Stillwater Mining (SWC) 10-Q 12 Nov 13 2013 Q3 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	9 Months Ended
	Sep. 30, 2013	Nov. 08, 2013
Entity Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Entity Registrant Name	'STILLWATER MINING CO /DE/	'
Entity Central Index Key	'0000931948	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	119,320,525

Consolidated_Statements_Of_Com

Consolidated Statements Of Comprehensive (Loss) Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
REVENUES	'	'	'	'
Mine Production	$123,193	$107,057	$364,249	$339,951
PGM Recycling	156,814	73,987	432,897	256,919
Total revenues	280,007	181,044	797,146	596,870
Costs of metals sold	'	'	'	'
Mine Production	83,913	69,910	237,042	218,935
PGM Recycling	136,843	72,096	402,859	249,360
Total costs of metals sold	220,756	142,006	639,901	468,295
Depletion, depreciation and amortization	'	'	'	'
Mine Production	15,057	13,843	43,824	42,848
PGM Recycling	285	264	804	793
Total depletion, depreciation and amortization	15,342	14,107	44,628	43,641
Total costs of revenues	236,098	156,113	684,529	511,936
Marketing	207	1,886	4,197	7,874
Exploration	2,143	1,668	10,247	13,785
Research and development	104	82	192	864
Proxy contest expense	0	0	4,307	0
Accelerated equity based compensation expense	0	0	9,063	0
General and administrative	9,316	9,882	35,846	32,477
Loss on long-term investments	112	1,697	1,766	1,697
Impairment of non-producing mineral property	290,417	0	290,417	0
Abandonment of non-producing property	0	0	0	2,835
Loss on disposal of property, plant and equipment	66	71	106	363
Total costs and expenses	538,463	171,399	1,040,670	571,831
OPERATING (LOSS) INCOME	-258,456	9,645	-243,524	25,039
OTHER INCOME (EXPENSE)	'	'	'	'
Other	8	82	1,170	667
Interest income	1,102	271	3,516	1,706
Interest expense	-5,556	-1,493	-17,646	-4,361
Foreign currency transaction gain, net	6,220	6,407	15,679	12,981
(LOSS) INCOME BEFORE INCOME TAX BENEFIT (PROVISION)	-256,682	14,912	-240,805	36,032
Income tax benefit (provision)	54,698	-2,109	47,468	1,508
NET (LOSS) INCOME	-201,984	12,803	-193,337	37,540
Net loss attributable to noncontrolling interest	-489	-273	-1,117	-631
NET (LOSS) INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	-201,495	13,076	-192,220	38,171
Other comprehensive income, net of tax	'	'	'	'
Net unrealized gains on securities available-for-sale	219	421	288	620
COMPREHENSIVE (LOSS) INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	-201,276	13,497	-191,932	38,791
Comprehensive loss attributable to noncontrolling interest	-489	-273	-1,117	-631
TOTAL COMPREHENSIVE (LOSS) INCOME	($201,765)	$13,224	($193,049)	$38,160
Weighted average common shares outstanding	'	'	'	'
Basic (in shares)	119,153	116,377	118,347	115,918
Diluted (in shares)	119,153	117,145	118,347	116,847
Basic (loss) earnings per share attributable to common stockholders (in usd per share)	($1.69)	$0.11	($1.62)	$0.33
Diluted (loss) earnings per share attributable to common stockholders (in usd per share)	($1.69)	$0.11	($1.62)	$0.33

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets	'	'
Cash and cash equivalents	$235,055	$379,680
Investments, at fair market value	229,174	261,983
Inventories	181,888	153,208
Trade receivables	18,739	9,953
Deferred income taxes	21,304	21,304
Prepaids	6,340	4,967
Other current assets	23,475	21,767
Total current assets	715,975	852,862
Mineral properties	285,942	576,359
Mine development, net	373,357	322,866
Property, plant and equipment, net	121,105	122,677
Deferred debt issuance costs	8,315	9,609
Other noncurrent assets	6,795	6,390
Total assets	1,511,489	1,890,763
Current liabilities	'	'
Accounts payable	32,226	28,623
Accrued compensation and benefits	32,340	31,369
Property, production and franchise taxes payable	12,057	13,722
Current portion of long-term debt and capital lease obligations	2,009	168,432
Income taxes payable	9,454	0
Other current liabilities	8,549	4,702
Total current liabilities	96,635	246,848
Long-term debt and capital lease obligations	305,105	292,685
Deferred income taxes	130,911	199,802
Accrued workers compensation	5,851	5,815
Asset retirement obligation	8,477	7,965
Other noncurrent liabilities	9,023	5,068
Total liabilities	556,002	758,183
Stockholders’ equity	'	'
Preferred stock, $0.01 par value, 1,000,000 shares authorized; none issued	0	0
Common stock, $0.01 par value, 200,000,000 shares authorized; 119,246,710 and 116,951,081 shares issued and outstanding	1,192	1,170
Paid-in capital	1,074,913	1,058,978
Accumulated (deficit) earnings	-171,451	20,770
Accumulated other comprehensive income (loss)	189	-99
Total stockholders’ equity	904,843	1,080,819
Noncontrolling interest	50,644	51,761
Total equity	955,487	1,132,580
Total liabilities and equity	$1,511,489	$1,890,763

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]	'	'
Preferred stock, par value (in usd per share)	$0.01	$0.01
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in usd per share)	$0.01	$0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	119,246,710	116,951,081
Common stock, shares outstanding (in shares)	119,246,710	116,951,081

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES	'	'
Net (loss) income	($193,337)	$37,540
Adjustments to reconcile net (loss) income to net cash provided by operating activities:	'	'
Depletion, depreciation and amortization	44,628	43,641
Loss on disposal of property, plant and equipment	106	363
Impairment of non-producing mineral property	290,417	0
Loss on long-term investments	1,766	1,697
Deferred taxes	-60,743	-4,913
Foreign currency transaction gain, net	-15,679	-12,981
Abandonment of non-producing property	0	2,835
Accretion of asset retirement obligation	512	470
Amortization of debt issuance costs	1,294	944
Accretion of convertible debenture debt discount	11,722	0
Accelerated equity based compensation expense	9,063	0
Share based compensation and other benefits	13,673	12,899
Non-cash capitalized interest	-1,918	0
Changes in operating assets and liabilities:	'	'
Inventories	-28,961	6,221
Trade receivables	-8,786	-3,727
Prepaids	-1,373	-1,870
Accrued compensation and benefits	989	2,258
Accounts payable	2,270	-1,270
Property, production and franchise taxes payable	1,330	1,041
Income taxes payable	9,454	-1,235
Workers compensation	36	490
Restricted cash	0	15,825
Other	5,238	206
NET CASH PROVIDED BY OPERATING ACTIVITIES	81,701	100,434
CASH FLOWS FROM INVESTING ACTIVITIES	'	'
Capital expenditures	-91,187	-84,688
Proceeds from disposal of property, plant and equipment	126	39
Purchases of investments	-116,769	-68,286
Proceeds from maturities of investments	147,103	42,003
NET CASH USED IN INVESTING ACTIVITIES	-60,727	-110,932
CASH FLOWS FROM FINANCING ACTIVITIES	'	'
Proceeds from sale of noncontrolling interest, net of transaction costs	0	93,821
Issuance of long-term debt	0	7,176
Payments on debt and capital lease obligations	-165,714	-946
Payments for debt issuance costs	0	-219
Issuance of common stock	115	44
NET CASH (USED IN) PROVIDED BY FINANCING ACTIVITIES	-165,599	99,876
CASH AND CASH EQUIVALENTS	'	'
Net (decrease) increase	-144,625	89,378
Balance at beginning of period	379,680	109,097
BALANCE AT END OF PERIOD	$235,055	$198,475

