the effective interest method over the term of the Senior Secured Notes. Deferred financing fees incurred in connection with the issuance of the ABL Facility, as defined in note 8, “Other Noncurrent Assets,” in these notes to the consolidated financial statements, are amortized on a straight-line basis over the term of the ABL Facility.
Derivative Contracts	'
	Derivative Contracts
	The Company’s operating activities expose it to a variety of market risks, including risks related to the effects of commodity prices and interest rates. These financial exposures are monitored and managed by the Company as an integral part of its overall risk-management program. The Company does not enter into derivative contracts for speculation purposes where the objective is to generate profits. The Company has not applied hedge accounting to its derivative contracts in any of the years ended December 31, 2012, 2011 or 2010. The Company includes the fair value of the derivative contracts as assets or liabilities in its balance sheet and recognizes all amounts paid and received and changes in fair value of derivative contracts, including unrealized gains and losses, as adjustments to income. See note 13, “Derivative Contracts,” in these notes to the consolidated financial statements.
Revenue Recognition	'
	Revenue Recognition
	The Company recognizes revenue for both toll and non-toll basis sales only when risk of loss and title passes to the customer, which generally occurs upon shipment. For the years ended December 31, 2012, 2011 and 2010, non-toll net sales were $1,576,070, $1,710,595 and $1,577,771, respectively. For the years ended December 31, 2012, 2011 and 2010, toll net sales were $74,450, $68,548 and $80,958, respectively. Estimates for future rebates on certain product lines and product returns are recognized in the period in which the revenue is recorded. Such rebates were not material for the years ended December 31, 2012, 2011 and 2010. Billings to customers for shipping costs are included in net sales and the cost of shipping product to those customers is reflected in cost of sales in the consolidated statements of operations.
Research and Development	'
	Research and Development
	The Company conducts research and development primarily through the Olin Brass reportable segment, the costs for which are expensed as incurred. Research and development expenditures for the years ended December 31, 2012, 2011 and 2010 were $1,516, $1,540 and $1,740, respectively, and are included as a component of selling, general and administrative expenses in the consolidated statements of operations.
Income Taxes	'
	Income Taxes
	The provision for income taxes is determined using the asset and liability approach. The current and deferred tax consequences are measured by applying the provisions of enacted tax laws to determine the amount of taxes payable currently or in future years. Deferred income taxes are provided for temporary differences between the income tax basis of assets and liabilities and their carrying amounts for financial reporting purposes. A valuation allowance is recorded to reduce deferred tax assets when management determines it is “more likely than not” that some portion or all of the deferred tax assets will not be realized.
Profits Interest Compensation	'
	Profits Interest Compensation
	Halkos has granted, pursuant to the Halkos Holdings, LLC Executive Equity Incentive Plan (“Halkos Equity Plan”), non-voting membership interests to select members of the Company’s management in the form of shares. The shares are profits interests in Halkos. See note 17, “Profits Interest Awards,” in these notes to the consolidated financial statements.
	The shares are accounted for as a profit sharing arrangement under ASC 710, Compensation—General. Expense is recorded in the period in which distributions to award holders are determined to be probable. These distributions are accounted for by the Company as non-cash compensation expense with a corresponding increase in additional paid-in capital.
Foreign Currency Translation	'
	Foreign Currency Translation
	The financial statements of foreign subsidiaries are translated into United States dollars in accordance with ASC 830, Foreign Currency Matters. The functional currency of the Company’s foreign subsidiaries is the local currency. The consolidated statements of foreign operations are translated at weighted-average exchange rates for the periods. Assets and liabilities are translated at period-end exchange rates and equity transactions are translated at historical rates. Gains and losses resulting from the translation adjustment are reported as a component of other comprehensive income. The income tax effect of currency translation adjustments related to foreign subsidiaries and joint ventures that are not considered indefinitely reinvested are recorded as a component of deferred taxes with an offset to other comprehensive income.
Concentrations of Credit Risk and Certain Other Exposures	'
	Concentrations of Credit Risk and Certain Other Exposures
	The Company sells and distributes its products to a wide range of companies primarily in the ammunition, automotive, electronics, housing and coinage industries. The Company performs ongoing credit evaluations of its customers and generally does not require collateral. For the years ended December 31, 2012, 2011 and 2010, sales to any one customer did not exceed 10% of consolidated net sales.
	The Company uses various strategies to minimize the impact of changes in the base metal prices between the date of order and the date of sale. Generally, the Company prices a forward replacement purchase of an equivalent amount of copper and other metals under flexible pricing arrangements it maintains with its suppliers, at the same time it determines the forward selling price of finished products to its customers. The Company has various sources of raw materials and is not materially dependent on any one supplier.
	There are nine unions at the Olin Brass division, two labor unions at the Oster division, and one labor union at the Chase division. In 2012, employees at an Olin Brass downstream operation elected a union representative which was subsequently certified. The relationship with these unions has been satisfactory. The collective bargaining agreements with the Olin Brass unions expire between November 2013 and September 2014, the collective bargaining agreements with Oster’s unions expire January 2014 and the other has an indeterminable term, and the collective bargaining agreement with Chase’s union expires in June 2013. Since the Company’s establishment in November 2007, the Company has not experienced any work stoppages at any of its facilities.
Self-Insurance Programs	'
	Self-Insurance Programs
	The Company is self-insured for workers’ compensation claims and benefits paid under employee health care programs. Accruals for employee health care are primarily based on estimated undiscounted cost of claims, which includes incurred but not reported claims. Accruals for workers’ compensation benefits and related expenses for claims are estimated, in part, by considering historical claims experience and undiscounted claims estimates provided by insurance carriers, third-party administrators and actuaries. Self-insurance accruals are deemed to be sufficient to cover outstanding claims, including those incurred but not reported as of the estimation date.
	Workers’ compensation claims relating to activity after November 19, 2007 are covered by a loss funding insurance arrangement whereby the Company makes a fixed payment to the insurer which is used to pay submitted claims. Loss fund payments to the insurer in excess of workers’ compensation claim payments are classified as prepaid expenses and other current assets. The amount of the loss fund payments to the insurer is based on a combination of claims experience and a contractually agreed upon loss development factor.
Environmental Reserves and Environmental Expenses	'
	Environmental Reserves and Environmental Expenses
	The Company recognizes an environmental liability when it is probable the liability exists and the amount is reasonably estimable. The Company estimates the duration and extent of its remediation obligations based upon internal analyses of clean-up costs, ongoing monitoring costs and estimated legal fees, communications with regulatory agencies and changes in environmental law. If the Company were to determine that its estimates of the duration or extent of its environmental obligations were no longer accurate, the Company would adjust its environmental liabilities accordingly in the period that such determination is made. Estimated future expenditures for environmental remediation are not discounted to their present value. Accrued environmental liabilities are not reduced by potential insurance reimbursements.
	Environmental expenses that relate to ongoing operations are included as a component of cost of sales. See note 16, “Commitments and Contingencies,” in these notes to the consolidated financial statements.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In February 2013, the FASB issued Accounting Standards Update (“ASU”) 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income. This guidance requires entities to provide disclosures about items that are required by U.S. GAAP to be reclassified from accumulated other comprehensive income (“AOCI”) to net income in their entirety in the same reporting period. The disclosure would include the amount of the reclassification and identify the line item on the statement where net income is presented that is affected by the reclassification. For other items reclassified from AOCI, the disclosure would list cross-references to other disclosures where additional details about their effects are disclosed. This guidance is effective for reporting periods beginning after December 15, 2012. The Company does not expect that adoption of the guidance will have a material effect on its financial statements and disclosures.
	In December 2011, the FASB issued ASU 2011-11, Disclosures about Offsetting Assets and Liabilities. This guidance requires entities to disclose both gross and net information about both instruments and transactions eligible for offset in the statement of financial position and instruments and transactions subject to an agreement similar to a master netting arrangement. This guidance does not amend existing guidance on when it is appropriate to offset. In January 2013, the FASB issued ASU 2013-01, Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities, which limits the scope of ASU 2011-11 to derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and lending arrangements. The guidance is effective for annual periods beginning January 1, 2013 and interim periods within those annual periods. Early adoption is not permitted, but retrospective application is required. Adoption of the guidance is not expected to have a material impact on the Company’s consolidated financial statements and disclosures.

Revision_of_Prior_Period_Finan1

Revision of Prior Period Financial Statements (Unaudited) (Tables)	9 Months Ended										12 Months Ended
	Sep. 30, 2013										Dec. 31, 2012
Summary of Revisions to Consolidated Financial Statements	'										'
	A summary of the revisions to the consolidated financial statements as of September 30, 2012 and for the three and nine months ended September 30, 2012 is as follows:										A summary of the revisions to the consolidated financial statements as of December 31, 2011 and 2010 and for the periods ended December 31, 2011 and 2010 is as follows:
		As			Adjustment			As Revised				As Previously			Adjustment			As Revised
		Previously										Reported
		Reported									Consolidated Balance Sheet
	Consolidated Statement of Operations											December 31, 2010
		Three Months Ended September 30, 2012									Inventories	$	192,898		$	(275	)	$	192,623
	Cost of sales	$	348,995		$	585		$	349,580		Prepaid expenses and other current assets		30,662			7,779			38,441
	Gross profit		44,982			(585	)		44,397		Deferred income tax assets—current		28,433			879			29,312
	Operating income		27,629			(585	)		27,044		Income tax receivable		2,139			137			2,276
	Income before provision for income taxes and equity income		18,230			(585	)		17,645		Total current assets		431,044			8,520			439,564
	Provision for income taxes		6,670			99			6,769		Deferred income tax assets—noncurrent		34,354			(100	)		34,254
	Income before equity income		11,560			(684	)		10,876		Total assets		529,301			8,420			537,721
	Net income		11,821			(684	)		11,137		Accrued liabilities		78,002			6,990			84,992
	Net income attributable to Global Brass and Copper Holdings, Inc.		11,716			(684	)		11,032		Income tax payable		—			199			199
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:										Total current liabilities		163,810			7,189			170,999
	Basic	$	0.55		$	(0.03	)	$	0.52		Total liabilities		502,063			7,189			509,252
	Consolidated Statement of Operations										Retained earnings		12,355			1,231			13,586
		Nine Months Ended September 30, 2012									Total Global Brass and Copper Holdings, Inc. stockholder’s equity		24,333			1,231			25,564
	Cost of sales	$	1,112,909		$	(34	)	$	1,112,875		Total equity		27,238			1,231			28,469
	Gross profit		141,438			34			141,472		Total liabilities and equity		529,301			8,420			537,721
	Operating income		68,197			34			68,231
	Income before provision for income taxes and equity income		18,519			34			18,553		Consolidated Statement of Operations
	Provision for income taxes		13,891			105			13,996			Year Ended December 31, 2010
	Income before equity income		4,628			(71	)		4,557		Cost of sales	$	1,497,944		$	(1,249	)	$	1,496,695
	Net income		5,364			(71	)		5,293		Gross profit		160,785			1,249			162,034
	Net income attributable to Global Brass and Copper Holdings, Inc.		5,091			(71	)		5,020		Operating income		91,928			1,249			93,177
	Net income attributable to Global Brass and										Income before provision for income taxes and equity income		66,042			1,249			67,291
	Copper Holdings, Inc. per common share:										Provision for income taxes		26,176			500			26,676
	Basic	$	0.24		$	—		$	0.24		Income before equity income		39,866			749			40,615
	Consolidated Statement of Comprehensive Income										Net income		41,396			749			42,145
		Three Months Ended September 30, 2012									Net income attributable to Global Brass and Copper Holdings, Inc.		40,884			749			41,633
	Net income	$	11,821		$	(684	)	$	11,137		Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Comprehensive income		11,814			(684	)		11,130		Basic	$	1.94		$	0.03		$	1.97
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		11,731			(684	)		11,047
	Consolidated Statement of Comprehensive Income										Consolidated Statement of Comprehensive Income
		Nine Months Ended September 30, 2012										Year Ended December 31, 2010
	Net income	$	5,364		$	(71	)	$	5,293		Net income	$	41,396		$	749		$	42,145
	Comprehensive income		5,234			(71	)		5,163		Comprehensive income		41,909			749			42,658
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		4,961			(71	)		4,890		Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		41,326			749			42,075
	Consolidated Statement of Changes in Deficit
		Nine Months Ended September 30, 2012									Consolidated Statement of Changes in Equity
	Net income	$	5,364		$	(71	)	$	5,293			Year Ended December 31, 2010
	Net income attributable to Global Brass and Copper Holdings, Inc.		5,091			(71	)		5,020		Net income	$	41,396		$	749		$	42,145
	Accumulated deficit—Balance, September 30, 2012		(56,083	)		429			(55,654	)	Net income attributable to Global Brass and Copper Holdings, Inc.		40,884			749			41,633
	Total Global Brass and Copper Holdings, Inc. stockholders’ deficit—Balance, September 30, 2012		(58,928	)		429			(58,499	)	Retained earnings —Balance, December 31, 2010		12,355			1,231			13,586
	Total deficit—Balance, September 30, 2012		(55,487	)		429			(55,058	)	Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, December 31, 2010		24,333			1,231			25,564
											Total equity—Balance, December 31, 2010		27,238			1,231			28,469
												As			Adjustment			As Revised
												Previously
												Reported
											Consolidated Balance Sheet
												31-Dec-11
											Accounts receivable, net of allowance	$	160,731		$	984		$	161,715
											Inventories		186,370			(423	)		185,947
											Deferred income tax assets—current		27,972			1,055			29,027
											Income tax receivable		5,017			29			5,046
											Total current assets		449,539			1,645			451,184
											Deferred income tax assets—noncurrent		20,218			(248	)		19,970
											Total assets		547,343			1,397			548,740
											Accounts payable		78,276			(388	)		77,888
											Accrued liabilities		47,619			985			48,604
											Income tax payable		—			300			300
											Total current liabilities		161,844			897			162,741
										Total liabilities		465,183			897			466,080
										Retained earnings		68,218			500			68,718
										Total Global Brass and Copper Holdings, Inc. stockholder’s equity		78,992			500			79,492
										Total equity		82,160			500			82,660
										Total liabilities and equity		547,343			1,397			548,740
										Consolidated Statement of Operations
											Year Ended December 31, 2011
										Cost of sales	$	1,582,925		$	548		$	1,583,473
										Gross profit		196,218			(548	)		195,670
										Operating income		126,827			(548	)		126,279
										Income before provision for income taxes and equity income		86,385			(548	)		85,837
										Provision for income taxes		31,254			183			31,437
										Income before equity income		55,131			(731	)		54,400
										Net income		56,019			(731	)		55,288
										Net income attributable to Global Brass and Copper Holdings, Inc.		55,863			(731	)		55,132
										Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
										Basic	$	2.65		$	(0.04	)	$	2.61
										Consolidated Statement of Comprehensive Income
											Year Ended December 31, 2011
										Net income	$	56,019		$	(731	)	$	55,288
										Comprehensive income		56,488			(731	)		55,757
										Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		56,225			(731	)		55,494
										Consolidated Statement of Changes in Equity
											Year Ended December 31, 2011
										Net income	$	56,019		$	(731	)	$	55,288
										Net income attributable to Global Brass and Copper Holdings, Inc.		55,863			(731	)		55,132
										Retained earnings —Balance, December 31, 2011		68,218			500			68,718
										Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, December 31, 2011		78,992			500			79,492
										Total equity—Balance, December 31, 2011		82,160			500			82,660
Interim Period [Member]	'										'
Summary of Revisions to Consolidated Financial Statements	'										'
											A summary of the revisions to the consolidated financial statements during the interim periods is as follows:
												As			Adjustment			As Revised
												Previously
												Reported
											Consolidated Balance Sheet
												March 31, 2011
											Inventories	$	202,745		$	(230	)	$	202,515
											Prepaid expenses and other current assets		23,623			7,478			31,101
											Deferred income tax assets—current		27,143			1,251			28,394
											Income tax receivable		2,666			327			2,993
											Total current assets		501,575			8,826			510,401
											Property, plant and equipment, net		42,475			112			42,587
											Deferred income tax assets—noncurrent		32,867			(347	)		32,520
											Total assets		601,811			8,591			610,402
											Accrued liabilities		65,352			7,240			72,592
											Income tax payable		—			398			398
											Total current liabilities		193,688			7,638			201,326
											Total liabilities		559,825			7,638			567,463
											Retained earnings		26,691			953			27,644
											Total Global Brass and Copper Holdings, Inc. stockholder’s equity		38,954			953			39,907
											Total equity		41,987			953			42,940
											Total liabilities and equity		601,811			8,591			610,402
											Consolidated Statement of Operations
												Three Months Ended March 31, 2011
											Cost of sales	$	442,383		$	506		$	442,889
											Gross profit		50,532			(506	)		50,026
											Operating income		31,672			(506	)		31,166
											Third party interest expense		9,562			(112	)		9,450
											Income before provision for income taxes and equity income		22,106			(394	)		21,712
											Provision for income taxes		7,956			(116	)		7,840
											Income before equity income		14,150			(278	)		13,872
											Net income		14,448			(278	)		14,170
											Net income attributable to Global Brass and Copper Holdings, Inc.		14,336			(278	)		14,058
											Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
											Basic	$	0.68		$	(0.01	)	$	0.67
											Consolidated Statement of Comprehensive Income
												Three Months Ended March 31, 2011
											Net income	$	14,448		$	(278	)	$	14,170
											Comprehensive income		14,771			(278	)		14,493
											Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		14,643			(278	)		14,365
											Consolidated Statement of Changes in Equity
												Three Months Ended March 31, 2011
											Net income	$	14,448		$	(278	)	$	14,170
											Net income attributable to Global Brass and Copper Holdings, Inc.		14,336			(278	)		14,058
											Retained earnings—Balance, March 31, 2011		26,691			953			27,644
											Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, March 31, 2011		38,954			953			39,907
											Total equity—Balance, March 31, 2011		41,987			953			42,940
											Consolidated Statement of Cash Flows
												Three Months Ended March 31, 2011
											Cash flows from operating activities:
											Net cash used in operating activities	$	(22,494	)	$	112		$	(22,382	)
											Cash flows from investing activities:
											Capital expenditures		(3,476	)		(112	)		(3,588	)
											Net cash used in investing activities		(3,476	)		(112	)		(3,588	)
											Consolidated Balance Sheet
												June 30, 2011
											Inventories	$	169,137		$	(402	)	$	168,735
											Prepaid expenses and other current assets		13,989			8,212			22,201
											Deferred income tax assets—current		25,823			1,230			27,053
											Income tax receivable		2,147			(343	)		1,804
											Total current assets		464,534			8,697			473,231
											Property, plant and equipment, net		47,507			273			47,780
											Deferred income tax assets—noncurrent		32,450			(529	)		31,921
Total assets		565,534			8,441			573,975
Accrued liabilities		55,849			7,465			63,314
Total current liabilities		176,521			7,465			183,986
Total liabilities		514,032			7,465			521,497
Retained earnings		36,869			976			37,845
Total Global Brass and Copper Holdings, Inc. stockholder’s equity		48,371			976			49,347
Total equity		51,502			976			52,478
Total liabilities and equity		565,534			8,441			573,975
Consolidated Statements of Operations
	Three Months Ended June 30, 2011
Cost of sales	$	429,357		$	(337	)	$	429,020
Gross profit		43,894			337			44,231
Operating income		27,411			337			27,748
Third party interest expense		11,149			(161	)		10,988
Income before provision for income taxes and equity income		17,000			498			17,498
Provision for income taxes		6,783			475			7,258
Income before equity income		10,217			23			10,240
Net income		10,245			23			10,268
Net income attributable to Global Brass and Copper Holdings, Inc.		10,178			23			10,201
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	0.48		$	—		$	0.48
	Six Months Ended June 30, 2011
Cost of sales	$	871,740		$	169		$	871,909
Gross profit		94,426			(169	)		94,257
Operating income		59,083			(169	)		58,914
Third party interest expense		20,711			(273	)		20,438
Income before provision for income taxes and equity income		39,106			104			39,210
Provision for income taxes		14,739			359			15,098
Income before equity income		24,367			(255	)		24,112
Net income		24,693			(255	)		24,438
Net income attributable to Global Brass and Copper Holdings, Inc.		24,514			(255	)		24,259
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	1.16		$	(0.01	)	$	1.15
Consolidated Statements of Comprehensive Income
	Three Months Ended June 30, 2011
Net income	$	10,245		$	23		$	10,268
Comprehensive income		10,452			23			10,475
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		10,354			23			10,377
	Six Months Ended June 30, 2011
Net income	$	24,693		$	(255	)	$	24,438
Comprehensive income		25,223			(255	)		24,968
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		24,997			(255	)		24,742
Consolidated Statement of Changes in Equity
	Six Months Ended June 30, 2011
Net income	$	24,693		$	(255	)	$	24,438
Net income attributable to Global Brass and Copper Holdings, Inc.		24,514			(255	)		24,259
Retained earnings—Balance, June 30, 2011		36,869			976			37,845
Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, June 30, 2011		48,371			976			49,347
Total equity—Balance, June 30, 2011		51,502			976			52,478
Consolidated Statement of Cash Flows
	Six Months Ended June 30, 2011
Cash flows from operating activities:
Net cash provided by operating activities	$	32,428		$	273		$	32,701
Cash flows from investing activities:
Capital expenditures		(9,709	)		(273	)		(9,982	)
Net cash used in investing activities		(9,683	)		(273	)		(9,956	)
Consolidated Balance Sheet
	September 30, 2011
Inventories	$	163,880		$	(388	)	$	163,492
Prepaid expenses and other current assets		24,752			994			25,746
Deferred income tax assets—current		26,658			1,058			27,716
Income tax receivable		3,612			(352	)		3,260
Total current assets		462,786			1,312			464,098
Property, plant and equipment, net		51,589			478			52,067
Deferred income tax assets—noncurrent		31,903			(646	)		31,257
Total assets		565,819			1,144			566,963
Accounts payable		107,971			(12	)		107,959
Accrued liabilities		59,526			(235	)		59,291
Total current liabilities		175,291			(247	)		175,044
Total liabilities		507,655			(247	)		507,408
Retained earnings		43,737			1,391			45,128
Total Global Brass and Copper Holdings, Inc. stockholder’s equity		54,991			1,391			56,382
Total equity		58,164			1,391			59,555
Total liabilities and equity		565,819			1,144			566,963
Consolidated Statements of Operations
	Three Months Ended September 30, 2011
Cost of sales	$	401,931		$	(508	)	$	401,423
Gross profit		37,569			508			38,077
Operating income		20,471			508			20,979
Third party interest expense		10,159			(205	)		9,954
Income before provision for income taxes and equity income		10,066			713			10,779
Provision for income taxes		3,428			298			3,726
Income before equity income		6,638			415			7,053
Net income		6,865			415			7,280
Net income attributable to Global Brass and Copper Holdings, Inc.		6,868			415			7,283
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	0.33		$	0.02		$	0.35
	Nine Months Ended September 30, 2011
Cost of sales	$	1,273,671		$	(339	)	$	1,273,332
Gross profit		131,995			339			132,334
Operating income		79,554			339			79,893
Third party interest expense		30,870			(478	)		30,392
Income before provision for income taxes and equity income		49,172			817			49,989
Provision for income taxes		18,167			657			18,824
Income before equity income		31,005			160			31,165
Net income		31,558			160			31,718
Net income attributable to Global Brass and Copper Holdings, Inc.		31,382			160			31,542
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	1.49		$	—		$	1.49
Consolidated Statements of Comprehensive Income
	Three Months Ended September 30, 2011
Net income	$	6,865		$	415		$	7,280
Comprehensive income		6,955			415			7,370
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		6,913			415			7,328
	Nine Months Ended September 30, 2011
Net income	$	31,558		$	160		$	31,718
Comprehensive income		32,178			160			32,338
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		31,910			160			32,070
Consolidated Statement of Changes in Equity
	Nine Months Ended September 30, 2011
Net income	$	31,558		$	160		$	31,718
Net income attributable to Global Brass and Copper Holdings, Inc.		31,382			160			31,542
Retained earnings—Balance, September 30, 2011		43,737			1,391			45,128
Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, September 30, 2011		54,991			1,391			56,382
Total equity—Balance, September 30, 2011		58,164			1,391			59,555
Consolidated Statement of Cash Flows
	Nine Months Ended September 30, 2011
Cash flows from operating activities:
Net cash provided by operating activities	$	44,367		$	478		$	44,845
Cash flows from investing activities:
Capital expenditures		(15,062	)		(478	)		(15,540	)
Net cash used in investing activities		(14,992	)		(478	)		(15,470	)
Consolidated Statement of Operations
	Three Months Ended December 31, 2011
Cost of sales	$	309,254		$	887		$	310,141
Gross profit		64,223			(887	)		63,336
Operating income		47,273			(887	)		46,386
Third party interest expense		9,140			478			9,618
Income before provision for income taxes and equity income		37,213			(1,365	)		35,848
Provision for income taxes		13,087			(474	)		12,613
Income before equity income		24,126			(891	)		23,235
Net income		24,461			(891	)		23,570
Net income attributable to Global Brass and Copper Holdings, Inc.		24,481			(891	)		23,590
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	1.16		$	(0.04	)	$	1.12
Consolidated Statement of Comprehensive Income
	Three Months Ended December 31, 2011
Net income	$	24,461		$	(891	)	$	23,570
Comprehensive income		24,310			(891	)		23,419
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		24,315			(891	)		23,424
Consolidated Balance Sheet
	March 31, 2012
Accounts receivable, net of allowance	$	202,756		$	984		$	203,740
Inventories		173,538			(861	)		172,677
Deferred income tax assets—current		26,793			1,326			28,119
Income tax receivable		1,567			(162	)		1,405
Total current assets		496,052			1,287			497,339
Deferred income tax assets—noncurrent		20,092			(294	)		19,798
Total assets		593,912			993			594,905
Accounts payable		111,814			(389	)		111,425
Income Tax payable		—			64			64
Accrued liabilities		47,080			1,284			48,364
Total current liabilities		194,498			959			195,457
Total liabilities		497,460			959			498,419
Retained earnings		82,677			34			82,711
Total Global Brass and Copper Holdings, Inc. stockholder’s equity		93,213			34			93,247
Total equity		96,452			34			96,486
Total liabilities and equity		593,912			993			594,905
Consolidated Statement of Operations
	Three Months Ended March 31, 2012
Cost of sales	$	392,701		$	736		$	393,437
Gross profit		50,690			(736	)		49,954
Operating income		32,767			(736	)		32,031
Income before provision for income taxes and equity income		22,707			(736	)		21,971
Provision for income taxes		8,468			(270	)		8,198
Income before equity income		14,239			(466	)		13,773
Net income		14,513			(466	)		14,047
Net income attributable to Global Brass and Copper Holdings, Inc.		14,459			(466	)		13,993
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	0.68		$	(0.02	)	$	0.66
Consolidated Statement of Comprehensive Income
	Three Months Ended March 31, 2012
Net income	$	14,513		$	(466	)	$	14,047
Comprehensive income		14,533			(466	)		14,067
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		14,462			(466	)		13,996
Consolidated Statement of Changes in Equity
	Three Months Ended March 31, 2012
Net income	$	14,513		$	(466	)	$	14,047
Net income attributable to Global Brass and Copper Holdings, Inc.		14,459			(466	)		13,993
Retained earnings—Balance, March 31, 2012		82,677			34			82,711
Total Global Brass and Copper Holdings, Inc. stockholder’s equity—Balance, March 31, 2012		93,213			34			93,247
Total equity—Balance, March 31, 2012		96,452			34			96,486
Consolidated Balance Sheet
	June 30, 2012
Accounts receivable, net of allowance	$	192,326		$	984		$	193,310
Inventories		180,815			(811	)		180,004
Deferred income tax assets—current		28,079			1,264			29,343
Income tax receivable		4,996			(476	)		4,520
Total current assets		429,443			961			430,404
Deferred income tax assets—noncurrent		19,917			(260	)		19,657
Total assets		538,522			701			539,223
Accounts payable		105,981			(1,396	)		104,585
Accrued liabilities		39,590			984			40,574
Total current liabilities		148,919			(412	)		148,507
Total liabilities		605,586			(412	)		605,174
Accumulated deficit		(67,799	)		1,113			(66,686	)
Total Global Brass and Copper Holdings, Inc. stockholder’s deficit		(70,422	)		1,113			(69,309	)
Total deficit		(67,064	)		1,113			(65,951	)
Total liabilities and deficit		538,522			701			539,223
Consolidated Statements of Operations
	Three Months Ended June 30, 2012
Cost of sales	$	371,213		$	(1,355	)	$	369,858
Gross profit		45,766			1,355			47,121
Operating income		7,801			1,355			9,156
Loss before provision for income taxes and equity income		(22,418	)		1,355			(21,063	)
Benefit from income taxes		(1,247	)		276			(971	)
Income before equity income		(21,171	)		1,079			(20,092	)
Net loss		(20,970	)		1,079			(19,891	)
Net loss attributable to Global Brass and Copper Holdings, Inc.		(21,084	)		1,079			(20,005	)
Net loss attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	(1.00	)	$	0.05		$	(0.95	)
	Six Months Ended June 30, 2012
Cost of sales	$	763,914		$	(619	)	$	763,295
Gross profit		96,456			619			97,075
Operating income		40,568			619			41,187
Income before provision for income taxes and equity income		289			619			908
Provision for income taxes		7,221			6			7,227
Loss before equity income		(6,932	)		613			(6,319	)
Net loss		(6,457	)		613			(5,844	)
Net loss attributable to Global Brass and Copper Holdings, Inc.		(6,625	)		613			(6,012	)
Net loss attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	(0.31	)	$	0.03		$	(0.28	)
Consolidated Statements of Comprehensive Loss
	Three Months Ended June 30, 2012
Net loss	$	(20,970	)	$	1,079		$	(19,891	)
Comprehensive loss		(21,113	)		1,079			(20,034	)
Comprehensive loss attributable to Global Brass and Copper Holdings, Inc.		(21,232	)		1,079			(20,153	)
	Six Months Ended June 30, 2012
Net loss	$	(6,457	)	$	613		$	(5,844	)
Comprehensive loss		(6,580	)		613			(5,967	)
Comprehensive loss attributable to Global Brass and Copper Holdings, Inc.		(6,770	)		613			(6,157	)
Consolidated Statement of Changes in Equity
	Six Months Ended June 30, 2012
Net loss	$	(6,457	)	$	613		$	(5,844	)
Net loss attributable to Global Brass and Copper Holdings, Inc.		(6,625	)		613			(6,012	)
Accumulated deficit—Balance, June 30, 2012		(67,799	)		1,113			(66,686	)
Total Global Brass and Copper Holdings, Inc. stockholder’s deficit—Balance, June 30, 2012		(70,422	)		1,113			(69,309	)
Total deficit—Balance, June 30, 2012		(67,064	)		1,113			(65,951	)
Consolidated Balance Sheet
	September 30, 2012
Accounts receivable, net of allowance	$	210,654		$	984		$	211,638
Deferred income tax assets—current		25,390			971			26,361
Income tax receivable		648			(174	)		474
Total current assets		445,517			1,781			447,298
Deferred income tax assets—noncurrent		17,350			(310	)		17,040
Total assets		554,198			1,471			555,669
Accrued liabilities		58,620			984			59,604
Income tax payable		—			58			58
Total current liabilities		179,553			1,042			180,595
Total liabilities		609,685			1,042			610,727
Accumulated deficit		(56,083	)		429			(55,654	)
Total Global Brass and Copper Holdings, Inc. stockholder’s deficit		(58,928	)		429			(58,499	)
Total deficit		(55,487	)		429			(55,058	)
Total liabilities and deficit		554,198			1,471			555,669
Consolidated Statements of Operations
	Three Months Ended September 30, 2012
Cost of sales	$	348,995		$	585		$	349,580
Gross profit		44,982			(585	)		44,397
Operating income		27,629			(585	)		27,044
Income before provision for income taxes and equity income		18,230			(585	)		17,645
Provision for income taxes		6,670			99			6,769
Income before equity income		11,560			(684	)		10,876
Net income		11,821			(684	)		11,137
Net income attributable to Global Brass and Copper Holdings, Inc.		11,716			(684	)		11,032
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	0.55		$	(0.03	)	$	0.52
	Nine Months Ended September 30, 2012
Cost of sales	$	1,112,909		$	(34	)	$	1,112,875
Gross profit		141,438			34			141,472
Operating income		68,197			34			68,231
Income before provision for income taxes and equity income		18,519			34			18,553
Provision for income taxes		13,891			105			13,996
Income before equity income		4,628			(71	)		4,557
Net income		5,364			(71	)		5,293
Net income attributable to Global Brass and Copper Holdings, Inc.		5,091			(71	)		5,020
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
Basic	$	0.24		$	—		$	0.24
Consolidated Statements of Comprehensive Income
	Three Months Ended September 30, 2012
Net income	$	11,821		$	(684	)	$	11,137
Comprehensive income		11,814			(684	)		11,130
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		11,731			(684	)		11,047
	Nine Months Ended September 30, 2012
Net income	$	5,364		$	(71	)	$	5,293
Comprehensive income		5,234			(71	)		5,163
Comprehensive income attributable to Global Brass and Copper Holdings, Inc.		4,961			(71	)		4,890
Consolidated Statement of Changes in Equity
	Nine Months Ended September 30, 2012
Net income	$	5,364		$	(71	)	$	5,293
Net income attributable to Global Brass and Copper Holdings, Inc.		5,091			(71	)		5,020
Accumulated deficit—Balance, September 30, 2012		(56,083	)		429			(55,654	)
Total Global Brass and Copper Holdings, Inc. stockholder’s deficit—Balance, September 30, 2012		(58,928	)		429			(58,499	)
Total deficit—Balance, September 30, 2012		(55,487	)		429			(55,058	)

