Globe Specialty Metals 10-Q 8 May 15 2015 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Mar. 31, 2015	5-May-15
Document and Entity Information [Abstract]
Entity Registrant Name	GLOBE SPECIALTY METALS INC
Entity Central Index Key	1383571
Current Fiscal Year End Date	-24
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		73,749,990
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2015	Jun. 30, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$72,067	$97,792
Marketable securities	4,571	10,399
Accounts receivable, net of allowance for doubtful accounts of $790 and $811 at March 31, 2015 and June 30, 2014, respectively	75,958	100,829
Inventories	122,052	80,924
Deferred tax assets	3,779	7,042
Prepaid expenses and other current assets	18,636	26,259
Total current assets	297,063	323,245
Property, plant, and equipment, net of accumulated depreciation, depletion and amortization	450,309	469,169
Deferred tax assets	778	901
Goodwill	43,343	43,343
Other intangible assets	477	477
Investments in unconsolidated affiliates	5,973	5,973
Other assets	1,755	2,018
Total assets	799,698	845,126
Current liabilities:
Accounts payable	42,838	46,613
Short-term debt	656	59
Share-based liabilities	5,376	12,552
Accrued expenses and other current liabilities	39,941	38,758
Total current liabilities	88,811	97,982
Long-term liabilities:
Revolving credit agreements and other long-term debt	100,113	125,145
Deferred tax liabilities	48,241	50,845
Other long-term liabilities	46,995	50,626
Total liabilities	284,160	324,598
Commitments and contingencies (note 11)
Stockholders' equity:
Common stock, $0.0001 par value. Authorized, 150,000,000 shares; issued, 75,637,059 and 75,623,454 shares at March 31, 2015 and June 30, 2014, respectively	8	8
Additional paid-in capital	402,234	398,685
Retained earnings	83,310	70,875
Accumulated other comprehensive loss	-26,251	-5,377
Treasury stock at cost, 1,887,069 and 1,874,003 shares at March 31, 2015 and June 30, 2014, respectively	-29,208	-28,966
Total Globe Specialty Metals, Inc. stockholders' equity	430,093	435,225
Noncontrolling interest	85,445	85,303
Total stockholders' equity	515,538	520,528
Total liabilities and stockholders' equity	$799,698	$845,126

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2015	Jun. 30, 2014
In Thousands, except Share data, unless otherwise specified
ASSETS
Allowance for doubtful accounts	$790	$811
Stockholders' equity:
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, issued (in shares)	75,637,059	75,623,454
Treasury stock at cost (in shares)	1,887,069	1,874,003

Condensed_Consolidated_Income_

Condensed Consolidated Income Statements (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Condensed Consolidated Income Statements (Unaudited) [Abstract]
Net sales	$194,653	$196,057	$598,752	$547,457
Cost of goods sold	153,793	164,926	480,155	467,919
Selling, general, and administrative expenses	25,011	23,392	63,600	75,029
Contract acquisition cost	0	0	0	14,400
Curtailment gain	0	0	0	-5,831
Operating income (loss)	15,849	7,739	54,997	-4,060
Other income (expense):
Bargain purchase gain	0	0	0	29,538
Interest income	69	1	207	33
Interest expense, net of capitalized interest	-983	-1,012	-3,356	-6,940
Foreign exchange loss	-992	-1,999	-1,982	-3,008
Other income	620	5	1,409	23
Income before provision for (benefit from) income taxes	14,563	4,734	51,275	15,586
Provision for (benefit from) income taxes	6,036	2,717	19,359	-3,199
Net income	8,527	2,017	31,916	18,785
Income attributable to noncontrolling interest, net of tax	-804	-456	-2,518	-3,308
Net income attributable to Globe Specialty Metals, Inc.	$7,723	$1,561	$29,398	$15,477
Weighted average shares outstanding:
Basic (in shares)	73,749,990	74,291,202	73,751,022	74,963,601
Diluted (in shares)	73,881,472	74,434,780	73,886,358	75,070,154
Earnings per common share:
Basic (in dollars per share)	$0.10	$0.02	$0.40	$0.21
Diluted (in dollars per share)	$0.10	$0.02	$0.40	$0.21
Cash dividends declared per common share (in dollars per share)	$0.08	$0.08	$0.23	$0.21

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Comprehensive (Loss) Income (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Condensed Consolidated Statements of Comprehensive (Loss) Income (Unaudited) [Abstract]
Net income	$8,527	$2,017	$31,916	$18,785
Other comprehensive loss:
Foreign currency translation adjustment	-9,672	-3,189	-22,457	-4,150
Unrealized loss on available for sale securities, net of tax	-165	0	-793	0
Total other comprehensive loss	-9,837	-3,189	-23,250	-4,150
Comprehensive (loss) income	-1,310	-1,172	8,666	14,635
Comprehensive (loss) income attributable to noncontrolling interest	-478	-102	142	2,637
Comprehensive (loss) income attributable to Globe Specialty Metals, Inc.	($832)	($1,070)	$8,524	$11,998

Condensed_Consolidated_Stateme1

Condensed Consolidated Statement of Changes in Stockholders' Equity (Unaudited) (USD $)	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock at Cost [Member]	Noncontrolling Interest [Member]	Total
In Thousands, except Share data, unless otherwise specified
Balance at Jun. 30, 2013	$8	$399,234	$70,628	($4,918)	($4)	$81,132	$546,080
Balance (in shares) at Jun. 30, 2013	75,589,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	0	-1,275	0	0	0	0	-1,275
Share-based compensation (in shares)	4,000
Stock option exercises	0	180	0	0	0	0	180
Stock option exercises (in shares)	30,000
Share repurchase	0	0	0	0	-26,614	0	-26,614
Share repurchase (in shares)	0
Cash dividend	0	0	-15,915	0	0	0	-15,915
Comprehensive income (loss)	0	0	15,477	-3,479	0	2,637	14,635
Balance at Mar. 31, 2014	8	398,139	70,190	-8,397	-26,618	83,769	517,091
Balance (in shares) at Mar. 31, 2014	75,623,000
Balance at Jun. 30, 2014	8	398,685	70,875	-5,377	-28,966	85,303	520,528
Balance (in shares) at Jun. 30, 2014	75,623,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	0	3,469	0	0	0	0	3,469
Share-based compensation (in shares)	7,000
Stock option exercises	0	80	0	0	0	0	80
Stock option exercises (in shares)	7,000						56,990
Share repurchase	0	0	0	0	-242	0	-242
Share repurchase (in shares)	0
Cash dividend	0	0	-16,963	0	0	0	-16,963
Comprehensive income (loss)	0	0	29,398	-20,874	0	142	8,666
Balance at Mar. 31, 2015	$8	$402,234	$83,310	($26,251)	($29,208)	$85,445	$515,538
Balance (in shares) at Mar. 31, 2015	75,637,000

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$31,916	$18,785
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	37,327	32,983
Depletion	542	948
Share-based compensation	3,469	-1,275
Curtailment gain	0	-5,831
Bargain purchase gain	0	-29,538
Unrealized foreign exchange loss	242	473
Amortization of deferred financing fees	130	3,621
Deferred taxes	2,990	3,345
Amortization of customer contract liabilities	-3,727	-5,293
Accretion	183	192
Changes in operating assets and liabilities:
Accounts receivable, net	21,879	-11,706
Inventories	-46,259	25,227
Prepaid expenses and other current assets	3,107	3,926
Accounts payable	-2,480	3,974
Accrued expenses and other current liabilities	-652	-45
Other	1,617	1,430
Net cash provided by operating activities	50,284	41,216
Cash flows from investing activities:
Capital expenditures	-41,163	-28,018
Proceeds from sale (purchase) of marketable securities	8,326	-5,841
Acquisition of business, net of cash acquired of $0 and $200, respectively	0	-3,800
Net cash used in investing activities	-32,837	-37,659
Cash flows from financing activities:
Borrowings of short-term debt	597	0
Payments of short-term debt	-32	-269
Borrowings under revolving credit agreements	0	156,400
Payments under revolving credit agreements	-25,000	-170,650
Dividend payment	-16,963	-15,915
Debt issuance costs	0	-1,080
Proceeds from stock option exercises	80	180
Purchase of treasury shares	-242	-26,614
Other financing activities	-1,925	-1,917
Net cash used in financing activities	-43,485	-59,865
Effect of exchange rate changes on cash and cash equivalents	313	-446
Net decrease in cash and cash equivalents	-25,725	-56,754
Cash and cash equivalents at beginning of period	97,792	169,676
Cash and cash equivalents at end of period	72,067	112,922
Supplemental disclosures of cash flow information:
Cash paid for interest, net of capitalized interest	1,432	2,783
Cash paid (refunded) for income taxes, net of refunds totaling $554 and $7,698, respectively	$11,166	($5,982)

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from investing activities:
Net cash acquired for acquisition of a business	$0	$200
Supplemental disclosures of cash flow information:
Refunds for income taxes	$554	$7,698

Organization_and_Business_Oper

Organization and Business Operations	9 Months Ended
	Mar. 31, 2015
Organization and Business Operations [Abstract]
Organization and Business Operations	(1)           Organization and Business Operations
	Globe Specialty Metals, Inc. and subsidiaries (the Company, we, or our) is among the world’s largest producers of silicon metal and silicon-based alloys, important ingredients in a variety of industrial and consumer products. The Company’s customers include major silicone chemical, aluminum and steel manufacturers, auto companies and their suppliers, ductile iron foundries, manufacturers of photovoltaic solar cells and computer chips, and concrete producers.
	Proposed Business Combination
	On February 23, 2015, the Company, Grupo Villar Mir, S.A.U., a public limited company (sociedad anónima) incorporated under the laws of Spain (“Grupo VM”), Grupo FerroAtlántica, S.A.U., a Spanish public limited liability company in the form of a sociedad anónima and wholly owned subsidiary of Grupo VM (“FerroAtlántica”), VeloNewco Limited, a newly formed private UK holding company and wholly owned subsidiary of Grupo VM (“VeloNewco”), and Gordon Merger Sub, Inc., a newly formed Delaware corporation and a direct wholly owned subsidiary of VeloNewco (“Merger Sub”), entered into a Business Combination Agreement (the “Original Business Combination Agreement”) pursuant to which the parties agreed, subject to the terms and conditions of the Original Business Combination Agreement, to combine the businesses of the Company and FerroAtlántica under VeloNewco as described below (the “Business Combination”). The Original Business Combination Agreement was amended and restated on May 5, 2015.  The Original Business Combination Agreement, as so amended and restated, is referred to as the “Business Combination Agreement”.
	Transaction Overview
	Subject to the terms and conditions of the Business Combination Agreement, VeloNewco agreed to acquire from Grupo VM all of the issued and outstanding ordinary shares of FerroAtlántica in exchange for an aggregate of 98,078,161 newly issued VeloNewco Class A ordinary shares (each an “A Ordinary Share”), which will result in FerroAtlántica becoming a wholly owned subsidiary of VeloNewco (the “Stock Exchange”). After consummation of the Stock Exchange, Merger Sub will merge with and into the Company, with the Company surviving the merger as a wholly owned subsidiary of VeloNewco (the “Merger”).
	In the Stock Exchange, Grupo VM may be required to pay to VeloNewco as additional consideration for the A Ordinary Shares an amount in cash, if any, based upon FerroAtlántica’s net debt at closing. In the Merger, each share of common stock of the Company will be converted into the right to receive one VeloNewco ordinary share (each an “Ordinary Share”). The A Ordinary Shares and the Ordinary Shares will have the same rights, powers and preferences, and vote together as a single class, except for the right of the holders of Ordinary Shares to the R&W Proceeds as described below.
	In connection with the transaction, VeloNewco expects to purchase a buy side representations and warranties insurance policy (the “R&W Policy”) to insure against certain breaches of certain representations and warranties made by FerroAtlántica and Grupo VM in the Business Combination Agreement. Under the terms of the Articles of Association of VeloNewco (the “VeloNewco Articles”), if VeloNewco receives proceeds under the R&W Policy (after deduction of taxes applicable to such proceeds, if any) (the “R&W Proceeds”), VeloNewco is required to distribute the aggregate R&W Proceeds to the holders of the Ordinary Shares. Each A Ordinary Share automatically converts into one Ordinary Share upon the earlier to occur of: (a) the expiration of the R&W Policy; and (b) its transfer to any person or group which is not Grupo VM, any Grupo VM family member or any affiliate of Grupo VM or a Grupo VM family member.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Mar. 31, 2015
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	(2)             Summary of Significant Accounting Policies
	a. Basis of Presentation
	In the opinion of the Company’s management, the accompanying condensed consolidated financial statements include all adjustments necessary for a fair presentation in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) of the results for the interim periods presented and such adjustments are of a normal, recurring nature. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the fiscal year ended June 30, 2014 and Current Report on Form 8-K filed on May 5, 2015. The year-end balance sheet data was derived from audited financial statements, but does not include all of the information and disclosures required by U.S. GAAP. There have been no material changes to the Company’s significant accounting policies during the nine months ended March 31, 2015.
	The accompanying Condensed Consolidated Balance Sheet as of June 30, 2014, the Condensed Consolidated Income Statements and Statements of Comprehensive (Loss) Income  for the three and nine months ended March 31, 2014 and the Condensed Consolidated Statement of Cash Flows and the Condensed Consolidated Statement of Changes in  Shareholders’ Equity for the nine months ended March 31, 2014 have been revised to reflect the impact of completing the purchase price allocation for the acquisition of Silicon Technology (Pty) Ltd., as described in Note 3.
	b. Receivables Sale Arrangement
	The Company has the option to sell certain accounts receivables up to a cap of $55,000 on a non-recourse basis to an unrelated financial institution under a receivables purchase arrangement in the US. The Company accounts for this transaction as a sale of receivables, removes receivables sold from its financial statements, and records cash proceeds when received by the Company as cash provided by operating activities in the Consolidated Statement of Cash Flows. The receivables are sold at a discount rate of 30 day LIBOR plus 1.25% per annum discounted upfront on the date of purchase. The Company entered into the arrangement in the second quarter of fiscal 2015. The arrangement has a term of twelve months and will be renewed for an additional twelve month period in the absence of written termination notice provided by the Company no later than sixty days prior to the termination date of the arrangement. During fiscal 2015, the Company sold $59,000 of receivables under the arrangement and as of March 31, 2015, $24,000 of receivables was outstanding with the financial institution.
	c. Use of Estimates
	The Company prepares its condensed consolidated financial statements in accordance with U.S. GAAP. The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, as well as the disclosure of contingent assets and liabilities. The Company based its estimates and judgments on historical experience, known or expected trends and other factors that are believed to be reasonable under the circumstances. Actual results may differ from these estimates.
	d. Revenue Recognition
	Revenue is recognized when title, ownership, and risk of loss pass to the customer, all of which occurs when products are delivered to the Company’s customers or when products are picked up by a customer or a customer’s carrier. Written sales terms, including the selling price, are determined at the time of shipment or delivery. We have not experienced significant credit issues with our customers.  Shipping and other transportation costs charged to buyers are recorded in both net sales and cost of goods sold. Sales taxes collected from customers and remitted to governmental authorities are accounted for on a net basis and, therefore, are excluded from net sales.
	e. Recent Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board issued a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. This new guidance is effective for annual reporting periods beginning after December 15, 2016 and early adoption is not permitted. Accordingly, we will adopt this new guidance beginning in fiscal 2018. Companies may use either a full retrospective or a modified retrospective approach to adopt this new guidance and management is currently evaluating which transition approach to use. In April 2015, the FASB issued a proposal that, if approved, would extend the required implementation date one year to the first quarter of calendar 2018 but also would permit companies to adopt the standard at the original effective date of 2017. We are currently evaluating the impact of this guidance on our consolidated results of operations, financial position and cash flows.
	In April 2015, the FASB issued an accounting standards update relating to the presentation of debt issuance costs. The accounting update requires companies to present debt issuance costs related to a recognized debt liability presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The guidance is effective beginning fiscal 2017.  The adoption of this guidance is not expected to have a material impact on the Company's consolidated financial statements.