General

General	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
General	'
	GENERAL
	In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments (consisting only of normal recurring adjustments) necessary to present fairly the financial position of Stillwater Mining Company (the “Company”) as of September 30, 2013, the results of its operations for the three- and nine-month periods ended September 30, 2013 and 2012, and its cash flows for the nine-months then ended. The results of operations for the first nine months of 2013 are not necessarily indicative of the results to be expected for the full year. Certain prior period income statement and balance sheet amounts have been reclassified to conform to the current period presentation; there was no impact to the total amounts for net income (loss) or total assets, liabilities or stockholders' equity. The accompanying consolidated financial statements in this quarterly report should be read in conjunction with the consolidated financial statements and notes thereto included in the Company's previously filed 2013 Quarterly Reports on Form 10-Q and the Company's 2012 Annual Report on Form 10-K. All intercompany transactions and balances have been eliminated in consolidation.
	The preparation of the Company’s consolidated financial statements in conformity with United States generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in these consolidated financial statements and accompanying notes. The more significant areas requiring the use of management’s estimates relate to mineral reserves, reclamation and environmental obligations, valuation allowance for deferred tax assets, useful lives utilized for depreciation, amortization and accretion calculations, future cash flows from long-lived assets, and fair value of derivatives and other financial instruments. Actual results could differ from these estimates.
	The Company evaluates subsequent events through the date the consolidated financial statements are issued. No subsequent events were identified that required additional disclosure in the consolidated financial statements through the date of this filing.

Sales

Sales	9 Months Ended
	Sep. 30, 2013
Sales Revenue, Goods, Net [Abstract]	'
Sales	'
	SALES
	MINE PRODUCTION
	The Company mines and processes ores from its Montana operations containing palladium, platinum, rhodium, gold, silver, copper and nickel into intermediate and final products for sale to customers. Palladium, platinum, rhodium, gold and silver are sent to third party refineries for final processing from where they are sold to a number of consumers and dealers with whom the Company has established trading relationships. Refined platinum group metals (PGMs) of 99.95% purity (rhodium of 99.9%) in sponge form are transferred upon sale from the Company’s account at third party refineries to the account of the purchaser. By-product metals are normally sold at market prices to customers, brokers or outside refiners. By-products of copper and nickel are produced by the Company at less than commercial grade, so prices for these metals typically reflect a quality discount. By-product sales are included in revenues from Mine Production. During the third quarter of 2013 and 2012, total by-product (copper, nickel, gold, silver and mined rhodium) sales were $6.7 million and $7.2 million, respectively. During the first nine months of 2013 and 2012, total by-product sales were $21.1 million and $23.6 million, respectively.
	The Company has a supply agreement with General Motors Corporation (GM) that provides for fixed quantities of palladium to be delivered each month, a platinum supply agreement with Tiffany & Co., and PGM supply agreements with Johnson Matthey, BASF and Ford Motor Company, all of which expire at the end of 2013. Some of these agreements provide for pricing at a small discount to a trailing market price. Based on the targeted 2013 mine production of about 505,000 to 515,000 ounces, up to 93% of the Company's mined palladium production and up to 88% of its platinum production is committed under its supply agreements. The Company currently sells its remaining uncommitted mined production under spot sales agreements.
	Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred either physically or through an irrevocable transfer of metals to customers’ accounts, the price is fixed or determinable, no related obligations remain and collectability is probable.
	PGM RECYCLING
	The Company purchases spent catalyst material from third parties and processes this material in its facilities in Columbus, Montana to recover palladium, platinum and rhodium for sale. It also accepts material supplied from third parties on a tolling basis, processing it for a fee and returning the recovered metals to the supplier. The Company has entered into sourcing arrangements for catalyst material with multiple suppliers. Under these sourcing arrangements as currently structured, the Company sometimes advances cash against a shipment of material shortly before actually receiving the physical shipment. These advances are included in Other current assets on the Company’s Consolidated Balance Sheets until such time as the material has been physically received and title has transferred to the Company. The Company holds a security interest in materials procured by its largest recycling supplier that have not been received by the Company. Once the material is physically received and title has transferred, the associated advance is reclassified from Other current assets into Inventories. Finance charges collected on advances and inventories prior to being earned are included in Other current liabilities on the Company’s Consolidated Balance Sheets. Finance charges are reclassified from Other current liabilities to Interest income ratably from the time the advance was made until the out-turn date of the inventory.
	At the same time the Company purchases recycling material, it typically enters into a fixed forward contract for future delivery of the PGMs contained in the recycled material at a price consistent with the purchase cost of the recycled material. The contract commits the Company to deliver finished metal on a specified date that normally corresponds to the expected out-turn date for the metal from the final refiner. The purpose of this arrangement is to eliminate the Company’s exposure to fluctuations in market prices during processing. However, doing so does create an obligation for the Company to deliver metal at a future point in time that could be subject to operational risks. If the Company is unable to complete the processing of the recycled material by the contractual delivery date, it could either cover its delivery commitments with mine production or purchase finished metal in the open market. If open market purchases are used, the Company bears the risk of any changes in the market price relative to the price stipulated in the delivery contract.
	TOTAL SALES
	Total sales to significant customers as a percentage of total revenues for the three- and nine-month periods ended September 30, 2013 and 2012 were as follows:
		Three Months Ended September 30,				Nine Months Ended September 30,
		2013(1)		2012(1)		2013(1)		2012(1)
	Customer A	30	%	28	%	28	%	26	%
	Customer B	14	%	16	%	14	%	17	%
	Customer C	14	%	—		14	%	—
	Customer D	—		18	%	13	%	18	%
	Customer E	—		—		—		10	%
		58	%	62	%	69	%	71	%
	(1) The “—” symbol represents less than 10% of total revenues.

Asset_Impairment_Notes

Asset Impairment (Notes)	9 Months Ended
	Sep. 30, 2013
Asset Impairment Charges [Abstract]	'
Asset Impairment Charges [Text Block]	'
	ASSET IMPAIRMENT
	The Company reviews and evaluates its long-lived assets for impairment when events and changes in circumstances indicate that the related carrying amounts of its assets may not be recoverable.
	The Company identified certain events and changes in circumstances that occurred both during the third quarter of 2013 and subsequently, but prior to the filing of its quarterly report on Form 10-Q. Continuing uncertainty in the legal and business climate in Argentina, announcements of reduced investment or the placement on care and maintenance of certain projects in the vicinity of the Company’s Altar mineral property, significant changes in the global mining industry and on-going technical reviews within the Company were all considered in the Company’s assessment. Considering these events individually, and in the aggregate, the Company concluded that a triggering event had occurred during the 2013 third quarter requiring it to assess whether its investment in the Altar mineral property was impaired. These adverse changes required the Company to assess whether it could generate cash flows sufficient to recover its investment in the Altar mineral property utilizing scenarios under current consideration by the Company on an undiscounted basis. Based on these scenarios for the Altar mineral property, which have been evolving pursuant to the technical reviews described above, the Company determined that the probability-weighted undiscounted future cash flows from the Altar mineral property more likely than not are not sufficient to recover the carrying value at September 30, 2013. Having made such determination, the Company undertook an assessment of the fair market value of the property which included examining recent comparable transactions for similar undeveloped mineral properties and market multiples for similar projects. Accordingly, the Company’s reported loss at September 30, 2013, includes a $290.4 million (before-tax) impairment in the carrying value of the Altar mineral property in Argentina, reducing the carrying value to its estimated fair market value of $102.0 million.