Inventories_Tables

Inventories (Tables)	9 Months Ended					12 Months Ended
	Sep. 30, 2013					Dec. 31, 2012
Inventory Disclosure [Abstract]	'					'
Summary of Inventories	'					'
	The Company’s inventories were as follows:					The Company’s inventories are as follows:
		As of					As of December 31,
		September 30,		December 31,			2012		2011
		2013		2012		Raw materials and supplies	$	37,766	$	21,320
	Raw materials and supplies	$	34,646	$	37,766	Work-in-process		69,286		93,555
	Work-in-process		99,119		69,286	Finished goods		67,326		71,072
	Finished goods		75,013		67,326
						Total inventories	$	174,378	$	185,947
	Total inventories	$	208,778	$	174,378

Prepaid_Expenses_and_Other_Cur1

Prepaid Expenses and Other Current Assets (Tables)	9 Months Ended					12 Months Ended
	Sep. 30, 2013					Dec. 31, 2012
Text Block [Abstract]	'					'
Components of Prepaid Expenses and Other Current Assets	'					'
	The Company’s prepaid expenses and other current assets were as follows:					The Company’s prepaid expenses and other current assets are as follows:
		As of					As of December 31,
		September 30,		December 31,			2012		2011
		2013		2012		Collateral on deposit—commodity derivative contracts	$	767	$	4,622
	Collateral on deposit—commodity derivative contracts	$	1,861	$	767	Commodity derivative contracts		548		—
	Commodity derivative contracts		5		548	Deferred financing fees, net		—		3,646
	Deferred expense		13,018		—	Loss fund payments—workers’ compensation		6,968		7,538
	Loss fund payments—workers’ compensation		6,466		6,968	Prepaid insurance		1,261		1,974
	Prepaid insurance		1,705		1,261	Other		2,597		2,132
	Prepaid tooling		1,926		764
	Other		1,610		1,833	Total prepaid expenses and other current assets	$	12,141	$	19,912
	Total prepaid expenses and other current assets	$	26,591	$	12,141

Other_Noncurrent_Assets_Tables

Other Noncurrent Assets (Tables)	9 Months Ended					12 Months Ended
	Sep. 30, 2013					Dec. 31, 2012
Text Block [Abstract]	'					'
Other Noncurrent Assets	'					'
	Other noncurrent assets consisted of the following:					Other noncurrent assets consisted of the following:
		As of					As of December 31,
		September 30,		December 31,			2012		2011
		2013		2012		Deferred financing fees, net	$	17,082	$	9,779
	Deferred financing fees, net	$	15,225	$	17,082	Utility and other deposits		668		1,060
	Utility and other deposits		1,395		668	Interest rate cap agreements		1		157
	Interest rate cap agreements		—		1	Other		4		177
	Other		—		4
						Total other noncurrent assets	$	17,755	$	11,173
	Total other noncurrent assets	$	16,620	$	17,755

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	9 Months Ended					12 Months Ended
	Sep. 30, 2013					Dec. 31, 2012
Payables And Accruals [Abstract]	'					'
Components of Accrued Liabilities	'					'
	Accrued liabilities consisted of the following:					Accrued liabilities consisted of the following:
		As of					As of December 31,
		September 30,		December 31,			2012		2011
		2013		2012		Commodity derivative contracts	$	—	$	1,825
	Personnel expense	$	20,685	$	20,872	Personnel expense		20,872		20,548
	Workers’ compensation		14,383		15,754	Workers’ compensation		15,754		15,653
	Deferred revenue		13,018		—	Professional fees		2,145		2,623
	Professional fees		1,826		2,145	Insurance		2,253		1,689
	Insurance		2,358		2,253	Utilities		1,844		1,531
	Utilities		1,877		1,844	Taxes		1,745		1,471
	Taxes		1,371		1,745	Other		3,811		3,264
	Tooling		737		686
	Commodity derivative contracts		357		—	Total accrued liabilities	$	48,424	$	48,604
	Other		3,027		3,125
	Total accrued liabilities	$	59,639	$	48,424

Financing_Tables

Financing (Tables)	9 Months Ended					12 Months Ended
	Sep. 30, 2013					Dec. 31, 2012
Debt Disclosure [Abstract]	'					'
Components of Long-Term Debt	'					'
	Long-term debt consisted of the following:					Long-term debt consisted of the following:
		As of					As of December 31,
		September 30,		December 31,			2012		2011
		2013		2012		ABL Facility	$	14,522	$	—
	ABL Facility	$	22,500	$	14,522	Senior Secured Notes		375,000		—
	Senior Secured Notes		375,000		375,000	Term Loan Facility		—		310,875
						Discount, net of amortization		—		(7,297	)
	Total long-term debt	$	397,500	$	389,522
								389,522		303,578
						Less: Current maturities of long-term debt		—		31,880
						Total long-term debt	$	389,522	$	271,698

Income_Taxes_Tables

Income Taxes (Tables)	9 Months Ended							12 Months Ended
	Sep. 30, 2013							Dec. 31, 2012
Income Tax Disclosure [Abstract]	'							'
Summary of Effective Income Tax Rate	'							'
	The effective income tax rate, which is provision for income taxes as a percentage of income before provision for income taxes and equity income, differs from the amount determined by applying the applicable U.S. statutory federal income tax rate to pretax results primarily as a result of the following:							The effective income tax rate differs from the amount determined by applying the applicable U.S. statutory federal income tax rate to pretax results primarily as a result of the following:
		Nine Months Ended							Year Ended December 31,
		September  30,							2012			2011			2010
		2013			2012			Statutory provision rate		35	%		35	%		35	%
	Statutory provision rate		35	%		35	%	Permanent differences and other items
	Permanent differences and other items							State tax provision		6.7	%		3.9	%		6	%
	State tax provision		7.9	%		3.6	%	Section 199 manufacturing credit		(3.2	%)		(2.3	%)		(1.5	%)
	Section 199 manufacturing credit		(6.9	%)		(2.8	%)	Incremental tax effects of foreign earnings		1.8	%		0.2	%		0.3	%
	Return to provision adjustments / Uncertain tax positions		(1.4	%)		(3.1	%)	Return to provision adjustments		1.2	%		(0.7	%)		(2.2	%)
	Non-deductible non-cash compensation		48.7	%		41.2	%	Re-rate of deferred taxes		(0.8	%)		(0.3	%)		(0.2	%)
	Other		1.1	%		1.5	%	Non-deductible non-cash compensation		22	%		0.4	%		1.8	%
								Other		(1.0	%)		0.4	%		0.4	%
	Effective income tax rate		84.4	%		75.4	%
								Effective income tax rate		61.7	%		36.6	%		39.6	%
Income Before Provision for Income Taxes and Equity Income	'							'
								Income before provision for income taxes and equity income is comprised of the following:
									Year Ended December 31,
									2012			2011			2010
								Domestic	$	24,583		$	81,534		$	61,903
								Foreign		6,502			4,303			5,388
								Total	$	31,085		$	85,837		$	67,291
Provision for Income Taxes	'							'
								The provision for income taxes is summarized as follows:
									Year Ended December 31,
									2012			2011			2010
								Current tax provision
								U.S. federal	$	10,329		$	16,518		$	13,663
								State and local		1,923			3,347			5,660
								Foreign		1,685			1,081			1,312
								Total current		13,937			20,946			20,635
								Deferred tax provision
								U.S. federal		4,389			10,209			5,760
								State and local		571			188			372
								Foreign		288			94			(91	)
								Total deferred		5,248			10,491			6,041
								Total provision	$	19,185		$	31,437		$	26,676
Deferred Tax Assets and Liabilities	'							'
								Deferred tax assets and liabilities are comprised of the following:
									As of December 31,
									2012			2011
								Deferred tax assets
								Inventory	$	48,932		$	50,936
								Accruals and other reserves		7,721			8,376
								Financing fees		—			731
								Accounts receivable		1,082			939
								UNICAP adjustment		1,278			1,319
								Derivative contracts		487			1,104
								Other		680			—
								Gross deferred tax assets	$	60,180		$	63,405
								Deferred tax liabilities
								Investments in foreign entities	$	7,310		$	6,507
								Fixed assets and intangibles		11,122			7,139
								Financing fees		2,145			—
								Other		—			762
								Gross deferred tax liability		20,577			14,408
								Net deferred tax asset	$	39,603		$	48,997
								Net current deferred tax asset	$	33,465		$	29,027
								Net long-term deferred tax asset		6,138			19,970
								Net deferred tax asset	$	39,603		$	48,997
Reconciliation of Summary of Activity of Uncertain Tax Positions	'							'
								A reconciliation of the summary of activity of the Company’s uncertain tax positions is summarized as follows:
								Balance at January 1, 2011	$	35,483
								Additions for tax positions related to prior years		207
								Reductions for tax positions related to prior years		(4,350	)
								Balance at December 31, 2011	$	31,340
								Additions for tax positions related to prior years		—
								Reductions for tax positions related to prior years		(1,963	)
								Reductions due to tax settlements		(1,515	)
								Reductions due to tax statute of limitations		(461	)
								Balance at December 31, 2012	$	27,401

Derivative_Contracts_Tables

Derivative Contracts (Tables)	9 Months Ended															12 Months Ended
	Sep. 30, 2013															Dec. 31, 2012
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'															'
Effects of Derivative Contracts in Condensed Consolidated Financial Statements	'															'
	The following tables summarize the gross amounts of recognized derivative assets and liabilities, the net amounts presented in the consolidated balance sheet, and the net amounts after deducting collateral that has been deposited with counterparties:															The following tables summarize the gross amounts of recognized derivative assets and liabilities, the net amounts presented in the consolidated balance sheet, and the net amounts after deducting collateral that has been deposited with counterparties:
		As of September 30, 2013															As of December 31, 2012
										Amounts Not Offset in															Amounts Not Offset in
										the Consolidated															the Consolidated
										Balance Sheet															Balance Sheet
		Gross			Gross			Net Amounts		Financial		Cash		Net			Gross		Gross			Net Amounts			Financial		Cash			Net
		Amounts of			Amounts			of Assets		Instruments		Collateral		Amount			Amounts of		Amounts			of Assets			Instruments		Collateral			Amount
		Recognized			Offset in			Presented in				Received					Recognized		Offset in			Presented in					Received
		Assets			Consolidated			Consolidated									Assets		Consolidated			Consolidated
					Balance			Balance											Balance			Balance
					Sheet			Sheet											Sheet			Sheet
	Open metal contracts	$	722		$	(722	)	$	—	$	—	$	—	$	—	Open metals contracts	$	603	$	(224	)	$	379		$	—	$	—		$	379
	(361 contracts)															(208 contracts)
	Open electricity contracts		56			(51	)		5		—		—		5	Open natural gas contracts		2		—			2			—		—			2
	(10 contracts)															(6 contracts)
																Open electricity contracts		169		(2	)		167			—		—			167
	Total	$	778		$	(773	)	$	5	$	—	$	—	$	5	(17 contracts)
																Interest rate cap agreements		1		—			1			—		—			1
	Consolidated balance sheet location:															(2 contracts)
	Prepaid expenses and other current assets				$	5
																Total	$	775	$	(226	)	$	549		$	—	$	—		$	549
	Total				$	5
																Consolidated balance sheet location:
																Prepaid expenses and other current assets			$	548
										Amounts Not Offset in						Other noncurrent assets				1
										the Consolidated
										Balance Sheet						Total			$	549
		Gross			Gross			Net Amounts		Financial		Cash		Net
		Amounts of			Amounts			of Liabilities		Instruments		Collateral		Amount
		Recognized			Offset in			Presented in				Deposited													Amounts Not Offset in
		Liabilities			Consolidated			Consolidated																	the Consolidated
					Balance			Balance																	Balance Sheet
					Sheet			Sheet									Gross		Gross			Net Amounts			Financial		Cash			Net
	Open metal contracts	$	1,074		$	(722	)	$	352	$	—	$	352	$	—		Amounts of		Amounts			of Liabilities			Instruments		Collateral			Amount
	(406 contracts)																Recognized		Offset in			Presented in					Deposited
	Open natural gas contracts		5			—			5		—		5		—		Liabilities		Consolidated			Consolidated
	(4 contracts)																		Balance			Balance
	Open electricity contracts		51			(51	)		—		—		—		—				Sheet			Sheet
	(14 contract)															Open metals contracts	$	224	$	(224	)	$	—		$	—	$	—		$	—
																(85 contracts)
	Total	$	1,130		$	(773	)	$	357	$	—	$	357	$	—	Open electricity contracts		2		(2	)		—			—		—			—
																(1 contract)
	Consolidated balance sheet location:
	Accrued liabilities				$	357										Total	$	226	$	(226	)	$	—		$	—	$	—		$	—
	Total				$	357
	Not included in the above table is $1,504 of collateral included in prepaid expenses and other current assets, which is because collateral is limited to the net amounts of assets or liabilities presented in the consolidated balance sheet.
																	As of December 31, 2011
																									Gross Amounts Not
		As of December 31, 2012																							Offset in the
										Amounts Not Offset in															Consolidated Balance
										the Consolidated															Sheet
										Balance Sheet						(dollars in thousands)	Gross		Gross			Net Amounts			Financial		Cash			Net
		Gross			Gross			Net Amounts		Financial		Cash		Net			Amounts of		Amounts			of Assets			Instruments		Collateral			Amount
		Amounts of			Amounts			of Assets		Instruments		Collateral		Amount			Recognized		Offset in			Presented in					Received
		Recognized			Offset in			Presented in				Received					Assets		Consolidated			Consolidated
		Assets			Consolidated			Consolidated											Balance			Balance
					Balance			Balance											Sheet			Sheet
					Sheet			Sheet								Open metals contracts (88 contracts)	$	294	$	(294	)	$	—		$	—	$	—		$	—
	Open metals contracts	$	603		$	(224	)	$	379	$	—	$	—	$	379	Open electricity contracts (6 contracts)		43		(43	)		—			—		—			—
	(208 contracts)															Interest rate cap agreements (2 contracts)		157		—			157			—		—			157
	Open natural gas contracts		2			—			2		—		—		2
	(6 contracts)															Total	$	494	$	(337	)	$	157		$	—	$	—		$	157
	Open electricity contracts		169			(2	)		167		—		—		167
(17 contracts)	Consolidated balance sheet location:
Interest rate cap agreements		1			—			1		—		—		1	Other noncurrent assets						$	157
(2 contracts)
Total	$	775		$	(226	)	$	549	$	—	$	—	$	549										Gross Amounts Not
																								Offset in the
Consolidated balance sheet location:																								Consolidated Balance
Prepaid expenses and other current assets				$	548																			Sheet
Other noncurrent assets					1										(dollars in thousands)	Gross		Gross			Net Amounts			Financial		Cash			Net
																Amounts of		Amounts			of Liabilities			Instruments		Collateral			Amount
Total				$	549											Recognized		Offset in			Presented in					Deposited
																Liabilities		Consolidated			Consolidated
																		Balance			Balance
									Amounts Not Offset in									Sheet			Sheet
									the Consolidated						Open metals contracts (151 contracts)	$	1,647	$	(294	)	$	1,353		$	—	$	(1,353	)	$	—
									Balance Sheet						Open natural gas contracts (31 contracts)		384		—			384			—		(384	)		—
	Gross			Gross			Net Amounts		Financial		Cash		Net		Open electricity contracts (8 contracts)		131		(43	)		88			—		—			88
	Amounts of			Amounts			of Liabilities		Instruments		Collateral		Amount
	Recognized			Offset in			Presented in				Deposited				Total	$	2,162	$	(337	)	$	1,825		$	—	$	(1,737	)	$	88
	Liabilities			Consolidated			Consolidated
				Balance			Balance								Consolidated balance sheet location:
				Sheet			Sheet								Accrued liabilities						$	1,825
Open metals contracts	$	224		$	(224	)	$	—	$	—	$	—	$	—
(85 contracts)
Open electricity contracts		2			(2	)		—		—		—		—
(1 contract)															The following table summarizes the effects of derivative contracts in the consolidated statements of operations:
Total	$	226		$	(226	)	$	—	$	—	$	—	$	—
																Year Ended December 31,
																2012		2011			2010
Not included in the above table is $767 of collateral included in prepaid expenses and other current assets, which is because collateral is limited to the net amounts of assets or liabilities presented in the consolidated balance sheet.															Cost of sales
The following table summarizes the effects of derivative contracts in the consolidated statements of operations:															Realized and unrealized loss—metal contracts	$	1,339	$	3,884		$	7,605
															Realized and unrealized loss—natural gas contracts		76		517			1,825
															Realized and unrealized loss—electricity contracts		243		57			—
	Nine Months Ended
	September 30,														Total	$	1,658	$	4,458		$	9,430
	2013			2012
Cost of sales															Interest expense
Realized and unrealized (loss) gain—metal contracts	$	(143	)	$	614										Unrealized loss (gain)—interest rate cap agreements	$	156	$	1,851		$	(800	)
Realized and unrealized (loss) gain—natural gas contracts		(12	)		113
Realized and unrealized (loss) gain—electricity contracts		(193	)		222
Total	$	(348	)	$	949
Interest expense
Unrealized loss—interest rate cap agreements	$	(1	)	$	(156	)

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended									12 Months Ended
	Sep. 30, 2013									Dec. 31, 2012
Fair Value Disclosures [Abstract]	'									'
Schedule of Assets and Liabilities Measured at Fair Value	'									'
	The following tables provide the hierarchy of inputs used to derive the fair value of the Company’s assets and liabilities at fair value on a recurring basis as of September 30, 2013 and December 31, 2012:									The following tables provide the hierarchy of inputs used to derive the fair value of the Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2012 and December 31, 2011:
		As of September 30, 2013									As of December 31, 2012
		Level 1		Level 2		Level 3		Total			Level 1		Level 2		Level 3		Total
	Open electricity contracts	$	—	$	5	$	—	$	5	Open metal contracts	$	—	$	379	$	—	$	379
										Open natural gas contracts		—		2		—		2
	Total assets	$	—	$	5	$	—	$	5	Open electricity contracts		—		167		—		167
										Interest rate cap agreements		—		1		—		1
	Open metal contracts	$	—	$	352	$	—	$	352
	Open natural gas contracts		—		5		—		5	Total assets	$	—	$	549	$	—	$	549
	Total liabilities	$	—	$	357	$	—	$	357
											As of December 31, 2011
											Level 1		Level 2		Level 3		Total
										Interest rate cap agreements	$	—	$	157	$	—	$	157
		As of December 31, 2012
		Level 1		Level 2		Level 3		Total		Total assets	$	—	$	157	$	—	$	157
	Open metal contracts	$	—	$	379	$	—	$	379
	Open natural gas contracts		—		2		—		2	Open metal contracts	$	—	$	1,353	$	—	$	1,353
	Open electricity contracts		—		167		—		167	Open natural gas contracts		—		384		—		384
	Interest rate cap agreements		—		1		—		1	Open electricity contracts		—		88		—		88
	Total assets	$	—	$	549	$	—	$	549	Total liabilities	$	—	$	1,825	$	—	$	1,825