Business_Combinations

Business Combinations	9 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Business Combinations	(3)             Business Combinations
	Siltech:
	On November 21, 2013, the Company purchased 100% of the outstanding shares of Silicon Technology (Pty) Ltd. (Siltech) for $4,000. The Company paid for the acquisition from available cash. Siltech is a silicon-based alloy producer in South Africa with an annual production capacity of approximately 45,000 metric tons. The acquisition was made to increase the Company’s current silicon-based alloy capacity by approximately 30% and its strategic location will enable the Company to supplement its existing facility to service the large European, Asian and Middle Eastern markets. The Siltech facility was in an idled status when purchased. The Company restarted operations at the facility in October of 2014.
	The Siltech acquisition was recorded as a business combination under Accounting Standards Codification 805 (“ASC 805”), Business Combinations, with identifiable assets acquired and liabilities assumed provisionally recorded at their estimated fair values on the acquisition date while costs associated with the acquisition were expensed as incurred. The Company utilized the services of third-party valuation consultants, along with estimates and assumptions provided by the Company, to estimate the fair value of the assets acquired and liabilities assumed. The third-party valuation consultants utilized several appraisal methodologies including income, market and cost approaches to estimate the fair value of the identifiable net assets acquired.
	The preliminary fair value estimates for the assets acquired and liabilities assumed were based upon preliminary calculations, valuations, and assumptions that were subject to change as the Company obtained additional information during the measurement period. The purchase price allocation for the Siltech acquisition was finalized during the quarter ended December 31, 2014. The adjustments, which primarily relate to the finalization of environmental remediation obligation assumed (the adjustment was recorded to Other long-term liabilities), were made to the preliminary purchase accounting amounts. The following table summarizes the provisional amounts recognized for assets acquired and liabilities assumed as of the acquisition date as well as adjustments made to arrive at the final purchase price allocation.
	Based on the final purchase price allocation, the fair value of the identifiable net assets acquired of $33,538 exceeded the purchase price of $4,000, resulting in a gain on bargain purchase of $29,538. The measurement period adjustments were recorded as an adjustment to the gain on bargain purchase. The purchase price of $4,000 was allocated as follows:
	(In thousands)				Amounts Recognized as of Acquisition Date (as previously reported)	Measurement Period Adjustments	Amounts Recognized as of Acquisition Date (as adjusted)
	Assets
		Current assets		$	2,298	101	2,399
		Property, plant and equipment			46,500	(233)	46,267
			Total assets acquired	$	48,798	(132)	48,666
	Liabilities
		Accounts payable		$	317	106	423
		Accrued expenses			478	(272)	206
		Deferred tax liabilities			11,760	1,586	13,346
		Other long-term liabilities			10,000	(8,847)	1,153
			Total liabilities assumed	$	22,555	(7,427)	15,128
			Net assets acquired		26,243	7,295	33,538
			Consideration paid		4,000	—	4,000
			Gain on bargain purchase	$	22,243	7,295	29,538
	ASC 805 requires that when the fair value of the net assets acquired exceeds the purchase price, resulting in a bargain purchase of a business, the acquirer must reassess the reasonableness of the values assigned to all of the net assets acquired, liabilities assumed and consideration transferred. The Company performed such reassessment and concluded that the fair values assigned for the Siltech acquisition are reasonable. The gain on bargain purchase was primarily attributable to the fact that Siltech was considered an ancillary business to the seller (Siltech being the seller’s only silicon-based alloy operation), coupled with the previous weaker silicon-based alloys pricing in the marketplace driven by end-user demand (which resulted in the idling of the facility by the seller in 2012).

Inventories

Inventories	9 Months Ended
	Mar. 31, 2015
Inventories [Abstract]
Inventories	(4)             Inventories
	Inventories comprise the following:
				March 31,	June 30,
				2015	2014
	Finished goods		$	43,957	27,406
	Work in process			5,009	5,120
	Raw materials			59,045	33,843
	Parts and supplies			14,041	14,555
		Total	$	122,052	80,924
	At March 31, 2015, $113,932 in inventory is valued using the first-in, first-out method and $8,120 using the average cost method. At June 30, 2014, $73,894 in inventory is valued using the first-in, first-out method and $7,030 using the average cost method.

Property_Plant_and_Equipment

Property, Plant, and Equipment	9 Months Ended
	Mar. 31, 2015
Property, Plant, and Equipment [Abstract]
Property, Plant, and Equipment	(5)             Property, Plant, and Equipment
	Property, plant, and equipment, net, comprise the following:
				March 31,	June 30,
				2015	2014
	Land, land improvements, and land use rights		$	12,654	13,615
	Building and improvements			92,625	89,222
	Machinery and equipment			233,707	217,358
	Furnaces			232,956	208,368
	Mineral reserves			55,843	55,843
	Mine development			10,291	9,317
	Other			15,830	14,712
	Construction in progress			18,324	53,753
		Property, plant, and equipment, gross		672,230	662,188
	Less accumulated depreciation, depletion and amortization			(221,921)	(193,019)
		Property, plant, and equipment, net	$	450,309	469,169
	Depreciation, depletion and amortization expense for the three and nine months ended March 31, 2015 was $13,603 and $37,869, of which $13,366 and $37,146 is recorded in cost of goods sold and $237 and $723 is recorded in selling, general, and administrative expenses, respectively. Depreciation, depletion and amortization expense for the three and nine months ended March 31, 2014 was $11,244 and $33,931, of which $10,977 and $33,127 is recorded in cost of goods sold and $267 and $804 is recorded in selling, general, and administrative expenses, respectively.
	There was no capitalized interest for both the three and nine months ended March 31, 2015. Capitalized interest for the three and nine months ended March 31, 2014 was $0 and $103, respectively.
	Mineral reserves are recorded at fair value at the date of acquisition. Mineral reserves are included in “Property, plant and equipment, net of accumulated depreciation, depletion and amortization” on the condensed consolidated balance sheets. Depletion of mineral reserves is computed using the units-of-production method utilizing only proven and probable reserves (as adjusted for recoverability factors) in the depletion base.

Goodwill_and_Other_Intangibles

Goodwill and Other Intangibles	9 Months Ended
	Mar. 31, 2015
Goodwill and Other Intangibles [Abstract]
Goodwill and Other Intangibles	(6)             Goodwill and Other Intangibles
	Goodwill and other intangibles presented below have been allocated to the Company’s operating segments.
	a. Goodwill
	Changes in the carrying amount of goodwill, by reportable segment, during the nine months ended March 31, 2015 are as follows:
					Globe
				GMI	Metales	Solsil	Other	Total
	Goodwill		$	34,900	14,313	57,656	7,260	114,129
	Accumulated impairment loss			—	(6,000)	(57,656)	(7,130)	(70,786)
		Balance at June 30, 2014		34,900	8,313	—	130	43,343
	Goodwill			34,900	14,313	57,656	7,260	114,129
	Accumulated impairment loss			—	(6,000)	(57,656)	(7,130)	(70,786)
		Balance at March 31, 2015	$	34,900	8,313	—	130	43,343
	b. Other Intangible Assets
	There were no changes in the value of the Company’s indefinite lived intangible assets during the nine months ended March 31, 2015.
	c. Annual Impairment Tests
	The Company performed its annual goodwill and indefinite-lived intangible asset tests during the quarter ended March 31, 2015. A test is also performed whenever events or changes in circumstances indicate the carrying amount of goodwill may not be recoverable. Impairment is the condition that exists when the carrying amount of goodwill exceeds its implied fair value. The implied fair value of goodwill is determined in the same manner as the amount of goodwill recognized in a business combination. The excess of the fair value of a reporting unit over the amounts assigned to its assets and liabilities is the implied fair value of goodwill. An impairment loss would be recognized when the carrying amount of goodwill exceeds the implied fair value of goodwill of the reporting unit. Fair value is measured based on a discounted cash flow method, using a discount rate determined by the Company to be commensurate with the risk inherent in its current business model, and a valuation technique based on multiples of earnings consistent with the objective of measuring fair value. The estimates of cash flows, future earnings, and discount rates are subject to change due to the economic environment and business trends, including such factors as raw material and product pricing, interest rates, expected market returns and volatility of markets served, as well as our future manufacturing capabilities, government regulation and technological change. The Company believes that the estimates of future cash flows, future earnings, and fair value are reasonable; however, changes in estimates, circumstances or conditions could have a significant impact on its fair valuation determination, which could then result in a material impairment charge in the Company’s results of operations.
	As of February 28, 2015, all reporting units had fair values that exceeded carrying values and no impairment charge was required.