Noncontrolling_Interest

Noncontrolling Interest	9 Months Ended
	Sep. 30, 2013
Noncontrolling Interest [Abstract]	'
Noncontrolling Interest	'
	NONCONTROLLING INTEREST
	In March 2012, the Company entered into an agreement with Mitsubishi Corporation (Mitsubishi) in which a Mitsubishi subsidiary acquired a 25% interest in the Company's wholly-owned subsidiary, Stillwater Canada Inc (SCI), which owns the Marathon PGM-copper project and related properties, for approximately $81.25 million in cash and contributed an additional $13.6 million to satisfy Mitsubishi's portion of the venture's initial cash call. Mitsubishi will be responsible for funding its 25% share of operating, capital and exploration expenditures on the Marathon properties and has agreed to cooperate and support efforts to secure project financing for Marathon. Mitsubishi will have an option to purchase up to 100% of Marathon's future PGM production under a related supply agreement at a relatively small discount to market. The transaction closed in April 2012. The change in the parent company's equity as a result of the sale of the noncontrolling interest in SCI was an increase to Additional paid in capital of $42.5 million, offset in part by expenses incurred of $1.1 million.
	The noncontrolling interest's share of equity in SCI is reflected as Noncontrolling interest in the Company's Consolidated Balance Sheets and was $50.6 million as of September 30, 2013.

Derivative_Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Instruments	'
	DERIVATIVE INSTRUMENTS
	The Company uses various derivative financial instruments to manage its exposure to changes in interest rates and PGM market commodity prices. Some of these derivatives are designated as hedges. Because the Company hedges only with instruments that have a high correlation with the value of the underlying exposures, changes in the derivatives’ fair value are expected to be offset by changes in the value of the hedged transaction.
	COMMODITY DERIATIVES
	The Company customarily enters into fixed forward contracts and on occasion it also enters into financially settled forward contracts to offset the price risk in its PGM Recycling segment. From time to time, it also has entered into these types of contracts on portions of its mine production. Under these customary fixed forward transactions, the Company agrees to deliver a stated quantity of metal on a specific future date at a price stipulated in advance. The Company uses fixed forward transactions primarily to price in advance the metals acquired for processing in its PGM Recycling segment. Under financially settled forward transactions, at each settlement date the Company receives the difference between the forward price and the market price if the market price is below the forward price and the Company pays the difference between the forward price and the market price if the market price is above the forward price. These financially settled forward contracts are settled in cash at maturity and do not require physical delivery of metal at settlement. The Company typically has used financially settled forward contracts with third parties to reduce its exposure to price risk on metal it is obligated to deliver under long-term sales agreements.
	MINE PRODUCTION
	The Company had no outstanding derivative contracts pertaining to its mined production during the nine-month periods ended September 30, 2013 and 2012.
	PGM RECYCLING
	The Company customarily enters into fixed forward sales relating to PGM recycling of catalyst materials. The metals recovered from recycling of catalyst material are typically sold forward at the time of purchase of the catalyst material and delivered against the fixed forward contracts once the metals are recovered. All of the fixed forward sales contracts for recovered metals in effect at September 30, 2013 will settle at various periods through March 2014. The Company has credit agreements with its major trading partners that provide for margin deposits in the event that forward prices for metals exceed the Company’s hedged prices by a predetermined margin limit. As of September 30, 2013, no such margin deposits were outstanding or due.
	Occasionally, the Company also has entered into financially settled forward contracts on its recycled materials. Such contracts are utilized when the Company wishes to establish a firm forward price for recycled metal on a specific future date. No financially settled forward contracts were entered into during the three- and nine-month periods ended September 30, 2013 and 2012. The Company generally has not designated these contracts as cash flow hedges, so they are marked to market at the end of each accounting period. The change in the fair value of the derivatives is reflected in the Company's Consolidated Statements of Comprehensive (Loss) Income.
	The following is a summary of the Company’s obligations to deliver metal under commodity derivatives in place as of September 30, 2013:
	PGM Recycling:
	Fixed Forwards
		Platinum			Palladium			Rhodium
	Settlement Period	Ounces	Average		Ounces	Average		Ounces	Average
			Price			Price			Price
	Fourth Quarter 2013	36,280	$	1,457	62,903	$	724	9,764	$	982
	First Quarter 2014	3,014	$	1,453	5,197	$	726	1,472	$	970