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended								12 Months Ended
	Sep. 30, 2013								Dec. 31, 2012
Segment Reporting [Abstract]	'								'
Reconciliation of Segment Adjusted EBITDA to Income Before Provision for Income Taxes and Equity Income	'								'
	Below is a reconciliation of the Company’s Segment Adjusted EBITDA to income before provision for income taxes and equity income:								Below is a reconciliation of the Company’s Segment Adjusted EBITDA to income before provision for income taxes and equity income:
			Nine Months Ended											Year Ended December 31,
			September 30,											2012			2011			2010
			2013			2012			Net Sales, External Customers
	Net Sales, External Customers								Olin Brass					$	676,563		$	718,244		$	710,271
	Olin Brass		$	613,926		$	496,786		Chase						647,711			704,968			611,870
	Chase			488,475			505,951		Oster						326,246			355,931			336,588
	Oster			243,277			251,610
									Total net sales, external customers					$	1,650,520		$	1,779,143		$	1,658,729
	Total net sales, external customers		$	1,345,678		$	1,254,347
									Intersegment Net Sales
	Intersegment Net Sales								Olin Brass					$	46,287		$	48,312		$	57,919
	Olin Brass		$	40,539		$	36,315		Chase						305			626			765
	Chase			7			302		Oster						167			285			928
	Oster			173			81
									Total intersegment net sales					$	46,759		$	49,223		$	59,612
	Total intersegment net sales		$	40,719		$	36,698
									Segment Adjusted EBITDA
	Segment Adjusted EBITDA								Olin Brass					$	45,115		$	45,320		$	23,291
	Olin Brass		$	41,209		$	37,432		Chase						66,641			73,658			61,158
	Chase			53,831			53,311		Oster						19,517			17,898			21,324
	Oster			13,164			15,137
									Total segment adjusted EBITDA						131,273			136,876			105,773
	Total segment adjusted EBITDA			108,204			105,880		Corporate and Eliminations						(20,562	)		(19,518	)		(15,714	)
	Corporate and Other			(19,101	)		(14,664	)	Loss on extinguishment of debt						(19,612	)		—			—
	Loss on extinguishment of debt			—			(19,612	)	Depreciation and amortization						(6,934	)		(4,759	)		(2,971	)
	Depreciation and amortization			(6,101	)		(4,891	)	Interest expense						(39,727	)		(40,010	)		(25,076	)
	Interest expense			(29,938	)		(29,894	)	Equity method investment income			(A	)		(271	)		(164	)		(806	)
	Equity method investment income(A)			(605	)		(193	)	Net income attributable to noncontrolling interest						374			156			512
	Net income attributable to noncontrolling interest			228			273		LIFO liquidation gain						4,775			15,236			21,009
	Lower of cost or market adjustment to inventory			(318	)		(302	)	Lower of cost or market adjustment to inventory						(302	)		—			—
	(Loss) gain on derivative contracts			(1,062	)		1,473		Gain (loss) on derivative contracts						1,588			(1,095	)		(11,984	)
	Share-based compensation expense			(989	)		—		Compensation expense—profits interest awards						(19,517	)		(885	)		(3,452	)
	Compensation expense—profits interest awards			(29,271	)		(19,517	)
									Income before provision for income taxes and equity income					$	31,085		$	85,837		$	67,291
	Income before provision for income taxes and equity income		$	21,047		$	18,553
										(A)	Excludes accretion income of $724 in each of the years ended December 31, 2012, 2011 and 2010. Equity method investment income is exclusive to Olin Brass.
		(A)	Excludes accretion income of $543 in both the nine months ended September 30, 2013 and 2012. Equity method investment income is exclusive to Olin Brass.
											Year Ended December 31,
											2012			2011			2010
									Depreciation and amortization
									Olin Brass		$	3,849		$	2,622		$	1,624
									Chase			2,521			1,921			1,200
									Oster			247			196			147
									Corporate and Eliminations			317			20			—
									Total depreciation and amortization		$	6,934		$	4,759		$	2,971
									LIFO liquidation gain/(loss)
									Olin Brass		$	175		$	8,401		$	23,253
									Chase			1,623			—			75
									Oster			4,478			7,050			(48	)
									Corporate and Eliminations			(1,501	)		(215	)		(2,271	)
									Total LIFO liquidation gain		$	4,775		$	15,236		$	21,009
									Capital expenditures
									Olin Brass		$	12,455		$	10,818		$	3,999
									Chase			6,846			10,171			7,377
									Oster			558			505			551
									Corporate and Eliminations			549			946			—
									Total capital expenditures		$	20,408		$	22,440		$	11,927
Summarized Geographic Information	'								'
									Summarized geographic information is shown in the following table. Net sales are attributed to individual countries based on the location from which the products are shipped. No customer represented 10 percent or more of consolidated revenues in 2012, 2011 or 2010.
											Year Ended December 31,
											2012			2011			2010
									Net sales:
									United States		$	1,556,865		$	1,691,007		$	1,567,472
									Asia Pacific			53,668			54,638			62,358
									Mexico			39,987			33,498			28,899
									Total net sales		$	1,650,520		$	1,779,143		$	1,658,729

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Schedule of Basic and Diluted Earning Per Shares Attributable to Company	'
	The following table sets forth the computation of basic and diluted earnings per share attributable to the Company:
		Nine Months Ended
		September 30,
		2013		2012
	Numerator
	Net income attributable to Global Brass and Copper Holdings, Inc.	$	4,205	$	5,020
	Denominator
	Weighted-average common shares outstanding		21,110,000		21,110,000
	Effect of potentially dilutive securities:
	Stock options and nonvested share awards		24,169		—
	Weighted-average common shares outstanding, assuming dilution		21,134,169		21,110,000
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic	$	0.2	$	0.24
	Diluted	$	0.2	$	0.24

Condensed_Consolidating_Financ1

Condensed Consolidating Financial Information (Tables)	9 Months Ended																			12 Months Ended
	Sep. 30, 2013																			Dec. 31, 2012
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'																			'
Condensed Consolidating Balance Sheet	'																			'
																				Global Brass and Copper Holdings, Inc.
		Condensed Consolidating Balance Sheet																		Condensed Consolidating Balance Sheet
		As of September 30, 2013																		31-Dec-12
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
								Subsidiaries			Subsidiaries
	Assets																				Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
	Current assets:																										Subsidiaries			Subsidiaries
	Cash	$	—		$	11,164		$	2,633		$	4,291		$	—		$	18,088		Assets
	Accounts receivable, net of allowance		—			4,914			176,272			17,287			—			198,473		Current assets:
	Inventories		—			—			193,825			15,363			(410	)		208,778		Cash	$	—		$	8,537		$	—		$	5,446		$	(121	)	$	13,862
	Prepaid expenses and other current assets		—			10,064			16,441			86			—			26,591		Accounts receivable, net of allowance		—			4,630			144,533			15,154			—			164,317
	Deferred income taxes		—			32,122			—			—			—			32,122		Inventories		—			343			158,713			15,885			(563	)		174,378
	Income tax receivable, net		—			799			—			—			(174	)		625		Prepaid expenses and other current assets		—			9,229			2,600			312			—			12,141
																				Deferred income taxes		—			33,465			—			—			—			33,465
	Total current assets		—			59,063			389,171			37,027			(584	)		484,677		Income tax receivable, net		—			1,656			—			—			(356	)		1,300
	Property, plant and equipment, net		—			976			76,810			351			—			78,137
	Investment in joint venture		—			—			2,184			—			—			2,184		Total current assets		—			57,860			305,846			36,797			(1,040	)		399,463
	Investment in subsidiaries		—			623,442			19,974			—			(643,416	)		—		Property, plant and equipment, net		—			1,154			69,646			327			—			71,127
	Intercompany accounts		—			—			270,599			—			(270,599	)		—		Investment in joint venture		—			—			2,972			—			—			2,972
	Goodwill		—			—			4,399			—			—			4,399		Investment in subsidiaries		—			522,912			19,850			—			(542,762	)		—
	Intangible assets, net		—			—			762			—			—			762		Intercompany accounts		—			—			223,081			—			(223,081	)		—
	Deferred income taxes		—			5,736			—			—			—			5,736		Goodwill		—			—			4,399			—			—			4,399
	Other noncurrent assets		—			15,705			915			—			—			16,620		Intangible assets, net		—			—			839			—			—			839
																				Deferred income taxes		—			6,138			—			—			—			6,138
	Total assets	$	—		$	704,922		$	764,814		$	37,378		$	(914,599	)	$	592,515		Other noncurrent assets		—			17,115			640			—			—			17,755
	Liabilities and (deficit) / equity																			Total assets	$	—		$	605,179		$	627,273		$	37,124		$	(766,883	)	$	502,693
	Current liabilities:
	Accounts payable	$	—		$	2,455		$	101,105		$	2,161		$	(410	)	$	105,311		Liabilities and (deficit) / equity
	Accrued liabilities		—			18,710			40,232			697			—			59,639		Current liabilities:
	Accrued interest		—			12,448			—			—			—			12,448		Accounts payable	$	—		$	1,398		$	77,390		$	2,910		$	(121	)	$	81,577
	Income tax payable		—			—			35			295			(174	)		156		Accrued liabilities		—			20,592			26,971			861			—			48,424
																				Accrued interest		—			3,287			—			—			—			3,287
	Total current liabilities		—			33,613			141,372			3,153			(584	)		177,554		Income taxes payable		—			248			—			356			(356	)		248
	Long-term debt		—			397,500			—			—			—			397,500
	Other noncurrent liabilities		—			26,312			—			—			—			26,312		Total current liabilities		—			25,525			104,361			4,127			(477	)		133,536
	Obligations and advances in excess of investment in subsidiary		5,447			—			—			—			(5,447	)		—		Long-term debt		—			389,522			—			—			—			389,522
	Intercompany accounts		7,269			252,944			—			10,386			(270,599	)		—		Other noncurrent liabilities		—			27,436			—			—			—			27,436
																				Obligations and advances in excess of investment in subsidiary		42,522			—			—			—			(42,522	)		—
	Total liabilities		12,716			710,369			141,372			13,539			(276,630	)		601,366		Intercompany accounts		8,829			205,218			—			9,597			(223,644	)		—
	Commitments and contingencies		—			—			—			—			—			—		Total liabilities		51,351			647,701			104,361			13,724			(266,643	)		550,494
	Global Brass and Copper Holdings, Inc. stockholders’ (deficit) / equity		(12,716	)		(5,447	)		623,442			19,974			(637,969	)		(12,716	)
	Noncontrolling interest		—			—			—			3,865			—			3,865		Commitments and contingencies		—			—			—			—			—			—
																				Global Brass and Copper Holdings, Inc. stockholder’s (deficit) / equity		(51,351	)		(42,522	)		522,912			19,850			(500,240	)		(51,351	)
	Total (deficit) / equity		(12,716	)		(5,447	)		623,442			23,839			(637,969	)		(8,851	)	Noncontrolling interest		—			—			—			3,550			—			3,550
	Total liabilities and (deficit) / equity	$	—		$	704,922		$	764,814		$	37,378		$	(914,599	)	$	592,515		Total (deficit) / equity		(51,351	)		(42,522	)		522,912			23,400			(500,240	)		(47,801	)
																				Total liabilities and (deficit) / equity	$	—		$	605,179		$	627,273		$	37,124		$	(766,883	)	$	502,693
		Condensed Consolidating Balance Sheet
		As of December 31, 2012																		Global Brass and Copper Holdings, Inc.
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated			Condensed Consolidating Balance Sheet
								Subsidiaries			Subsidiaries									31-Dec-11
	Assets
	Current assets:
	Cash	$	—		$	8,537		$	—		$	5,446		$	(121	)	$	13,862			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
	Accounts receivable, net of allowance		—			4,630			144,533			15,154			—			164,317									Subsidiaries			Subsidiaries
	Inventories		—			343			158,713			15,885			(563	)		174,378		Assets
	Prepaid expenses and other current assets		—			9,229			2,600			312			—			12,141		Current assets:
	Deferred income taxes		—			33,465			—			—			—			33,465		Cash	$	—		$	45,302		$	—		$	4,648		$	(413	)	$	49,537
	Income tax receivable, net		—			1,656			—			—			(356	)		1,300		Accounts receivable, net of allowance		—			4,184			145,083			12,448			—			161,715
																				Inventories		—			218			174,429			11,921			(621	)		185,947
	Total current assets		—			57,860			305,846			36,797			(1,040	)		399,463		Prepaid expenses and other current assets		—			17,916			2,245			135			(384	)		19,912
	Property, plant and equipment, net		—			1,154			69,646			327			—			71,127		Deferred income taxes		—			29,027			—			—			—			29,027
	Investment in joint venture		—			—			2,972			—			—			2,972		Income tax receivable, net		—			5,204			128			—			(286	)		5,046
	Investment in subsidiaries		—			522,912			19,850			—			(542,762	)		—
Intercompany accounts		—			—			223,081			—			(223,081	)		—		Total current assets		—			101,851			321,885			29,152			(1,704	)		451,184
Goodwill		—			—			4,399			—			—			4,399		Property, plant and equipment, net		—			923			56,322			311			—			57,556
Intangible assets, net		—			—			839			—			—			839		Investment in joint venture		—			—			3,507			—			—			3,507
Deferred income taxes		—			6,138			—			—			—			6,138		Investment in subsidiaries		85,020			393,708			13,351			—			(492,079	)		—
Other noncurrent assets		—			17,115			640			—			—			17,755		Intercompany accounts		—			—			92,889			—			(92,889	)		—
																			Goodwill		—			—			4,399			—			—			4,399
Total assets	$	—		$	605,179		$	627,273		$	37,124		$	(766,883	)	$	502,693		Intangible assets, net		—			—			951			—			—			951
																			Deferred income taxes		—			19,970			—			—			—			19,970
Liabilities and (deficit) / equity																			Other noncurrent assets		—			9,963			1,210			—			—			11,173
Current liabilities:
Accounts payable	$	—		$	1,398		$	77,390		$	2,910		$	(121	)	$	81,577		Total assets	$	85,020		$	526,415		$	494,514		$	29,463		$	(586,672	)	$	548,740
Accrued liabilities		—			20,592			26,971			861			—			48,424
Accrued interest		—			3,287			—			—			—			3,287		Liabilities and (deficit) / equity
Income tax payable		—			248			—			356			(356	)		248		Current liabilities:
																			Current maturities of long-term debt	$	—		$	31,880		$	—		$	—		$	—		$	31,880
Total current liabilities		—			25,525			104,361			4,127			(477	)		133,536		Accounts payable		—			—			76,190			2,495			(797	)		77,888
Long-term debt		—			389,522			—			—			—			389,522		Accrued liabilities		—			23,202			24,616			786			—			48,604
Other noncurrent liabilities		—			27,436			—			—			—			27,436		Accrued interest		—			4,069			—			—			—			4,069
Obligations and advances in excess of investment in subsidiary		42,522			—			—			—			(42,522	)		—		Income taxes payable		—			300			—			286			(286	)		300
Intercompany accounts		8,829			205,218			—			9,597			(223,644	)		—
																			Total current liabilities		—			59,451			100,806			3,567			(1,083	)		162,741
Total liabilities		51,351			647,701			104,361			13,724			(266,643	)		550,494		Long-term debt		—			271,698			—			—			—			271,698
																			Other noncurrent liabilities		—			31,641			—			—			—			31,641
Commitments and contingencies		—			—			—			—			—			—		Intercompany accounts		5,528			78,605			—			9,377			(93,510	)		—
Global Brass and Copper Holdings, Inc. stockholders’ (deficit) / equity		(51,351	)		(42,522	)		522,912			19,850			(500,240	)		(51,351	)
Noncontrolling interest		—			—			—			3,550			—			3,550		Total liabilities		5,528			441,395			100,806			12,944			(94,593	)		466,080
Total (deficit) / equity		(51,351	)		(42,522	)		522,912			23,400			(500,240	)		(47,801	)	Commitments and contingencies		—			—			—			—			—			—
																			Global Brass and Copper Holdings, Inc. stockholder’s (deficit) / equity		79,492			85,020			393,708			13,351			(492,079	)		79,492
Total liabilities and (deficit) / equity	$	—		$	605,179		$	627,273		$	37,124		$	(766,883	)	$	502,693		Noncontrolling interest		—			—			—			3,168			—			3,168
																			Total (deficit) / equity		79,492			85,020			393,708			16,519			(492,079	)		82,660
																			Total liabilities and (deficit) / equity	$	85,020		$	526,415		$	494,514		$	29,463		$	(586,672	)	$	548,740
Condensed Consolidating Statement of Operations	'																			'
																				Global Brass and Copper Holdings, Inc.
		Condensed Consolidating Statement of Operations																		Condensed Consolidating Statement of Operations
		Nine Months Ended September 30, 2013																		Year Ended December 31, 2012
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
								Subsidiaries			Subsidiaries
	Net sales	$	—		$	—		$	1,294,809		$	73,586		$	(22,717	)	$	1,345,678			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
	Cost of sales		—			1,208			1,155,186			68,138			(22,717	)		1,201,815									Subsidiaries			Subsidiaries
																				Net sales	$	—		$	—		$	1,584,301		$	93,655		$	(27,436	)	$	1,650,520
	Gross profit (loss)		—			(1,208	)		139,623			5,448			—			143,863		Cost of sales		—			83			1,409,588			85,099			(27,436	)		1,467,334
	Selling, general and administrative expenses		5,390			33,569			51,444			2,219			—			92,622
																				Gross profit (loss)		—			(83	)		174,713			8,556			—			183,186
	Operating income (loss)		(5,390	)		(34,777	)		88,179			3,229			—			51,241		Selling, general and administrative expenses		1,427			30,756			57,879			2,579			—			92,641
	Interest expense		—			29,938			—			—			—			29,938
	Other (income) expense, net		—			264			(134	)		126			—			256		Operating income (loss)		(1,427	)		(30,839	)		116,834			5,977			—			90,545
																				Interest expense		—			39,730			(3	)		—			—			39,727
	Income (loss) before provision for (benefit from) income taxes and equity income		(5,390	)		(64,979	)		88,313			3,103			—			21,047		Loss on extinguishment of debt		—			19,612			—			—			—			19,612
	Provision for (benefit from) income taxes		(2,075	)		(15,753	)		34,676			914			—			17,762		Other (income) expense, net		—			766			(120	)		(525	)		—			121
	Income (loss) before equity income		(3,315	)		(49,226	)		53,637			2,189			—			3,285		Income (loss) before provision for income taxes and equity income		(1,427	)		(90,947	)		116,957			6,502			—			31,085
	Equity income, net of tax		7,520			56,746			3,109			—			(66,227	)		1,148		Provision for (benefit from) income taxes		(550	)		(30,066	)		47,828			1,973			—			19,185
	Net income		4,205			7,520			56,746			2,189			(66,227	)		4,433		Income (loss) before equity income		(877	)		(60,881	)		69,129			4,529			—			11,900
	Less: Net income attributable to noncontrolling interest		—			—			—			228			—			228		Equity income, net of tax		13,398			74,279			5,150			—			(91,832	)		995
	Net income attributable to Global Brass and Copper Holdings, Inc.	$	4,205		$	7,520		$	56,746		$	1,961		$	(66,227	)	$	4,205		Net income		12,521			13,398			74,279			4,529			(91,832	)		12,895
																				Less: Net income attributable to noncontrolling interest		—			—			—			374			—			374
																				Net income attributable to Global Brass and Copper Holdings, Inc.	$	12,521		$	13,398		$	74,279		$	4,155		$	(91,832	)	$	12,521
		Condensed Consolidating Statement of Operations
		Nine Months Ended September 30, 2012
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated			Global Brass and Copper Holdings, Inc.
								Subsidiaries			Subsidiaries									Condensed Consolidating Statement of Operations
	Net sales	$	—		$	—		$	1,204,470		$	69,679		$	(19,802	)	$	1,254,347		Year Ended December 31, 2011
	Cost of sales		—			(1,896	)		1,071,405			63,168			(19,802	)		1,112,875
	Gross profit		—			1,896			133,065			6,511			—			141,472			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
	Selling, general and administrative expenses		1,086			26,223			43,969			1,963			—			73,241									Subsidiaries			Subsidiaries
																				Net sales	$	—		$	—		$	1,713,367		$	88,136		$	(22,360	)	$	1,779,143
	Operating income (loss)		(1,086	)		(24,327	)		89,096			4,548			—			68,231		Cost of sales		—			735			1,523,655			81,443			(22,360	)		1,583,473
	Interest expense (income)		—			29,896			(2	)		—			—			29,894
	Loss on extinguishment of debt		—			19,612			—			—			—			19,612		Gross profit (loss)		—			(735	)		189,712			6,693			—			195,670
	Other (income) expense, net		—			689			2			(519	)		—			172		Selling, general and administrative expenses		1,650			15,721			49,451			2,569			—			69,391
	Income (loss) before provision for (benefit from) income taxes and equity income		(1,086	)		(74,524	)		89,096			5,067			—			18,553		Operating income (loss)		(1,650	)		(16,456	)		140,261			4,124			—			126,279
	Provision for (benefit from) income taxes		(418	)		(24,813	)		38,710			517			—			13,996		Interest expense		—			39,950			60			—			—			40,010
																				Other (income) expense, net		—			292			317			(177	)		—			432
	Income (loss) before equity income		(668	)		(49,711	)		50,386			4,550			—			4,557
	Equity income, net of tax		5,688			55,399			5,013			—			(65,364	)		736		Income (loss) before provision for income taxes and equity income		(1,650	)		(56,698	)		139,884			4,301			—			85,837
																				Provision for (benefit from) income taxes		(635	)		(20,765	)		51,662			1,175			—			31,437
	Net income		5,020			5,688			55,399			4,550			(65,364	)		5,293
	Less: Net income attributable to noncontrolling interest		—			—			—			273			—			273		Income (loss) before equity income		(1,015	)		(35,933	)		88,222			3,126			—			54,400
																				Equity income, net of tax		56,147			92,080			3,858			—			(151,197	)		888
	Net income attributable to Global Brass and Copper Holdings, Inc.	$	5,020		$	5,688		$	55,399		$	4,277		$	(65,364	)	$	5,020
																				Net income		55,132			56,147			92,080			3,126			(151,197	)		55,288
																				Less: Net income attributable to noncontrolling interest		—			—			—			156			—			156
																				Net income attributable to Global Brass and Copper Holdings, Inc.	$	55,132		$	56,147		$	92,080		$	2,970		$	(151,197	)	$	55,132
																				Global Brass and Copper Holdings, Inc.
																				Condensed Consolidating Statement of Operations
																				Year Ended December 31, 2010
																					Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
																											Subsidiaries			Subsidiaries
																				Net sales	$	—		$	—		$	1,599,714		$	91,256		$	(32,241	)	$	1,658,729
																				Cost of sales		—			16,759			1,428,661			83,516			(32,241	)		1,496,695
																				Gross profit (loss)		—			(16,759	)		171,053			7,740			—			162,034
																				Selling, general and administrative expenses		1,102			12,337			52,988			2,430			—			68,857
																				Operating income (loss)		(1,102	)		(29,096	)		118,065			5,310			—			93,177
																				Interest expense		—			25,070			6			—			—			25,076
																				Other (income) expense, net		—			668			219			(77	)		—			810
																				Income (loss) before provision for income taxes and equity income		(1,102	)		(54,834	)		117,840			5,387			—			67,291
																			Provision for (benefit from) income taxes		(424	)		(20,214	)		46,093			1,221			—			26,676
																			Income (loss) before equity income		(678	)		(34,620	)		71,747			4,166			—			40,615
																			Equity income, net of tax		42,311			76,931			5,184			—			(122,896	)		1,530
																			Net income		41,633			42,311			76,931			4,166			(122,896	)		42,145
																			Less: Net income attributable to noncontrolling interest		—			—			—			512			—			512
																			Net income attributable to Global Brass and Copper Holdings, Inc.	$	41,633		$	42,311		$	76,931		$	3,654		$	(122,896	)	$	41,633
Condensed Consolidating Statement of Comprehensive Income	'																			'
																				Global Brass and Copper Holdings, Inc.
		Condensed Consolidating Statement of Comprehensive Income																		Condensed Consolidating Statement of Comprehensive Income
		Nine Months Ended September 30, 2013																		Year Ended December 31, 2012
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
								Subsidiaries			Subsidiaries
	Net income	$	4,205		$	7,520		$	56,746		$	2,189		$	(66,227	)	$	4,433			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
	Foreign currency translation adjustment, net of tax		(705	)		(705	)		(1,181	)		340			1,633			(618	)								Subsidiaries			Subsidiaries
																				Net income	$	12,521		$	13,398		$	74,279		$	4,529		$	(91,832	)	$	12,895
	Comprehensive income		3,500			6,815			55,565			2,529			(64,594	)		3,815		Other comprehensive income (loss):
	Less: Comprehensive income attributable to noncontrolling interest		—			—			—			315			—			315		Foreign currency translation adjustment		(457	)		(457	)		(521	)		1,060			(74	)		(449	)
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.	$	3,500		$	6,815		$	55,565		$	2,214		$	(64,594	)	$	3,500		Comprehensive income		12,064			12,941			73,758			5,589			(91,906	)		12,446
																				Less: Comprehensive income attributable to noncontrolling interest		—			—			—			382			—			382
																				Comprehensive income attributable to Global Brass and Copper Holdings, Inc.	$	12,064		$	12,941		$	73,758		$	5,207		$	(91,906	)	$	12,064
		Condensed Consolidating Statement of Comprehensive Income
		Nine Months Ended September 30, 2012
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated			Global Brass and Copper Holdings, Inc.
								Subsidiaries			Subsidiaries									Condensed Consolidating Statement of Comprehensive Income
	Net income	$	5,020		$	5,688		$	55,399		$	4,550		$	(65,364	)	$	5,293		Year Ended December 31, 2011
	Foreign currency translation adjustment, net of tax		(130	)		(130	)		(200	)		983			(653	)		(130	)
	Comprehensive income		4,890			5,558			55,199			5,533			(66,017	)		5,163			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
	Less: Comprehensive income attributable to noncontrolling interest		—			—			—			273			—			273									Subsidiaries			Subsidiaries
																				Net income	$	55,132		$	56,147		$	92,080		$	3,126		$	(151,197	)	$	55,288
	Comprehensive income attributable to Global Brass and Copper Holdings, Inc.	$	4,890		$	5,558		$	55,199		$	5,260		$	(66,017	)	$	4,890		Other comprehensive income (loss):
																				Foreign currency translation adjustment		362			362			415			(417	)		(253	)		469
																				Comprehensive income		55,494			56,509			92,495			2,709			(151,450	)		55,757
																				Less: Comprehensive income attributable to noncontrolling interest		—			—			—			263			—			263
																				Comprehensive income attributable to Global Brass and Copper Holdings, Inc.	$	55,494		$	56,509		$	92,495		$	2,446		$	(151,450	)	$	55,494
																				Global Brass and Copper Holdings, Inc.
																				Condensed Consolidating Statement of Comprehensive Income
																				Year Ended December 31, 2010
																					Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
																											Subsidiaries			Subsidiaries
																				Net income	$	41,633		$	42,311		$	76,931		$	4,166		$	(122,896	)	$	42,145
																				Other comprehensive income (loss):
																				Foreign currency translation adjustment		442			442			1,430			(1,741	)		(60	)		513
																				Comprehensive income		42,075			42,753			78,361			2,425			(122,956	)		42,658
																				Less: Comprehensive income attributable to noncontrolling interest		—			—			—			583			—			583
																				Comprehensive income attributable to Global Brass and Copper Holdings, Inc.	$	42,075		$	42,753		$	78,361		$	1,842		$	(122,956	)	$	42,075
Condensed Consolidating Statement of Cash Flows	'																			'
																				Global Brass and Copper Holdings, Inc.
		Condensed Consolidating Statement of Cash Flows																		Condensed Consolidating Statement of Cash Flows
		Nine Months Ended September 30, 2013																		Year Ended December 31, 2012
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
								Subsidiaries			Subsidiaries
	Cash flows from operating activities																				Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
	Net cash provided by (used in) operating activities	$	—		$	(5,275	)	$	15,537		$	1,024		$	(6,754	)	$	4,532									Subsidiaries			Subsidiaries
	Cash flows from investing activities																			Cash flows from operating activities
	Capital expenditures		—			(76	)		(13,074	)		(55	)		—			(13,205	)	Net cash provided by operating activities	$	73,624		$	58,118		$	19,781		$	1,299		$	(70,908	)	$	81,914
	Payable to subsidiaries		(4,875	)		—			—			—			4,875			—		Cash flows from investing activities
	Proceeds from sale of property, plant and equipment		—			—			170			4			—			174		Capital expenditures		—			(549	)		(19,813	)		(46	)		—			(20,408	)
																				Capital distributions from subsidiary		86,376			—			—			—			(86,376	)		—
	Net cash used in investing activities		(4,875	)		(76	)		(12,904	)		(51	)		4,875			(13,031	)	Payable to subsidiaries		2,424			—			—			—			(2,424	)		—
	Cash flows from financing activities																			Other		—			—			32			—			—			32
	Borrowings on ABL Facility		—			337,236			—			—			—			337,236
	Payments on ABL Facility		—			(329,258	)		—			—			—			(329,258	)	Net cash provided by (used in) investing activities		88,800			(549	)		(19,781	)		(46	)		(88,800	)		(20,376	)
	Distribution to stockholder		—			—			—			(2,000	)		2,000			—		Cash flows from financing activities
	Net payments (amounts due) from stockholder		4,875			—			—			—			—			4,875		Deferred financing fees		—			(12,981	)		—			—			—			(12,981	)
																				Proceeds from senior secured notes		—			375,000			—			—			—			375,000
	Net cash provided by (used in) financing activities		4,875			7,978			—			(2,000	)		2,000			12,853		Payments on term loan		—			(310,875	)		—			—			—			(310,875	)
	Effect of foreign currency exchange rate changes		—			—			—			(128	)		—			(128	)	Borrowings on ABL Facility		—			204,275			—			—			—			204,275
																				Payments on ABL Facility		—			(189,753	)		—			—			—			(189,753	)
	Net increase (decrease) in cash		—			2,627			2,633			(1,155	)		121			4,226		Distributions to stockholder		(160,000	)		(160,000	)		—			—			160,000			(160,000	)
	Cash at beginning of period		—			8,537			—			5,446			(121	)		13,862		Amounts due from stockholder		(2,424	)		—			—			—			—			(2,424	)
	Cash at end of period	$	—		$	11,164		$	2,633		$	4,291		$	—		$	18,088		Net cash used in financing activities		(162,424	)		(94,334	)		—			—			160,000			(96,758	)
																				Effect of foreign currency exchange rate changes		—			—			—			(455	)		—			(455	)
																				Net (decrease) increase in cash		—			(36,765	)		—			798			292			(35,675	)
		Condensed Consolidating Statement of Cash Flows																		Cash at beginning of year		—			45,302			—			4,648			(413	)		49,537
		Nine Months Ended September 30, 2012
		Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated			Cash at end of year	$	—		$	8,537		$	—		$	5,446		$	(121	)	$	13,862
								Subsidiaries			Subsidiaries
	Cash flows from operating activities
	Net cash provided by (used for) operating activities	$	73,624		$	49,063		$	10,765		$	(30	)	$	(75,170	)	$	58,252		Global Brass and Copper Holdings, Inc.
	Cash flows from investing activities																			Condensed Consolidating Statement of Cash Flows
	Capital expenditures		—			(549	)		(10,790	)		(21	)		—			(11,360	)	Year Ended December 31, 2011
	Capital distributions from subsidiary		86,376			—			—						(86,376	)		—
	Payable to subsidiaries		2,398			—			—			—			(2,398	)		—
	Proceeds from sale of property, plant and equipment		—			—			25			—			—			25			Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
																											Subsidiaries			Subsidiaries
	Net cash provided by (used in) investing activities		88,774			(549	)		(10,765	)		(21	)		(88,774	)		(11,335	)	Cash flows from operating activities
	Cash flows from financing activities																			Net cash provided by operating activities	$	—		$	37,381		$	22,250		$	2,687		$	2,530		$	64,848
	Deferred financing fees		—			(12,981	)		—			—			—			(12,981	)	Cash flows from investing activities
	Proceeds from senior secured notes		—			375,000			—			—			—			375,000		Capital expenditures		—			(946	)		(21,429	)		(65	)		—			(22,440	)
	Payments on term loan		—			(310,875	)		—			—			—			(310,875	)	Payable to subsidiaries		2,451			—			—			—			(2,451	)		—
	Borrowings on ABL Facility		—			142,400			—			—			—			142,400		Other		—			—			95			2			—			97
	Payments on ABL Facility		—			(113,900	)		—			—			—			(113,900	)
	Distribution to stockholder		(160,000	)		(160,000	)		—			—			160,000			(160,000	)	Net cash provided by (used in) investing activities		2,451			(946	)		(21,334	)		(63	)		(2,451	)		(22,343	)
	Amounts due from stockholder		(2,398	)		—			—			—			—			(2,398	)	Cash flows from financing activities
																				Deferred financing fees		—			(1,675	)		—			—			—			(1,675	)
	Net cash used in financing activities		(162,398	)		(80,356	)		—			—			160,000			(82,754	)	Payments on term loan		—			(3,300	)		—			—			—			(3,300	)
	Effect of foreign currency exchange rate changes		—			—			—			(682	)		—			(682	)	Borrowings on ABL Facility		—			168,021			—			—			—			168,021
																				Payments on ABL Facility		—			(168,021	)		—			—			—			(168,021	)
	Net decrease in cash		—			(31,842	)		—			(733	)		(3,944	)		(36,519	)	Principal payments under capital lease obligation		—			—			(916	)		—			—			(916	)
	Cash at beginning of period		—			45,302			—			4,648			(413	)		49,537		Amounts due from stockholder		(2,451	)		—			—			—			—			(2,451	)
	Cash at end of period	$	—		$	13,460		$	—		$	3,915		$	(4,357	)	$	13,018		Net cash used in financing activities		(2,451	)		(4,975	)		(916	)		—			—			(8,342	)
																				Effect of foreign currency exchange rate changes		—			—			—			(149	)		—			(149	)
																				Net increase in cash		—			31,460			—			2,475			79			34,014
																				Cash at beginning of year		—			13,842			—			2,173			(492	)		15,523
																				Cash at end of year	$	—		$	45,302		$	—		$	4,648		$	(413	)	$	49,537
																				Global Brass and Copper Holdings, Inc.
																				Condensed Consolidating Statement of Cash Flows
																				Year Ended December 31, 2010
																					Parent			Issuer			Guarantor			Non-Guarantor			Eliminations			Consolidated
																			Subsidiaries								Subsidiaries
																			Cash flows from operating activities
																			Net cash provided by operating activities	$	42,500		$	60,079		$	9,237		$	590		$	(42,992	)	$	69,414
																			Cash flows from investing activities
																			Capital expenditures		—			—			(11,664	)		(263	)		—			(11,927	)
																			Other		—			—			39			—			—			39
																			Net cash provided by (used in) investing activities		—			—			(11,625	)		(263	)		—			(11,888	)
																			Cash flows from financing activities
																			Deferred financing fees		—			(15,131	)		—			—			—			(15,131	)
																			Proceeds from term loan		—			305,550			—			—			—			305,550
																			Payments on term loan		—			(825	)		—			—			—			(825	)
																			Borrowings on ABL Facility		—			1,096,578			—			—			—			1,096,578
																			Payments on ABL Facility		—			(1,272,197	)		—			—			—			(1,272,197	)
																			Principal payments under capital lease obligation		—			—			(52	)		—			—			(52	)
																			Payments on related party debt		—			(119,805	)		—			—			—			(119,805	)
																			Distribution to stockholder		(42,500	)		(42,500	)		—			—			42,500			(42,500	)
																			Cash overdrafts		—			(1,228	)		—			—			—			(1,228	)
																			Net cash used in financing activities		(42,500	)		(49,558	)		(52	)		—			42,500			(49,610	)
																			Effect of foreign currency exchange rate changes		—			—			—			(225	)		—			(225	)
																			Net increase (decrease) in cash		—			10,521			(2,440	)		102			(492	)		7,691
																			Cash at beginning of year		—			3,321			2,440			2,071			—			7,832
																			Cash at end of year	$	—		$	13,842		$	—		$	2,173		$	(492	)	$	15,523