Debt

Debt	9 Months Ended
	Mar. 31, 2015
Debt [Abstract]
Debt	(7)             Debt
	a. Short-Term Debt
	Short-term debt comprises the following:
									Weighted
							Outstanding		Average		Unused
							Balance		Interest Rate		Credit Line
	March 31, 2015:
	Type debt:
		Export financing				$	597		8.50%	$	2,877
		Other					59		12.37%		—
			Total			$	656			$	2,877
	June 30, 2014:
	Type debt:
		Export financing				$	—		NA	$	9,208
		Other					59		14.47%		—
			Total			$	59			$	9,208
	Export Financing Agreements – The Company’s Argentine subsidiary maintains various short-term export financing agreements. Generally, these arrangements are for periods ranging between seven and eleven months, and require the Company to pledge as collateral certain export accounts receivable.
	b. Revolving Credit Agreements
	A summary of the Company’s revolving credit agreements at March 31, 2015 is as follows:
									Weighted
							Outstanding		Average			Unused	Total
							Balance		Interest Rate			Commitment	Commitment
	Revolving multi-currency credit facility					$	100,000		1.66%		$	198,978	300,000
	Revolving credit agreement						—		5.00%		$	11,827	11,827
	On August 20, 2013, the Company entered into a $300,000 five-year revolving multi-currency credit facility, which includes a $10,000 sublimit for swing line loans and a $25,000 sublimit letter of credit facility. The credit facility refinanced existing debt under the revolving multi-currency credit agreement dated May 31, 2012 and closing costs. The credit facility currently provides up to an additional $198,978 of borrowing capacity as of March 31, 2015. At the Company’s election, the credit facility may be increased by an amount up to $150,000 in the aggregate; such increase may be in the form of term loans or increases in the revolving credit line, subject to lender commitments and certain conditions as described in the credit agreement. The agreement contains provisions for adding domestic and foreign subsidiaries of the Company as additional borrowers under the credit facility. The agreement terminates on August 20, 2018 and requires no scheduled prepayments before that date. The Company classifies borrowings under this credit facility as long-term liabilities.
	Interest on borrowings under the multi-currency credit facility is payable, at the Company’s election, at either (a) a base rate (the higher of (i) the U.S. federal funds rate plus 0.50% per annum, (ii) the Administrative Agent’s prime rate or (iii) a Eurocurrency Rate for loans with a one month interest period plus 1.00% per annum plus a margin ranging from 0.50% to 1.50% per annum (such margin determined by reference to the leverage ratio set forth in the credit agreement), or (b) the Eurocurrency Rate plus a margin ranging from 1.50% to 2.50% per annum (such margin determined by reference to the leverage ratio set forth in the credit agreement). Certain commitment fees are also payable under the credit agreement. The credit agreement contains various covenants. They include, among others, a maximum net debt to earnings before income tax, depreciation and amortization ratio and a minimum interest coverage ratio. The credit facility is guaranteed by certain of the Company’s domestic subsidiaries (the “Guarantors”). Borrowings under the credit agreement are collateralized by the assets of the Company and the Guarantors, including certain real property, equipment, accounts receivable, inventory and the stock of certain of the Company’s and the Guarantors’ subsidiaries. The Company was in compliance with its financial loan covenants at March 31, 2015.
	At March 31, 2015, there was a $100,000 balance outstanding on the revolving multi-currency credit facility. The total commitment outstanding on this credit facility includes $722 outstanding letters of credit associated with landlord guarantees and $300 outstanding letters of credit associated with economic development.
	The Company’s subsidiary, Quebec Silicon, entered into a revolving credit agreement dated October 1, 2010, amended on November 23, 2011 and further amended and restated on September 20, 2012, which provides for up to $15,000 Canadian Dollars to fund Quebec Silicon’s working capital requirements. Funding under the revolving credit agreement is available upon request at any time, up to the full amount of the unused credit commitment and subject to continued compliance with the terms of the agreement. Interest on borrowings under the credit agreement is payable at a variable rate of Canadian prime plus 2.00% (5.00% at March 31, 2015), payable quarterly. The credit agreement expires on September 20, 2015, and may be terminated earlier, at the lender’s discretion subject to certain change in ownership conditions being met. All of Quebec Silicon’s assets, properties and revenues have been pledged as security for Quebec Silicon’s obligations under the revolving credit agreement. As of March 31, 2015, there was no outstanding balance under the facility.
	c. Other Long-Term Debt
						Weighted
					Outstanding	Average			Unused
					Balance	Interest Rate			Credit Line
	Other			$	113	19.00%		$	—
	d. Fair Value of Debt
	The recorded carrying values of our debt balances approximate fair value given our debt is at variable rates tied to market indicators.

Derivative_Instruments

Derivative Instruments	9 Months Ended
	Mar. 31, 2015
Derivative Instruments [Abstract]
Derivative Instruments	(8)             Derivative Instruments
	The Company enters into derivative instruments to hedge certain interest rate, currency, and commodity price risks. The Company does not engage in interest rate, currency, or commodity speculation, and no derivatives are held for trading purposes. All derivatives are accounted for using mark-to-market accounting. The Company believes it is not practical to designate its derivative instruments as hedging instruments as defined under ASC Subtopic 815-10, Derivatives and Hedging (ASC 815). Accordingly, the Company adjusts its derivative financial instruments to current market value through the condensed consolidated income statements based on the fair value of the agreement as of period end. Although not designated as hedged items as defined under ASC 815, these derivative instruments serve to significantly offset the Company’s interest rate, currency, and commodity risks. Gains or losses from these transactions offset gains or losses on the assets, liabilities, or transactions being hedged. No credit loss is anticipated as the counterparties to these agreements are major financial institutions that are highly rated.
	Interest Rate Risk:
	The Company is exposed to market risk from changes in interest rates on certain of its short-term and long-term debt obligations. The Company currently has no interest rate derivatives to reduce exposure to interest rate fluctuations.
	Foreign Currency Risk:
	The Company is exposed to market risk arising from changes in currency exchange rates as a result of its operations outside the United States, principally in Argentina, China, Canada, and South Africa. A portion of the Company’s net sales generated from its non-U.S. operations is denominated in currencies other than the U.S. dollar. Most of the Company’s operating costs for its non-U.S. operations are denominated in local currencies, principally the Canadian dollar, Argentine peso, Chinese renminbi, and South African rand. Consequently, the translated U.S. dollar value of the Company’s non-U.S. dollar net sales, and related accounts receivable balances, and its operating costs are subject to currency exchange rate fluctuations. Derivative instruments are not used extensively to manage this risk. At March 31, 2015, the Company had no outstanding foreign exchange forward and option contracts.
	Commodity Price Risk:
	The Company is exposed to price risk for certain raw materials and energy used in its production process. The raw materials and energy that the Company uses are largely commodities subject to price volatility caused by changes in global supply and demand and governmental controls. Derivative financial instruments are not used extensively to manage the Company’s exposure to fluctuations in the cost of commodity products used in its operations. The Company attempts to reduce the impact of increases in its raw material and energy costs by negotiating long-term contracts and through the acquisition of companies or assets for the purpose of increasing its access to raw materials with favorable pricing terms. The Company currently has no commodity derivatives to reduce exposure to commodity price fluctuations.
	The effect of the Company’s derivative instruments on the condensed consolidated income statements is summarized in the following table:
			Loss Recognized			Loss Recognized
			During the Three Months			During the Nine Months
			Ended March 31,			Ended March 31,		Location
			2015	2014		2015	2014	of Loss
	Foreign exchange forward and option contracts	$	—	—	$	—	(603)	Foreign exchange loss
	There are no derivative instruments outstanding at March 31, 2015.

Benefit_Plans

Benefit Plans	9 Months Ended
	Mar. 31, 2015
Benefit Plans [Abstract]
Benefit Plans	(9)           Benefit Plans
	The Company’s subsidiary, Globe Metallurgical Inc. (GMI), sponsors three noncontributory defined benefit pension plans covering certain employees. These plans were frozen in 2003. The Company’s subsidiary, Core Metals, sponsors a noncontributory defined benefit pension plan covering certain domestic employees. This plan was closed to new participants in April 2009. The Company’s subsidiary, Quebec Silicon, sponsors a contributory defined benefit pension plan. This plan was closed to new participants in December 2013.
	Quebec Silicon sponsors a postretirement benefit plan for certain employees, based on length of service and remuneration. Postretirement benefits consist of a group insurance plan covering plan members for life insurance, disability, hospital, medical, and dental benefits. On December 27, 2013, the Communications, Energy and Paper Workers Union of Canada (“CEP”) ratified a new collective bargaining agreement, which resulted in a curtailment pertaining to the closure of the postretirement benefit plan for union employees retiring after January 31, 2016. The Company remeasured the benefit obligations reflecting the curtailment which resulted in a curtailment gain of $5,831. The curtailment gain is included in operating income for the second quarter of fiscal 2014.
	The components of net periodic pension expense for the Company’s defined benefit pension and postretirement plans are as follows:
			Three Months Ended			Nine Months Ended
			March 31,			March 31,
			2015	2014		2015	2014
	Interest cost	$	675	682	$	2,100	2,210
	Service cost		213	236		678	1,138
	Expected return on plan assets		(777)	(667)		(2,384)	(2,028)
	Amortization of net loss		174	310		522	937
	Net periodic pension expense	$	285	561	$	916	2,257
	The Company expects to make required and discretionary contributions of approximately $2,033 to the defined benefit pension and postretirement plans for the fiscal year ending June 30, 2015, of which $1,034 has been contributed through March 31, 2015.