ShareBased_Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Share-Based Compensation	'
	SHARE-BASED COMPENSATION
	STOCK PLANS
	The Company sponsors stock plans (the “Plans”) that enable the Company to grant stock options or other equity based compensation to employees and non-employee directors. Effective March 1, 2011, the Company ceased offering stock options as incentive compensation to employees and non-employee directors, and began to and expects to continue to issue only cash awards or restricted stock units in lieu of stock options. The Company continues to have previously issued stock options that remain outstanding under three separate plans: the 1994 Incentive Plan (amended by the 1998 Incentive Plan), the General Employee Plan and the 2004 Equity Incentive Plan. In April 2012, stockholders approved the 2012 Equity Incentive Plan. At inception of the plans, approximately 16.4 million shares of common stock were authorized for issuance under the Plans, including approximately 5.0 million, 5.2 million, 1.4 million and 4.8 million authorized shares for the 2012 Equity Incentive Plan, 2004 Equity Incentive Plan, the General Employee Plan and the 1994 Incentive Plan (as amended by the 1998 Incentive Plan), respectively. The 1998 Incentive Plan and the General Employee Plan have been terminated and no additional options, shares or units may be issued under these two terminated plans. Approximately 5.0 million shares remain available and reserved for grant under the 2004 Equity Incentive Plan and the 2012 Equity Incentive Plan combined, as of September 30, 2013.
	The Compensation Committee of the Company’s Board of Directors administers the Plans and determines the type of equity awards to be issued, the exercise period, vesting period and all other terms of instruments issued under the Plans. Employees’ options and restricted stock units vest in equal annual installments over a three year period after date of grant. Options expire ten years after the date of grant. Certain of the Company's equity incentive plans and award agreements contain "change in control" provisions which provide that, among other triggering events, a "change in control" occurs if following the election of new directors to the Board of Directors, a majority of the members of the Board of Directors are not considered "incumbent directors."
	On May 7, 2013, the Company announced the election of four new directors to the Company's Board of Directors. The election resulted in four incumbent directors being retained on the board and four new directors being elected to the board. This four/four split constituted a "change in control" event under the 2004 and 2012 Plans. As a result of this change in control, all unvested stock options and unvested restricted stock units that had previously been granted under the 2004 and 2012 Plans (excluding those unrestricted stock units granted under the 2004 Plan to individuals eligible for the Company's 409A deferral plans) became fully vested, effective May 7, 2013.
	On June 7, 2013, Francis R. McAllister, the Company's former Chief Executive Officer, announced his retirement from the Company. At the time of his retirement, Mr. McAllister was a member of the Company's Board of Directors. His retirement constituted another "change in control" event that resulted in the accelerated vesting of all remaining unvested restricted stock that had been granted through the date of Mr. McAllister's retirement.
	Historically, the Company recognized compensation expense associated with its stock option grants based on their fair market value on the date of grant as determined using a Black-Scholes option pricing model. As discussed above, the change in control that occurred in the second quarter of this year resulted in all outstanding, unvested stock options granted under the 2004 and 2012 Plans becoming fully vested. Unless vesting is accelerated due to a change in control or other event, the Company recognizes stock option expense ratably over the vesting period of the options. If options are canceled or forfeited prior to vesting, the Company stops recognizing the related expense effective with the date of forfeiture. However, because of the accelerated vesting of all outstanding stock options in the second quarter of 2013, the Company was required to recognize the remaining expense of such vesting immediately. Total compensation expense related to the accelerated vesting of unvested stock options and nonvested shares was approximately $9.1 million (non-cash charge) in the second quarter of 2013 and is recorded as Accelerated equity based compensation expense in the Company's Consolidated Statements of Comprehensive (Loss) Income.
	Because all outstanding, unvested stock options vested in the second quarter of 2013, there was no compensation expense associated with stock option grants recorded for the three- month period ended September 30, 2013. Compensation expense related to the fair value of stock options during the three- month period ended September 30, 2012, was approximately $22,900. Compensation expense related to the fair value of stock options during the nine-month periods ended September 30, 2013 and 2012 was $41,400 and $78,200, respectively. The compensation expense for prior periods was recorded in General and administrative in the Company's Consolidated Statements of Comprehensive (Loss) Income. The Company received approximately $0.1 million in cash from the exercise of stock options in the nine-month period ended September 30, 2013 and less than $0.1 million in the comparable period in 2012.
	NONVESTED SHARES
	The following table summarizes the status of and changes in the Company’s nonvested shares during the first nine months of 2013:
		Nonvested Shares		Weighted-Average
				Grant-Date Fair Value
	Nonvested shares at January 1, 2013	1,149,333		$	14.38
	Granted	469,498		13.89
	Vested	(712,401	)	13.73
	Forfeited	(250	)	15.79
	Nonvested shares at March 31, 2013	906,180		$	14.63
	Granted	44,942		12.47
	Vested (1)	(949,448	)	14.53
	Forfeited	(133	)	13.99
	Nonvested shares at June 30, 2013	1,541		$	11.85
	Granted	3,149		11.57
	Vested	—		—
	Forfeited	(100	)	10.82
	Nonvested shares at September 30, 2013	4,590		$	11.68
	(1) Pursuant to the terms of the 2004 and 2012 Plans, the change in control that occurred in the second quarter of this year resulted in all outstanding nonvested shares granted under those Plans immediately becoming fully vested.
	Total compensation expense related to grants of nonvested shares was $3,300 and $2.8 million in each of the three- month periods ended September 30, 2013 and 2012, respectively. Compensation expense related to grants of nonvested shares was $14.6 million and $6.5 million in the nine-month periods ended September 30, 2013 and 2012, respectively. Of the total compensation expense related to grants of nonvested shares for the nine months ended September 30, 2013, $5.5 million is included within General and administrative in the Company's Consolidated Statements of Comprehensive (Loss) Income and $9.1 million (non-cash charge) resulting from the triggering of the change in control provisions under the 2004 and 2012 Equity Incentive Plans is recorded as Accelerated equity based compensation expense in the Company's Consolidated Statements of Comprehensive (Loss) Income.
	Total compensation expense related to nonvested shares is currently expected to be approximately $4,500, $17,600, $17,800 and $9,900 for the remainder of 2013 and the years 2014, 2015 and 2016, respectively.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	INCOME TAXES
	The Company determines income taxes using the asset and liability method which results in the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the carrying amount and the tax basis of those assets and liabilities, as well as operating loss and tax credit carryforwards, using enacted tax rates in effect in the years in which the differences are expected to reverse. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Deferred tax assets and liabilities are recorded on a jurisdictional basis.
	At September 30, 2013, the Company has U.S. net operating loss carryforwards (NOLs), which expire at various times in years through 2028. The Company has reviewed its net deferred tax assets and has provided a valuation allowance to reflect the estimated amount of net deferred tax assets which management considers, more likely than not, will not be realized.
	The Company recorded an income tax benefit of $54.7 million and $47.5 million for the three- and nine-month periods ended September 30, 2013, respectively. The three- and nine-month periods ended September 30, 2013 include an income tax benefit of $63.9 million that resulted from the reduction of the carrying value of the Altar mineral property in Argentina to its estimated fair market value.
	The provision for income taxes for the three- and nine-month periods ended September 30, 2013 consists of U.S. Alternative Minimum Tax (AMT), state tax expense, as well as deferred tax benefit from certain foreign jurisdictions. During the three- month period ended September 30, 2013, the Company made immaterial adjustments to income tax expense and additional paid-in capital as a result of the completion of the 2012 income tax return. Changes in the Company’s net deferred tax assets and liabilities have been partially offset by a corresponding change in the valuation allowance. As a result of an analysis concluded during the three- month period ended June 30, 2013, the Company determined it has tax exposure in certain states for which tax filings had not previously been made. Tax returns will be filed in such states for the tax years affected, and any unpaid taxes will be paid. This will also require the amendment of tax returns previously filed in Montana for the tax years affected. As of September 30, 2013, the tax provision impact of the unpaid tax, net of expense recorded including interest and penalties, associated with this matter is estimated at $1.6 million.
	The Company recognized an income tax provision of $2.1 million and an income tax benefit of $1.5 million for the three- and nine-month periods ended September 30, 2012, respectively.
	The Company’s policy is to recognize interest and penalties on unrecognized tax benefits in Income tax benefit (provision) in the Company's Consolidated Statements of Comprehensive (Loss) Income. There were no interest or penalties on unrecognized tax (provision) benefits for the nine-month periods ended September 30, 2013 and 2012. The Company made income tax payments of $2.4 million and $4.8 million in the nine-month periods ended September 30, 2013 and 2012, respectively. Tax years still open for examination by the taxing authorities are the years ended December 31, 2012, 2011 and 2010 although net operating loss and credit carryforwards from all years are subject to examination and adjustments for the three years following the year in which the carryforwards are utilized.