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2012
Accounting Policies [Abstract]	'
Reconciliation of Activity in Allowance for Doubtful Accounts	'
	The reconciliation of the activity in the allowance for doubtful accounts is summarized below:
		Year Ended December 31,
		2012			2011			2010
	Balance at beginning of period	$	2,067		$	7,921		$	7,505
	Provision for bad debts, net of reductions		(814	)		(4,171	)		1,324
	Write-offs, net of recoveries		—			(1,683	)		(908	)
	Recoveries, net of write-offs		155			—			—
	Balance at end of period	$	1,408		$	2,067		$	7,921

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2012
Property Plant And Equipment [Abstract]	'
Property, Plant and Equipment Balances	'
	The Company’s property, plant and equipment balances are as follows:
		As of December 31,						Useful Life
		2012			2011			(in years)
	Land and land improvements	$	1,726		$	1,598
	Buildings		9,077			8,489		20
	Machinery and equipment		55,175			42,715		12
	Information technology		4,477			2,462		5
	Motor vehicles		2,521			1,403		5
	Leasehold improvements		1,083			127
	Construction-in-process		13,324			10,279
	Gross property, plant and equipment		87,383			67,073
	Accumulated depreciation		(16,256	)		(9,517	)
	Property, plant and equipment, net	$	71,127		$	57,556

Intangible_Assets_Tables

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2012
Goodwill And Intangible Assets Disclosure [Abstract]	'
Intangible Assets Other Than Goodwill	'
	Intangible assets other than goodwill consisted of the following:
		As of						Amortization
		December 31,						Period (in  years)
		2012			2011
	Gross carrying amount:
	Customer relationships	$	1,350		$	1,350			13
	Non-compete agreement		380			380			4
	Total gross intangible assets		1,730			1,730
	Accumulated amortization:
	Customer relationships		(511	)		(407	)
	Non-compete agreement		(380	)		(372	)
	Total accumulated amortization		(891	)		(779	)
	Intangible assets, net	$	839		$	951
Amortization Expense Expected to be Incurred in Subsequent Years	'
	Amortization expense is expected to be incurred in subsequent years as follows:
	Year	Amortization
	2013	$	104
	2014		104
	2015		104
	2016		104
	2017		104
	Thereafter		319
		$	839

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2012
Commitments And Contingencies Disclosure [Abstract]	'
Future Minimum Lease Payments under Non-cancelable Leases	'
	Future minimum lease payments under non-cancelable leases in effect are as follows:
	Year	Payment
	2013	$	2,654
	2014		1,621
	2015		956
	2016		612
	2017		122
	Thereafter		—
	Total minimum lease payments	$	5,965

Quarterly_Financial_Informatio1

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]	'
Quarterly Financial Information	'
		21		Quarterly Financial Information (Unaudited)
			2012
			First		Second			Third		Fourth
			Quarter (A)		Quarter (A)			Quarter (A)		Quarter
	Net sales		$	443,391	$	416,979		$	393,977	$	396,173
	Gross profit			49,954		47,121			44,397		41,714	(C)
	Income (loss) before provision for (benefit from) income taxes and equity income			21,971		(21,063	) (B)		17,645		12,532
	Net income (loss)			14,047		(19,891	)		11,137		7,602
	Net income (loss) attributable to Global Brass and Copper Holdings, Inc.			13,993		(20,005	)		11,032		7,501
	Net income (loss) attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic			0.66		(0.95	)		0.52		0.36
			2011
			First		Second			Third		Fourth
			Quarter (A)		Quarter (A)			Quarter (A)		Quarter (A)
	Net sales		$	492,915	$	473,251		$	439,500	$	373,477
	Gross profit			50,026		44,231			38,077		63,336	(D)
	Income before provision for income taxes and equity income			21,712		17,498			10,779		35,848
	Net income			14,170		10,268			7,280		23,570
	Net income attributable to Global Brass and Copper Holdings, Inc.			14,058		10,201			7,283		23,590
	Net income attributable to Global Brass and Copper Holdings, Inc. per common share:
	Basic			0.67		0.48			0.35		1.12
		(A)	The above data have been adjusted for prior period revisions discussed in note 2, “Summary of Significant Accounting Policies” and as illustrated in note 22, “Revision of Prior Period Financial Statements (Unaudited)”.
		(B)	Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.
		(C)	Includes $4,775 gain from liquidation of LIFO inventory layers.
		(D)	Includes $15,236 gain from liquidation of LIFO inventory layers.

Basis_of_Presentation_and_Prin1

Basis of Presentation and Principles of Consolidation - Additional Information (Detail) (USD $)

9 Months Ended

12 Months Ended

9 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

In Thousands, except Share data, unless otherwise specified

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Oct. 01, 2013

Oct. 01, 2013

Sep. 30, 2012

Sep. 30, 2012

Dec. 31, 2011

Dec. 31, 2010

Sep. 30, 2012

Sep. 30, 2012

Dec. 31, 2011

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Segment

Segment

Halkos [Member]

IPO [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Duplicate accruals for receipt of raw material [Member]

Duplicate accruals for receipt of raw material [Member]

Duplicate accruals for receipt of raw material [Member]

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

Secondary Public Offering [Member]

Secondary Public Offering [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Halkos [Member]

Cost of sales [Member]

Cost of sales [Member]

Cost of sales [Member]

Cost of sales [Member]

Cost of sales [Member]

Cost of sales [Member]

Cost of sales [Member]

Consolidation And Basis Of Presentation [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, shares issued

'

'

'

8,050,000

5,750,000

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of common stock share outstanding

'

'

61.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of common stock share outstanding

'

'

'

'

'

34.40%

'

'

'

'

'

'

'

'

'

'

'

Number of reportable segments

3

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of ownership, equity method investment

'

'

'

'

'

'

'

'

'

'

'

'

'

20.00%

20.00%

50.00%

50.00%

Overstated/(understated) amount

'

'

'

'

'

'

$811

$423

($148)

($297)

($1,396)

($389)

$389

'

'

'

'

Summary_of_Revisions_to_Consol

Summary of Revisions to Consolidated Statement of Operation (Detail) (USD $)	3 Months Ended																6 Months Ended		9 Months Ended			12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cost of sales	'		$349,580		$369,858		$393,437		$310,141		$401,423		$429,020		$442,889		$763,295	$871,909	$1,201,815	$1,112,875	$1,273,332	$1,467,334	$1,583,473	$1,496,695
Gross profit	41,714	[1]	44,397	[2]	47,121	[2]	49,954	[2]	63,336	[2],[3]	38,077	[2]	44,231	[2]	50,026	[2]	97,075	94,257	143,863	141,472	132,334	183,186	195,670	162,034
Operating income	'		27,044		9,156		32,031		46,386		20,979		27,748		31,166		41,187	58,914	51,241	68,231	79,893	90,545	126,279	93,177
Third party interest expense	'		'		'		'		9,618		9,954		10,988		9,450		'	20,438	29,938	29,894	30,392	39,727	40,010	25,076
Income (loss) before provision for income taxes and equity income	12,532		17,645	[2]	-21,063	[2],[4]	21,971	[2]	35,848	[2]	10,779	[2]	17,498	[2]	21,712	[2]	908	39,210	21,047	18,553	49,989	31,085	85,837	67,291
Provision (benefit) for income taxes	'		6,769		-971		8,198		12,613		3,726		7,258		7,840		7,227	15,098	17,762	13,996	18,824	19,185	31,437	26,676
Income (loss) before equity income	'		10,876		-20,092		13,773		23,235		7,053		10,240		13,872		-6,319	24,112	3,285	4,557	31,165	11,900	54,400	40,615
Net income (loss)	7,602		11,137	[2]	-19,891	[2]	14,047	[2]	23,570	[2]	7,280	[2]	10,268	[2]	14,170	[2]	-5,844	24,438	4,433	5,293	31,718	12,895	55,288	42,145
Net income (loss) attributable to Global Brass and Copper Holdings, Inc.	7,501		11,032	[2]	-20,005	[2]	13,993	[2]	23,590	[2]	7,283	[2]	10,201	[2]	14,058	[2]	-6,012	24,259	4,205	5,020	31,542	12,521	55,132	41,633
Net income (loss) attributable to Global Brass and Copper Holdings, Inc. per common share:	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Basic	$0.36		$0.52	[2]	($0.95)	[2]	$0.66	[2]	$1.12	[2]	$0.35	[2]	$0.48	[2]	$0.67	[2]	($0.28)	$1.15	$0.20	$0.24	$1.49	$0.59	$2.61	$1.97
Scenario, Previously Reported [Member]	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Cost of sales	'		348,995		371,213		392,701		309,254		401,931		429,357		442,383		763,914	871,740	'	1,112,909	1,273,671	'	1,582,925	1,497,944
Gross profit	'		44,982		45,766		50,690		64,223		37,569		43,894		50,532		96,456	94,426	'	141,438	131,995	'	196,218	160,785
Operating income	'		27,629		7,801		32,767		47,273		20,471		27,411		31,672		40,568	59,083	'	68,197	79,554	'	126,827	91,928
Third party interest expense	'		'		'		'		9,140		10,159		11,149		9,562		'	20,711	'	'	30,870	'	'	'
Income (loss) before provision for income taxes and equity income	'		18,230		-22,418		22,707		37,213		10,066		17,000		22,106		289	39,106	'	18,519	49,172	'	86,385	66,042
Provision (benefit) for income taxes	'		6,670		-1,247		8,468		13,087		3,428		6,783		7,956		7,221	14,739	'	13,891	18,167	'	31,254	26,176
Income (loss) before equity income	'		11,560		-21,171		14,239		24,126		6,638		10,217		14,150		-6,932	24,367	'	4,628	31,005	'	55,131	39,866
Net income (loss)	'		11,821		-20,970		14,513		24,461		6,865		10,245		14,448		-6,457	24,693	'	5,364	31,558	'	56,019	41,396
Net income (loss) attributable to Global Brass and Copper Holdings, Inc.	'		11,716		-21,084		14,459		24,481		6,868		10,178		14,336		-6,625	24,514	'	5,091	31,382	'	55,863	40,884
Net income (loss) attributable to Global Brass and Copper Holdings, Inc. per common share:	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Basic	'		$0.55		($1)		$0.68		$1.16		$0.33		$0.48		$0.68		($0.31)	$1.16	'	$0.24	$1.49	'	$2.65	$1.94
Scenario, Adjustment [Member]	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Cost of sales	'		585		-1,355		736		887		-508		-337		506		-619	169	'	-34	-339	'	548	-1,249
Gross profit	'		-585		1,355		-736		-887		508		337		-506		619	-169	'	34	339	'	-548	1,249
Operating income	'		-585		1,355		-736		-887		508		337		-506		619	-169	'	34	339	'	-548	1,249
Third party interest expense	'		'		'		'		478		-205		-161		-112		'	-273	'	'	-478	'	'	'
Income (loss) before provision for income taxes and equity income	'		-585		1,355		-736		-1,365		713		498		-394		619	104	'	34	817	'	-548	1,249
Provision (benefit) for income taxes	'		99		276		-270		-474		298		475		-116		6	359	'	105	657	'	183	500
Income (loss) before equity income	'		-684		1,079		-466		-891		415		23		-278		613	-255	'	-71	160	'	-731	749
Net income (loss)	'		-684		1,079		-466		-891		415		23		-278		613	-255	'	-71	160	'	-731	749
Net income (loss) attributable to Global Brass and Copper Holdings, Inc.	'		($684)		$1,079		($466)		($891)		$415		$23		($278)		$613	($255)	'	($71)	$160	'	($731)	$749
Net income (loss) attributable to Global Brass and Copper Holdings, Inc. per common share:	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Basic	'		($0.03)		$0.05		($0.02)		($0.04)		$0.02		'		($0.01)		$0.03	($0.01)	'	'	'	'	($0.04)	$0.03
[1]	Includes $4,775 gain from liquidation of LIFO inventory layers.
[2]	The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".
[3]	Includes $15,236 gain from liquidation of LIFO inventory layers.
[4]	Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.

Summary_of_Revisions_to_Consol1

Summary of Revisions to Consolidated Statement of Comprehensive Income (Detail) (USD $)	3 Months Ended															6 Months Ended		9 Months Ended			12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income	$7,602	$11,137	[1]	($19,891)	[1]	$14,047	[1]	$23,570	[1]	$7,280	[1]	$10,268	[1]	$14,170	[1]	($5,844)	$24,438	$4,433	$5,293	$31,718	$12,895	$55,288	$42,145
Comprehensive income (loss)	'	11,130		-20,034		14,067		23,419		7,370		10,475		14,493		-5,967	24,968	3,815	5,163	32,338	12,446	55,757	42,658
Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.	'	11,047		-20,153		13,996		23,424		7,328		10,377		14,365		-6,157	24,742	3,500	4,890	32,070	12,064	55,494	42,075
Scenario, Previously Reported [Member]	'	'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Net income	'	11,821		-20,970		14,513		24,461		6,865		10,245		14,448		-6,457	24,693	'	5,364	31,558	'	56,019	41,396
Comprehensive income (loss)	'	11,814		-21,113		14,533		24,310		6,955		10,452		14,771		-6,580	25,223	'	5,234	32,178	'	56,488	41,909
Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.	'	11,731		-21,232		14,462		24,315		6,913		10,354		14,643		-6,770	24,997	'	4,961	31,910	'	56,225	41,326
Scenario, Adjustment [Member]	'	'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Net income	'	-684		1,079		-466		-891		415		23		-278		613	-255	'	-71	160	'	-731	749
Comprehensive income (loss)	'	-684		1,079		-466		-891		415		23		-278		613	-255	'	-71	160	'	-731	749
Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.	'	($684)		$1,079		($466)		($891)		$415		$23		($278)		$613	($255)	'	($71)	$160	'	($731)	$749
[1]	The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

Summary_of_Revisions_to_Consol2

Summary of Revisions to Consolidated Statement of Changes in Equity (Detail) (USD $)	3 Months Ended															6 Months Ended		9 Months Ended			12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 01, 2010
Net income (loss)	$7,602	$11,137	[1]	($19,891)	[1]	$14,047	[1]	$23,570	[1]	$7,280	[1]	$10,268	[1]	$14,170	[1]	($5,844)	$24,438	$4,433	$5,293	$31,718	$12,895	$55,288	$42,145	'
Net income (loss) attributable to Global Brass and Copper Holdings, Inc.	7,501	11,032	[1]	-20,005	[1]	13,993	[1]	23,590	[1]	7,283	[1]	10,201	[1]	14,058	[1]	-6,012	24,259	4,205	5,020	31,542	12,521	55,132	41,633	'
Retained earnings (accumulated deficit)	-48,153	-55,654		-66,686		82,711		68,718		45,128		37,845		27,644		-66,686	37,845	-43,948	-55,654	45,128	-48,153	68,718	13,586	'
Total Global Brass and Copper Holdings, Inc. stockholders' equity (deficit)	-51,351	-58,499		-69,309		93,247		79,492		56,382		49,347		39,907		-69,309	49,347	-12,716	-58,499	56,382	-51,351	79,492	25,564	'
Total equity (deficit)	-47,801	-55,058		-65,951		96,486		82,660		59,555		52,478		42,940		-65,951	52,478	-8,851	-55,058	59,555	-47,801	82,660	28,469	24,859
Scenario, Previously Reported [Member]	'	'		'		'		'		'		'		'		'	'	'	'	'	'	'	'	'
Net income (loss)	'	11,821		-20,970		14,513		24,461		6,865		10,245		14,448		-6,457	24,693	'	5,364	31,558	'	56,019	41,396	'
Net income (loss) attributable to Global Brass and Copper Holdings, Inc.	'	11,716		-21,084		14,459		24,481		6,868		10,178		14,336		-6,625	24,514	'	5,091	31,382	'	55,863	40,884	'
Retained earnings (accumulated deficit)	'	-56,083		-67,799		82,677		68,218		43,737		36,869		26,691		-67,799	36,869	'	-56,083	43,737	'	68,218	12,355	'
Total Global Brass and Copper Holdings, Inc. stockholders' equity (deficit)	'	-58,928		-70,422		93,213		78,992		54,991		48,371		38,954		-70,422	48,371	'	-58,928	54,991	'	78,992	24,333	'
Total equity (deficit)	'	-55,487		-67,064		96,452		82,160		58,164		51,502		41,987		-67,064	51,502	'	-55,487	58,164	'	82,160	27,238	'
Scenario, Adjustment [Member]	'	'		'		'		'		'		'		'		'	'	'	'	'	'	'	'	'
Net income (loss)	'	-684		1,079		-466		-891		415		23		-278		613	-255	'	-71	160	'	-731	749	'
Net income (loss) attributable to Global Brass and Copper Holdings, Inc.	'	-684		1,079		-466		-891		415		23		-278		613	-255	'	-71	160	'	-731	749	'
Retained earnings (accumulated deficit)	'	429		1,113		34		500		1,391		976		953		1,113	976	'	429	1,391	'	500	1,231	'
Total Global Brass and Copper Holdings, Inc. stockholders' equity (deficit)	'	429		1,113		34		500		1,391		976		953		1,113	976	'	429	1,391	'	500	1,231	'
Total equity (deficit)	'	$429		$1,113		$34		$500		$1,391		$976		$953		$1,113	$976	'	$429	$1,391	'	$500	$1,231	'
[1]	The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