Income_Taxes

Income Taxes	9 Months Ended
	Mar. 31, 2015
Income Taxes [Abstract]
Income Taxes	(10)           Income Taxes
	The provision for income taxes is based on the current estimate of the annual effective tax rate, adjusted as necessary for quarterly events. In accordance with ASC Topic 740, Income Taxes — Accounting for Income Taxes in Interim Periods, the Company’s quarterly effective tax rate does not reflect a benefit associated with losses related to certain foreign subsidiaries. The effective tax rates for the nine months ended March 31, 2015 and 2014 were based on our forecasted annualized effective tax rates, adjusted for discrete items that occurred within the respective periods.
	The Company’s effective tax rate for the nine months ended March 31, 2015 was a tax expense of 37.8% compared to a tax benefit of 20.5% for the nine months ended March 31, 2014. The increase in the effective tax rate is primarily due to the operations in certain jurisdictions shifting to a profit this year while certain loss jurisdictions continue to not provide a benefit. The estimated annual effective tax expense rate excluding discrete items is 36.5%.
	The Company maintains valuation allowances where it is more likely than not that all or a portion of a deferred tax asset will not be realized. In determining whether a valuation allowance is warranted, the Company evaluates factors such as prior earnings history, expected future earnings, carry back and carry forward periods, and tax strategies that could potentially enhance the likelihood of the realization of a deferred tax asset. During the nine months ended March 31, 2015, the Company’s net valuation allowances increased by $1,611, primarily due to the establishment of additional valuation allowances against net operating losses (NOLs) in foreign jurisdictions where it is more likely than not the NOLs will not be utilized.
	The Company files a consolidated U.S. income tax return and tax returns in various state and local jurisdictions. Our subsidiaries also file tax returns in various foreign jurisdictions. The Company’s principal jurisdictions include the U.S., Argentina, Canada, Poland, and China. A number of years may elapse before a tax return is audited and finally resolved. The open tax years subject to examination varies depending on the tax jurisdiction. The Company’s major taxing jurisdictions and the related open tax years subject to examination are as follows: the U.S. from 2011 to present, Canada from 2012 to present, Argentina from 2010 to present, and China from 2011 to present.
	The Company regularly evaluates its tax positions for additional unrecognized tax benefits and associated interest and penalties, if applicable. There are many factors that are considered when evaluating these tax positions including: interpretation of tax laws, recent tax litigation on a position, past audit or examination history, and subjective estimates and assumptions that have been deemed reasonable by management. However, if management’s estimates are not representative of actual outcomes, the Company’s results could be materially impacted. There were no material changes in the Company’s uncertain tax positions during the nine months ended March 31, 2015.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Mar. 31, 2015
Commitments and Contingencies [Abstract]
Commitments and Contingencies	(11)             Commitments and Contingencies
	a. Legal Contingencies
	The Company is subject to various lawsuits, investigations, claims, and proceedings that arise in the normal course of business, including, but not limited to, labor and employment, commercial, environmental, safety, and health matters, as well as claims and indemnities associated with its historical acquisitions and divestitures. Although it is not presently possible to determine the outcome of these matters, in the opinion of management, it is not reasonably possible that the ultimate disposition of these matters will have a material adverse effect on the Company’s consolidated financial position, results of operations, or liquidity. During the nine months ended March 31, 2015, the Company recorded $4,559 with respect to an indemnification obligation from a prior divestiture.
	Litigation Related to the Proposed Business Combination
	On March 23, 2015, a putative class action lawsuit was filed on behalf of the Company’s shareholders (“Company Shareholders”) in the Court of Chancery of the State of Delaware.  The action, captioned Fraser v. Globe Specialty Metals, Inc., et al., C.A. No. 10823-VCG, names as defendants the Company, the members of its board of directors, Grupo VM, FerroAtlántica, Merger Sub and VeloNewco.  The complaint alleges, among other things, that the Company directors breached their fiduciary duties by failing to obtain the best price possible for Company Shareholders, that the proposed merger consideration to be received by Company Shareholders is inadequate and significantly undervalues the Company, that the Company directors failed to adequately protect against conflicts of interest in approving the transaction, and that the Business Combination Agreement unfairly deters competitive offers.  The complaint also alleges that the Company, Grupo VM, FerroAtlántica, Merger Sub and VeloNewco aided and abetted these alleged breaches.  The action seeks to enjoin or rescind the Business Combination, damages, and attorneys’ fees and costs.
	On April 1, 2015, a purported Company Shareholder filed a second putative class action lawsuit on behalf of Company Shareholders challenging the Business Combination in the Court of Chancery of the State of Delaware.  The action, captioned City of Providence v. Globe Specialty Metals, Inc., et al., C.A. No. 10865-VCG, names as defendants the Company, the members of its board of directors, its Chief Executive Officer, Grupo VM, FerroAtlántica, Merger Sub and VeloNewco.  The complaint alleges, among other things, that the Company’s board of directors and Chief Executive Officer, aided and abetted by Grupo VM, FerroAtlántica, Merger Sub and VeloNewco, breached their fiduciary duties by entering into the Business Combination for inadequate consideration and that certain provisions in the Business Combination Agreement unfairly deter a potential alternative transaction.  The complaint further alleges, among other things, that the Company’s Executive Chairman and Chief Executive Officer, aided and abetted by Grupo VM, FerroAtlántica, Merger Sub and VeloNewco, breached their fiduciary duties by negotiating the Business Combination Agreement, and, in the case of the Executive Chairman, by entering into a voting agreement in favor of the Business Combination Agreement, out of self-interest.  The action seeks to enjoin the Business Combination, to order the board of directors to obtain an alternate transaction, damages, and attorneys’ fees and costs.
	On April 10, 2015, a purported Company Shareholder filed a third putative class action lawsuit on behalf of Company Shareholders challenging the Business Combination in the Court of Chancery of the State of Delaware.  The action, captioned Int’l Union of Operating Engineers Local 478 Pension Fund v. Globe Specialty Metals, Inc., et al., C.A. No. 10899-VCG, names as defendants the Company, the members of its board of directors, its Chief Executive Officer, Grupo VM, FerroAtlántica, Merger Sub and VeloNewco.  The complaint makes identical allegations and seeks the identical relief sought in City of Providence v. Globe Specialty Metals, Inc., et al., C.A. No. 10865-VCG.
	On April 21, 2015, a purported Company Shareholder filed a putative class action lawsuit on behalf of Company Shareholders challenging the Business Combination in the Court of Chancery of the State of Delaware.  The action, captioned Cirillo v. Globe Specialty Metals, Inc., et al., C.A. No. 10929-VCG, names as defendants the Company, its board of directors, Grupo VM, FerroAtlántica, Merger Sub and VeloNewco.  The complaint alleges, among other things, that the Company’s directors, aided and abetted by the Company, Grupo VM, FerroAtlántica, Merger Sub and VeloNewco, breached their fiduciary duties in agreeing to the Business Combination for inadequate consideration and that certain provisions in the Business Combination Agreement unfairly deters a potential alternative transaction.  The action seeks to enjoin or rescind the Business Combination, disclosure of information, damages, and attorneys’ fees and costs.
	On May 4, 2015, the Court of Chancery of the State of Delaware consolidated these four actions for all purposes into Civil Action No. 10865-VCG, now captioned In re Globe Specialty Metals, Inc. Stockholders Litigation, Consolidated Civil Action No. 10865-VCG. The Court further designated the complaint filed in Civil Action No. 10865-VCG as the operative complaint in the consolidated action.  Plaintiffs in the consolidated action have filed a motion for expedited proceedings, and supporting brief, in which they have requested that the Court schedule a trial in this action before the Company Shareholders vote on the Business Combination.
	As it is not presently possible to determine the outcome of these matters, the possible loss related to these matters cannot be reasonably estimated.
	b. Environmental Contingencies
	It is the Company’s policy to accrue for costs associated with environmental assessments, remedial efforts, or other environmental liabilities when it becomes probable that a liability has been incurred and the costs can be reasonably estimated. When a liability for environmental remediation is recorded, such amounts will be recorded without giving effect to any possible future recoveries. At March 31, 2015, there are no significant liabilities recorded for environmental contingencies. With respect to the cost for ongoing environmental compliance, including maintenance and monitoring, such costs are expensed as incurred unless there is a long-term monitoring agreement with a governmental agency, in which case a liability is established at the inception of the agreement.
	c. Asset Retirement Obligations
	As of March 31, 2015 and June 30, 2014, the Company has recorded asset retirement obligation accruals for mine reclamation and preparation plant closure costs totaling $8,390 and $9,134, respectively. There were no assets that were legally restricted for purposes of settling asset retirement obligations at March 31, 2015 or June 30, 2014.
	d. Employee Contracts
	As of March 31, 2015, there are 91 employees that are covered by union agreements expiring within one year.
	e. Contract Acquisition Cost
	During the nine months ended March 31, 2014, the Company acquired a supply arrangement that resulted in a payment of $14,400, which impacted operating income for the period.
	f. Contractual Obligations
	The Company has minimum power charges that are enforceable and legally binding, and do not represent total anticipated purchases. Minimum charge requirements expire after providing one year notice of contract cancellation. The Company has outstanding purchase obligations with suppliers for raw materials in the normal course of business. These purchase obligation amounts represent only those items which are based on annual agreements that are enforceable and legally binding, and do not represent total anticipated purchases. The Company’s contractual obligations have not changed materially from June 30, 2014.

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Mar. 31, 2015
Stockholders' Equity [Abstract]
Stockholders' Equity	(12)             Stockholders’ Equity
	Dividend
	On February 10, 2014, the Company’s Board of Directors approved an increase to the annual dividend to $0.300 per common share, payable quarterly in March 2014, June 2014, September 2014, and December 2014.  The March 2014 quarterly dividend of $0.075 per share, totaling $5,559, was paid on March 12, 2014 to shareholders of record at the close of business on February 26, 2014.  The June 2014 quarterly dividend of $0.075 per share, totaling $5,541, was paid on June 24, 2014 to shareholders of record at the close of business on June 10, 2014.  The September 2014 quarterly dividend of $0.075 per share, totaling $5,532, was paid on September 24, 2014 to shareholders of record at the close of business on September 10, 2014.  The December 2014 quarterly dividend of $0.075 per share, totaling $5,531, was paid on December 22, 2014 to shareholders of record at the close of business on December 8, 2014.  On February 3, 2015, the Company’s Board of Directors approved an annual dividend of $0.32 per common share, payable quarterly.  Accordingly, a quarterly dividend of $0.08 per share, totaling $5,900, was paid on March 12, 2015 to shareholders of record at the close of business on February 26, 2015.
	Treasury Stock
	On December 13, 2013, the Company’s Board of Directors approved a share repurchase program that authorized the Company to repurchase up to $75,000 of the Company’s common stock valid through December 31, 2014. The program did not obligate the Company to acquire any particular amount of shares. On November 5, 2014, the Company extended its previously announced stock repurchase program, authorizing the repurchase of up to $45,800 of its common shares through December 31, 2015. During the nine months ended March 31, 2015, 13,066 shares were repurchased at an aggregated cost of $242.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share	(13)             Earnings Per Share
	Basic earnings per common share are calculated based on the weighted average number of common shares outstanding during the three and nine months ended March 31, 2015 and 2014, respectively. Diluted earnings per common share assumes the exercise of stock options or the vesting of restricted stock grants, provided in each case the effect is dilutive.
	The reconciliation of the amounts used to compute basic and diluted earnings per common share for the three and nine months ended March 31, 2015 and 2014 is as follows:
			Three Months Ended			Nine Months Ended
			March 31,			March 31,
			2015	2014		2015	2014
	Basic earnings per share computation
	Numerator:
	Net income attributable to Globe Specialty Metals, Inc.	$	7,723	1,561	$	29,398	15,477
	Denominator:
	Weighted average basic shares outstanding		73,749,990	74,291,202		73,751,022	74,963,601
	Basic earnings per common share	$	0.10	0.02	$	0.40	0.21
	Diluted earnings per share computation
	Numerator:
	Net income attributable to Globe Specialty Metals, Inc.	$	7,723	1,561	$	29,398	15,477
	Denominator:
	Weighted average basic shares outstanding		73,749,990	74,291,202		73,751,022	74,963,601
	Effect of dilutive securities		131,482	143,578		135,336	106,553
	Weighted average diluted shares outstanding		73,881,472	74,434,780		73,886,358	75,070,154
	Diluted earnings per common share	$	0.10	0.02	$	0.40	0.21
	Potential common shares associated with outstanding stock options totaling 87,842 and 881,192 for the three months ended March 31, 2015 and 2014, respectively, and 81,590 and 289,443 for the nine months ended March 31, 2015 and 2014, respectively, were excluded from the calculation of diluted earnings per common share because their effect would be anti-dilutive.