Debt_and_Capital_Lease_Obligat

Debt and Capital Lease Obligations	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Debt and Capital Lease Obligations	'
	DEBT AND CAPITAL LEASE OBLIGATIONS
	1.875% CONVERTIBLE DEBENTURES
	In March 2008, the Company issued and sold $181.5 million aggregate principal amount of senior unsecured convertible debentures due March 15, 2028, which pay interest at 1.875% per annum, payable semi-annually on March 15 and September 15 of each year, and commenced paying interest on September 15, 2008 (1.875% debentures). The 1.875% debentures will mature on March 15, 2028, subject to earlier repurchase or conversion. Each $1,000 principal amount of debentures is initially convertible, at the option of the holders, into approximately 42.5351 shares of the Company’s common stock, at any time prior to the maturity date. The conversion rate is subject to certain adjustments, but will not be adjusted for accrued interest or any unpaid interest. The conversion rate initially represents a conversion price of $23.51 per share.
	In October 2009, the Company undertook an exchange of $15.0 million in aggregate face amount of the 1.875% debentures for 1.84 million shares of the Company's common stock. Holders of $164.3 million of the 1.875% debentures exercised their option to require the Company to repurchase all or a portion of their 1.875% debentures on March 15, 2013. Holders of the remaining $2.2 million of outstanding 1.875% debentures may require the Company to repurchase all or a portion of their 1.875% debentures on March 15, 2018 or March 15, 2023, or at any time before March 15, 2028 upon the occurrence of certain events including a change in control. As of March 22, 2013, the Company has available the option to redeem the remaining $2.2 million of outstanding 1.875% debentures for cash at its discretion. The outstanding balance of $2.2 million is reported as a long-term debt obligation as of September 30, 2013.
	There was no amortization expense related to the issuance costs of the 1.875% debentures for the three- month period ended September 30, 2013, and for the same period of 2012 there was approximately $0.2 million of such expense. Amortization expense related to the 1.875% debentures was $0.2 million and $0.7 million for the nine- month periods ended September 30, 2013 and 2012, respectively. The interest expense on the 1.875% debentures was approximately $10,500 and $0.7 million for the three- month periods ended September 30, 2013 and 2012, respectively. Interest expense for the nine-month periods ended September 30, 2013 and 2012 was $0.7 million and $2.3 million, respectively. The Company made cash payments of $21,000 and $1.6 million for interest on the debentures for the three- and nine-month periods ended September 30, 2013, respectively. Cash payments in the comparable periods of 2012 were $1.6 million and $3.1 million, respectively.
	1.75% CONVERTIBLE DEBENTURES
	In October 2012, the Company completed the issuance and sale of $396.75 million of 1.75% senior unsecured convertible debentures, due October 15, 2032 (1.75% debentures). Each $1,000 principal amount of the 1.75% debentures is initially convertible, under certain circumstances and during certain periods, into 60.4961 shares (subject to customary anti-dilution adjustments) of the Company's common stock, which represents an initial conversion price of $16.53 per share. The 1.75% debentures also include an embedded conversion enhancement feature that is equivalent to including with each debenture a warrant initially exercisable for 30.2481 shares at $16.53 per share (both subject to customary anti-dilution adjustments). The Company, at its election, may settle conversions of the 1.75% debentures in cash, shares of its common stock or any combination of cash and shares of its common stock. Holders have the right to redeem their 1.75% debentures on October 15 of each of 2019, 2024, 2029, and upon the occurrence of certain corporate events, at face value plus accrued and unpaid interest, up to, but excluding, the relevant repurchase date. The Company will have the option to redeem the 1.75% debentures at any time on or after October 20, 2019.
	The 1.75% debentures were bifurcated under U.S. GAAP into separate debt and equity components, and reflect an effective maturity (to the first optional redemption date) of seven years. The residual amount of $141.6 million recorded within equity is treated for accounting purposes as additional debt discount and accreted as an additional non-cash interest charge to earnings over the expected life. Debt and equity issuance costs totaling approximately $12.4 million were deducted from the gross proceeds of the offering of the 1.75% debentures and the debt portion is being amortized ratably over seven years. Net proceeds of $384.3 million from the offering were used in part to retire $164.3 million of the Company's outstanding 1.875% debentures on March 18, 2013, with the remaining proceeds to be used for general corporate purposes.
	The 1.75% debentures have an effective interest rate of 8.50% and a stated interest rate of 1.75% with interest paid semi-annually. The balance outstanding for the period ended September 30, 2013 was $269.9 million, which is net of unamortized discount of $126.8 million.
	Amortization expense related to the issuance costs of the 1.75% debentures was approximately $0.3 million and $0.9 million for the three- and nine-month periods ended September 30, 2013, respectively. The interest expense was approximately $5.7 million and $16.9 million for the three- and nine-month periods ended September 30, 2013, respectively. The Company made $3.2 million in interest payments on the 1.75% debentures during the nine-month period ended September 30, 2013.
	The 1.75% and 1.875% debentures contain a “change in control” provision, which provides that a “change in control” occurs if, following the election of new directors to the Board of Directors a majority of the members of the Board of Directors are not considered “incumbent directors.” In the second quarter of 2013, the Company's Board of Directors took steps pursuant to the indentures governing the 1.75% and 1.875% debentures to ensure that the election of four non-incumbent directors at the 2013 annual meeting of the Company did not constitute a “change in control” under such indenture.
	EXEMPT FACILITY REVENUE BONDS
	The Company also has outstanding $30.0 million in aggregate principal amount of 8.0% Exempt Facility Revenue Bonds, Series 2000 (exempt facility revenue bonds), issued through the State of Montana Board of Investments and maturing on July 1, 2020. The balance outstanding at September 30, 2013, was $29.6 million, which is net of unamortized discount of $0.4 million. The Company made $1.2 million in interest payments on the revenue bonds during each of the nine-month periods ended September 30, 2013 and 2012.
	ASSET-BACKED REVOLVING CREDIT FACILITY
	In December 2011, the Company entered into a $100.0 million asset-backed revolving credit agreement incurring debt issuance costs of $1.1 million. In January 2012, the Company completed the syndication of the credit facility and simultaneously expanded the maximum line of credit to $125.0 million. Borrowings under this working capital credit facility are limited to a borrowing base equal to the sum of 85% of eligible accounts receivable and 70% of eligible inventories. Any borrowings are secured by the Company’s accounts receivable, metals inventories and other accounts. The asset-backed revolving credit facility includes a single fixed-charge coverage covenant that only takes effect when less than 30% of the total borrowing capacity under the facility remains available. The facility includes a $60.0 million letter of credit sub-facility. Outstanding borrowings under the facility accrue interest at a spread over the London Interbank Offer Rate that varies from 2.25% to 2.75%, decreasing progressively as the percentage drawn under the facility increases. The Company also pays an unused capacity fee on committed but unutilized borrowing capacity available under the facility at a rate per annum of 0.375% or 0.5%, depending on utilization of the facility. The asset-backed revolving credit agreement does contain a “change in control” provision which if triggered would constitute an event of default under the credit agreement. If an event of default occurs under the credit agreement, the holders of any indebtedness outstanding under the facility would have a right to accelerate such indebtedness.
	The “change in control” provision provides that a “change in control” event will have occurred if the composition of the Board of Directors of the Company changes such that a majority of the members of the Company's Board of Directors are not Continuing Directors. On May 7, 2013, the Company announced the election of four new directors to its Board of Directors. The election resulted in four incumbent (continuing) directors being retained on the board and four new directors being elected to the board. This four/four split constituted a "change in control" event under the credit facility. As a result of this change in control, the Company was considered to be in default of the credit agreement. On July 1, 2013, the Company was issued a waiver by the four banks that have provided commitments under the facility. At the time of default, the Company had not yet drawn a balance, although approximately $17.5 million had been utilized to collateralize outstanding irrevocable letters of credit in support of the Company's long-term reclamation obligations.
	The Company recognized $0.3 million and $0.2 million in fees associated with the asset-backed revolving credit agreement in the three- month periods ended September 30, 2013 and 2012, respectively, and $0.8 million and $0.7 million for the nine-month periods ended September 30, 2013 and 2012, respectively. Amortization expense related to the issuance costs of the credit agreement was less than $0.1 million for each of the three- month periods ended September 30, 2013 and 2012, and $0.2 million for each of the nine-month periods ended September 30, 2013 and 2012.
	CAPITAL LEASE OBLIGATIONS
	In June 2012, the Company entered into a lease agreement with General Electric Capital Corporation (GECC) covering the acquisition of a tunnel-boring machine for use on the Blitz project adjacent to the Stillwater Mine. The transaction is structured as a capital lease with a four-year term; lease payments are due quarterly in advance. In the third quarter of 2012, the Company increased the lease balance due under the original GECC capital lease by $0.7 million. The Company made cash payments of $1.6 million and $1.0 million on its capital lease obligations in each of the nine-month periods ended September 30, 2013 and 2012, respectively. The cash payment for the nine- month period ended September 30, 2013 included interest of $0.2 million. There was $0.1 million of interest included in the cash payment for the nine-month period ended September 30, 2012. As of September 30, 2013, the outstanding balance under the capital lease was $5.1 million.
	The following is a schedule, by year, of the future minimum lease payments for the capital lease together with the present value of the net minimum lease payments:
	(In thousands)
	Remaining 2013	$	541
	2014	2,168
	2015	2,168
	2016	590
	Total minimum lease payments	$	5,467
	Less interest at rates ranging from 5.21% to 5.46% (before tax)	390
	Net minimum lease payments	$	5,077
	Less current portion	1,931
	Total long-term capital lease obligation	$	3,146
	CAPITALIZED INTEREST
	The Company capitalizes interest incurred on its various debt instruments as a cost of specific and identified projects under development. For the three- month periods ended September 30, 2013 and 2012, the Company capitalized interest of $1.2 million and $0.3 million, respectively. For the nine-month periods ended September 30, 2013 and 2012, the Company capitalized interest of $3.3 million and $0.9 million, respectively. Capitalized interest is recorded as a reduction to Interest expense in the Company's Consolidated Statements of Comprehensive (Loss) Income.