Inventories_Summary_of_Invento

Inventories - Summary of Inventories (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'	'	'	'	'	'	'	'
Raw materials and supplies	$34,646	$37,766	'	'	$21,320	'	'	'	'
Work-in-process	99,119	69,286	'	'	93,555	'	'	'	'
Finished goods	75,013	67,326	'	'	71,072	'	'	'	'
Total inventories	$208,778	$174,378	$180,004	$172,677	$185,947	$163,492	$168,735	$202,515	$192,623

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Inventory [Line Items]	'	'	'	'	'	'	'
Percentage of material component in inventory	70.00%	72.00%	73.00%	'	70.00%	72.00%	'
Lower of cost or market adjustment	'	'	$318	$302	$302	'	'
Inventories valued at period-end market value	319,282	347,840	331,213	'	319,282	347,840	'
Effect of liquidation of LIFO inventory layers	4,775	15,236	'	'	4,775	15,236	21,009
Cost of sales [Member]	'	'	'	'	'	'	'
Inventory [Line Items]	'	'	'	'	'	'	'
Effect of liquidation of LIFO inventory layers	'	'	'	'	-4,775	-15,236	-21,009
Net Income Loss [Member]	'	'	'	'	'	'	'
Inventory [Line Items]	'	'	'	'	'	'	'
Effect of liquidation of LIFO inventory layers	'	'	'	'	$2,908	$9,291	$12,862

Prepaid_Expenses_and_Other_Cur2

Prepaid Expenses and Other Current Assets - Components of Prepaid Expenses and Other Current Assets (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
In Thousands, unless otherwise specified
Prepaid Expenses And Other Current Assets [Line Items]	'	'	'	'	'	'	'
Collateral on deposit-commodity derivative contracts	$1,861	$767	$4,622	'	'	'	'
Commodity derivative contracts	5	548	'	'	'	'	'
Deferred expense	13,018	'	'	'	'	'	'
Deferred financing fees, net	'	'	3,646	'	'	'	'
Loss fund payments-workers' compensation	6,466	6,968	7,538	'	'	'	'
Prepaid insurance	1,705	1,261	1,974	'	'	'	'
Prepaid tooling	1,926	764	'	'	'	'	'
Other	1,610	1,833	'	'	'	'	'
Total prepaid expenses and other current assets	26,591	12,141	19,912	25,746	22,201	31,101	38,441
Including Prepaid Tooling [Member]	'	'	'	'	'	'	'
Prepaid Expenses And Other Current Assets [Line Items]	'	'	'	'	'	'	'
Other	'	$2,597	$2,132	'	'	'	'

Goodwill_Additional_Informatio

Goodwill - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Goodwill [Line Items]	'	'	'
Carrying value of goodwill	$4,399	$4,399	$4,399
Goodwill deductible for tax purpose	1,973	2,131	'
Chase [Member]	'	'	'
Goodwill [Line Items]	'	'	'
Carrying value of goodwill	$4,399	$4,399	'

Investment_in_Joint_Venture_Ad

Investment in Joint Venture - Additional Information (Detail) (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Nov. 19, 2007
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'	'
Cash dividends received, recorded as reduction in Company's investment in joint venture	$452	$500	$1,000	$500	$566	'
Equity income, net of tax	1,148	736	995	888	1,530	'
Dowa - Olin Metal Corporation [Member]	'	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'	'
Interest in joint venture	50.00%	'	50.00%	'	'	'
Carrying value as a result of bargain purchase event	'	'	'	'	'	0
Negative basis difference	5,192	'	5,735	6,459	'	9,416
Negative basis difference accreted on a straight-line basis Period	'13 years	'	'13 years	'	'	'
Accretion of negative basis difference	543	543	724	724	724	'
Undistributed earnings of joint venture in retained earnings	$758	'	$62	$67	'	'

Other_Noncurrent_Assets_Schedu

Other Noncurrent Assets - Schedule of Other Noncurrent Assets (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]	'	'	'
Deferred financing fees, net	$15,225	$17,082	$9,779
Utility and other deposits	1,395	668	1,060
Interest rate cap agreements	'	1	157
Other	'	4	177
Total other noncurrent assets	$16,620	$17,755	$11,173

Accrued_Liabilities_Components

Accrued Liabilities - Components of Accrued Liabilities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
In Thousands, unless otherwise specified
Accrued Liabilities [Line Items]	'	'	'	'	'	'	'	'	'	'
Personnel expense	$20,685	$20,872	'	'	'	$20,548	'	'	'	'
Workers' compensation	14,383	15,754	'	'	'	15,653	'	'	'	'
Deferred revenue	13,018	'	'	'	'	'	'	'	'	'
Professional fees	1,826	2,145	'	'	'	2,623	'	'	'	'
Insurance	2,358	2,253	'	'	'	1,689	'	'	'	'
Utilities	1,877	1,844	'	'	'	1,531	'	'	'	'
Taxes	1,371	1,745	'	'	'	1,471	'	'	'	'
Tooling	737	686	'	'	'	'	'	'	'	'
Commodity derivative contracts	357	'	'	'	'	1,825	'	'	'	'
Other	3,027	3,125	'	'	'	'	'	'	'	'
Total accrued liabilities	59,639	48,424	59,604	40,574	48,364	48,604	59,291	63,314	72,592	84,992
Including Accrued Tooling [Member]	'	'	'	'	'	'	'	'	'	'
Accrued Liabilities [Line Items]	'	'	'	'	'	'	'	'	'	'
Other	'	$3,811	'	'	'	$3,264	'	'	'	'

Financing_Components_of_LongTe

Financing - Components of Long-Term Debt (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012	Jun. 01, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified				ABL Facility [Member]	ABL Facility [Member]	Senior Secured Notes [Member]	Senior Secured Notes [Member]	Senior Secured Notes [Member]	Term Loan Facility [Member]
Debt Instrument [Line Items]	'	'	'	'	'	'	'	'	'
Long-term debt	'	'	'	$22,500	$14,522	$375,000	$375,000	$375,000	$310,875
Discount, net of amortization	'	-1,234	-7,297	'	'	'	'	'	'
Long-term Debt	'	389,522	303,578	'	'	'	'	'	'
Less: Current maturities of long-term debt	'	'	31,880	'	'	'	'	'	'
Total long-term debt	$397,500	$389,522	$271,698	'	'	'	'	'	'

Financing_Additional_Informati

Financing - Additional Information (Detail) (USD $)

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

12 Months Ended

Jun. 01, 2012

Jun. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Dec. 31, 2010

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Jun. 01, 2012

Sep. 30, 2013

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2011

ABL Facility [Member]

ABL Facility [Member]

ABL Facility [Member]

ABL Facility [Member]

ABL Facility [Member]

ABL Facility [Member]

ABL Facility [Member]

ABL Facility [Member]

Senior Secured Notes [Member]

Senior Secured Notes [Member]

Senior Secured Notes [Member]

Senior Secured Notes [Member]

Senior Secured Notes [Member]

Senior Secured Notes [Member]

Senior Secured Notes [Member]

Term Loan Facility [Member]

Term Loan Facility [Member]

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

In the event of increased commodity prices [Member]

Minimum [Member]

Maximum [Member]

Upon the occurrence of certain change of control events [Member]

Upon the completion of certain asset dispositions [Member]

Prime Rate [Member]

London Interbank Offered Rate (LIBOR) [Member]

Prime Rate [Member]

London Interbank Offered Rate (LIBOR) [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate principal amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$375,000,000

$375,000,000

$375,000,000

'

'

'

'

'

$310,875,000

Debt instrument stated interest rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9.50%

'

'

'

'

'

'

'

'

Senior Secured Notes maturity period

'

'

'

'

'

'

1-Jun-17

'

'

'

'

'

'

'

1-Jun-19

'

1-Jun-19

'

'

'

'

'

'

Dividend and cash distributed to meet expenses

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,000,000

5,000,000

'

'

'

'

'

'

Percentage of dividend to net income

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

50.00%

50.00%

'

'

'

'

'

'

Restricted net assets of subsidiaries

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

34,957,000

16,432,000

'

'

'

'

'

'

Unused portion of ABL credit facility

'

'

'

'

'

'

184,978,000

177,000,000

149,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest rate at end of period

'

'

'

'

'

'

4.50%

3.33%

5.25%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Distribution to stockholder

160,000,000

'

'

160,000,000

160,000,000

42,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt instrument payment description

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'Interest on the Senior Secured Notes accrues at the rate of 9.50% per annum and is payable semiannually in arrears on June 1 and December 1, commencing on December 1, 2012.

'

'

'

'

'

'

Debt instrument, principal outstanding redemption price percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

101.00%

100.00%

'

'

Additional interest on the Notes in default

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.25%

0.50%

'

'

'

'

Line of credit facility, current borrowing capacity

'

'

'

'

'

'

150,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit facility, maximum borrowing capacity

'

'

'

'

'

'

200,000,000

'

'

'

'

'

'

250,000,000

'

'

'

'

'

'

'

'

'

Eligible Accounts

'

'

'

'

'

'

85.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Eligible Inventory

'

'

'

'

'

'

80.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net Recovery Percentage for the Eligible Inventory

'

'

'

'

'

'

90.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Letters of credit outstanding

'

'

'

'

'

'

500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unused credit facility fee rate

'

'

'

'

'

'

0.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loans, basis spread

'

'

'

'

'

'

'

'

'

1.00%

2.00%

1.50%

2.50%

'

'

'

'

'

'

'

'

'

'

Percentage of applicable interest rate spread increased on account of default

'

'

'

'

'

'

2.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss from extinguishment of debt

'

-19,612,000

'

-19,612,000

-19,612,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-19,612,000

'

Loss on extinguishment of debt, write-off of unamortized debt issuance costs

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,126,000

'

Write-off of unamortized debt discount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,932,000

'

Payment of call premium

'

'

'

'

6,394,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,394,000

'

Professional services fees on loss on extinguishment of debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

21,000

'

Debt issuance costs expensed as incurred

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1,139,000

'

Income_Taxes_Summary_of_Effect

Income Taxes - Summary of Effective Income Tax Rate (Detail)	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]	'	'	'	'	'
Statutory provision rate	35.00%	35.00%	35.00%	35.00%	35.00%
Permanent differences and other items	'	'	'	'	'
State tax provision	7.90%	3.60%	6.70%	3.90%	6.00%
Section 199 manufacturing credit	-6.90%	-2.80%	-3.20%	-2.30%	-1.50%
Incremental tax effects of foreign earnings	'	'	1.80%	0.20%	0.30%
Return to provision adjustments	-1.40%	-3.10%	1.20%	-0.70%	-2.20%
Re-rate of deferred taxes	'	'	-0.80%	-0.30%	-0.20%
Non-deductible non-cash compensation	48.70%	41.20%	22.00%	0.40%	1.80%
Other	1.10%	1.50%	-1.00%	0.40%	0.40%
Effective income tax rate	84.40%	75.40%	61.70%	36.60%	39.60%

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax [Line Items]	'	'	'	'	'
Unrecognized tax benefits	$25,841	'	$27,401	$31,340	$35,483
Unrecognized tax benefits that would impact effective tax rate	0	'	0	0	'
Estimated interest and penalties expense related to the underpayment of income taxes	29	-138	'	'	'
Accrued interest and penalties related to the underpayment of income taxes	64	'	35	301	'
Liability for uncertain tax positions	25,905	'	27,436	31,641	'
Inventory deferred tax asset	'	'	48,932	50,936	'
Deferred tax liabilities establish on U.S.Federal and State Income Taxes	'	'	7,310	6,507	'
Foreign tax credit carryforward expiry year	'	'	1-Jan-22	'	'
Foreign Tax Authority [Member]	'	'	'	'	'
Income Tax [Line Items]	'	'	'	'	'
Foreign Tax Carryforward	'	'	514	'	'
LIFO [Member]	'	'	'	'	'
Income Tax [Line Items]	'	'	'	'	'
Inventory deferred tax asset	'	'	$25,521	'	'

Derivative_Contracts_Additiona

Derivative Contracts - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Senior secured term loan	50.00%	50.00%	'	'
Derivative collateral included in prepaid expenses and other current assets	$1,504	$767	'	$2,885
Interest rate cap agreement term	'	'	'3 years	'
Interest rate cap agreements [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Notional Amount of Interest Rate Cap Agreements	'	'	300,000	'

Derivative_Contracts_Effects_o

Derivative Contracts - Effects of Derivative Contracts in Condensed Consolidated Financial Statements (Detail) (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Gross Amounts of Recognized Assets	$778	'	$775	$494	'
Gross Amounts Offset in Consolidated Balance Sheet	-773	'	-226	-337	'
Net Amounts of Assets Presented in Consolidated Balance Sheet	5	'	549	157	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	'	'	'	'	'
Net Amount	5	'	549	157	'
Derivative Asset	5	'	549	'	'
Gross Amounts of Recognized Liabilities	1,130	'	226	2,162	'
Derivative liabilities	357	'	'	'	'
Gross Amounts Offset in Consolidated Balance Sheet	-773	'	-226	-337	'
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	357	'	'	1,825	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Deposited	357	'	'	-1,737	'
Net Amount	'	'	'	88	'
Cost of sales [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Realized and unrealized (loss) gain	-348	949	1,658	4,458	9,430
Prepaid Expenses and Other Current Assets [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Derivative Asset	5	'	548	'	'
Accrued Liabilities [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Derivative liabilities	357	'	'	1,825	'
Other Noncurrent Assets [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Derivative Asset	'	'	1	157	'
Open metal contracts [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Gross Amounts of Recognized Assets	722	'	603	294	'
Gross Amounts Offset in Consolidated Balance Sheet	-722	'	-224	-294	'
Net Amounts of Assets Presented in Consolidated Balance Sheet	'	'	379	'	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	'	'	'	'	'
Net Amount	'	'	379	'	'
Gross Amounts of Recognized Liabilities	1,074	'	224	1,647	'
Gross Amounts Offset in Consolidated Balance Sheet	-722	'	-224	-294	'
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	352	'	'	1,353	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Deposited	352	'	'	-1,353	'
Net Amount	'	'	'	'	'
Open metal contracts [Member] | Cost of sales [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Realized and unrealized (loss) gain	-143	614	1,339	3,884	7,605
Open electricity contracts [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Gross Amounts of Recognized Assets	56	'	169	43	'
Gross Amounts Offset in Consolidated Balance Sheet	-51	'	-2	-43	'
Net Amounts of Assets Presented in Consolidated Balance Sheet	5	'	167	'	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	'	'	'	'	'
Net Amount	5	'	167	'	'
Gross Amounts of Recognized Liabilities	51	'	2	131	'
Gross Amounts Offset in Consolidated Balance Sheet	-51	'	-2	-43	'
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	'	'	'	88	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Deposited	'	'	'	'	'
Net Amount	'	'	'	88	'
Open natural gas contracts [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Gross Amounts of Recognized Assets	'	'	2	'	'
Net Amounts of Assets Presented in Consolidated Balance Sheet	'	'	2	'	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	'	'	'	'	'
Net Amount	'	'	2	'	'
Gross Amounts of Recognized Liabilities	5	'	'	384	'
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	5	'	'	384	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Deposited	5	'	'	-384	'
Net Amount	'	'	'	'	'
Interest rate cap agreements [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Gross Amounts of Recognized Assets	'	'	1	157	'
Net Amounts of Assets Presented in Consolidated Balance Sheet	'	'	1	157	'
Amount Not Offset in the Consolidated Balance Sheet, Financial Instruments	'	'	'	'	'
Amount Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	'	'	'	'	'
Net Amount	'	'	1	157	'
Interest rate cap agreements [Member] | Interest Expense [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Unrealized loss	-1	-156	156	1,851	-800
Natural gas contracts [Member] | Cost of sales [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Realized and unrealized (loss) gain	-12	113	76	517	1,825
Electricity contracts [Member] | Cost of sales [Member]	'	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'	'
Realized and unrealized (loss) gain	($193)	$222	$243	$57	'

Derivative_Contracts_Effects_o1

Derivative Contracts - Effects of Derivative Contracts in Condensed Consolidated Financial Statements (Parenthetical) (Detail)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
	Contract	Contract	Contract
Open metal contracts [Member]	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'
Number of contracts - assets	361	208	88
Number of contacts - liabilities	406	85	151
Open electricity contracts [Member]	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'
Number of contracts - assets	10	17	6
Number of contacts - liabilities	14	1	8
Open natural gas contracts [Member]	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'
Number of contracts - assets	'	6	'
Number of contacts - liabilities	4	'	31
Interest rate cap agreements [Member]	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'
Number of contracts - assets	'	2	2

Fair_Value_Measurements_Schedu

Fair Value Measurements - Schedule of Inputs Used to Derive Fair Value of Company's Assets and Liabilities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	$5	$549	$157
Total liabilities, fair value	357	'	1,825
Open electricity contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	5	167	'
Total liabilities, fair value	'	'	88
Open metal contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	379	'
Total liabilities, fair value	352	'	1,353
Open natural gas contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	2	'
Total liabilities, fair value	5	'	384
Interest rate cap agreements [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	1	157
Level 1 [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Total liabilities, fair value	'	'	'
Level 1 [Member] | Open electricity contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Level 1 [Member] | Open metal contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Total liabilities, fair value	'	'	'
Level 1 [Member] | Open natural gas contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Total liabilities, fair value	'	'	'
Level 1 [Member] | Interest rate cap agreements [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Level 2 [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	5	549	157
Total liabilities, fair value	357	'	1,825
Level 2 [Member] | Open electricity contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	5	167	'
Total liabilities, fair value	'	'	88
Level 2 [Member] | Open metal contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	379	'
Total liabilities, fair value	352	'	1,353
Level 2 [Member] | Open natural gas contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	2	'
Total liabilities, fair value	5	'	384
Level 2 [Member] | Interest rate cap agreements [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	1	157
Level 3 [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Total liabilities, fair value	'	'	'
Level 3 [Member] | Open electricity contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Level 3 [Member] | Open metal contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Total liabilities, fair value	'	'	'
Level 3 [Member] | Open natural gas contracts [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'
Total liabilities, fair value	'	'	'
Level 3 [Member] | Interest rate cap agreements [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Total assets, fair value	'	'	'

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Maximum [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Derivative commodity contracts, term	'24 months	'24 months
Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of the Company's Senior Secured Notes	415,781	406,875

Related_Parties_Additional_Inf

Related Parties - Additional Information (Detail) (USD $)

1 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

In Thousands, except Share data, unless otherwise specified

31-May-13

Jun. 01, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Oct. 01, 2013

Sep. 30, 2013

Oct. 01, 2013

Selling, General and Administrative Expenses [Member]

Selling, General and Administrative Expenses [Member]

Selling, General and Administrative Expenses [Member]

Selling, General and Administrative Expenses [Member]

Selling, General and Administrative Expenses [Member]

Secondary Public Offering [Member]

Halkos [Member]

Halkos [Member]

Subsequent Event [Member]

Secondary Public Offering [Member]

Subsequent Event [Member]

Related Party Transaction [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding shares of holdings

'

'

'

'

'

'

'

'

'

'

'

'

'

61.50%

'

Common stock, shares issued

'

'

'

'

'

'

'

'

'

'

'

'

5,750,000

'

'

Percentage of common stock share outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

34.40%

Selling, general and administrative expenses under Management Services Agreement

'

'

'

'

'

'

'

$4,750

$750

$1,000

$1,000

$1,000

'

'

'

Accrued liabilities under Management Services Agreement

'

'

'

'

250

250

'

'

'

'

'

'

'

'

'

Termination fee and management advisory fees

4,500

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reimbursement cost under Management Services Agreement

'

'

24

62

77

167

102

'

'

'

'

'

'

'

'

Receivable from stockholder under KPS Reimbursement Obligation

'

'

'

'

4,875

2,451

'

'

'

'

'

'

'

'

'

Distribution to stockholder

'

$160,000

'

$160,000

$160,000

'

$42,500

'

'

'

'

'

'

'

'

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended				9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Nov. 19, 2007	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2012
					Global Brass and Copper Employees Excluding Chase [Member]	Global Brass and Copper Employees Excluding Chase [Member]	Chase [Member]	Chase [Member]
Commitments And Contingencies [Line Items]	'	'	'	'	'	'	'	'
Comprehensive Medical Plans, Stop loss policy deductible	'	'	'	'	$275	$275	$100	$100
Maximum comprehensive Medical Plans, Stop loss policy deductible	'	'	'	'	'	'	2,000	2,000
Annual workers' compensation costs	'	'	'	500	'	'	'	'
Rental expense under all operating leases	$3,606	$3,603	$3,543	'	'	'	'	'

Profits_Interest_Awards_Additi

Profits Interest Awards - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Profit Interest Units [Line Items]	'	'	'	'	'	'
Profits interest compensation expense	$19,517	$29,271	$19,517	$19,517	$885	$3,452
Profit sharing plan, Class B Shares, vesting period	'	'	'	'Three years	'	'
Distributions received	'	'	'	20,110	292	3,452
Class B Shares [Member]	'	'	'	'	'	'
Profit Interest Units [Line Items]	'	'	'	'	'	'
Profits interest compensation expense	'	8,902	19,517	'	'	'
Incremental non cash compensation expense	'	$20,369	'	'	'	'

Segment_Information_Additional

Segment Information - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
	Segment	Segment
Segment Reporting [Abstract]	'	'
Number of reportable segments	3	3

Segment_Information_Reconcilia

Segment Information - Reconciliation of Segment Adjusted EBITDA to Income Before Provision for Income Taxes and Equity Income (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Jun. 30, 2012

Jun. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

$396,173

$393,977

[1]

$416,979

[1]

$443,391

[1]

$373,477

[1]

$439,500

[1]

$473,251

[1]

$492,915

[1]

'

'

$1,345,678

$1,254,347

'

$1,650,520

$1,779,143

$1,658,729

Total segment adjusted EBITDA

'

'

'

'

'

'

'

'

'

'

108,204

105,880

'

131,273

136,876

105,773

Loss on extinguishment of debt

'

'

-19,612

'

'

'

'

'

'

'

'

-19,612

'

-19,612

'

'

Depreciation and amortization

'

'

'

'

'

'

'

'

'

'

-6,101

-4,891

'

-6,934

-4,759

-2,971

Interest expense

'

'

'

'

-9,618

-9,954

-10,988

-9,450

'

-20,438

-29,938

-29,894

-30,392

-39,727

-40,010

-25,076

Equity method investment income

'

'

'

'

'

'

'

'

'

'

-605

[2]

-193

[2]

'

-271

[3]

-164

[3]

-806

[3]

Net income attributable to noncontrolling interest

'

'

'

'

'

'

'

'

'

'

228

273

'

374

156

512

Lower of cost or market adjustment to inventory

'

'

'

'

'

'

'

'

'

'

-318

-302

'

-302

'

'

(Loss) gain on derivative contracts

'

'

'

'

'

'

'

'

'

'

-1,062

1,473

'

1,588

-1,095

-11,984

Share-based compensation expense

'

'

'

'

'

'

'

'

'

'

-989

'

'

'

'

'

Compensation expense - profits interest awards

'

'

-19,517

'

'

'

'

'

'

'

-29,271

-19,517

'

-19,517

-885

-3,452

Income before provision for income taxes and equity income

12,532

17,645

[1]

-21,063

[1],[4]

21,971

[1]

35,848

[1]

10,779

[1]

17,498

[1]

21,712

[1]

908

39,210

21,047

18,553

49,989

31,085

85,837

67,291

LIFO liquidation gain

4,775

'

'

'

15,236

'

'

'

'

'

'

'

'

4,775

15,236

21,009

Intersegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

40,719

36,698

'

46,759

49,223

59,612

Corporate, Non-Segment [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Corporate and Eliminations

'

'

'

'

'

'

'

'

'

'

-19,101

-14,664

'

-20,562

-19,518

-15,714

Olin Brass [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

613,926

496,786

'

676,563

718,244

710,271

Total segment adjusted EBITDA

'

'

'

'

'

'

'

'

'

'

41,209

37,432

'

45,115

45,320

23,291

Depreciation and amortization

'

'

'

'

'

'

'

'

'

'

'

'

'

-3,849

-2,622

-1,624

LIFO liquidation gain

'

'

'

'

'

'

'

'

'

'

'

'

'

175

8,401

23,253

Olin Brass [Member] | Intersegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

40,539

36,315

'

46,287

48,312

57,919

Chase [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

488,475

505,951

'

647,711

704,968

611,870

Total segment adjusted EBITDA

'

'

'

'

'

'

'

'

'

'

53,831

53,311

'

66,641

73,658

61,158

Depreciation and amortization

'

'

'

'

'

'

'

'

'

'

'

'

'

-2,521

-1,921

-1,200

LIFO liquidation gain

'

'

'

'

'

'

'

'

'

'

'

'

'

1,623

'

75

Chase [Member] | Intersegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

7

302

'

305

626

765

Oster [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

243,277

251,610

'

326,246

355,931

336,588

Total segment adjusted EBITDA

'

'

'

'

'

'

'

'

'

'

13,164

15,137

'

19,517

17,898

21,324

Depreciation and amortization

'

'

'

'

'

'

'

'

'

'

'

'

'

-247

-196

-147

LIFO liquidation gain

'

'

'

'

'

'

'

'

'

'

'

'

'

4,478

7,050

-48

Oster [Member] | Intersegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

$173

$81

'

$167

$285

$928

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

[2]

Excludes accretion income of $181 in each of the nine months ended September 30, 2013 and 2012. Equity method investment income is exclusive to Olin Brass.

[3]

Excludes accretion income of $724 in each of the years ended December 31, 2012, 2011 and 2010. Equity method investment income is exclusive to Olin Brass.

[4]

Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.