ShareBased_Compensation

Share-Based Compensation	9 Months Ended
	Mar. 31, 2015
Share-Based Compensation [Abstract]
Share-Based Compensation	(14)             Share-Based Compensation
	a. Stock Plan
	The Company’s share-based compensation program consists of the Globe Specialty Metals, Inc. 2006 Employee, Director and Consultant Stock Plan (the Stock Plan). The Stock Plan was initially approved by the Company’s stockholders on November 10, 2006, and was amended and approved by the Company’s stockholders on December 6, 2010 to increase by 1,000,000 the number of shares of common stock authorized for issuance under the Stock Plan. The Stock Plan, as amended, provides for the issuance of a maximum of 6,000,000 shares of common stock for the granting of incentive stock options, nonqualified options, stock grants, and share-based awards. Any remaining shares available for grant, but not yet granted, will be carried over and used in the following fiscal years.
	On August 17, 2012, the Board authorized the Company to offer to amend certain outstanding options representing the right to purchase shares issued to directors, officers and current employees pursuant to the Stock Plan, to permit these options alternatively to be settled for cash or exercised for the issuance of shares, at the election of the option holder. This modification of the outstanding options changed its classification from equity awards to liability awards and the fair value of the liability awards is remeasured at the end of each reporting period through settlement. These outstanding options are excluded from the weighted average diluted shares outstanding calculation in note 13 (Earnings Per Share). The Company believes the outstanding options will be settled in cash.
	At March 31, 2015, there were 2,445,421 shares available for grant. All option grants have vesting terms of up to 3 years and maximum contractual terms ranging from 5 to 10 years.  It is the Company’s policy to issue new shares to satisfy the requirements of its share-based compensation plan.  Currently the Company does not expect to repurchase shares in the future to support its share-based compensation plan.
	During the nine months ended March 31, 2015, share-based compensation awards consisted of the issuance of 31,130 nonqualified stock options and 5,100 restricted stock grants. A summary of the changes in options outstanding under the Stock Plan during the nine months ended March 31, 2015 is presented below:
					Weighted-
					Average
				Weighted-	Remaining		Aggregate
		Number of		Average	Contractual		Intrinsic
		Options		Exercise Price	Term in Years		Value
	Outstanding as of June 30, 2014	1,714,996	$	17.05	2.96	$	6,874
	Granted	31,130		17.46
	Exercised	-56,990		11.92
	Cancelled	-100,000		19.87
	Outstanding as of March 31, 2015	1,589,136	$	17.06	2.22	$	3,692
	Exercisable as of March 31, 2015	1,250,323	$	17.29	2.03	$	2,697
	The Company estimates the fair value of grants using the Black-Scholes option pricing model. The following assumptions were used to estimate the fair value of stock options granted during the nine months ended March 31, 2015:
			2015
	Risk-free interest rate		1.56 to1.74%
	Expected dividend yield		1.46 to 1.92%
	Expected volatility		40.42 to 44.25%
	Expected term (years)		5
	The risk-free interest rate is based on the yield of zero coupon U.S. Treasury bonds with terms similar to the expected term of the options. The expected dividend yield is estimated over the expected life of the options based on our historical annual dividend activity. The expected volatility reflects movements in our stock price over the most recent historical period equivalent to the expected life of the options. The expected forfeiture rate is zero as anticipated forfeitures are estimated to be minimal based on historical data.  The expected term is the average of the vesting period and contractual term.
	During the nine months ended March 31, 2015, 429,825 options vested.  There are total vested options of 1,250,323 and 338,813 unvested options outstanding at March 31, 2015.
	For the three and nine months ended March 31, 2015, pre-tax share-based compensation expense was $1,260 and $2,205, respectively.  For the three and nine months ended March 31, 2014, pre-tax share-based compensation expense was $1,448 and $13,421, respectively. The expense is reported within selling, general, and administrative expenses.  The $2,834 liability associated with share-based compensation awards at March 31, 2015 is included in Share-based liabilities.
	b. Executive Bonus Plan
	In addition to share-based awards issued under the Stock Plan, the Company issues restricted stock units under the Company’s Executive Bonus Plan. The fair value of restricted stock units is based on quoted market prices of the Company’s stock at the end of each reporting period. These restricted stock units proportionally vest over three years, but are not delivered until the end of the third year. The Company will settle these awards by cash transfer, based on the Company’s stock price on the date of transfer. During the nine months ended March 31, 2015, there were 137,597 restricted stock units granted, 452,142 restricted stock units were exercised, and as of March 31, 2015, 348,866 restricted stock units were outstanding. For the three and nine months ended March 31, 2015, pre-tax compensation expense for these restricted stock units was $756 and $690, respectively. For the three and nine months ended March 31, 2014, pre-tax compensation expense for these restricted stock units was $2,076 and $6,196, respectively. The expense is reported within selling, general, and administrative expenses. Of the $2,712 liability associated with these restricted stock units at March 31, 2015, $2,083 is included in Share-based liabilities and $629 is included in Other long-term liabilities.
	c. Stock Appreciation Rights
	The Company issues cash-settled stock appreciation rights as an additional form of incentivized bonus. Stock appreciation rights vest and become exercisable in one-third increments over three years.  The Company settles all awards by cash transfer, based on the difference between the Company’s stock price on the date of exercise and the date of grant.  The Company estimates the fair value of stock appreciation rights using the Black-Scholes option pricing model. During the nine months ended March 31, 2015, there were 155,530 stock appreciation rights issued. During the nine months ended March 31, 2015, there were 4,262 stock appreciation rights that were exercised.  There were 1,476,957 stock appreciation rights outstanding as of March 31, 2015.  For the three and nine months ended March 31, 2015, pre-tax compensation expense for these stock appreciation rights was $1,109 and $1,615, respectively.  For the three and nine months ended March 31, 2014, pre-tax compensation expense for these stock appreciation rights was $6,253 and $13,811, respectively. The expense is reported within selling, general, and administrative expenses.  Of the $4,669 liability associated with these stock appreciation rights at March 31, 2015, $155 is included in Share-based liabilities and $4,514 is included in Other long-term liabilities.
	d. Unearned Compensation Expense
	As of March 31, 2015, the Company has unearned pre-tax compensation expense of $676, related to nonvested liability classified stock options, which will be recognized over a weighted average term of 0.36 years. The unearned compensation expense represents the minimum expense to be recognized over the grant date vesting terms or earlier as a result of accelerated expense recognition due to remeasurement of compensation cost for liability classified awards. Future expense may exceed the unearned compensation expense in the future due to the remeasurement of liability classified awards. As of March 31, 2015, the Company has unearned pre-tax compensation expense of $842 and $1,130 related to nonvested equity classified stock options and restricted stock grants, which will be recognized over a weighted average term of 1.61 and 5.63 years, respectively.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Mar. 31, 2015
Fair Value Measurements [Abstract]
Fair Value Measurements	(15)             Fair Value Measurements
	ASC 820, Fair Value Measurements, establishes a fair value hierarchy for disclosure of fair value measurements. The fair value framework requires the categorization of assets and liabilities into three levels based upon the assumptions (inputs) used to value the assets or liabilities. Level 1 provides the most reliable measure of fair value, whereas Level 3 generally requires significant management judgment. The three levels are defined as follows:
	Level 1 — Quoted prices in active markets for identical assets or liabilities.
	Level 2 — Observable inputs other than those included in Level 1. For example, quoted prices for similar assets or liabilities in active markets or quoted prices for identical assets or liabilities in inactive markets.
	Level 3 — Unobservable inputs reflecting management’s own assumptions about the inputs used in pricing the asset or liability. For example, cash flow modeling using inputs based on management’s assumptions.
	The following table summarizes assets measured at fair value on a recurring basis at March 31, 2015:
				Total	Level 1
	Marketable securities		$	4,571	4,571
		Total assets at fair value	$	4,571	4,571
	The following table summarizes assets measured at fair value on a recurring basis at June 30, 2014:
				Total	Level 1
	Marketable securities		$	10,399	10,399
		Total assets at fair value	$	10,399	10,399
	The Company does not have any liabilities that are required to be remeasured at fair value at March 31, 2015 or at June 30, 2014.
	Marketable securities consist of corporate bonds and money market funds for which fair values were based on quoted prices in active markets and were therefore classified within Level 1 of the fair value hierarchy. During the nine months ended March 31, 2015, the Company sold $3,338 of these bonds for a gain of $14.
	See note 7 (Debt) for information regarding the fair value of the Company’s outstanding debt.

Related_Party_Transactions

Related Party Transactions	9 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions	(16)             Related Party Transactions
	From time to time, the Company enters into transactions in the normal course of business with related parties.
	A current and a former member of the board of directors are affiliated with Marco International. During the three and nine months ended March 31, 2015 and 2014, the Company:
		•	Entered into agreements with Marco International to purchase carbon electrodes. Marco International billed $449 and $5,481 during the three months ended March 31, 2015 and 2014, respectively, and $13,814 and $11,249 during the nine months ended March 31, 2015 and 2014, respectively, under these agreements. At March 31, 2015 and June 30, 2014, payables to Marco International under these agreements totaled $0 and $1,140, respectively.
		•	Entered into agreements with Marco International to purchase rare earth minerals. Marco International billed $333 and $0 during the three months ended March 31, 2015 and 2014, respectively, and $865 and $378 during the nine months ended March 31, 2015 and 2014, respectively, under these agreements. At March 31, 2015 and June 30, 2014, payables to Marco International under these agreements totaled $158 and $0, respectively.
		•	Entered into an agreement to sell ferrosilicon to Marco International. Net sales were $211 and $124 during the three months ended March 31, 2015 and 2014, respectively, and $566 and $368 during the nine months ended March 31, 2015 and 2014, respectively, under this agreement. At March 31, 2015 and June 30, 2014, receivables from Marco International under this agreement totaled $71 and $0, respectively.
		•	Entered into an agreement to sell calcium silicon powder to Marco International. Net sales were $0 and $1,730 during the three months ended March 31, 2015 and 2014, respectively, and $0 and $3,663 during the nine months ended March 31, 2015 and 2014, respectively, under this agreement. At March 31, 2015 and June 30, 2014, there were no receivables from Marco International under this agreement.

Operating_Segments

Operating Segments	9 Months Ended
	Mar. 31, 2015
Operating Segments [Abstract]
Operating Segments	(17)             Operating Segments
	Operating segments are based upon the Company’s management reporting structure and include the following five reportable segments:
		•	GMI — a manufacturer of silicon metal and silicon-based alloys and a provider of specialty metallurgical coal for the silicon metal and silicon-based alloys industries located in North America.
		•	Globe Metales — a manufacturer of silicon-based alloys located in Argentina.
		•	Solsil — a developer of upgraded metallurgical grade silicon metal located in the United States.
		•	Corporate — general corporate expenses, investments, and related investment income.
		•	Other — operations that do not fit into the above reportable segments and are immaterial for purposes of separate disclosure. The operating segments include Yonvey’s electrode production operations as well as Siltech’s silicon alloy production and certain other distribution operations for the sale of silicon metal and silicon-based alloys.
	Each of the Company’s reportable segments distributes its products in both its country of domicile, as well as to other international customers. The following presents the Company’s consolidated net sales by product line:
					Three Months Ended					Nine Months Ended
					March 31,					March 31,
					2015		2014			2015		2014
	Silicon metal			$	112,322		101,966		$	335,047		274,778
	Silicon-based alloys				62,131		74,818			197,431		205,594
	Other				20,200		19,273			66,274		67,085
		Total		$	194,653		196,057		$	598,752		547,457
	a. Segment Data
	Summarized financial information for our reportable segments as of and for the three and nine months ended March 31, 2015 and 2014, is shown in the following tables:
			Three Months Ended					Three Months Ended
			March 31,					March 31,
			2015					2014
			Net Sales	Operating Income (Loss)	Income (Loss) Before Income Taxes			Net Sales	Operating Income (Loss)	Income (Loss) Before Income Taxes
	GMI	$	181,610	29,963	29,500		$	181,749	20,411	19,555
	Globe Metales		9,631	-240	-387			13,472	2,260	869
	Solsil		—	-11	-2			—	—	—
	Corporate		—	-13,528	-13,461			—	-13,694	-14,172
	Other		12,995	-562	-1,312			3,067	-1,126	-1,406
	Eliminations		-9,583	227	225			-2,231	-112	-112
		$	194,653	15,849	14,563		$	196,057	7,739	4,734
			Nine Months Ended						Nine Months Ended
			March 31,						March 31,
			2015						2014
			Net Sales	Operating Income (Loss)	Income (Loss) Before Income Taxes	Total Assets			Net Sales	Operating Income (Loss)	Income (Loss) Before Income Taxes
	GMI	$	565,928	88,350	87,083	614,333		$	505,225	40,952	38,653
	Globe Metales		35,143	1,380	702	67,690			38,212	4,754	1,564
	Solsil		—	-81	-54	15,553			—	-32	-32
	Corporate		—	-30,122	-30,689	324,591			—	-46,977	-21,535
	Other		22,608	-4,624	-5,858	99,584			9,708	-2,805	-3,112
	Eliminations		-24,927	94	91	-322,053			-5,688	48	48
		$	598,752	54,997	51,275	799,698		$	547,457	-4,060	15,586
	The accounting policies of our operating segments are the same as those disclosed in note 2 (Summary of Significant Accounting Policies) to our June 30, 2014 financial statements. We evaluate segment performance principally based on operating income (loss).
	b. Geographic Data
	Net sales are attributed to geographic regions based upon the location of the selling unit. Net sales by geographic region for the three and nine months ended March 31, 2015 and 2014 consist of the following:
					Three Months Ended					Nine Months Ended
					March 31,					March 31,
					2015		2014			2015		2014
	United States			$	151,341		163,249		$	475,372		464,066
	Argentina				7,086		11,377			25,037		33,309
	Canada				29,995		18,364			85,215		40,653
	China				11		26			22		243
	Poland				3,269		3,041			8,885		9,186
	South Africa				2,951		—			4,221		—
		Total		$	194,653		196,057		$	598,752		547,457
	Long-lived assets by geographical region at March 31, 2015 and June 30, 2014 consist of the following:
					March 31,		June 30,
					2015		2014
	United States			$	334,144		334,559
	Argentina				25,019		25,611
	Canada				73,240		90,071
	China				13,649		15,029
	Poland				759		813
	South Africa				47,317		46,906
		Total		$	494,128		512,989
	Long-lived assets consist of property, plant, and equipment, net of accumulated depreciation, depletion and amortization, and goodwill and other intangible assets.
	c. Major Customer Data
The following is a summary of the Company’s major customers and their respective percentages of consolidated net sales for the three and nine months ended March 31, 2015 and 2014:
	Three Months Ended				Nine Months Ended
	March 31,				March 31,
	2015		2014		2015		2014
Dow Corning	21%		19%		20%		18%
Momentive Performance Materials	8%		11%		10%		9%
All other customers	71%		70%		70%		73%
Total	100%		100%		100%		100%
Sales to Dow Corning for the three and nine months ended March 31, 2015 and 2014 consist of sales associated with Dow Corning’s 49% ownership interest in WVA Manufacturing, LLC (WVA LLC), and Quebec Silicon Limited Partnership (QSLP).  Sales to Dow Corning are included in the GMI segment.