Mineral_Properties_and_Mine_De

Mineral Properties and Mine Development	9 Months Ended
	Sep. 30, 2013
Extractive Industries [Abstract]	'
Mineral Properties and Mine Development	'
	MINERAL PROPERTIES AND MINE DEVELOPMENT
	Mineral properties and mine development reflected in the accompanying balance sheets consisted of the following:
	(In thousands)	September 30,			December 31, 2012
		2013
	Mineral Properties:
	Ontario, Canada
	Marathon property	$	169,916		$	169,916
	Coldwell Complex property	14,056			14,056
	San Juan, Argentina
	Altar property	101,970			392,387
	Mine Development:
	Montana, United States of America
	Stillwater Mine	$	515,565		$	464,882
	East Boulder Mine	173,897			155,878
	Ontario, Canada
	Marathon	39,393			28,083
		$	1,014,797		$	1,225,202
	Less accumulated depletion and amortization	(355,498		)	(325,977		)
	Total mineral properties and mine development	$	659,299		$	899,225

Property_Plant_and_Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2013
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment	'
	PROPERTY, PLANT AND EQUIPMENT
	Property, plant and equipment reflected in the accompanying balance sheets consisted of the following:
	(In thousands)	September 30,			December 31, 2012
		2013
	Machinery and equipment	$	132,012		$	107,957
	Buildings and structural components	156,372			145,347
	Land	8,692			8,418
	Construction-in-progress:
	Stillwater Mine	2,896			18,515
	East Boulder Mine	481			888
	Marathon	720			238
	Processing facilities and other	8,177			11,247
		$	309,350		$	292,610
	Less accumulated depreciation	(188,245		)	(169,933		)
	Total property, plant, and equipment	$	121,105		$	122,677

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Segment Information	'
	SEGMENT INFORMATION
	The Company operates five reportable business segments: Mine Production, PGM Recycling, Canadian Properties, South American Properties and All Other. These segments are managed separately based on fundamental differences in their operations and geographic separation.
	The Mine Production segment consists of two business components: the Stillwater Mine and the East Boulder Mine. The Mine Production segment is engaged in the development, extraction, processing and refining of PGMs. The Company sells PGMs from mine production under short-term and long-term sales agreements and in open PGM markets. The financial results for the Stillwater Mine and the East Boulder Mine have been aggregated, as both have similar products, processes, customers, distribution methods and economic characteristics.
	The PGM Recycling segment is engaged in the recycling of spent catalyst material to recover the PGMs contained in the material. The Company purchases the majority of catalyst material processed by the PGM Recycling segment from multiple third party suppliers for its own account and sells the recovered metals directly, and it also accepts catalyst material supplied from several third parties on a tolling basis, processing it for a fee and returning the recovered metals to the supplier. The Company allocates costs of the Company's smelting and base metal refining facilities to both the Mine Production segment and to the PGM Recycling segment for internal and segment reporting purposes because these facilities support the PGM extraction requirements of both business segments.
	The Canadian Properties segment consists of the Marathon PGM assets (which consist primarily of the Marathon project mineral property) and the Coldwell Complex exploration mineral properties. The Marathon project mineral property is a large PGM and copper deposit located near the town of Marathon, Ontario, Canada. The Marathon project is currently in the environmental review and permitting stage and will not be in production for several years. The Coldwell Complex exploration mineral properties are located adjacent to the Marathon property. Financial information for this segment consists of total asset values, general and administrative costs, exploration costs and capital expenditures as the properties are developed.
	The South American Properties segment consists of the Peregrine Metals Ltd. assets. The principal Peregrine property is the Altar project, a copper-gold resource, located in the San Juan province of Argentina. The Peregrine project is currently in the exploration stage. Financial information for this segment consists of total asset values, general and administrative costs and exploration costs.
	The All Other group primarily consists of assets, including investments, revenues, and expenses of various corporate and support functions and, historically, marketing expenditures related to promoting palladium.
	The Company evaluates performance and allocates resources based on income or loss before income taxes.
	The following financial information relates to the Company’s business segments:
	(In thousands)								South American Properties
	Three Months Ended September 30, 2013	Mine		PGM		Canadian						All Other			Total
		Production		Recycling		Properties
	Revenues	$	123,193	$	156,814	$	—		$	—		$	—		$	280,007
	Depletion, depreciation and amortization	$	15,057	$	285	$	—		$	—		$	—		$	15,342
	General and administrative expenses	$	—	$	—	$	245		$	322		$	8,749		$	9,316
	Interest income	$	—	$	867	$	6		$	23		$	206		$	1,102
	Interest expense	$	—	$	—	$	—		$	—		$	5,556		$	5,556
	Income (loss) before impairment charge and income taxes	$	24,223	$	20,553	$	(1,941	)	$	5,470		$	(14,570	)	$	33,735
	Impairment charge	$	—	$	—	$	—		$	290,417		$	—		$	290,417
	Income (loss) after impairment charge, before income taxes	$	24,223	$	20,553	$	(1,941	)	$	(284,947	)	$	(14,570	)	$	(256,682	)
	Capital expenditures	$	26,425	$	153	$	3,036		$	—		$	1,837		$	31,451
	Total assets	$	529,980	$	110,503	$	257,030		$	111,113		$	502,863		$	1,511,489
	(In thousands)								South American Properties
	Three Months Ended September 30, 2012	Mine		PGM		Canadian						All Other			Total
		Production		Recycling		Properties
	Revenues	$	107,057	$	73,987	$	—		$	—		$	—		$	181,044
	Depletion, depreciation and amortization	$	13,843	$	264	$	—		$	—		$	—		$	14,107
	General and administrative expenses	$	—	$	—	$	661		$	251		$	8,970		$	9,882
	Interest income	$	—	$	472	$	15		$	44		$	(260	)	$	271
	Interest expense	$	—	$	—	$	—		$	—		$	1,493		$	1,493
	Income (loss) before income taxes	$	23,307	$	1,884	$	(1,282	)	$	4,821		$	(13,818	)	$	14,912
	Capital expenditures	$	19,530	$	61	$	3,558		$	6		$	2,220		$	25,375
	Total assets	$	452,734	$	63,105	$	245,351		$	425,322		$	277,985		$	1,464,497
	(In thousands)								South
									American
	Nine Months Ended September 30, 2013	Mine		PGM		Canadian			Properties			All Other			Total
		Production		Recycling		Properties
	Revenues	$	364,249	$	432,897	$	—		$	—		$	—		$	797,146
	Depletion, depreciation and amortization	$	43,824	$	804	$	—		$	—		$	—		$	44,628
	General and administrative expenses	$	—	$	—	$	952		$	2,264		$	32,630		$	35,846
	Interest income	$	—	$	2,638	$	15		$	165		$	698		$	3,516
	Interest expense	$	—	$	—	$	—		$	—		$	17,646		$	17,646
	Income (loss) before impairment charge and income taxes	$	83,382	$	31,873	$	(4,024	)	$	7,434		$	(69,053	)	$	49,612
	Impairment charge	$	—	$	—	$	—		$	290,417		$	—		$	290,417
	Income (loss) after impairment charge, before income taxes	$	83,382	$	31,873	$	(4,024	)	$	(282,983	)	$	(69,053	)	$	(240,805	)
	Capital expenditures	$	75,966	$	285	$	9,189		$	100		$	5,647		$	91,187
	Total assets	$	529,980	$	110,503	$	257,030		$	111,113		$	502,863		$	1,511,489
	(In thousands)								South
									American
	Nine Months Ended September 30, 2012	Mine		PGM		Canadian			Properties			All Other			Total
		Production		Recycling		Properties
	Revenues	$	339,951	$	256,919	$	—		$	—		$	—		$	596,870
	Depletion, depreciation and amortization	$	42,848	$	793	$	—		$	—		$	—		$	43,641
	General and administrative expenses	$	—	$	—	$	2,436		$	2,793		$	27,248		$	32,477
	Interest income	$	—	$	1,661	$	24		$	166		$	(145	)	$	1,706
	Interest expense	$	—	$	—	$	12		$	—		$	4,349		$	4,361
	Income (loss) before income taxes	$	77,879	$	7,912	$	(6,174	)	$	(2,861	)	$	(40,724	)	$	36,032
	Capital expenditures	$	73,354	$	115	$	6,881		$	6		$	4,332		$	84,688
	Total assets	$	452,734	$	63,105	$	245,351		$	425,322		$	277,985		$	1,464,497