Segment_Information_Reconcilia1

Segment Information - Reconciliation of Segment Adjusted EBITDA to Income Before Provision for Income Taxes and Equity Income (Parenthetical) (Detail) (Dowa - Olin Metal Corporation [Member], USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Dowa - Olin Metal Corporation [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Accretion income	$543	$543	$724	$724	$724

Earnings_Per_Share_Schedule_of

Earnings Per Share - Schedule of Basic and Diluted Earning Per Shares Attributable to Company (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

12 Months Ended

In Thousands, except Share data, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Jun. 30, 2012

Jun. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Numerator

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net income attributable to Global Brass and Copper Holdings, Inc.

$7,501

$11,032

[1]

($20,005)

[1]

$13,993

[1]

$23,590

[1]

$7,283

[1]

$10,201

[1]

$14,058

[1]

($6,012)

$24,259

$4,205

$5,020

$31,542

$12,521

$55,132

$41,633

Denominator

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted-average common shares outstanding

'

'

'

'

'

'

'

'

'

'

21,110,000

21,110,000

'

21,110,000

21,110,000

21,110,000

Effect of potentially dilutive securities:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock options and nonvested share awards

'

'

'

'

'

'

'

'

'

'

24,169

'

'

'

'

'

Weighted-average common shares outstanding, assuming dilution

'

'

'

'

'

'

'

'

'

'

21,134,169

21,110,000

'

'

'

'

Net income attributable to Global Brass and Copper Holdings, Inc. per common share:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Basic

$0.36

$0.52

[1]

($0.95)

[1]

$0.66

[1]

$1.12

[1]

$0.35

[1]

$0.48

[1]

$0.67

[1]

($0.28)

$1.15

$0.20

$0.24

$1.49

$0.59

$2.61

$1.97

Diluted

'

'

'

'

'

'

'

'

'

'

$0.20

$0.24

'

'

'

'

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

Earnings_Per_Share_Additional_

Earnings Per Share - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Line Items]	'
Options granted to purchase of common stock	107,895
Restricted Stock [Member]	'
Earnings Per Share [Line Items]	'
Nonvested shares issued to members and directors	141,486
Performance Shares [Member]	'
Earnings Per Share [Line Items]	'
Nonvested shares issued to members and directors	101,754

Stock_Split_Additional_Informa

Stock Split - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Apr. 10, 2013	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013
					Scenario, Adjustment [Member]	Scenario, Adjustment [Member]	IPO [Member]
Equity [Line Items]	'	'	'	'	'	'	'
Stock split Ratio	211,100	211,100	'	'	'	'	'
Common stock, Shares issued under initial public offering	'	'	'	'	'	'	8,050,000
Common stock per share value issued to underwriters	'	'	'	'	'	'	$11
Adjustment to accumulated deficit	'	'	'	'	($211)	($211)	'
Impact to common stock	'	$211	$211	$211	$211	$211	'

Condensed_Consolidating_Financ2

Condensed Consolidating Financial Information - Additional Information (Detail)	1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013	Dec. 31, 2012
	Senior Secured Notes [Member]	Senior Secured Notes [Member]	ABL Facility [Member]	ABL Facility [Member]
Condensed Consolidating Financial Information [Line Items]	'	'	'	'
Ownership percentage of equity holdings	100.00%	100.00%	100.00%	100.00%

Condensed_Consolidating_Financ3

Condensed Consolidating Financial Information - Consolidating Balance Sheet (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Jan. 01, 2010
In Thousands, unless otherwise specified
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	$18,088	$13,862	$13,018	'	'	$49,537	'	'	'	$15,523	$7,832
Accounts receivable, net of allowance	198,473	164,317	211,638	193,310	203,740	161,715	'	'	'	'	'
Inventories	208,778	174,378	'	180,004	172,677	185,947	163,492	168,735	202,515	192,623	'
Prepaid expenses and other current assets	26,591	12,141	'	'	'	19,912	25,746	22,201	31,101	38,441	'
Deferred income taxes	32,122	33,465	26,361	29,343	28,119	29,027	27,716	27,053	28,394	29,312	'
Income tax receivable, net	625	1,300	474	4,520	1,405	5,046	3,260	1,804	2,993	2,276	'
Total current assets	484,677	399,463	447,298	430,404	497,339	451,184	464,098	473,231	510,401	439,564	'
Property, plant and equipment, net	78,137	71,127	'	'	'	57,556	52,067	47,780	42,587	'	'
Investment in joint venture	2,184	2,972	'	'	'	3,507	'	'	'	'	'
Investment in subsidiaries	'	'	'	'	'	'	'	'	'	'	'
Intercompany accounts	'	'	'	'	'	'	'	'	'	'	'
Goodwill	4,399	4,399	'	'	'	4,399	'	'	'	'	'
Intangible assets, net	762	839	'	'	'	951	'	'	'	'	'
Deferred income taxes	5,736	6,138	17,040	19,657	19,798	19,970	31,257	31,921	32,520	34,254	'
Other noncurrent assets	16,620	17,755	'	'	'	11,173	'	'	'	'	'
Total assets	592,515	502,693	555,669	539,223	594,905	548,740	566,963	573,975	610,402	537,721	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Current maturities of long-term debt	'	'	'	'	'	31,880	'	'	'	'	'
Accounts payable	105,311	81,577	'	104,585	111,425	77,888	107,959	'	'	'	'
Accrued liabilities	59,639	48,424	59,604	40,574	48,364	48,604	59,291	63,314	72,592	84,992	'
Accrued interest	12,448	3,287	'	'	'	4,069	'	'	'	'	'
Income tax payable	156	248	'	'	'	300	'	'	'	'	'
Total current liabilities	177,554	133,536	180,595	148,507	195,457	162,741	175,044	183,986	201,326	170,999	'
Long-term debt	397,500	389,522	'	'	'	271,698	'	'	'	'	'
Other noncurrent liabilities	26,312	27,436	'	'	'	31,641	'	'	'	'	'
Obligations and advances in excess of investment in subsidiary	'	'	'	'	'	'	'	'	'	'	'
Intercompany accounts	'	'	'	'	'	'	'	'	'	'	'
Total liabilities	601,366	550,494	610,727	605,174	498,419	466,080	507,408	521,497	567,463	509,252	'
Commitments and contingencies	'	'	'	'	'	'	'	'	'	'	'
Global Brass and Copper Holdings, Inc. stockholders' (deficit) / equity	-12,716	-51,351	-58,499	-69,309	93,247	79,492	56,382	49,347	39,907	25,564	'
Noncontrolling interest	3,865	3,550	'	'	'	3,168	'	'	'	'	'
Total (deficit) / equity	-8,851	-47,801	-55,058	-65,951	96,486	82,660	59,555	52,478	42,940	28,469	24,859
Total liabilities and (deficit) / equity	592,515	502,693	555,669	539,223	594,905	548,740	566,963	573,975	610,402	537,721	'
Parent [Member]	'	'	'	'	'	'	'	'	'	'	'
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	'	'	'	'	'	'	'	'	'	'	'
Accounts receivable, net of allowance	'	'	'	'	'	'	'	'	'	'	'
Inventories	'	'	'	'	'	'	'	'	'	'	'
Prepaid expenses and other current assets	'	'	'	'	'	'	'	'	'	'	'
Deferred income taxes	'	'	'	'	'	'	'	'	'	'	'
Income tax receivable, net	'	'	'	'	'	'	'	'	'	'	'
Total current assets	'	'	'	'	'	'	'	'	'	'	'
Property, plant and equipment, net	'	'	'	'	'	'	'	'	'	'	'
Investment in joint venture	'	'	'	'	'	85,020	'	'	'	'	'
Investment in subsidiaries	'	'	'	'	'	85,020	'	'	'	'	'
Intercompany accounts	'	'	'	'	'	'	'	'	'	'	'
Goodwill	'	'	'	'	'	'	'	'	'	'	'
Intangible assets, net	'	'	'	'	'	'	'	'	'	'	'
Deferred income taxes	'	'	'	'	'	'	'	'	'	'	'
Other noncurrent assets	'	'	'	'	'	'	'	'	'	'	'
Total assets	'	'	'	'	'	85,020	'	'	'	'	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Accounts payable	'	'	'	'	'	'	'	'	'	'	'
Accrued liabilities	'	'	'	'	'	'	'	'	'	'	'
Accrued interest	'	'	'	'	'	'	'	'	'	'	'
Income tax payable	'	'	'	'	'	'	'	'	'	'	'
Total current liabilities	'	'	'	'	'	'	'	'	'	'	'
Long-term debt	'	'	'	'	'	'	'	'	'	'	'
Other noncurrent liabilities	'	'	'	'	'	'	'	'	'	'	'
Obligations and advances in excess of investment in subsidiary	5,447	42,522	'	'	'	'	'	'	'	'	'
Intercompany accounts	7,269	8,829	'	'	'	5,528	'	'	'	'	'
Total liabilities	12,716	51,351	'	'	'	5,528	'	'	'	'	'
Commitments and contingencies	'	'	'	'	'	'	'	'	'	'	'
Global Brass and Copper Holdings, Inc. stockholders' (deficit) / equity	-12,716	-51,351	'	'	'	79,492	'	'	'	'	'
Noncontrolling interest	'	'	'	'	'	'	'	'	'	'	'
Total (deficit) / equity	-12,716	-51,351	'	'	'	79,492	'	'	'	'	'
Total liabilities and (deficit) / equity	'	'	'	'	'	85,020	'	'	'	'	'
Issuer [Member]	'	'	'	'	'	'	'	'	'	'	'
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	11,164	8,537	13,460	'	'	45,302	'	'	'	13,842	3,321
Accounts receivable, net of allowance	4,914	4,630	'	'	'	4,184	'	'	'	'	'
Inventories	'	343	'	'	'	218	'	'	'	'	'
Prepaid expenses and other current assets	10,064	9,229	'	'	'	17,916	'	'	'	'	'
Deferred income taxes	32,122	33,465	'	'	'	29,027	'	'	'	'	'
Income tax receivable, net	799	1,656	'	'	'	5,204	'	'	'	'	'
Total current assets	59,063	57,860	'	'	'	101,851	'	'	'	'	'
Property, plant and equipment, net	976	1,154	'	'	'	923	'	'	'	'	'
Investment in joint venture	'	'	'	'	'	'	'	'	'	'	'
Investment in subsidiaries	623,442	522,912	'	'	'	393,708	'	'	'	'	'
Intercompany accounts	'	'	'	'	'	'	'	'	'	'	'
Goodwill	'	'	'	'	'	'	'	'	'	'	'
Intangible assets, net	'	'	'	'	'	'	'	'	'	'	'
Deferred income taxes	5,736	6,138	'	'	'	19,970	'	'	'	'	'
Other noncurrent assets	15,705	17,115	'	'	'	9,963	'	'	'	'	'
Total assets	704,922	605,179	'	'	'	526,415	'	'	'	'	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Current maturities of long-term debt	'	'	'	'	'	31,880	'	'	'	'	'
Accounts payable	2,455	1,398	'	'	'	'	'	'	'	'	'
Accrued liabilities	18,710	20,592	'	'	'	23,202	'	'	'	'	'
Accrued interest	12,448	3,287	'	'	'	4,069	'	'	'	'	'
Income tax payable	'	248	'	'	'	300	'	'	'	'	'
Total current liabilities	33,613	25,525	'	'	'	59,451	'	'	'	'	'
Long-term debt	397,500	389,522	'	'	'	271,698	'	'	'	'	'
Other noncurrent liabilities	26,312	27,436	'	'	'	31,641	'	'	'	'	'
Obligations and advances in excess of investment in subsidiary	'	'	'	'	'	'	'	'	'	'	'
Intercompany accounts	252,944	205,218	'	'	'	78,605	'	'	'	'	'
Total liabilities	710,369	647,701	'	'	'	441,395	'	'	'	'	'
Commitments and contingencies	'	'	'	'	'	'	'	'	'	'	'
Global Brass and Copper Holdings, Inc. stockholders' (deficit) / equity	-5,447	-42,522	'	'	'	85,020	'	'	'	'	'
Noncontrolling interest	'	'	'	'	'	'	'	'	'	'	'
Total (deficit) / equity	-5,447	-42,522	'	'	'	85,020	'	'	'	'	'
Total liabilities and (deficit) / equity	704,922	605,179	'	'	'	526,415	'	'	'	'	'
Guarantor Subsidiaries [Member]	'	'	'	'	'	'	'	'	'	'	'
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	2,633	'	'	'	'	'	'	'	'	'	2,440
Accounts receivable, net of allowance	176,272	144,533	'	'	'	145,083	'	'	'	'	'
Inventories	193,825	158,713	'	'	'	174,429	'	'	'	'	'
Prepaid expenses and other current assets	16,441	2,600	'	'	'	2,245	'	'	'	'	'
Deferred income taxes	'	'	'	'	'	'	'	'	'	'	'
Income tax receivable, net	'	'	'	'	'	128	'	'	'	'	'
Total current assets	389,171	305,846	'	'	'	321,885	'	'	'	'	'
Property, plant and equipment, net	76,810	69,646	'	'	'	56,322	'	'	'	'	'
Investment in joint venture	2,184	2,972	'	'	'	3,507	'	'	'	'	'
Investment in subsidiaries	19,974	19,850	'	'	'	13,351	'	'	'	'	'
Intercompany accounts	270,599	223,081	'	'	'	92,889	'	'	'	'	'
Goodwill	4,399	4,399	'	'	'	4,399	'	'	'	'	'
Intangible assets, net	762	839	'	'	'	951	'	'	'	'	'
Deferred income taxes	'	'	'	'	'	'	'	'	'	'	'
Other noncurrent assets	915	640	'	'	'	1,210	'	'	'	'	'
Total assets	764,814	627,273	'	'	'	494,514	'	'	'	'	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Accounts payable	101,105	77,390	'	'	'	76,190	'	'	'	'	'
Accrued liabilities	40,232	26,971	'	'	'	24,616	'	'	'	'	'
Accrued interest	'	'	'	'	'	'	'	'	'	'	'
Income tax payable	35	'	'	'	'	'	'	'	'	'	'
Total current liabilities	141,372	104,361	'	'	'	100,806	'	'	'	'	'
Long-term debt	'	'	'	'	'	'	'	'	'	'	'
Other noncurrent liabilities	'	'	'	'	'	'	'	'	'	'	'
Obligations and advances in excess of investment in subsidiary	'	'	'	'	'	'	'	'	'	'	'
Intercompany accounts	'	'	'	'	'	'	'	'	'	'	'
Total liabilities	141,372	104,361	'	'	'	100,806	'	'	'	'	'
Commitments and contingencies	'	'	'	'	'	'	'	'	'	'	'
Global Brass and Copper Holdings, Inc. stockholders' (deficit) / equity	623,442	522,912	'	'	'	393,708	'	'	'	'	'
Noncontrolling interest	'	'	'	'	'	'	'	'	'	'	'
Total (deficit) / equity	623,442	522,912	'	'	'	393,708	'	'	'	'	'
Total liabilities and (deficit) / equity	764,814	627,273	'	'	'	494,514	'	'	'	'	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'	'	'	'	'	'	'	'
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	4,291	5,446	3,915	'	'	4,648	'	'	'	2,173	2,071
Accounts receivable, net of allowance	17,287	15,154	'	'	'	12,448	'	'	'	'	'
Inventories	15,363	15,885	'	'	'	11,921	'	'	'	'	'
Prepaid expenses and other current assets	86	312	'	'	'	135	'	'	'	'	'
Deferred income taxes	'	'	'	'	'	'	'	'	'	'	'
Income tax receivable, net	'	'	'	'	'	'	'	'	'	'	'
Total current assets	37,027	36,797	'	'	'	29,152	'	'	'	'	'
Property, plant and equipment, net	351	327	'	'	'	311	'	'	'	'	'
Investment in joint venture	'	'	'	'	'	'	'	'	'	'	'
Investment in subsidiaries	'	'	'	'	'	'	'	'	'	'	'
Intercompany accounts	'	'	'	'	'	'	'	'	'	'	'
Goodwill	'	'	'	'	'	'	'	'	'	'	'
Intangible assets, net	'	'	'	'	'	'	'	'	'	'	'
Deferred income taxes	'	'	'	'	'	'	'	'	'	'	'
Other noncurrent assets	'	'	'	'	'	'	'	'	'	'	'
Total assets	37,378	37,124	'	'	'	29,463	'	'	'	'	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Accounts payable	2,161	2,910	'	'	'	2,495	'	'	'	'	'
Accrued liabilities	697	861	'	'	'	786	'	'	'	'	'
Accrued interest	'	'	'	'	'	'	'	'	'	'	'
Income tax payable	295	356	'	'	'	286	'	'	'	'	'
Total current liabilities	3,153	4,127	'	'	'	3,567	'	'	'	'	'
Long-term debt	'	'	'	'	'	'	'	'	'	'	'
Other noncurrent liabilities	'	'	'	'	'	'	'	'	'	'	'
Obligations and advances in excess of investment in subsidiary	'	'	'	'	'	'	'	'	'	'	'
Intercompany accounts	10,386	9,597	'	'	'	9,377	'	'	'	'	'
Total liabilities	13,539	13,724	'	'	'	12,944	'	'	'	'	'
Commitments and contingencies	'	'	'	'	'	'	'	'	'	'	'
Global Brass and Copper Holdings, Inc. stockholders' (deficit) / equity	19,974	19,850	'	'	'	13,351	'	'	'	'	'
Noncontrolling interest	3,865	3,550	'	'	'	3,168	'	'	'	'	'
Total (deficit) / equity	23,839	23,400	'	'	'	16,519	'	'	'	'	'
Total liabilities and (deficit) / equity	37,378	37,124	'	'	'	29,463	'	'	'	'	'
Eliminations [Member]	'	'	'	'	'	'	'	'	'	'	'
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	'	-121	-4,357	'	'	-413	'	'	'	-492	'
Accounts receivable, net of allowance	'	'	'	'	'	'	'	'	'	'	'
Inventories	-410	-563	'	'	'	-621	'	'	'	'	'
Prepaid expenses and other current assets	'	'	'	'	'	-384	'	'	'	'	'
Deferred income taxes	'	'	'	'	'	'	'	'	'	'	'
Income tax receivable, net	-174	-356	'	'	'	-286	'	'	'	'	'
Total current assets	-584	-1,040	'	'	'	-1,704	'	'	'	'	'
Property, plant and equipment, net	'	'	'	'	'	'	'	'	'	'	'
Investment in joint venture	'	'	'	'	'	'	'	'	'	'	'
Investment in subsidiaries	-643,416	-542,762	'	'	'	-492,079	'	'	'	'	'
Intercompany accounts	-270,599	-223,081	'	'	'	-92,889	'	'	'	'	'
Goodwill	'	'	'	'	'	'	'	'	'	'	'
Intangible assets, net	'	'	'	'	'	'	'	'	'	'	'
Deferred income taxes	'	'	'	'	'	'	'	'	'	'	'
Other noncurrent assets	'	'	'	'	'	'	'	'	'	'	'
Total assets	-914,599	-766,883	'	'	'	-586,672	'	'	'	'	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Accounts payable	-410	-121	'	'	'	-797	'	'	'	'	'
Accrued liabilities	'	'	'	'	'	'	'	'	'	'	'
Accrued interest	'	'	'	'	'	'	'	'	'	'	'
Income tax payable	-174	-356	'	'	'	-286	'	'	'	'	'
Total current liabilities	-584	-477	'	'	'	-1,083	'	'	'	'	'
Long-term debt	'	'	'	'	'	'	'	'	'	'	'
Other noncurrent liabilities	'	'	'	'	'	'	'	'	'	'	'
Obligations and advances in excess of investment in subsidiary	-5,447	-42,522	'	'	'	'	'	'	'	'	'
Intercompany accounts	-270,599	-223,644	'	'	'	-93,510	'	'	'	'	'
Total liabilities	-276,630	-266,643	'	'	'	-94,593	'	'	'	'	'
Commitments and contingencies	'	'	'	'	'	'	'	'	'	'	'
Global Brass and Copper Holdings, Inc. stockholders' (deficit) / equity	-637,969	-500,240	'	'	'	-492,079	'	'	'	'	'
Noncontrolling interest	'	'	'	'	'	'	'	'	'	'	'
Total (deficit) / equity	-637,969	-500,240	'	'	'	-492,079	'	'	'	'	'
Total liabilities and (deficit) / equity	($914,599)	($766,883)	'	'	'	($586,672)	'	'	'	'	'

Condensed_Consolidating_Financ4

Condensed Consolidating Financial Information - Consolidating Statement of Operations (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Jun. 30, 2012

Jun. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

$396,173

$393,977

[1]

$416,979

[1]

$443,391

[1]

$373,477

[1]

$439,500

[1]

$473,251

[1]

$492,915

[1]

'

'

$1,345,678

$1,254,347

'

$1,650,520

$1,779,143

$1,658,729

Cost of sales

'

349,580

369,858

393,437

310,141

401,423

429,020

442,889

763,295

871,909

1,201,815

1,112,875

1,273,332

1,467,334

1,583,473

1,496,695

Gross profit (loss)

41,714

[2]

44,397

[1]

47,121

[1]

49,954

[1]

63,336

[1],[3]

38,077

[1]

44,231

[1]

50,026

[1]

97,075

94,257

143,863

141,472

132,334

183,186

195,670

162,034

Selling, general and administrative expenses

'

'

'

'

'

'

'

'

'

'

92,622

73,241

'

92,641

69,391

68,857

Operating income (loss)

'

27,044

9,156

32,031

46,386

20,979

27,748

31,166

41,187

58,914

51,241

68,231

79,893

90,545

126,279

93,177

Interest expense

'

'

'

'

9,618

9,954

10,988

9,450

'

20,438

29,938

29,894

30,392

39,727

40,010

25,076

Third party interest expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

22,613

Related party interest expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,463

Loss on extinguishment of debt

'

'

19,612

'

'

'

'

'

'

'

'

19,612

'

19,612

'

'

Other (income) expense, net

'

'

'

'

'

'

'

'

'

'

256

172

'

121

432

810

Income (loss) before provision for (benefit from) income taxes and equity income

12,532

17,645

[1]

-21,063

[1],[4]

21,971

[1]

35,848

[1]

10,779

[1]

17,498

[1]

21,712

[1]

908

39,210

21,047

18,553

49,989

31,085

85,837

67,291

Provision for (benefit from) income taxes

'

6,769

-971

8,198

12,613

3,726

7,258

7,840

7,227

15,098

17,762

13,996

18,824

19,185

31,437

26,676

Income (loss) before equity income

'

10,876

-20,092

13,773

23,235

7,053

10,240

13,872

-6,319

24,112

3,285

4,557

31,165

11,900

54,400

40,615

Equity income, net of tax

'

'

'

'

'

'

'

'

'

'

1,148

736

'

995

888

1,530

Net (loss) income

7,602

11,137

[1]

-19,891

[1]

14,047

[1]

23,570

[1]

7,280

[1]

10,268

[1]

14,170

[1]

-5,844

24,438

4,433

5,293

31,718

12,895

55,288

42,145

Less: Net income attributable to noncontrolling interest

'

'

'

'

'

'

'

'

'

'

228

273

'

374

156

512

Net income attributable to Global Brass and Copper Holdings, Inc.