Subsequent_Events

Subsequent Events	9 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	(18)             Subsequent Events
	On May 5, 2015, the Company’s board of directors approved the quarterly payment of the annual dividend of $0.32 per common share. A quarterly dividend of $0.08 per share will be payable on June 24, 2015 to shareholders of record at the close of business on June 10, 2015.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Mar. 31, 2015
Summary of Significant Accounting Policies [Abstract]
Basis of Presentation	a. Basis of Presentation
	In the opinion of the Company’s management, the accompanying condensed consolidated financial statements include all adjustments necessary for a fair presentation in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) of the results for the interim periods presented and such adjustments are of a normal, recurring nature. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the fiscal year ended June 30, 2014 and Current Report on Form 8-K filed on May 5, 2015. The year-end balance sheet data was derived from audited financial statements, but does not include all of the information and disclosures required by U.S. GAAP. There have been no material changes to the Company’s significant accounting policies during the nine months ended March 31, 2015.
	The accompanying Condensed Consolidated Balance Sheet as of June 30, 2014, the Condensed Consolidated Income Statements and Statements of Comprehensive (Loss) Income  for the three and nine months ended March 31, 2014 and the Condensed Consolidated Statement of Cash Flows and the Condensed Consolidated Statement of Changes in  Shareholders’ Equity for the nine months ended March 31, 2014 have been revised to reflect the impact of completing the purchase price allocation for the acquisition of Silicon Technology (Pty) Ltd., as described in Note 3.
Receivables Sale Arrangement	b. Receivables Sale Arrangement
	The Company has the option to sell certain accounts receivables up to a cap of $55,000 on a non-recourse basis to an unrelated financial institution under a receivables purchase arrangement in the US. The Company accounts for this transaction as a sale of receivables, removes receivables sold from its financial statements, and records cash proceeds when received by the Company as cash provided by operating activities in the Consolidated Statement of Cash Flows. The receivables are sold at a discount rate of 30 day LIBOR plus 1.25% per annum discounted upfront on the date of purchase. The Company entered into the arrangement in the second quarter of fiscal 2015. The arrangement has a term of twelve months and will be renewed for an additional twelve month period in the absence of written termination notice provided by the Company no later than sixty days prior to the termination date of the arrangement. During fiscal 2015, the Company sold $59,000 of receivables under the arrangement and as of March 31, 2015, $24,000 of receivables was outstanding with the financial institution.
Use of Estimates	c. Use of Estimates
	The Company prepares its condensed consolidated financial statements in accordance with U.S. GAAP. The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, as well as the disclosure of contingent assets and liabilities. The Company based its estimates and judgments on historical experience, known or expected trends and other factors that are believed to be reasonable under the circumstances. Actual results may differ from these estimates.
Revenue Recognition	d. Revenue Recognition
	Revenue is recognized when title, ownership, and risk of loss pass to the customer, all of which occurs when products are delivered to the Company’s customers or when products are picked up by a customer or a customer’s carrier. Written sales terms, including the selling price, are determined at the time of shipment or delivery. We have not experienced significant credit issues with our customers.  Shipping and other transportation costs charged to buyers are recorded in both net sales and cost of goods sold. Sales taxes collected from customers and remitted to governmental authorities are accounted for on a net basis and, therefore, are excluded from net sales.
Recent Accounting Pronouncements	e. Recent Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board issued a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. This new guidance is effective for annual reporting periods beginning after December 15, 2016 and early adoption is not permitted. Accordingly, we will adopt this new guidance beginning in fiscal 2018. Companies may use either a full retrospective or a modified retrospective approach to adopt this new guidance and management is currently evaluating which transition approach to use. In April 2015, the FASB issued a proposal that, if approved, would extend the required implementation date one year to the first quarter of calendar 2018 but also would permit companies to adopt the standard at the original effective date of 2017. We are currently evaluating the impact of this guidance on our consolidated results of operations, financial position and cash flows.
	In April 2015, the FASB issued an accounting standards update relating to the presentation of debt issuance costs. The accounting update requires companies to present debt issuance costs related to a recognized debt liability presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The guidance is effective beginning fiscal 2017.  The adoption of this guidance is not expected to have a material impact on the Company's consolidated financial statements.

Business_Combinations_Tables

Business Combinations (Tables)	9 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Preliminary Purchase Price Allocation	The purchase price of $4,000 was allocated as follows:
	(In thousands)				Amounts Recognized as of Acquisition Date (as previously reported)	Measurement Period Adjustments	Amounts Recognized as of Acquisition Date (as adjusted)
	Assets
		Current assets		$	2,298	101	2,399
		Property, plant and equipment			46,500	(233)	46,267
			Total assets acquired	$	48,798	(132)	48,666
	Liabilities
		Accounts payable		$	317	106	423
		Accrued expenses			478	(272)	206
		Deferred tax liabilities			11,760	1,586	13,346
		Other long-term liabilities			10,000	(8,847)	1,153
			Total liabilities assumed	$	22,555	(7,427)	15,128
			Net assets acquired		26,243	7,295	33,538
			Consideration paid		4,000	—	4,000
			Gain on bargain purchase	$	22,243	7,295	29,538

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Mar. 31, 2015
Inventories [Abstract]
Inventories	Inventories comprise the following:
				March 31,	June 30,
				2015	2014
	Finished goods		$	43,957	27,406
	Work in process			5,009	5,120
	Raw materials			59,045	33,843
	Parts and supplies			14,041	14,555
		Total	$	122,052	80,924

Property_Plant_and_Equipment_T

Property, Plant, and Equipment (Tables)	9 Months Ended
	Mar. 31, 2015
Property, Plant, and Equipment [Abstract]
Property, Plant, and Equipment, Net	Property, plant, and equipment, net, comprise the following:
				March 31,	June 30,
				2015	2014
	Land, land improvements, and land use rights		$	12,654	13,615
	Building and improvements			92,625	89,222
	Machinery and equipment			233,707	217,358
	Furnaces			232,956	208,368
	Mineral reserves			55,843	55,843
	Mine development			10,291	9,317
	Other			15,830	14,712
	Construction in progress			18,324	53,753
		Property, plant, and equipment, gross		672,230	662,188
	Less accumulated depreciation, depletion and amortization			(221,921)	(193,019)
		Property, plant, and equipment, net	$	450,309	469,169

Goodwill_and_Other_Intangibles1

Goodwill and Other Intangibles (Tables)	9 Months Ended
	Mar. 31, 2015
Goodwill and Other Intangibles [Abstract]
Changes in Carrying Amount of Goodwill, by Reportable Segment	Changes in the carrying amount of goodwill, by reportable segment, during the nine months ended March 31, 2015 are as follows:
					Globe
				GMI	Metales	Solsil	Other	Total
	Goodwill		$	34,900	14,313	57,656	7,260	114,129
	Accumulated impairment loss			—	(6,000)	(57,656)	(7,130)	(70,786)
		Balance at June 30, 2014		34,900	8,313	—	130	43,343
	Goodwill			34,900	14,313	57,656	7,260	114,129
	Accumulated impairment loss			—	(6,000)	(57,656)	(7,130)	(70,786)
		Balance at March 31, 2015	$	34,900	8,313	—	130	43,343

Debt_Tables

Debt (Tables)	9 Months Ended
	Mar. 31, 2015
Debt [Abstract]
Short-term Debt	Short-term debt comprises the following:
									Weighted
							Outstanding		Average		Unused
							Balance		Interest Rate		Credit Line
	March 31, 2015:
	Type debt:
		Export financing				$	597		8.50%	$	2,877
		Other					59		12.37%		—
			Total			$	656			$	2,877
	June 30, 2014:
	Type debt:
		Export financing				$	—		NA	$	9,208
		Other					59		14.47%		—
			Total			$	59			$	9,208
Summary of Revolving Credit Agreements	A summary of the Company’s revolving credit agreements at March 31, 2015 is as follows:
									Weighted
							Outstanding		Average			Unused	Total
							Balance		Interest Rate			Commitment	Commitment
	Revolving multi-currency credit facility					$	100,000		1.66%		$	198,978	300,000
	Revolving credit agreement						—		5.00%		$	11,827	11,827
Other Long-term Debt	Other Long-Term Debt
						Weighted
					Outstanding	Average			Unused
					Balance	Interest Rate			Credit Line
	Other			$	113	19.00%		$	—

Derivative_Instruments_Tables

Derivative Instruments (Tables)	9 Months Ended
	Mar. 31, 2015
Derivative Instruments [Abstract]
Summary of The Effect of Derivative Instruments on The Condensed Consolidated Income Statements	The effect of the Company’s derivative instruments on the condensed consolidated income statements is summarized in the following table:
			Loss Recognized			Loss Recognized
			During the Three Months			During the Nine Months
			Ended March 31,			Ended March 31,		Location
			2015	2014		2015	2014	of Loss
	Foreign exchange forward and option contracts	$	—	—	$	—	(603)	Foreign exchange loss

Benefit_Plans_Tables

Benefit Plans (Tables)	9 Months Ended
	Mar. 31, 2015
Benefit Plans [Abstract]
Net Periodic Pension Expense	The components of net periodic pension expense for the Company’s defined benefit pension and postretirement plans are as follows:
			Three Months Ended			Nine Months Ended
			March 31,			March 31,
			2015	2014		2015	2014
	Interest cost	$	675	682	$	2,100	2,210
	Service cost		213	236		678	1,138
	Expected return on plan assets		(777)	(667)		(2,384)	(2,028)
	Amortization of net loss		174	310		522	937
	Net periodic pension expense	$	285	561	$	916	2,257

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Reconciliation of Earnings (Loss) per Share	The reconciliation of the amounts used to compute basic and diluted earnings per common share for the three and nine months ended March 31, 2015 and 2014 is as follows:
			Three Months Ended			Nine Months Ended
			March 31,			March 31,
			2015	2014		2015	2014
	Basic earnings per share computation
	Numerator:
	Net income attributable to Globe Specialty Metals, Inc.	$	7,723	1,561	$	29,398	15,477
	Denominator:
	Weighted average basic shares outstanding		73,749,990	74,291,202		73,751,022	74,963,601
	Basic earnings per common share	$	0.10	0.02	$	0.40	0.21
	Diluted earnings per share computation
	Numerator:
	Net income attributable to Globe Specialty Metals, Inc.	$	7,723	1,561	$	29,398	15,477
	Denominator:
	Weighted average basic shares outstanding		73,749,990	74,291,202		73,751,022	74,963,601
	Effect of dilutive securities		131,482	143,578		135,336	106,553
	Weighted average diluted shares outstanding		73,881,472	74,434,780		73,886,358	75,070,154
	Diluted earnings per common share	$	0.10	0.02	$	0.40	0.21

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	9 Months Ended
	Mar. 31, 2015
Share-Based Compensation [Abstract]
Summary of Changes in Options Outstanding	A summary of the changes in options outstanding under the Stock Plan during the nine months ended March 31, 2015 is presented below:
					Weighted-
					Average
				Weighted-	Remaining		Aggregate
		Number of		Average	Contractual		Intrinsic
		Options		Exercise Price	Term in Years		Value
	Outstanding as of June 30, 2014	1,714,996	$	17.05	2.96	$	6,874
	Granted	31,130		17.46
	Exercised	-56,990		11.92
	Cancelled	-100,000		19.87
	Outstanding as of March 31, 2015	1,589,136	$	17.06	2.22	$	3,692
	Exercisable as of March 31, 2015	1,250,323	$	17.29	2.03	$	2,697
Assumptions Used to Estimate Fair Value of Stock Option Awards Using the Black-Scholes Model	The following assumptions were used to estimate the fair value of stock options granted during the nine months ended March 31, 2015:
			2015
	Risk-free interest rate		1.56 to1.74%
	Expected dividend yield		1.46 to 1.92%
	Expected volatility		40.42 to 44.25%
	Expected term (years)		5

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Mar. 31, 2015
Fair Value Measurements [Abstract]
Summary of assets measured at fair value on recurring basis	The following table summarizes assets measured at fair value on a recurring basis at March 31, 2015:
				Total	Level 1
	Marketable securities		$	4,571	4,571
		Total assets at fair value	$	4,571	4,571
	The following table summarizes assets measured at fair value on a recurring basis at June 30, 2014:
				Total	Level 1
	Marketable securities		$	10,399	10,399
		Total assets at fair value	$	10,399	10,399

Operating_Segments_Tables

Operating Segments (Tables)	9 Months Ended
	Mar. 31, 2015
Operating Segments [Abstract]
Consolidated Net Sales by Product Line	The following presents the Company’s consolidated net sales by product line:
					Three Months Ended					Nine Months Ended
					March 31,					March 31,
					2015		2014			2015		2014
	Silicon metal			$	112,322		101,966		$	335,047		274,778
	Silicon-based alloys				62,131		74,818			197,431		205,594
	Other				20,200		19,273			66,274		67,085
		Total		$	194,653		196,057		$	598,752		547,457
Financial Information for Reportable Segments	Summarized financial information for our reportable segments as of and for the three and nine months ended March 31, 2015 and 2014, is shown in the following tables:
			Three Months Ended					Three Months Ended
			March 31,					March 31,
			2015					2014
			Net Sales	Operating Income (Loss)	Income (Loss) Before Income Taxes			Net Sales	Operating Income (Loss)	Income (Loss) Before Income Taxes
	GMI	$	181,610	29,963	29,500		$	181,749	20,411	19,555
	Globe Metales		9,631	-240	-387			13,472	2,260	869
	Solsil		—	-11	-2			—	—	—
	Corporate		—	-13,528	-13,461			—	-13,694	-14,172
	Other		12,995	-562	-1,312			3,067	-1,126	-1,406
	Eliminations		-9,583	227	225			-2,231	-112	-112
		$	194,653	15,849	14,563		$	196,057	7,739	4,734
			Nine Months Ended						Nine Months Ended
			March 31,						March 31,
			2015						2014
			Net Sales	Operating Income (Loss)	Income (Loss) Before Income Taxes	Total Assets			Net Sales	Operating Income (Loss)	Income (Loss) Before Income Taxes
	GMI	$	565,928	88,350	87,083	614,333		$	505,225	40,952	38,653
	Globe Metales		35,143	1,380	702	67,690			38,212	4,754	1,564
	Solsil		—	-81	-54	15,553			—	-32	-32
	Corporate		—	-30,122	-30,689	324,591			—	-46,977	-21,535
	Other		22,608	-4,624	-5,858	99,584			9,708	-2,805	-3,112
	Eliminations		-24,927	94	91	-322,053			-5,688	48	48
		$	598,752	54,997	51,275	799,698		$	547,457	-4,060	15,586
Net Sales by Geographical Region	Net sales by geographic region for the three and nine months ended March 31, 2015 and 2014 consist of the following:
					Three Months Ended					Nine Months Ended
					March 31,					March 31,
					2015		2014			2015		2014
	United States			$	151,341		163,249		$	475,372		464,066
	Argentina				7,086		11,377			25,037		33,309
	Canada				29,995		18,364			85,215		40,653
	China				11		26			22		243
	Poland				3,269		3,041			8,885		9,186
	South Africa				2,951		—			4,221		—
		Total		$	194,653		196,057		$	598,752		547,457
Long-lived Assets by Geographical Region	Long-lived assets by geographical region at March 31, 2015 and June 30, 2014 consist of the following:
					March 31,		June 30,
					2015		2014
	United States			$	334,144		334,559
	Argentina				25,019		25,611
	Canada				73,240		90,071
	China				13,649		15,029
	Poland				759		813
	South Africa				47,317		46,906
		Total		$	494,128		512,989
Major Customers Percentage of Net Sales	The following is a summary of the Company’s major customers and their respective percentages of consolidated net sales for the three and nine months ended March 31, 2015 and 2014:
		Three Months Ended				Nine Months Ended
		March 31,				March 31,
		2015		2014		2015		2014
	Dow Corning	21%		19%		20%		18%
	Momentive Performance Materials	8%		11%		10%		9%
	All other customers	71%		70%		70%		73%
	Total	100%		100%		100%		100%