Investments

Investments	9 Months Ended
	Sep. 30, 2013
Investments, Debt and Equity Securities [Abstract]	'
Investments	'
	INVESTMENTS
	The Company classifies the marketable securities in which it invests as available-for-sale securities. These securities are measured at fair market value in the financial statements with unrealized gains or losses recorded in Other comprehensive income in the Company's Consolidated Statements of Comprehensive (Loss) Income. At the time the securities are sold, or otherwise disposed of, gross realized gains and losses are included in Net income. Gross realized gains and losses are based on the carrying value (cost, net of discount or premiums) of the sold investment. The Company adopted ASU 2013-02 Reporting Amounts Reclassified out of Other Comprehensive Income as of January 1, 2013. The amounts reclassified out of Other comprehensive income (loss) during the three- and nine- month periods ended September 30, 2013 and 2012 were insignificant. All of the marketable securities amounts are available to satisfy current obligations.
	The amortized cost, gross unrealized gains, gross unrealized losses, and fair market value of available-for-sale investment securities by major security type and class of security for the periods ended September 30, 2013 and December 31, 2012, are as follows:
				Investments
	(In thousands)			Amortized cost				Gross unrealized gains		Gross unrealized losses			Fair market value
	2013
		Federal agency notes		$	106,281			$	115	$	—		$	106,396
		Commercial paper		123,252				14		(488		)	122,778
		Mutual funds		1,211				548		—			1,759
		Total		$	230,744			$	677	$	(488	)	$	230,933
	2012
		Federal agency notes		$	124,682			$	37	$	(4	)	$	124,715
		Commercial paper		137,661				3		(396		)	137,268
		Mutual funds		1,556				261		—			1,817
		Total		$	263,899			$	301	$	(400	)	$	263,800
	The mutual funds included in the investment table above are included in Other noncurrent assets on the Company's Consolidated Balance Sheets.
	The maturities of available-for-sale securities at September 30, 2013, are as follows:
	(In thousands)	Amortized cost				Fair market value
	Federal agency notes
	Due in one year or less	$	52,523			$	52,565
	Due after one year through two years	53,758				53,831
	Total	$	106,281			$	106,396
	Commercial paper
	Due in one year or less	$	93,227			$	92,895
	Due after one year through two years	30,025				29,883
	Total	$	123,252			$	122,778
	The Company has long-term investments in several Canadian junior exploration companies, recorded on the Company's Consolidated Balance Sheets at cost. The Company determined that its long-term investments were other than temporarily impaired and recorded a loss of $0.1 million for the three- month period ended September 30, 2013 and $1.8 million year-to-date. At September 30, 2013, these long-term investments totaled $1.1 million and are recorded in Other noncurrent assets on the Company's Consolidated Balance Sheets.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Inventories	'
	INVENTORIES
	For purposes of inventory accounting, the market value of inventory is generally deemed equal to the Company’s current cost of replacing the inventory, provided that: (1) the market value of the inventory may not exceed the estimated selling price of such inventory in the ordinary course of business less reasonably predictable costs of completion and disposal, and (2) the market value may not be less than net realizable value reduced by an allowance for a normal profit margin. No adjustments were made to the inventory value in the first nine months of 2013 or 2012.
	The costs of mined PGM inventories as of any date are determined based on combined production costs per ounce and include all inventoriable production costs, including direct labor, direct materials, depreciation and amortization and other overhead costs relating to mining and processing activities incurred as of such date.
	The costs of recycled PGM inventories as of any date are determined based on the acquisition cost of the recycled material and include all inventoriable processing costs, including direct labor, direct materials, depreciation and third party refining costs which relate to the processing activities incurred as of such date.
	Inventories reflected in the accompanying balance sheets consisted of the following:
	(In thousands)	September 30,		December 31, 2012
		2013
	Metals inventory
	Raw ore	$	3,199	$	3,505
	Concentrate and in-process	63,517		51,498
	Finished goods	88,885		74,942
		155,601		129,945
	Materials and supplies	26,287		23,263
	Total inventory	$	181,888	$	153,208
	The Company also holds in its possession, but does not reflect in inventory, materials it processes on a toll basis for customers and holds for such customers until the tolled material is transported to a third party refiner.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	EARNINGS PER SHARE
	Basic earnings per share attributable to common stockholders is computed by dividing net earnings available to common stockholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share attributable to common stockholders reflects the potential dilution that could occur if the Company’s dilutive outstanding stock options and nonvested shares were exercised or vested and the Company’s convertible debt was converted. No adjustments were made to reported net income (loss) attributable to common stockholders in the calculation of basic earnings (loss) per share or diluted earnings (loss) per share during the three- and nine-month periods ended September 30, 2013 and 2012. The Company currently has only one class of equity shares outstanding.
	A total of 137,518 and 144,179 weighted shares of common stock from outstanding options were excluded from the computation of diluted earnings (loss) per share for the three- and nine-month periods ended September 30, 2013 because the Company reported a net loss in both periods and thus the effect would have been antidilutive because inclusion of these options would have reduced the net loss per share. A total of 48,742 and 58,793 weighted shares of common stock from outstanding options were included in the computation of diluted earnings (loss) per share for the three- and nine-month periods ended September 30, 2012. Outstanding options to purchase 118,928 and 123,996 of weighted shares of common stock were excluded from the computation of diluted earnings (loss) per share for the three- and nine-month periods ended September 30, 2012, respectively, because the market price at the end of each period was lower than the exercise price, and therefore the effect would have been antidilutive.
	There was no effect of outstanding nonvested shares on diluted weighted average shares outstanding in the three- and nine-month periods ended September 30, 2013 because the Company reported a net loss and the inclusion of these shares would have reduced the net loss per share amounts. The effect of including outstanding nonvested shares was to increase diluted weighted average shares outstanding by 718,977 and 870,870 for the three- and nine-month periods ended September 30, 2012.
	All 36.1 million and 38.0 million shares of common stock applicable to the outstanding 1.875% and 1.75% convertible debentures were excluded from the computation of diluted weighted average shares for the three- and nine-month periods ended September 30, 2013, respectively, because the Company reported a net loss in both periods, thus the effect would have been antidilutive because inclusion of these shares would have reduced the net loss per share.
	All 7.1 million shares of common stock applicable to the outstanding 1.875% convertible debentures were excluded from the computation of diluted weighted average shares for the three- and nine-month periods ended September 30, 2012 because the net effect of assuming all the debentures were converted would have been antidilutive.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	FAIR VALUE MEASUREMENTS
	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants. A three-level fair value hierarchy prioritizes the inputs used to measure fair value. This hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The classification of each financial asset or liability within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. The three levels of inputs used to measure fair value are as follows:
	•	Level 1 - Quoted prices in active markets for identical assets or liabilities.
	•	Level 2 - Observable inputs other than quoted prices included in Level 1 such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or inputs that are observable or can be corroborated by observable market data.
	•	Level 3 - Unobservable inputs supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	Financial assets and liabilities measured at fair value on a recurring basis at September 30, 2013 and December 31, 2012, consisted of the following:
	(In thousands)		Fair Value Measurements
	At September 30, 2013		Total		Level 1		Level 2		Level 3
	Mutual funds		$	1,759	$	1,759	$	—	$	—
	Investments
	Federal agency notes		$	106,396	$	—	$	106,396	$	—
	Commercial paper		$	122,778	$	—	$	122,778	$	—
	(In thousands)		Fair Value Measurements
	At December 31, 2012		Total		Level 1		Level 2		Level 3
	Mutual funds		$	1,817	$	1,817	$	—	$	—
	Investments
	Federal agency notes		$	124,715	$	—	$	124,715	$	—
	Commercial paper		$	137,268	$	—	$	137,268	$	—
	The fair value of the mutual funds is based on market prices which are readily available. The fair value of the investments is valued indirectly using observable data, quoted prices for similar assets or liabilities in active markets. Unrealized gains or losses on mutual funds and investments are recorded in Accumulated other comprehensive income (loss) on the Company's Consolidated Balance Sheets.
	Assets and liabilities measured at fair value on a nonrecurring basis at September 30, 2013 and December 31, 2012, consisted of the following:
	(In thousands)		Fair Value Measurements
	At September 30, 2013		Total		Level 1		Level 2		Level 3
	Altar mineral property		$	101,970	$	—	$	—	$	101,970
	1.875% Convertible debentures		$	2,245	$	—	$	2,245	$	—
	1.75% Convertible debentures		$	282,587	$	—	$	282,587	$	—
	Exempt facility revenue bonds		$	31,377	$	—	$	—	$	31,377
	Long-term investments		$	1,149	$	1,149	$	—	$	—
	(In thousands)		Fair Value Measurements
	At December 31, 2012		Total		Level 1		Level 2		Level 3
	1.875% Convertible debentures		$	166,292	$	—	$	166,292	$	—
	1.75% Convertible debentures		$	302,466	$	—	$	302,466	$	—
	Exempt facility revenue bonds		$	29,968	$	—	$	—	$	29,968
	Long-term investments		$	2,922	$	2,922	$	—	$	—
	The carrying value of the Company’s Altar mineral property in Argentina at September 30, 2013 was $392.4 million. An impairment charge of $290.4 million (before-tax) was taken on the Altar mineral property at September 30, 2013 reflecting an estimated fair market value of $102.0 million. The impairment charge was included in earnings for the period.
	The Company used implicit interest rates of comparable unsecured obligations to calculate the fair value of the Company’s $30 million in principal amount of 8% Series 2000 exempt facility revenue bonds at September 30, 2013, and December 31, 2012. The Company used its current trading data to determine the fair value of each of its convertible debentures, the $2.2 million of outstanding 1.875% debentures and the $396.75 million of outstanding 1.75% debentures at September 30, 2013 and December 31, 2012. The fair value of the Company's long-term investments in certain Canadian junior exploration companies at September 30, 2013 and December 31, 2012 is based on market prices which are readily available. The fair market value of the Altar mineral property is based on recent comparable transactions for similar undeveloped mineral properties and market multiples for similar projects.