7,501

11,032

[1]

-20,005

[1]

13,993

[1]

23,590

[1]

7,283

[1]

10,201

[1]

14,058

[1]

-6,012

24,259

4,205

5,020

31,542

12,521

55,132

41,633

Parent [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cost of sales

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gross profit (loss)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Selling, general and administrative expenses

'

'

'

'

'

'

'

'

'

'

5,390

1,086

'

1,427

1,650

1,102

Operating income (loss)

'

'

'

'

'

'

'

'

'

'

-5,390

-1,086

'

-1,427

-1,650

-1,102

Income (loss) before provision for (benefit from) income taxes and equity income

'

'

'

'

'

'

'

'

'

'

-5,390

-1,086

'

-1,427

-1,650

-1,102

Provision for (benefit from) income taxes

'

'

'

'

'

'

'

'

'

'

-2,075

-418

'

-550

-635

-424

Income (loss) before equity income

'

'

'

'

'

'

'

'

'

'

-3,315

-668

'

-877

-1,015

-678

Equity income, net of tax

'

'

'

'

'

'

'

'

'

'

7,520

5,688

'

13,398

56,147

42,311

Net (loss) income

'

'

'

'

'

'

'

'

'

'

4,205

5,020

'

12,521

55,132

41,633

Net income attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

4,205

5,020

'

12,521

55,132

41,633

Issuer [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cost of sales

'

'

'

'

'

'

'

'

'

'

1,208

-1,896

'

83

735

16,759

Gross profit (loss)

'

'

'

'

'

'

'

'

'

'

-1,208

1,896

'

-83

-735

-16,759

Selling, general and administrative expenses

'

'

'

'

'

'

'

'

'

'

33,569

26,223

'

30,756

15,721

12,337

Operating income (loss)

'

'

'

'

'

'

'

'

'

'

-34,777

-24,327

'

-30,839

-16,456

-29,096

Interest expense

'

'

'

'

'

'

'

'

'

'

29,938

29,896

'

39,730

39,950

25,070

Loss on extinguishment of debt

'

'

'

'

'

'

'

'

'

'

'

19,612

'

19,612

'

'

Other (income) expense, net

'

'

'

'

'

'

'

'

'

'

264

689

'

766

292

668

Income (loss) before provision for (benefit from) income taxes and equity income

'

'

'

'

'

'

'

'

'

'

-64,979

-74,524

'

-90,947

-56,698

-54,834

Provision for (benefit from) income taxes

'

'

'

'

'

'

'

'

'

'

-15,753

-24,813

'

-30,066

-20,765

-20,214

Income (loss) before equity income

'

'

'

'

'

'

'

'

'

'

-49,226

-49,711

'

-60,881

-35,933

-34,620

Equity income, net of tax

'

'

'

'

'

'

'

'

'

'

56,746

55,399

'

74,279

92,080

76,931

Net (loss) income

'

'

'

'

'

'

'

'

'

'

7,520

5,688

'

13,398

56,147

42,311

Net income attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

7,520

5,688

'

13,398

56,147

42,311

Guarantor Subsidiaries [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

1,294,809

1,204,470

'

1,584,301

1,713,367

1,599,714

Cost of sales

'

'

'

'

'

'

'

'

'

'

1,155,186

1,071,405

'

1,409,588

1,523,655

1,428,661

Gross profit (loss)

'

'

'

'

'

'

'

'

'

'

139,623

133,065

'

174,713

189,712

171,053

Selling, general and administrative expenses

'

'

'

'

'

'

'

'

'

'

51,444

43,969

'

57,879

49,451

52,988

Operating income (loss)

'

'

'

'

'

'

'

'

'

'

88,179

89,096

'

116,834

140,261

118,065

Interest expense

'

'

'

'

'

'

'

'

'

'

'

-2

'

-3

60

6

Other (income) expense, net

'

'

'

'

'

'

'

'

'

'

-134

2

'

-120

317

219

Income (loss) before provision for (benefit from) income taxes and equity income

'

'

'

'

'

'

'

'

'

'

88,313

89,096

'

116,957

139,884

117,840

Provision for (benefit from) income taxes

'

'

'

'

'

'

'

'

'

'

34,676

38,710

'

47,828

51,662

46,093

Income (loss) before equity income

'

'

'

'

'

'

'

'

'

'

53,637

50,386

'

69,129

88,222

71,747

Equity income, net of tax

'

'

'

'

'

'

'

'

'

'

3,109

5,013

'

5,150

3,858

5,184

Net (loss) income

'

'

'

'

'

'

'

'

'

'

56,746

55,399

'

74,279

92,080

76,931

Net income attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

56,746

55,399

'

74,279

92,080

76,931

Non-Guarantor Subsidiaries [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

73,586

69,679

'

93,655

88,136

91,256

Cost of sales

'

'

'

'

'

'

'

'

'

'

68,138

63,168

'

85,099

81,443

83,516

Gross profit (loss)

'

'

'

'

'

'

'

'

'

'

5,448

6,511

'

8,556

6,693

7,740

Selling, general and administrative expenses

'

'

'

'

'

'

'

'

'

'

2,219

1,963

'

2,579

2,569

2,430

Operating income (loss)

'

'

'

'

'

'

'

'

'

'

3,229

4,548

'

5,977

4,124

5,310

Other (income) expense, net

'

'

'

'

'

'

'

'

'

'

126

-519

'

-525

-177

-77

Income (loss) before provision for (benefit from) income taxes and equity income

'

'

'

'

'

'

'

'

'

'

3,103

5,067

'

6,502

4,301

5,387

Provision for (benefit from) income taxes

'

'

'

'

'

'

'

'

'

'

914

517

'

1,973

1,175

1,221

Income (loss) before equity income

'

'

'

'

'

'

'

'

'

'

2,189

4,550

'

4,529

3,126

4,166

Net (loss) income

'

'

'

'

'

'

'

'

'

'

2,189

4,550

'

4,529

3,126

4,166

Less: Net income attributable to noncontrolling interest

'

'

'

'

'

'

'

'

'

'

228

273

'

374

156

512

Net income attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

1,961

4,277

'

4,155

2,970

3,654

Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

-22,717

-19,802

'

-27,436

-22,360

-32,241

Cost of sales

'

'

'

'

'

'

'

'

'

'

-22,717

-19,802

'

-27,436

-22,360

-32,241

Equity income, net of tax

'

'

'

'

'

'

'

'

'

'

-66,227

-65,364

'

-91,832

-151,197

-122,896

Net (loss) income

'

'

'

'

'

'

'

'

'

'

-66,227

-65,364

'

-91,832

-151,197

-122,896

Net income attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

($66,227)

($65,364)

'

($91,832)

($151,197)

($122,896)

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

[2]

Includes $4,775 gain from liquidation of LIFO inventory layers.

[3]

Includes $15,236 gain from liquidation of LIFO inventory layers.

[4]

Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.

Condensed_Consolidating_Financ5

Condensed Consolidating Financial Information - Consolidating Statement of Comprehensive Income (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Jun. 30, 2012

Jun. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net (loss) income

$7,602

$11,137

[1]

($19,891)

[1]

$14,047

[1]

$23,570

[1]

$7,280

[1]

$10,268

[1]

$14,170

[1]

($5,844)

$24,438

$4,433

$5,293

$31,718

$12,895

$55,288

$42,145

Foreign currency translation adjustment, net of tax

'

'

'

'

'

'

'

'

'

'

-618

-130

'

-449

469

513

Comprehensive income (loss)

'

11,130

-20,034

14,067

23,419

7,370

10,475

14,493

-5,967

24,968

3,815

5,163

32,338

12,446

55,757

42,658

Less: Comprehensive income attributable to noncontrolling interest

'

'

'

'

'

'

'

'

'

'

315

273

'

382

263

583

Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.

'

11,047

-20,153

13,996

23,424

7,328

10,377

14,365

-6,157

24,742

3,500

4,890

32,070

12,064

55,494

42,075

Parent [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net (loss) income

'

'

'

'

'

'

'

'

'

'

4,205

5,020

'

12,521

55,132

41,633

Foreign currency translation adjustment, net of tax

'

'

'

'

'

'

'

'

'

'

-705

-130

'

-457

362

442

Comprehensive income (loss)

'

'

'

'

'

'

'

'

'

'

3,500

4,890

'

12,064

55,494

42,075

Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

3,500

4,890

'

12,064

55,494

42,075

Issuer [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net (loss) income

'

'

'

'

'

'

'

'

'

'

7,520

5,688

'

13,398

56,147

42,311

Foreign currency translation adjustment, net of tax

'

'

'

'

'

'

'

'

'

'

-705

-130

'

-457

362

442

Comprehensive income (loss)

'

'

'

'

'

'

'

'

'

'

6,815

5,558

'

12,941

56,509

42,753

Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

6,815

5,558

'

12,941

56,509

42,753

Guarantor Subsidiaries [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net (loss) income

'

'

'

'

'

'

'

'

'

'

56,746

55,399

'

74,279

92,080

76,931

Foreign currency translation adjustment, net of tax

'

'

'

'

'

'

'

'

'

'

-1,181

-200

'

-521

415

1,430

Comprehensive income (loss)

'

'

'

'

'

'

'

'

'

'

55,565

55,199

'

73,758

92,495

78,361

Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

55,565

55,199

'

73,758

92,495

78,361

Non-Guarantor Subsidiaries [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net (loss) income

'

'

'

'

'

'

'

'

'

'

2,189

4,550

'

4,529

3,126

4,166

Foreign currency translation adjustment, net of tax

'

'

'

'

'

'

'

'

'

'

340

983

'

1,060

-417

-1,741

Comprehensive income (loss)

'

'

'

'

'

'

'

'

'

'

2,529

5,533

'

5,589

2,709

2,425

Less: Comprehensive income attributable to noncontrolling interest

'

'

'

'

'

'

'

'

'

'

315

273

'

382

263

583

Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

2,214

5,260

'

5,207

2,446

1,842

Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net (loss) income

'

'

'

'

'

'

'

'

'

'

-66,227

-65,364

'

-91,832

-151,197

-122,896

Foreign currency translation adjustment, net of tax

'

'

'

'

'

'

'

'

'

'

1,633

-653

'

-74

-253

-60

Comprehensive income (loss)

'

'

'

'

'

'

'

'

'

'

-64,594

-66,017

'

-91,906

-151,450

-122,956

Comprehensive income (loss) attributable to Global Brass and Copper Holdings, Inc.

'

'

'

'

'

'

'

'

'

'

($64,594)

($66,017)

'

($91,906)

($151,450)

($122,956)

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

Condensed_Consolidating_Financ6

Condensed Consolidating Financial Information - Consolidating Statement of Cash Flows (Detail) (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities	'	'	'	'	'
Net cash provided by (used for) operating activities	$4,532	$58,252	$81,914	$64,848	$69,414
Cash flows from investing activities	'	'	'	'	'
Capital expenditures	-13,205	-11,360	-20,408	-22,440	-11,927
Proceeds from sale of property, plant and equipment	174	25	32	97	39
Net cash provided by (used in) investing activities	-13,031	-11,335	-20,376	-22,343	-11,888
Cash flows from financing activities	'	'	'	'	'
Deferred financing fees	'	-12,981	-12,981	-1,675	-15,131
Proceeds from senior secured notes	'	375,000	375,000	'	'
Proceeds from term loan	'	'	'	'	305,550
Payments on term loan	'	-310,875	-310,875	-3,300	-825
Borrowings on ABL Facility	337,236	142,400	204,275	168,021	1,096,578
Payments on ABL Facility	-329,258	-113,900	-189,753	-168,021	-1,272,197
Principal payments under capital lease obligation	'	'	'	-916	-52
Payments on related party debt	'	'	'	'	-119,805
Distribution to shareholder	'	-160,000	-160,000	'	-42,500
Amounts due from stockholder	4,875	-2,398	-2,424	-2,451	'
Cash overdrafts	'	'	'	'	-1,228
Net cash provided by (used in) financing activities	12,853	-82,754	-96,758	-8,342	-49,610
Effect of foreign currency exchange rate changes	-128	-682	-455	-149	-225
Net (decrease) increase in cash	4,226	-36,519	-35,675	34,014	7,691
Cash at beginning of period	13,862	49,537	49,537	15,523	7,832
Cash at end of period	18,088	13,018	13,862	49,537	15,523
Parent [Member]	'	'	'	'	'
Cash flows from operating activities	'	'	'	'	'
Net cash provided by (used for) operating activities	'	73,624	73,624	'	42,500
Cash flows from investing activities	'	'	'	'	'
Capital distributions from subsidiary	'	86,376	86,376	'	'
Payable to subsidiaries	-4,875	2,398	2,424	2,451	'
Net cash provided by (used in) investing activities	-4,875	88,774	88,800	2,451	'
Cash flows from financing activities	'	'	'	'	'
Distribution to shareholder	'	-160,000	-160,000	'	-42,500
Amounts due from stockholder	4,875	-2,398	-2,424	-2,451	'
Net cash provided by (used in) financing activities	4,875	-162,398	-162,424	-2,451	-42,500
Net (decrease) increase in cash	'	'	'	'	'
Cash at beginning of period	'	'	'	'	'
Cash at end of period	'	'	'	'	'
Issuer [Member]	'	'	'	'	'
Cash flows from operating activities	'	'	'	'	'
Net cash provided by (used for) operating activities	-5,275	49,063	58,118	37,381	60,079
Cash flows from investing activities	'	'	'	'	'
Capital expenditures	-76	-549	-549	-946	'
Net cash provided by (used in) investing activities	-76	-549	-549	-946	'
Cash flows from financing activities	'	'	'	'	'
Deferred financing fees	'	-12,981	-12,981	-1,675	-15,131
Proceeds from senior secured notes	'	375,000	375,000	'	'
Proceeds from term loan	'	'	'	'	305,550
Payments on term loan	'	-310,875	-310,875	-3,300	-825
Borrowings on ABL Facility	337,236	142,400	204,275	168,021	1,096,578
Payments on ABL Facility	-329,258	-113,900	-189,753	-168,021	-1,272,197
Payments on related party debt	'	'	'	'	-119,805
Distribution to shareholder	'	-160,000	-160,000	'	-42,500
Cash overdrafts	'	'	'	'	-1,228
Net cash provided by (used in) financing activities	7,978	-80,356	-94,334	-4,975	-49,558
Net (decrease) increase in cash	2,627	-31,842	-36,765	31,460	10,521
Cash at beginning of period	8,537	45,302	45,302	13,842	3,321
Cash at end of period	11,164	13,460	8,537	45,302	13,842
Guarantor Subsidiaries [Member]	'	'	'	'	'
Cash flows from operating activities	'	'	'	'	'
Net cash provided by (used for) operating activities	15,537	10,765	19,781	22,250	9,237
Cash flows from investing activities	'	'	'	'	'
Capital expenditures	-13,074	-10,790	-19,813	-21,429	-11,664
Proceeds from sale of property, plant and equipment	170	25	32	95	39
Net cash provided by (used in) investing activities	-12,904	-10,765	-19,781	-21,334	-11,625
Cash flows from financing activities	'	'	'	'	'
Principal payments under capital lease obligation	'	'	'	-916	-52
Net cash provided by (used in) financing activities	'	'	'	-916	-52
Net (decrease) increase in cash	2,633	'	'	'	-2,440
Cash at beginning of period	'	'	'	'	2,440
Cash at end of period	2,633	'	'	'	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'	'
Cash flows from operating activities	'	'	'	'	'
Net cash provided by (used for) operating activities	1,024	-30	1,299	2,687	590
Cash flows from investing activities	'	'	'	'	'
Capital expenditures	-55	-21	-46	-65	-263
Proceeds from sale of property, plant and equipment	4	'	'	2	'
Net cash provided by (used in) investing activities	-51	-21	-46	-63	-263
Cash flows from financing activities	'	'	'	'	'
Distribution to shareholder	-2,000	'	'	'	'
Net cash provided by (used in) financing activities	-2,000	'	'	'	'
Effect of foreign currency exchange rate changes	-128	-682	-455	-149	-225
Net (decrease) increase in cash	-1,155	-733	798	2,475	102
Cash at beginning of period	5,446	4,648	4,648	2,173	2,071
Cash at end of period	4,291	3,915	5,446	4,648	2,173
Eliminations [Member]	'	'	'	'	'
Cash flows from operating activities	'	'	'	'	'
Net cash provided by (used for) operating activities	-6,754	-75,170	-70,908	2,530	-42,992
Cash flows from investing activities	'	'	'	'	'
Capital distributions from subsidiary	'	-86,376	-86,376	'	'
Payable to subsidiaries	4,875	-2,398	-2,424	-2,451	'
Net cash provided by (used in) investing activities	4,875	-88,774	-88,800	-2,451	'
Cash flows from financing activities	'	'	'	'	'
Distribution to shareholder	2,000	160,000	160,000	'	42,500
Net cash provided by (used in) financing activities	2,000	160,000	160,000	'	42,500
Net (decrease) increase in cash	121	-3,944	292	79	-492
Cash at beginning of period	-121	-413	-413	-492	'
Cash at end of period	'	($4,357)	($121)	($413)	($492)

Organization_and_Formation_of_1

Organization and Formation of the Company - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
	Segment	Segment
Regulatory Assets [Abstract]	'	'
Number of reportable segments	3	3

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Sep. 30, 2013

Dec. 31, 2012

Dec. 31, 2011

Nov. 19, 2007

Dec. 31, 2011

Dec. 31, 2010

Jan. 01, 2010

Jan. 01, 2010

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2011

Dec. 31, 2010

Jan. 01, 2010

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2011

Sep. 30, 2012

Sep. 30, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2010

Jan. 01, 2010

Sep. 30, 2012

Sep. 30, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2011

Dec. 31, 2010

Jan. 01, 2010

Dec. 31, 2011

Dec. 31, 2010

Jan. 01, 2010

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Chase [Member]

Chase [Member]

Chase [Member]

Chase [Member]

Chase [Member]

Dowa - Olin Metal Corporation [Member]

Dowa - Olin Metal Corporation [Member]

Dowa - Olin Metal Corporation [Member]

Dowa - Olin Metal Corporation [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Income Tax Expense Benefit [Member]

Income Tax Expense Benefit [Member]

Non Toll [Member]

Non Toll [Member]

Non Toll [Member]

Toll [Member]

Toll [Member]

Toll [Member]

Derivative [Member]

Derivative [Member]

Derivative [Member]

Derivative [Member]

Derivative [Member]

Duplicate accruals for receipt of raw material [Member]

Duplicate accruals for receipt of raw material [Member]

Duplicate accruals for receipt of raw material [Member]

Duplicate accruals for receipt of raw material [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Raw material in-transit [Member]

Workers Compensation Insurance [Member]

Workers Compensation Insurance [Member]

Workers Compensation Insurance [Member]

Workers Compensation Insurance [Member]

Workers Compensation Insurance [Member]

Workers Compensation Insurance [Member]

Workers Compensation Insurance [Member]

Workers Compensation Insurance [Member]

Olin Luotong (GZ) Corporation ("Luotong") [Member]

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

Net Deferred Tax Asset [Member]

Net Deferred Tax Asset [Member]

Net Deferred Tax Asset [Member]

(Accumulated deficit)/ Retained Earnings [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Cost of sales [Member]

Cost of sales [Member]

Restatement Adjustment [Member]

Cost of sales [Member]

Cost of sales [Member]

Cost of sales [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Cost of sales [Member]

Cost of sales [Member]

Cost of sales [Member]

Cost of sales [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Cost of sales [Member]

Cost of sales [Member]

Prepaid Expenses and Other Current Assets [Member]

Prepaid Expenses and Other Current Assets [Member]

Prepaid Expenses and Other Current Assets [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Accrued Liabilities [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Inventory [Member]

Inventory [Member]

Inventory [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Accrued Liabilities [Member]

Accrued Liabilities [Member]

Accrued Liabilities [Member]

Prepaid Expenses and Other Current Assets [Member]

Prepaid Expenses and Other Current Assets [Member]

Prepaid Expenses and Other Current Assets [Member]

Restatement Adjustment [Member]

Restatement Adjustment [Member]

Consolidation And Basis Of Presentation [Line Items]

'

'

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'

'

'

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'

'

'

'

'

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'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest in joint venture

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

50.00%

50.00%

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20.00%

20.00%

50.00%

50.00%

Percentage of ownership

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

80.00%

'

'

'

'

Percentage of net income attributable to non controlling interest

20.00%

'

'

'

'

'

'

'

'

'

20.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Overstated (understated) amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$794

$888

$797

$482

($94)

$91

'

'

'

'

'

'

($510)

($510)

$303

$510

$813

$389

($1,396)

($389)

$389

$423

$275

($22)

$811

$423

($148)

($297)

($7,225)

($7,225)

($5,725)

($7,269)

($7,269)

($5,036)

$44

$733

'

'

'

'

'

Percentage of material component in inventory

70.00%

'

'

'

72.00%

'

'

'

73.00%

'

70.00%

72.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Negative basis difference

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,192

5,735

6,459

9,416

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Negative basis difference accreted on a straight-line basis Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'13 years

'13 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Carrying value of goodwill

4,399

'

'

'

4,399

'

'

'

4,399

'

4,399

4,399

'

4,399

'

4,399

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Goodwill deductible for tax purpose

2,131

'

'

'

'

'

'

'

1,973

'

2,131

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

396,173

393,977

[1]

416,979

[1]

443,391

[1]

373,477

[1]

439,500

[1]

473,251

[1]

492,915

[1]

1,345,678

1,254,347

1,650,520

1,779,143

1,658,729

488,475

505,951

647,711

704,968

611,870

'

'

'

'

'

'

'

'

'

'

1,576,070

1,710,595

1,577,771

74,450

68,548

80,958

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Research & development expenditure

'

'

'

'

'

'

'

'

'

'

$1,516

$1,540

$1,740

'

'

'

'

'

'

'

'

'

'

'

'

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'

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

Summary_of_Revisions_to_Consol3

Summary of Revisions to Consolidated Balance Sheet (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Jan. 01, 2010
In Thousands, unless otherwise specified
Accounts receivable, net of allowance	$198,473	$164,317	$211,638	$193,310	$203,740	$161,715	'	'	'	'	'
Inventories	208,778	174,378	'	180,004	172,677	185,947	163,492	168,735	202,515	192,623	'
Prepaid expenses and other current assets	26,591	12,141	'	'	'	19,912	25,746	22,201	31,101	38,441	'
Deferred income tax assets-current	32,122	33,465	26,361	29,343	28,119	29,027	27,716	27,053	28,394	29,312	'
Income tax receivable	625	1,300	474	4,520	1,405	5,046	3,260	1,804	2,993	2,276	'
Total current assets	484,677	399,463	447,298	430,404	497,339	451,184	464,098	473,231	510,401	439,564	'
Property, plant and equipment, net	78,137	71,127	'	'	'	57,556	52,067	47,780	42,587	'	'
Deferred income tax assets-noncurrent	5,736	6,138	17,040	19,657	19,798	19,970	31,257	31,921	32,520	34,254	'
Total assets	592,515	502,693	555,669	539,223	594,905	548,740	566,963	573,975	610,402	537,721	'
Accounts payable	105,311	81,577	'	104,585	111,425	77,888	107,959	'	'	'	'
Accrued liabilities	59,639	48,424	59,604	40,574	48,364	48,604	59,291	63,314	72,592	84,992	'
Income tax payable	'	'	58	'	64	300	'	'	398	199	'
Total current liabilities	177,554	133,536	180,595	148,507	195,457	162,741	175,044	183,986	201,326	170,999	'
Total liabilities	601,366	550,494	610,727	605,174	498,419	466,080	507,408	521,497	567,463	509,252	'
(Accumulated deficit)/Retained earnings	-43,948	-48,153	-55,654	-66,686	82,711	68,718	45,128	37,845	27,644	13,586	'
Total Global Brass and Copper Holdings, Inc. stockholder's (deficit)/equity	-12,716	-51,351	-58,499	-69,309	93,247	79,492	56,382	49,347	39,907	25,564	'
Total (deficit)/equity	-8,851	-47,801	-55,058	-65,951	96,486	82,660	59,555	52,478	42,940	28,469	24,859
Total liabilities and (deficit)/equity	592,515	502,693	555,669	539,223	594,905	548,740	566,963	573,975	610,402	537,721	'
Scenario, Previously Reported [Member]	'	'	'	'	'	'	'	'	'	'	'
Accounts receivable, net of allowance	'	'	210,654	192,326	202,756	160,731	'	'	'	'	'
Inventories	'	'	'	180,815	173,538	186,370	163,880	169,137	202,745	192,898	'
Prepaid expenses and other current assets	'	'	'	'	'	'	24,752	13,989	23,623	30,662	'
Deferred income tax assets-current	'	'	25,390	28,079	26,793	27,972	26,658	25,823	27,143	28,433	'
Income tax receivable	'	'	648	4,996	1,567	5,017	3,612	2,147	2,666	2,139	'
Total current assets	'	'	445,517	429,443	496,052	449,539	462,786	464,534	501,575	431,044	'
Property, plant and equipment, net	'	'	'	'	'	'	51,589	47,507	42,475	'	'
Deferred income tax assets-noncurrent	'	'	17,350	19,917	20,092	20,218	31,903	32,450	32,867	34,354	'
Total assets	'	'	554,198	538,522	593,912	547,343	565,819	565,534	601,811	529,301	'
Accounts payable	'	'	'	105,981	111,814	78,276	107,971	'	'	'	'
Accrued liabilities	'	'	58,620	39,590	47,080	47,619	59,526	55,849	65,352	78,002	'
Total current liabilities	'	'	179,553	148,919	194,498	161,844	175,291	176,521	193,688	163,810	'
Total liabilities	'	'	609,685	605,586	497,460	465,183	507,655	514,032	559,825	502,063	'
(Accumulated deficit)/Retained earnings	'	'	-56,083	-67,799	82,677	68,218	43,737	36,869	26,691	12,355	'
Total Global Brass and Copper Holdings, Inc. stockholder's (deficit)/equity	'	'	-58,928	-70,422	93,213	78,992	54,991	48,371	38,954	24,333	'
Total (deficit)/equity	'	'	-55,487	-67,064	96,452	82,160	58,164	51,502	41,987	27,238	'
Total liabilities and (deficit)/equity	'	'	554,198	538,522	593,912	547,343	565,819	565,534	601,811	529,301	'
Scenario, Adjustment [Member]	'	'	'	'	'	'	'	'	'	'	'
Accounts receivable, net of allowance	'	'	984	984	984	984	'	'	'	'	'
Inventories	'	'	'	-811	-861	-423	-388	-402	-230	-275	'
Prepaid expenses and other current assets	'	'	'	'	'	'	994	8,212	7,478	7,779	'
Deferred income tax assets-current	'	'	971	1,264	1,326	1,055	1,058	1,230	1,251	879	'
Income tax receivable	'	'	-174	-476	-162	29	-352	-343	327	137	'
Total current assets	'	'	1,781	961	1,287	1,645	1,312	8,697	8,826	8,520	'
Property, plant and equipment, net	'	'	'	'	'	'	478	273	112	'	'
Deferred income tax assets-noncurrent	'	'	-310	-260	-294	-248	-646	-529	-347	-100	'
Total assets	'	'	1,471	701	993	1,397	1,144	8,441	8,591	8,420	'
Accounts payable	'	'	'	-1,396	-389	-388	-12	'	'	'	'
Accrued liabilities	'	'	984	984	1,284	985	-235	7,465	7,240	6,990	'
Income tax payable	'	'	58	'	64	300	'	'	398	199	'
Total current liabilities	'	'	1,042	-412	959	897	-247	7,465	7,638	7,189	'
Total liabilities	'	'	1,042	-412	959	897	-247	7,465	7,638	7,189	'
(Accumulated deficit)/Retained earnings	'	'	429	1,113	34	500	1,391	976	953	1,231	'
Total Global Brass and Copper Holdings, Inc. stockholder's (deficit)/equity	'	'	429	1,113	34	500	1,391	976	953	1,231	'
Total (deficit)/equity	'	'	429	1,113	34	500	1,391	976	953	1,231	'
Total liabilities and (deficit)/equity	'	'	$1,471	$701	$993	$1,397	$1,144	$8,441	$8,591	$8,420	'

Reconciliation_of_Activity_in_

Reconciliation of Activity in Allowance for Doubtful Accounts (Detail) (Allowance for Doubtful Accounts, Current [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Accounts, Current [Member]	'	'	'
Movement in Valuation Allowances and Reserves [Roll Forward]	'	'	'
Balance at beginning of period	$2,067	$7,921	$7,505
Provision for bad debts, net of reductions	-814	-4,171	1,324
Write-offs, net of recoveries	'	-1,683	-908
Recoveries, net of write-offs	155	'	'
Balance at end of period	$1,408	$2,067	$7,921

Property_Plant_and_Equipment_B

Property, Plant and Equipment Balances (Detail) (USD $)

Sep. 30, 2013

Dec. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

In Thousands, unless otherwise specified

Building [Member]

Building [Member]

Machinery and Equipment [Member]

Machinery and Equipment [Member]

Information Technology [Member]

Information Technology [Member]

Vehicles [Member]

Vehicles [Member]

Land and Land Improvements [Member]

Land and Land Improvements [Member]

Leasehold Improvements [Member]

Leasehold Improvements [Member]

Construction in Progress [Member]

Construction in Progress [Member]

Property, Plant and Equipment [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gross property, plant and equipment

'

$87,383

$67,073

'

'

'

$9,077

$8,489

$55,175

$42,715

$4,477

$2,462

$2,521

$1,403

$1,726

$1,598

$1,083

$127

$13,324

$10,279

Accumulated depreciation

'

-16,256

-9,517

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Property, plant and equipment, net

$78,137

$71,127

$57,556

$52,067

$47,780

$42,587

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Useful Life (in years)

'

'

'

'

'

'

'20 years

'

'12 years

'

'5 years

'

'5 years

'

'

'

'

'

'

'

Property_Plant_and_Equipment_A

Property, Plant and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property Plant And Equipment [Abstract]	'	'	'
Capitalized interest costs	$0	$557	$0

Intangible_Assets_Other_Than_G

Intangible Assets Other Than Goodwill (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified				Customer Relationships [Member]	Customer Relationships [Member]	Noncompete Agreements [Member]	Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]	'	'	'	'	'	'	'
Gross intangible assets	'	$1,730	$1,730	$1,350	$1,350	$380	$380
Accumulated amortization	'	-891	-779	-511	-407	-380	-372
Intangible assets, net	$762	$839	$951	'	'	'	'
Amortization Period (in years)	'	'	'	'13 years	'	'4 years	'

Amortization_Expense_Expected_

Amortization Expense Expected to be Incurred in Subsequent Years (Detail) (USD $)	Dec. 31, 2012
In Thousands, unless otherwise specified
Goodwill And Intangible Assets Disclosure [Abstract]	'
2013	$104
2014	104
2015	104
2016	104
2017	104
Thereafter	319
Finite-Lived Intangible Assets, Net, Total	$839

Other_Non_Current_Assets_Addit

Other Non Current Assets - Additional Information (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Other Noncurrent Assets Disclosure [Line Items]	'	'
Deferred debt issuance cost	$12,981	'
Unamortized debt issuance cost	1,783	'
Unamortized issuance discount	1,234	7,297
Senior Secured Notes [Member]	'	'
Other Noncurrent Assets Disclosure [Line Items]	'	'
Aggregate principal amount	375,000	'
Deferred debt issuance cost	10,196	'
ABL Facility [Member]	'	'
Other Noncurrent Assets Disclosure [Line Items]	'	'
Deferred debt issuance cost	$2,785	'

Income_Taxes_Income_Before_Pro

Income Taxes - Income Before Provision for Income Taxes and Equity Income (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Jun. 30, 2012

Jun. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Income Tax Disclosure [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Domestic

'

'

'

'

'

'

'

'

'

'

'

'

'

$24,583

$81,534

$61,903

Foreign

'

'

'

'

'

'

'

'

'

'

'

'

'

6,502

4,303

5,388

Income (loss) before provision for (benefit from) income taxes and equity income

$12,532

$17,645

[1]

($21,063)

[1],[2]

$21,971

[1]

$35,848

[1]

$10,779

[1]

$17,498

[1]

$21,712

[1]

$908

$39,210

$21,047

$18,553

$49,989

$31,085

$85,837

$67,291

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

[2]

Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.