Organization_and_Business_Oper1

Organization and Business Operations (Details)	9 Months Ended
	Mar. 31, 2015
Organization and Business Operations [Abstract]
Number of shares issuable for exchange (in shares)	98,078,161
Conversion of stock (in shares)	1

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Mar. 31, 2015
Receivables Sale Arrangement [Line Items]
Option to sell accounts receivables up to a cap		$55,000
Receivables are sold at discount rate		LIBOR plus 1.25%
Number of days of discount rate		30 days
Term of sale arrangement	12 months
Renewal period of sale arrangement	12 months
Minimum period of termination notice	60 days
Options sold under arrangement		59,000
Receivables outstanding with financial institution		$24,000
LIBOR [Member]
Receivables Sale Arrangement [Line Items]
Variable interest rate (in hundredths)		1.25%

Business_Combinations_Details

Business Combinations (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Nov. 21, 2013
Liabilities
Gain on bargain purchase	$0	$0	$0	$29,538
Silicon Technology (Pty), Ltd [Member]
Business Acquisition [Abstract]
Percentage of interest acquired (in hundredths)					100.00%
Annual production capacity of acquiree (in metric tons)					45,000
Percentage of increase in annual capacity due to opportunistic acquisition (in hundredths)					30.00%
Assets
Current assets					2,399
Property, plant and equipment					46,267
Total assets acquired					48,666
Liabilities
Accounts payable					423
Accrued expenses					206
Deferred tax liabilities					13,346
Other long-term liabilities					1,153
Total liabilities assumed					15,128
Net assets acquired					33,538
Consideration paid					4,000
Gain on bargain purchase					29,538
Amounts Recognized as of Acquisition Date (as previously reported) [Member] | Silicon Technology (Pty), Ltd [Member]
Assets
Current assets					2,298
Property, plant and equipment					46,500
Total assets acquired					48,798
Liabilities
Accounts payable					317
Accrued expenses					478
Deferred tax liabilities					11,760
Other long-term liabilities					10,000
Total liabilities assumed					22,555
Net assets acquired					26,243
Consideration paid					4,000
Gain on bargain purchase					22,243
Measurement Period Adjustments Acquisition Date [Member] | Silicon Technology (Pty), Ltd [Member]
Assets
Current assets					101
Property, plant and equipment					-233
Total assets acquired					-132
Liabilities
Accounts payable					106
Accrued expenses					-272
Deferred tax liabilities					1,586
Other long-term liabilities					-8,847
Total liabilities assumed					-7,427
Net assets acquired					7,295
Consideration paid					0
Gain on bargain purchase					$7,295

Inventories_Details

Inventories (Details) (USD $)	Mar. 31, 2015	Jun. 30, 2014
In Thousands, unless otherwise specified
Inventories [Abstract]
Finished goods	$43,957	$27,406
Work in process	5,009	5,120
Raw materials	59,045	33,843
Parts and supplies	14,041	14,555
Total	122,052	80,924
Inventory valued using first-in, first-out method	113,932	73,894
Inventory valued using average cost method	$8,120	$7,030

Property_Plant_and_Equipment_D

Property, Plant, and Equipment (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	$672,230		$672,230		$662,188
Less accumulated depreciation, depletion and amortization	-221,921		-221,921		-193,019
Property, plant, and equipment, net	450,309		450,309		469,169
Depreciation [Abstract]
Depreciation, depletion and amortization	13,603	11,244	37,869	33,931
Capitalized interest	0	0	0	103
Cost of Goods Sold [Member]
Depreciation [Abstract]
Depreciation, depletion and amortization	13,366	10,977	37,146	33,127
Selling, General and Administrative Expenses [Member]
Depreciation [Abstract]
Depreciation, depletion and amortization	237	267	723	804
Land, Land Improvements, and Land Use Rights [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	12,654		12,654		13,615
Building and Improvements [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	92,625		92,625		89,222
Machinery and Equipment [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	233,707		233,707		217,358
Furnaces [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	232,956		232,956		208,368
Mineral Reserves [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	55,843		55,843		55,843
Mine Development [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	10,291		10,291		9,317
Other [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	15,830		15,830		14,712
Construction in Progress [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	$18,324		$18,324		$53,753

Goodwill_and_Other_Intangibles2

Goodwill and Other Intangibles (Details) (USD $)	Mar. 31, 2015	Jun. 30, 2014
In Thousands, unless otherwise specified
Goodwill [Roll Forward]
Goodwill	$114,129	$114,129
Accumulated impairment loss	-70,786	-70,786
Goodwill, net	43,343	43,343
Other Intangible Assets [Abstract]
Indefinite-lived intangible assets	0
GMI [Member]
Goodwill [Roll Forward]
Goodwill	34,900	34,900
Accumulated impairment loss	0	0
Goodwill, net	34,900	34,900
Globe Metales [Member]
Goodwill [Roll Forward]
Goodwill	14,313	14,313
Accumulated impairment loss	-6,000	-6,000
Goodwill, net	8,313	8,313
Solsil [Member]
Goodwill [Roll Forward]
Goodwill	57,656	57,656
Accumulated impairment loss	-57,656	-57,656
Goodwill, net	0	0
Other [Member]
Goodwill [Roll Forward]
Goodwill	7,260	7,260
Accumulated impairment loss	-7,130	-7,130
Goodwill, net	$130	$130

Debt_Details

Debt (Details)

Mar. 31, 2015

Jun. 30, 2014

Aug. 20, 2013

Mar. 31, 2015

Aug. 20, 2013

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Jun. 30, 2014

Mar. 31, 2015

Jun. 30, 2014

In Thousands, unless otherwise specified

USD ($)

USD ($)

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving multi-currency credit facility [Member]

Revolving credit agreement [Member]

Quebec Silicon Acquisition Revolving Credit Facility [Member]

Other Long-term Debt [Member]

Export Financing [Member]

Export Financing [Member]

Other [Member]

Other [Member]

USD ($)

USD ($)

Base Rate [Member]

Eurocurrency Rate [Member]

Eurocurrency Rate [Member]

US Federal Funds Rate [Member]

US Federal Funds Rate [Member]

Minimum [Member]

Maximum [Member]

USD ($)

CAD

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Eurocurrency Rate [Member]

Eurocurrency Rate [Member]

Short-term Debt [Line Items]

Outstanding Balance

$656

$59

$597

$0

$59

$59

Weighted Average Interest Rate (in hundredths)

8.50%

12.37%

14.47%

Unused Credit Line

2,877

9,208

2,877

9,208

0

0

Period for short-term export financing agreements, minimum

7 months

Period for short-term export financing agreements, maximum

11 months

Line of Credit Facility [Line Items]

Outstanding balance

100,000

0

113

Weighted average interest rate (in hundredths)

1.66%

5.00%

19.00%

Unused commitment

198,978

11,827

0

Total commitment

300,000

300,000

11,827

15,000

Term of credit facility

5 years

Sublimit for swing line loans

10,000

Sublimit letter of credit

25,000

Additional borrowing capacity

198,978

Aggregate amount by which maximum borrowing capacity may be increased

150,000

Expiration date

20-Aug-18

20-Sep-15

Interest rate on borrowings under the credit agreement

Interest on borrowings under the multi-currency credit facility is payable, at the Company's election, at either (a) a base rate (the higher of (i) the U.S. federal funds rate plus 0.50% per annum, (ii) the Administrative Agent's prime rate or (iii) a Eurocurrency Rate for loans with a one month interest period plus 1.00% per annum plus a margin ranging from 0.50% to 1.50% per annum (such margin determined by reference to the leverage ratio set forth in the credit agreement), or (b) the Eurocurrency Rate plus a margin ranging from 1.50% to 2.50% per annum (such margin determined by reference to the leverage ratio set forth in the credit agreement).

Interest rate on borrowings, variable rate basis

base rate

Eurocurrency Rate

U.S. federal funds rate

Canadian prime

Interest rate on borrowings, basis spread on variable rate (in hundredths)

1.00%

0.50%

2.00%

Interest rate on borrowings, basis spread on variable rate condition one (in hundredths)

0.50%

1.50%

Interest rate on borrowings, basis spread on variable rate condition two (in hundredths)

1.50%

2.50%

Letters of credit outstanding associated with landlord guarantees

722

Letters of credit outstanding associated with economic development

$300

Interest rate at period end (in hundredths)

5.00%

Derivative_Instruments_Details

Derivative Instruments (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivative outstanding	$0		$0
Foreign Exchange Forward and Option contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative outstanding	0		0
Foreign Exchange Forward and Option contracts [Member] | Foreign Exchange Loss [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized	$0	$0	$0	($603)

Benefit_Plans_Details

Benefit Plans (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013
Benefit Plans [Abstract]
Number of noncontributory defined benefit pension plans	3		3
Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net decrease in the pre-tax components of accumulated other comprehensive loss comprising net actuarial curtailment gain					$5,831
Pension Plans, Defined Benefit [Member]
Net periodic pension expense [Abstract]
Interest cost	675	682	2,100	2,210
Service cost	213	236	678	1,138
Expected return on plan assets	-777	-667	-2,384	-2,028
Amortization of net loss	174	310	522	937
Net periodic pension expense	285	561	916	2,257
Pension Plans, Defined Benefit [Member] | Postretirement Benefit Plan, Defined Benefit [Member]
Employer contributions [Abstract]
Estimated future employer contributions for the current fiscal year			2,033
Defined benefit plan contributions by employer			$1,034

Income_Taxes_Details

Income Taxes (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Taxes [Abstract]
Effective income tax rate (in hundredths)	37.80%	20.50%
Annual effective rate excluding discrete items (in hundredths)	36.50%
Increase in net valuation allowance	$1,611
United States [Member]
Income Tax Examination [Line Items]
Open Tax Year Range	2011 to present
Canada [Member]
Income Tax Examination [Line Items]
Open Tax Year Range	2012 to present
Argentina [Member]
Income Tax Examination [Line Items]
Open Tax Year Range	2010 to present
China [Member]
Income Tax Examination [Line Items]
Open Tax Year Range	2011 to present

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
	Employee		Employee
Asset Retirement Obligation [Abstract]
Mine reclamation and closure costs	$8,390		$8,390		$9,134
Restricted assets for legal settlements	0		0		0
Employee Contracts [Abstract]
Number of employees covered by union agreements	91		91
Period within which union agreements expiring			1 year
Contract Acquisition Cost [Abstract]
Contract acquisition cost	0	0	0	14,400
Indemnification Agreement [Member]
Legal Contingencies [Abstract]
Indemnification obligation			$4,559

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	3 Months Ended					9 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Mar. 31, 2015	Nov. 05, 2014
Stockholders' Equity [Abstract]
Date dividend declared	3-Feb-15				10-Feb-14
Dividends payable amount per share in each quarter (in dollars per share)	$0.32				$0.30	$0.32
Common stock dividends per share cash paid (in dollars per share)	$0.08	$0.08	$0.08	$0.08	$0.08
Total dividends paid	$5,900	$5,531	$5,532	$5,541	$5,559
Date dividends paid	12-Mar-15	22-Dec-14	24-Sep-14	24-Jun-14	12-Mar-14
Date of stockholders of record	26-Feb-15	8-Dec-14	10-Sep-14	10-Jun-14	26-Feb-14
Treasury Stock [Abstract]
Authorized amount of stock repurchase		75,000					45,800
Treasury stock purchased (in shares)						13,066
Treasury stock acquired under the repurchase program						$242