Income_Taxes_Provision_for_Inc

Income Taxes - Provision for Income Taxes (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Jun. 30, 2012

Jun. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Current tax provision

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

U.S. federal

'

'

'

'

'

'

'

'

'

'

'

'

$10,329

$16,518

$13,663

State and local

'

'

'

'

'

'

'

'

'

'

'

'

1,923

3,347

5,660

Foreign

'

'

'

'

'

'

'

'

'

'

'

'

1,685

1,081

1,312

Total current

'

'

'

'

'

'

'

'

'

'

'

'

13,937

20,946

20,635

Deferred tax provision

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

U.S. federal

'

'

'

'

'

'

'

'

'

'

'

'

4,389

10,209

5,760

State and local

'

'

'

'

'

'

'

'

'

'

'

'

571

188

372

Foreign

'

'

'

'

'

'

'

'

'

'

'

'

288

94

-91

Total deferred

'

'

'

'

'

'

'

'

'

691

2,273

'

5,248

10,491

6,041

Total provision

$6,769

($971)

$8,198

$12,613

$3,726

$7,258

$7,840

$7,227

$15,098

$17,762

$13,996

$18,824

$19,185

$31,437

$26,676

Income_Taxes_Deferred_Tax_Asse

Income Taxes - Deferred Tax Assets and Liabilities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
In Thousands, unless otherwise specified
Deferred tax assets	'	'	'	'	'	'	'	'	'	'
Inventory	'	$48,932	'	'	'	$50,936	'	'	'	'
Accruals and other reserves	'	7,721	'	'	'	8,376	'	'	'	'
Financing fees	'	'	'	'	'	731	'	'	'	'
Accounts receivable	'	1,082	'	'	'	939	'	'	'	'
UNICAP adjustment	'	1,278	'	'	'	1,319	'	'	'	'
Derivative contracts	'	487	'	'	'	1,104	'	'	'	'
Other	'	680	'	'	'	'	'	'	'	'
Gross deferred tax assets	'	60,180	'	'	'	63,405	'	'	'	'
Deferred tax liabilities	'	'	'	'	'	'	'	'	'	'
Investments in foreign entities	'	7,310	'	'	'	6,507	'	'	'	'
Fixed assets and intangibles	'	11,122	'	'	'	7,139	'	'	'	'
Financing fees	'	2,145	'	'	'	'	'	'	'	'
Other	'	'	'	'	'	762	'	'	'	'
Gross deferred tax liability	'	20,577	'	'	'	14,408	'	'	'	'
Net deferred tax asset	'	39,603	'	'	'	48,997	'	'	'	'
Net current deferred tax asset	'	33,465	'	'	'	29,027	'	'	'	'
Net long-term deferred tax asset	5,736	6,138	17,040	19,657	19,798	19,970	31,257	31,921	32,520	34,254
Net deferred tax asset	'	$39,603	'	'	'	$48,997	'	'	'	'

Reconciliation_of_Summary_of_A

Reconciliation of Summary of Activity of Company's Uncertain Tax Position (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'
Beginning Balance	$31,340	$35,483	$25,841
Additions for tax positions related to prior years	'	207	'
Reductions for tax positions related to prior years	-1,963	-4,350	'
Reductions due to tax settlements	-1,515	'	'
Reductions due to tax statute of limitations	-461	'	'
Ending Balance	$27,401	$31,340	$25,841

Employee_Defined_Contribution_1

Employee Defined Contribution Plans and Multi Employer Pension Plans - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]	'	'	'
Company contribution to retirement plan	$7,439	$7,412	$6,599
Multiemployer Plans, Pension [Member]	'	'	'
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]	'	'	'
Expenses incurred in change in benefit plan	2,714	2,669	2,779
Multiemployer Plans [Line Items]	'	'	'
Company contribution to retirement plan	$350,359	$332,430	'

Employee_Defined_Contribution_2

Employee Defined Contribution Plans and Multi-Employer Pension Plans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Compensation And Retirement Disclosure [Abstract]	'		'
Pension Fund	'IAM National Pension Fund		'
EIN	'516031295		'
Pension Plan Number	'002		'
Pension Protection Act Zone Status (2011 and 2010)	'Green	[1]	'
FIP/RP Status Pending/Implemented	'No		'
Company Contributions	$2,699		$2,689
Surcharge Imposed	'No		'
Expiration Date of Collective-BargainingAgreement	3-Nov-13		'
[1]	Plans in the green zone are at least 80 percent funded.

Employee_Defined_Contribution_3

Employee Defined Contribution Plans and Multi-Employer Pension Plans (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2012
Compensation And Retirement Disclosure [Abstract]	'
Green zone funded status	'At least 80 percent

Future_Minimum_Lease_Payments_

Future Minimum Lease Payments under Non-Cancelable Leases (Detail) (USD $)	Dec. 31, 2012
In Thousands, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]	'
2013	$2,654
2014	1,621
2015	956
2016	612
2017	122
Thereafter	'
Total minimum lease payments	$5,965

Segment_Information_Detail

Segment Information (Detail) (USD $)	3 Months Ended			6 Months Ended	9 Months Ended			12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Jun. 30, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'
Depreciation and amortization	'	'	'	'	$6,101	$4,891	'	$6,934	$4,759	$2,971
LIFO liquidation gain/(loss)	4,775	15,236	'	'	'	'	'	4,775	15,236	21,009
Capital expenditure	'	'	3,588	9,982	13,205	11,360	15,540	20,408	22,440	11,927
Olin Brass [Member]	'	'	'	'	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'
Depreciation and amortization	'	'	'	'	'	'	'	3,849	2,622	1,624
LIFO liquidation gain/(loss)	'	'	'	'	'	'	'	175	8,401	23,253
Capital expenditure	'	'	'	'	'	'	'	12,455	10,818	3,999
Chase [Member]	'	'	'	'	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'
Depreciation and amortization	'	'	'	'	'	'	'	2,521	1,921	1,200
LIFO liquidation gain/(loss)	'	'	'	'	'	'	'	1,623	'	75
Capital expenditure	'	'	'	'	'	'	'	6,846	10,171	7,377
Oster [Member]	'	'	'	'	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'
Depreciation and amortization	'	'	'	'	'	'	'	247	196	147
LIFO liquidation gain/(loss)	'	'	'	'	'	'	'	4,478	7,050	-48
Capital expenditure	'	'	'	'	'	'	'	558	505	551
Corporate and Eliminations [Member]	'	'	'	'	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'	'	'	'	'
Depreciation and amortization	'	'	'	'	'	'	'	317	20	'
LIFO liquidation gain/(loss)	'	'	'	'	'	'	'	-1,501	-215	-2,271
Capital expenditure	'	'	'	'	'	'	'	$549	$946	'

Summarized_Geographic_Informat

Summarized Geographic Information - Net Sales Attributable to Individual Countries (Detail) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

$396,173

$393,977

[1]

$416,979

[1]

$443,391

[1]

$373,477

[1]

$439,500

[1]

$473,251

[1]

$492,915

[1]

$1,345,678

$1,254,347

$1,650,520

$1,779,143

$1,658,729

UNITED STATES

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

1,556,865

1,691,007

1,567,472

Asia Pacific [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

53,668

54,638

62,358

MEXICO

'

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

$39,987

$33,498

$28,899

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

Quarterly_Financial_Informatio2

Quarterly Financial Information (Detail) (USD $)	3 Months Ended																6 Months Ended		9 Months Ended			12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information Disclosure [Abstract]	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Net sales	$396,173		$393,977	[1]	$416,979	[1]	$443,391	[1]	$373,477	[1]	$439,500	[1]	$473,251	[1]	$492,915	[1]	'	'	$1,345,678	$1,254,347	'	$1,650,520	$1,779,143	$1,658,729
Gross profit	41,714	[2]	44,397	[1]	47,121	[1]	49,954	[1]	63,336	[1],[3]	38,077	[1]	44,231	[1]	50,026	[1]	97,075	94,257	143,863	141,472	132,334	183,186	195,670	162,034
Income (loss) before provision for (benefit from) income taxes and equity income	12,532		17,645	[1]	-21,063	[1],[4]	21,971	[1]	35,848	[1]	10,779	[1]	17,498	[1]	21,712	[1]	908	39,210	21,047	18,553	49,989	31,085	85,837	67,291
Net income (loss)	7,602		11,137	[1]	-19,891	[1]	14,047	[1]	23,570	[1]	7,280	[1]	10,268	[1]	14,170	[1]	-5,844	24,438	4,433	5,293	31,718	12,895	55,288	42,145
Net income (loss) attributable to Global Brass and Copper Holdings, Inc.	$7,501		$11,032	[1]	($20,005)	[1]	$13,993	[1]	$23,590	[1]	$7,283	[1]	$10,201	[1]	$14,058	[1]	($6,012)	$24,259	$4,205	$5,020	$31,542	$12,521	$55,132	$41,633
Net income (loss) attributable to Global Brass and Copper Holdings, Inc. per common share:	'		'		'		'		'		'		'		'		'	'	'	'	'	'	'	'
Basic	$0.36		$0.52	[1]	($0.95)	[1]	$0.66	[1]	$1.12	[1]	$0.35	[1]	$0.48	[1]	$0.67	[1]	($0.28)	$1.15	$0.20	$0.24	$1.49	$0.59	$2.61	$1.97
[1]	The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".
[2]	Includes $4,775 gain from liquidation of LIFO inventory layers.
[3]	Includes $15,236 gain from liquidation of LIFO inventory layers.
[4]	Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.

Quarterly_Financial_Informatio3

Quarterly Financial Information (Parenthetical) (Detail) (USD $)	3 Months Ended			9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information Disclosure [Abstract]	'	'	'	'	'	'	'	'
Loss on debt extinguishment	'	($19,612)	'	'	($19,612)	($19,612)	'	'
Profits interest compensation expense	'	19,517	'	29,271	19,517	19,517	885	3,452
Gain from liquidation of LIFO inventory layers	$4,775	'	$15,236	'	'	$4,775	$15,236	$21,009

Basis_of_Presentation_and_Prin2

Basis of Presentation and Principles of Consolidation - Summary of Revisions to Consolidated Statement of Cash Flows (Detail) (USD $)	3 Months Ended	6 Months Ended	9 Months Ended			12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2011	Jun. 30, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:	'	'	'	'	'	'	'	'
Net cash provided by operating activities	($22,382)	$32,701	$4,532	$58,252	$44,845	$81,914	$64,848	$69,414
Cash flows from investing activities:	'	'	'	'	'	'	'	'
Capital expenditures	-3,588	-9,982	-13,205	-11,360	-15,540	-20,408	-22,440	-11,927
Net cash used in investing activities	-3,588	-9,956	-13,031	-11,335	-15,470	-20,376	-22,343	-11,888
Scenario, Previously Reported [Member]	'	'	'	'	'	'	'	'
Cash flows from operating activities:	'	'	'	'	'	'	'	'
Net cash provided by operating activities	-22,494	32,428	'	'	44,367	'	'	'
Cash flows from investing activities:	'	'	'	'	'	'	'	'
Capital expenditures	-3,476	-9,709	'	'	-15,062	'	'	'
Net cash used in investing activities	-3,476	-9,683	'	'	-14,992	'	'	'
Scenario, Adjustment [Member]	'	'	'	'	'	'	'	'
Cash flows from operating activities:	'	'	'	'	'	'	'	'
Net cash provided by operating activities	112	273	'	'	478	'	'	'
Cash flows from investing activities:	'	'	'	'	'	'	'	'
Capital expenditures	-112	-273	'	'	-478	'	'	'
Net cash used in investing activities	($112)	($273)	'	'	($478)	'	'	'

Condensed_Balance_Sheets_Paren

Condensed Balance Sheets (Parent Company Only) (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Jan. 01, 2010
In Thousands, unless otherwise specified
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	$18,088	$13,862	$13,018	'	'	$49,537	'	'	'	$15,523	$7,832
Total current assets	484,677	399,463	447,298	430,404	497,339	451,184	464,098	473,231	510,401	439,564	'
Investment in subsidiary	2,184	2,972	'	'	'	3,507	'	'	'	'	'
Total assets	592,515	502,693	555,669	539,223	594,905	548,740	566,963	573,975	610,402	537,721	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Accounts payable	105,311	81,577	'	104,585	111,425	77,888	107,959	'	'	'	'
Total current liabilities	177,554	133,536	180,595	148,507	195,457	162,741	175,044	183,986	201,326	170,999	'
Total liabilities	601,366	550,494	610,727	605,174	498,419	466,080	507,408	521,497	567,463	509,252	'
Stockholder's (deficit)/equity:	'	'	'	'	'	'	'	'	'	'	'
Common stock-$.01 par value; 80,000,000 shares authorized; 21,110,000 shares issued and outstanding at December 31, 2012 and 2011	211	211	'	'	'	211	'	'	'	'	'
Additional paid-in capital	30,260	'	'	'	'	11,091	'	'	'	'	'
(Accumulated deficit)/Retained earnings	-43,948	-48,153	-55,654	-66,686	82,711	68,718	45,128	37,845	27,644	13,586	'
Accumulated other comprehensive income	761	1,466	'	'	'	1,923	'	'	'	'	'
Receivable from stockholder	'	4,875	'	'	'	2,451	'	'	'	'	'
Total stockholder's (deficit)/equity	-12,716	-51,351	-58,499	-69,309	93,247	79,492	56,382	49,347	39,907	25,564	'
Total liabilities and stockholder's (deficit)/equity	592,515	502,693	555,669	539,223	594,905	548,740	566,963	573,975	610,402	537,721	'
Parent [Member]	'	'	'	'	'	'	'	'	'	'	'
Current assets:	'	'	'	'	'	'	'	'	'	'	'
Cash	'	'	'	'	'	'	'	'	'	'	'
Total current assets	'	'	'	'	'	'	'	'	'	'	'
Investment in subsidiary	'	'	'	'	'	85,020	'	'	'	'	'
Total assets	'	'	'	'	'	85,020	'	'	'	'	'
Current liabilities:	'	'	'	'	'	'	'	'	'	'	'
Accounts payable	'	'	'	'	'	'	'	'	'	'	'
Total current liabilities	'	'	'	'	'	'	'	'	'	'	'
Payable to subsidiary	'	8,829	'	'	'	5,528	'	'	'	'	'
Obligations and advances in excess of investment in subsidiary	'	42,522	'	'	'	'	'	'	'	'	'
Total liabilities	12,716	51,351	'	'	'	5,528	'	'	'	'	'
Stockholder's (deficit)/equity:	'	'	'	'	'	'	'	'	'	'	'
Common stock-$.01 par value; 80,000,000 shares authorized; 21,110,000 shares issued and outstanding at December 31, 2012 and 2011	'	211	'	'	'	211	'	'	'	'	'
Additional paid-in capital	'	'	'	'	'	11,091	'	'	'	'	'
(Accumulated deficit)/Retained earnings	'	-48,153	'	'	'	68,718	'	'	'	'	'
Accumulated other comprehensive income	'	1,466	'	'	'	1,923	'	'	'	'	'
Receivable from stockholder	'	-4,875	'	'	'	-2,451	'	'	'	'	'
Total stockholder's (deficit)/equity	-12,716	-51,351	'	'	'	79,492	'	'	'	'	'
Total liabilities and stockholder's (deficit)/equity	'	'	'	'	'	$85,020	'	'	'	'	'

Condensed_Balance_Sheets_Paren1

Condensed Balance Sheets (Parent Company Only) (Parenthetical) (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Balance Sheet Statements, Captions [Line Items]	'	'	'
Common stock, par value	$0.01	$0.01	$0.01
Common stock, shares authorized	80,000,000	80,000,000	80,000,000
Common stock, shares issued	21,110,000	21,110,000	21,110,000
Common stock, shares outstanding	21,110,000	21,110,000	21,110,000
Parent [Member]	'	'	'
Condensed Balance Sheet Statements, Captions [Line Items]	'	'	'
Common stock, par value	'	$0.01	$0.01
Common stock, shares authorized	'	80,000,000	80,000,000
Common stock, shares issued	'	21,110,000	21,110,000
Common stock, shares outstanding	'	21,110,000	21,110,000

Condensed_Statements_of_Operat

Condensed Statements of Operations (Parent Company Only) (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Jun. 30, 2012

Jun. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Condensed Income Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

$396,173

$393,977

[1]

$416,979

[1]

$443,391

[1]

$373,477

[1]

$439,500

[1]

$473,251

[1]

$492,915

[1]

'

'

$1,345,678

$1,254,347

'

$1,650,520

$1,779,143

$1,658,729

Cost of sales

'

349,580

369,858

393,437

310,141

401,423

429,020

442,889

763,295

871,909

1,201,815

1,112,875

1,273,332

1,467,334

1,583,473

1,496,695

Gross profit

41,714

[2]

44,397

[1]

47,121

[1]

49,954

[1]

63,336

[1],[3]

38,077

[1]

44,231

[1]

50,026

[1]

97,075

94,257

143,863

141,472

132,334

183,186

195,670

162,034

Selling, general and administrative expenses

'

'

'

'

'

'

'

'

'

'

92,622

73,241

'

92,641

69,391

68,857

Income (loss) before provision for (benefit from) income taxes and equity income

12,532

17,645

[1]

-21,063

[1],[4]

21,971

[1]

35,848

[1]

10,779

[1]

17,498

[1]

21,712

[1]

908

39,210

21,047

18,553

49,989

31,085

85,837

67,291

Benefit from income taxes

'

6,769

-971

8,198

12,613

3,726

7,258

7,840

7,227

15,098

17,762

13,996

18,824

19,185

31,437

26,676

Loss before equity income

'

10,876

-20,092

13,773

23,235

7,053

10,240

13,872

-6,319

24,112

3,285

4,557

31,165

11,900

54,400

40,615

Equity income, net of tax

'

'

'

'

'

'

'

'

'

'

1,148

736

'

995

888

1,530

Net income

7,602

11,137

[1]

-19,891

[1]

14,047

[1]

23,570

[1]

7,280

[1]

10,268

[1]

14,170

[1]

-5,844

24,438

4,433

5,293

31,718

12,895

55,288

42,145

Parent [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Income Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net sales

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cost of sales

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gross profit

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Selling, general and administrative expenses

'

'

'

'

'

'

'

'

'

'

5,390

1,086

'

1,427

1,650

1,102

Income (loss) before provision for (benefit from) income taxes and equity income

'

'

'

'

'

'

'

'

'

'

-5,390

-1,086

'

-1,427

-1,650

-1,102

Benefit from income taxes

'

'

'

'

'

'

'

'

'

'

-2,075

-418

'

-550

-635

-424

Loss before equity income

'

'

'

'

'

'

'

'

'

'

-3,315

-668

'

-877

-1,015

-678

Equity income, net of tax

'

'

'

'

'

'

'

'

'

'

7,520

5,688

'

13,398

56,147

42,311

Net income

'

'

'

'

'

'

'

'

'

'

$4,205

$5,020

'

$12,521

$55,132

$41,633

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

[2]

Includes $4,775 gain from liquidation of LIFO inventory layers.

[3]

Includes $15,236 gain from liquidation of LIFO inventory layers.

[4]

Includes $19,612 loss on debt extinguishment and $19,517 profits interest compensation expense.

Condensed_Statements_of_Compre

Condensed Statements of Comprehensive Income (Parent Company Only) (Detail) (USD $)

3 Months Ended

6 Months Ended

9 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Jun. 30, 2012

Jun. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Condensed Financial Information Of Parent Company Only Disclosure [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net income

$7,602

$11,137

[1]

($19,891)

[1]

$14,047

[1]

$23,570

[1]

$7,280

[1]

$10,268

[1]

$14,170

[1]

($5,844)

$24,438

$4,433

$5,293

$31,718

$12,895

$55,288

$42,145

Foreign currency translation adjustment, net of tax

'

'

'

'

'

'

'

'

'

'

-618

-130

'

-449

469

513

Comprehensive income

'

11,130

-20,034

14,067

23,419

7,370

10,475

14,493

-5,967

24,968

3,815

5,163

32,338

12,446

55,757

42,658

Parent [Member]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Information Of Parent Company Only Disclosure [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net income

'

'

'

'

'

'

'

'

'

'

4,205

5,020

'

12,521

55,132

41,633

Foreign currency translation adjustment, net of tax

'

'

'

'

'

'

'

'

'

'

-705

-130

'

-457

362

442

Comprehensive income

'

'

'

'

'

'

'

'

'

'

$3,500

$4,890

'

$12,064

$55,494

$42,075

[1]

The above data have been adjusted for prior period revisions discussed in note 2, "Summary of Significant Accounting Policies" and as illustrated in note 22, "Revision of Prior Period Financial Statements (Unaudited)".

Condensed_Statements_of_Cash_F

Condensed Statements of Cash Flows (Parent Company Only) (Detail) (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Cash Flow Statements, Captions [Line Items]	'	'	'	'	'
Net cash provided by operating activities	$4,532	$58,252	$81,914	$64,848	$69,414
Cash flows from investing activities	'	'	'	'	'
Net cash provided by investing activities	-13,031	-11,335	-20,376	-22,343	-11,888
Cash flows from financing activities	'	'	'	'	'
Distributions to stockholder	'	-160,000	-160,000	'	-42,500
Amounts due from stockholder	4,875	-2,398	-2,424	-2,451	'
Net cash used in financing activities	12,853	-82,754	-96,758	-8,342	-49,610
Net increase (decrease) in cash	4,226	-36,519	-35,675	34,014	7,691
Cash at beginning of period	13,862	49,537	49,537	15,523	7,832
Cash at end of period	18,088	13,018	13,862	49,537	15,523
Parent [Member]	'	'	'	'	'
Condensed Cash Flow Statements, Captions [Line Items]	'	'	'	'	'
Net cash provided by operating activities	'	73,624	73,624	'	42,500
Cash flows from investing activities	'	'	'	'	'
Capital distributions from subsidiary	'	86,376	86,376	'	'
Payable to subsidiary	-4,875	2,398	2,424	2,451	'
Net cash provided by investing activities	-4,875	88,774	88,800	2,451	'
Cash flows from financing activities	'	'	'	'	'
Distributions to stockholder	'	-160,000	-160,000	'	-42,500
Amounts due from stockholder	4,875	-2,398	-2,424	-2,451	'
Net cash used in financing activities	4,875	-162,398	-162,424	-2,451	-42,500
Net increase (decrease) in cash	'	'	'	'	'
Cash at beginning of period	'	'	'	'	'
Cash at end of period	'	'	'	'	'

Condensed_Financial_Informatio

Condensed Financial Information of Registrant - Basis of Presentation - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2012
Parent Company Only Financial Information [Line Items]	'	'
Restricted net asset percentage	'	25.00%
Senior Secured Notes [Member]	'	'
Parent Company Only Financial Information [Line Items]	'	'
Ownership percentage of equity holdings	100.00%	100.00%

Condensed_Financial_Informatio1

Condensed Financial Information of Registrant - Guarantees - Additional Information (Detail) (ABL Facility [Member])	1 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
ABL Facility [Member]	'	'
Parent Company Only Financial Information [Line Items]	'	'
Ownership percentage of equity holdings	100.00%	100.00%

Condensed_Financial_Informatio2

Condensed Financial Information of Registrant - Distributions from Subsidiary - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Jun. 01, 2012	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2010
Parent Company Only Financial Information [Line Items]	'	'	'	'
Cash distributions received	$160,000	$160,000	$160,000	$42,500
Return on Capital [Member]	'	'	'	'
Parent Company Only Financial Information [Line Items]	'	'	'	'
Cash distributions received	'	'	73,624	42,500
Return of Capital [Member]	'	'	'	'
Parent Company Only Financial Information [Line Items]	'	'	'	'
Cash distributions received	'	'	$86,376	'