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Basic earnings per share computation - numerator [Abstract]
Net income attributable to Globe Specialty Metals, Inc.	$7,723	$1,561	$29,398	$15,477
Basic earnings per share computation - denominator [Abstract]
Weighted average basic shares outstanding (in shares)	73,749,990	74,291,202	73,751,022	74,963,601
Basic earnings per common share (in dollars per share)	$0.10	$0.02	$0.40	$0.21
Diluted earnings per share computation - numerator [Abstract]
Net income attributable to Globe Specialty Metals, Inc.	$7,723	$1,561	$29,398	$15,477
Diluted earnings per share computation - denominator [Abstract]
Weighted average basic shares outstanding (in shares)	73,749,990	74,291,202	73,751,022	74,963,601
Effect of dilutive securities (in shares)	131,482	143,578	135,336	106,553
Weighted average diluted shares outstanding (in shares)	73,881,472	74,434,780	73,886,358	75,070,154
Diluted earnings per common share (in dollars per share)	$0.10	$0.02	$0.40	$0.21
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares (in shares)	87,842	881,192	81,590	289,443

ShareBased_Compensation_Detail

Share-Based Compensation (Details) (USD $)	9 Months Ended	12 Months Ended	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2014
Stock Plan Activity Since Inception [Abstract]
Increase in shares of common stock authorized for issuance under the Plan (in shares)	1,000,000		1,000,000
Shares of common stock authorized to be issued (in shares)	6,000,000		6,000,000
Shares available for grant (in shares)	2,445,421		2,445,421
Number of Options [Roll Forward]
Outstanding, beginning of period (in shares)	1,714,996
Granted (in shares)	31,130
Exercised (in shares)	-56,990
Cancelled (in shares)	-100,000
Outstanding, end of period (in shares)	1,589,136	1,714,996	1,589,136
Exercisable, end of period (in shares)	1,250,323		1,250,323
Weighted-Average Exercise Price [Abstract]
Outstanding, beginning of period (in dollars per share)	$17.05
Granted (in dollars per share)	$17.46
Exercised (in dollars per share)	$11.92
Cancelled (in dollars per share)	$19.87
Outstanding, end of period (in dollars per share)	$17.06	$17.05	$17.06
Exercisable, end of period (in dollars per share)	$17.29		$17.29
Weighted-Average Remaining Contractual Term in Years [Abstract]
Outstanding, beginning of period	2 years 2 months 19 days	2 years 11 months 16 days
Outstanding, end of period	2 years 2 months 19 days	2 years 11 months 16 days
Exercisable, end of period	2 years 0 months 11 days
Aggregate Intrinsic Value [Abstract]
Outstanding, beginning of period	$6,874
Outstanding, end of period	3,692	6,874	3,692
Exercisable, end of period	2,697		2,697
Assumptions used to estimate fair value of stock option awards granted [Abstract]
Expected term	5 years
Vested in period (in shares)	429,825
Total vested options (in shares)	1,250,323		1,250,323
Nonvested options outstanding (in shares)	338,813		338,813
Unearned Compensation Expense [Abstract]
Unearned compensation expense	676		676
Period in which unearned compensation expense will be recognized	0 years 4 months 10 days
Selling, General and Administrative Expenses [Member]
Assumptions used to estimate fair value of stock option awards granted [Abstract]
Share-based compensation expense	2,205		1,260	1,448	13,421
Share-based liabilities [Member]
Restricted Stock Units [Abstract]
Liability associated with share based compensation	2,834		2,834
Minimum [Member]
Assumptions used to estimate fair value of stock option awards granted [Abstract]
Risk free interest rate (in hundredths)	1.56%
Expected dividend yield (in hundredths)	1.46%
Expected volatility (in hundredths)	40.42%
Maximum [Member]
Assumptions used to estimate fair value of stock option awards granted [Abstract]
Risk free interest rate (in hundredths)	1.74%
Expected dividend yield (in hundredths)	1.92%
Expected volatility (in hundredths)	44.25%
Stock Options [Member]
Stock Plan Activity Since Inception [Abstract]
Contractual terms of option grants, minimum	5 years
Contractual terms of option grants, maximum	10 years
Restricted Stock Units [Abstract]
Vesting period of award	3 years
Unearned Compensation Expense [Abstract]
Unearned compensation expense	842		842
Period in which unearned compensation expense will be recognized	1 year 7 months 10 days
Restricted Stock Grants [Member]
Stock Plan Activity Since Inception [Abstract]
Share-based compensation awards issued (in shares)	5,100
Unearned Compensation Expense [Abstract]
Unearned compensation expense	1,130		1,130
Period in which unearned compensation expense will be recognized	5 years 7 months 17 days
Non-qualified Stock Option [Member]
Stock Plan Activity Since Inception [Abstract]
Share-based compensation awards issued (in shares)	31,130
Restricted Stock Units (RSUs) [Member]
Restricted Stock Units [Abstract]
Vesting period of award	3 years
Awards granted (in shares)	137,597
Awards exercised (in shares)	452,142
Awards outstanding (in shares)	348,866		348,866
Liability associated with share based compensation	2,712		2,712
Restricted Stock Units (RSUs) [Member] | Selling, General and Administrative Expenses [Member]
Assumptions used to estimate fair value of stock option awards granted [Abstract]
Share-based compensation expense	690		756	2,076	6,196
Restricted Stock Units (RSUs) [Member] | Share-based liabilities [Member]
Restricted Stock Units [Abstract]
Liability associated with share based compensation	2,083		2,083
Restricted Stock Units (RSUs) [Member] | Other Long Term Liabilities [Member]
Restricted Stock Units [Abstract]
Liability associated with share based compensation	629		629
Stock Appreciation Rights (SARs) [Member]
Restricted Stock Units [Abstract]
Vesting period of award	3 years
Awards granted (in shares)	155,530
Awards exercised (in shares)	4,262
Awards outstanding (in shares)	1,476,957		1,476,957
Liability associated with share based compensation	4,669		4,669
Stock Appreciation Rights (SARs) [Member] | Selling, General and Administrative Expenses [Member]
Assumptions used to estimate fair value of stock option awards granted [Abstract]
Share-based compensation expense	1,615		1,109	6,253	13,811
Stock Appreciation Rights (SARs) [Member] | Share-based liabilities [Member]
Restricted Stock Units [Abstract]
Liability associated with share based compensation	155		155
Stock Appreciation Rights (SARs) [Member] | Other Long Term Liabilities [Member]
Restricted Stock Units [Abstract]
Liability associated with share based compensation	$4,514		$4,514

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014
Level 1 [Member] | Corporate Bond Securities [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Marketable securities	$3,338
Gain on sale of marketable securities	14
Recurring [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Marketable securities	4,571	10,399
Total assets at fair value	4,571	10,399
Recurring [Member] | Level 1 [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Marketable securities	4,571	10,399
Total assets at fair value	$4,571	$10,399

Related_Party_Transactions_Det

Related Party Transactions (Details) (Marco International [Member], USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
Marco International [Member]
Related Party Transaction [Line Items]
Purchases from related party	$449	$5,481	$13,814	$11,249
Due to related party	0		0		1,140
Rare metal purchases from related party	333	0	865	378
Other purchases from related party	158				0
Sales of products to related party	211	124	566	368
Other sales of products to related party	71				0
Net sales under agreement	0	1,730	0	3,663
Due from related party	$0		$0		$0

Operating_Segments_External_cu

Operating Segments, External customers by products and services (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
			Segment
Operating Segments [Abstract]
Number of reportable segments			5
Revenue from External Customer by Product Line [Abstract]
Net sales	$194,653	$196,057	$598,752	$547,457
Silicon Metal [Member]
Revenue from External Customer by Product Line [Abstract]
Net sales	112,322	101,966	335,047	274,778
Silicon-based Alloys [Member]
Revenue from External Customer by Product Line [Abstract]
Net sales	62,131	74,818	197,431	205,594
Other [Member]
Revenue from External Customer by Product Line [Abstract]
Net sales	$20,200	$19,273	$66,274	$67,085

Operating_Segments_by_segment_

Operating Segments, by segment (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net Sales	$194,653	$196,057	$598,752	$547,457
Operating Income (Loss)	15,849	7,739	54,997	-4,060
Income (Loss) Before Income Taxes	14,563	4,734	51,275	15,586
Total Assets	799,698		799,698		845,126
Reportable Segments [Member] | GMI [Member]
Segment Reporting Information [Line Items]
Net Sales	181,610	181,749	565,928	505,225
Operating Income (Loss)	29,963	20,411	88,350	40,952
Income (Loss) Before Income Taxes	29,500	19,555	87,083	38,653
Total Assets	614,333		614,333
Reportable Segments [Member] | Globe Metales [Member]
Segment Reporting Information [Line Items]
Net Sales	9,631	13,472	35,143	38,212
Operating Income (Loss)	-240	2,260	1,380	4,754
Income (Loss) Before Income Taxes	-387	869	702	1,564
Total Assets	67,690		67,690
Reportable Segments [Member] | Solsil [Member]
Segment Reporting Information [Line Items]
Net Sales	0	0	0	0
Operating Income (Loss)	-11	0	-81	-32
Income (Loss) Before Income Taxes	-2	0	-54	-32
Total Assets	15,553		15,553
Reportable Segments [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Net Sales	0	0	0	0
Operating Income (Loss)	-13,528	-13,694	-30,122	-46,977
Income (Loss) Before Income Taxes	-13,461	-14,172	-30,689	-21,535
Total Assets	324,591		324,591
Reportable Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Net Sales	12,995	3,067	22,608	9,708
Operating Income (Loss)	-562	-1,126	-4,624	-2,805
Income (Loss) Before Income Taxes	-1,312	-1,406	-5,858	-3,112
Total Assets	99,584		99,584
Reportable Segments [Member] | Eliminations [Member]
Segment Reporting Information [Line Items]
Net Sales	-9,583	-2,231	-24,927	-5,688
Operating Income (Loss)	227	-112	94	48
Income (Loss) Before Income Taxes	225	-112	91	48
Total Assets	($322,053)		($322,053)

Operating_Segments_by_external

Operating Segments, by external customers and long lived assets (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$194,653	$196,057	$598,752	$547,457
Reportable Geographical Components [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	194,653	196,057	598,752	547,457
Long-lived assets	494,128		494,128		512,989
Reportable Geographical Components [Member] | United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	151,341	163,249	475,372	464,066
Long-lived assets	334,144		334,144		334,559
Reportable Geographical Components [Member] | Argentina [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	7,086	11,377	25,037	33,309
Long-lived assets	25,019		25,019		25,611
Reportable Geographical Components [Member] | Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	29,995	18,364	85,215	40,653
Long-lived assets	73,240		73,240		90,071
Reportable Geographical Components [Member] | China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	11	26	22	243
Long-lived assets	13,649		13,649		15,029
Reportable Geographical Components [Member] | Poland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	3,269	3,041	8,885	9,186
Long-lived assets	759		759		813
Reportable Geographical Components [Member] | South Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	2,951	0	4,221	0
Long-lived assets	$47,317		$47,317		$46,906

Operating_Segments_by_major_cu

Operating Segments, by major customers and by segments (Details)	3 Months Ended		9 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Revenue, Major Customer [Line Items]
Percentage of consolidated net sales (in hundredths)	100.00%	100.00%	100.00%	100.00%
Noncontrolling interest's ownership interest in consolidated affiliate (in hundredths)	49.00%	49.00%	49.00%	49.00%
Dow Corning [Member]
Revenue, Major Customer [Line Items]
Percentage of consolidated net sales (in hundredths)	21.00%	19.00%	20.00%	18.00%
Momentive Performance Materials [Member]
Revenue, Major Customer [Line Items]
Percentage of consolidated net sales (in hundredths)	8.00%	11.00%	10.00%	9.00%
All Other Customers [Member]
Revenue, Major Customer [Line Items]
Percentage of consolidated net sales (in hundredths)	71.00%	70.00%	70.00%	73.00%

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	3 Months Ended					9 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Mar. 31, 2015	5-May-15
Subsequent Event [Line Items]
Date dividends to be paid	12-Mar-15	22-Dec-14	24-Sep-14	24-Jun-14	12-Mar-14
Subsequent Event [Member] | Dividends declared [Member]
Subsequent Event [Line Items]
Dividends declared (in dollars per share)							$0.32
Dividends per share to be paid quarterly (in dollars per share)							$0.08
Date of stockholders of record						10-Jun-15
Date dividends to be paid						24-Jun-15