Correction_of_Immaterial_Error

Correction of Immaterial Error	9 Months Ended
	Sep. 30, 2013
Accounting Changes and Error Corrections [Abstract]	'
Correction of Immaterial Error	'
	CORRECTION OF IMMATERIAL ERROR
	During the year ended December 31, 2012, the Company recorded an immaterial error correction to recognize deferred tax benefits associated with its foreign exploration activities. For the three- and nine-month periods ended September 30, 2012, the Company revised net income by $0.1 million and $4.6 million, respectively, to recognize the tax benefit. For further information, see Note 21 “Quarterly Data (Unaudited)” in the Company’s audited consolidated financial statements as presented in the Company’s 2012 Annual Report on Form 10-K.

Related_Parties

Related Parties	9 Months Ended
	Sep. 30, 2013
Related Party Transactions [Abstract]	'
Related Parties	'
	RELATED PARTIES
	Mitsubishi Corporation owns a 25% interest in the Company's previously wholly-owned subsidiary, Stillwater Canada Inc (SCI), which owns the Marathon PGM-copper project and related properties located in Ontario, Canada. The Company made PGM sales of $82.8 million and $51.1 million to Mitsubishi Corporation in the three- month periods ended September 30, 2013 and 2012, respectively, and $222.5 million and $156.3 million for the nine-month periods ended September 30, 2013 and 2012, respectively.

Legal_Proceedings_Notes

Legal Proceedings (Notes)	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Legal Proceedings	'
	LEGAL PROCEEDINGS
	The Company is involved in various claims and legal actions arising in the ordinary course of business, primarily consisting of lawsuits brought against the Company by employees and former employees. In the opinion of management, the ultimate disposition of these matters is not expected to have a material adverse effect on the Company’s consolidated financial position, results of operations or liquidity.

Sales_Tables

Sales (Tables)	9 Months Ended
	Sep. 30, 2013
Sales Revenue, Goods, Net [Abstract]	'
Percentage Of Total Revenues From Significant Customers	'
	Total sales to significant customers as a percentage of total revenues for the three- and nine-month periods ended September 30, 2013 and 2012 were as follows:
		Three Months Ended September 30,				Nine Months Ended September 30,
		2013(1)		2012(1)		2013(1)		2012(1)
	Customer A	30	%	28	%	28	%	26	%
	Customer B	14	%	16	%	14	%	17	%
	Customer C	14	%	—		14	%	—
	Customer D	—		18	%	13	%	18	%
	Customer E	—		—		—		10	%
		58	%	62	%	69	%	71	%
	(1) The “—” symbol represents less than 10% of total revenues.

Derivative_Instruments_Tables

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of Company's outstanding commodity derivatives	'
	The following is a summary of the Company’s obligations to deliver metal under commodity derivatives in place as of September 30, 2013:
	PGM Recycling:
	Fixed Forwards
		Platinum			Palladium			Rhodium
	Settlement Period	Ounces	Average		Ounces	Average		Ounces	Average
			Price			Price			Price
	Fourth Quarter 2013	36,280	$	1,457	62,903	$	724	9,764	$	982
	First Quarter 2014	3,014	$	1,453	5,197	$	726	1,472	$	970

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Changes In The Company's Nonvested Shares	'
	The following table summarizes the status of and changes in the Company’s nonvested shares during the first nine months of 2013:
		Nonvested Shares		Weighted-Average
				Grant-Date Fair Value
	Nonvested shares at January 1, 2013	1,149,333		$	14.38
	Granted	469,498		13.89
	Vested	(712,401	)	13.73
	Forfeited	(250	)	15.79
	Nonvested shares at March 31, 2013	906,180		$	14.63
	Granted	44,942		12.47
	Vested (1)	(949,448	)	14.53
	Forfeited	(133	)	13.99
	Nonvested shares at June 30, 2013	1,541		$	11.85
	Granted	3,149		11.57
	Vested	—		—
	Forfeited	(100	)	10.82
	Nonvested shares at September 30, 2013	4,590		$	11.68
	(1) Pursuant to the terms of the 2004 and 2012 Plans, the change in control that occurred in the second quarter of this year resulted in all outstanding nonvested shares granted under those Plans immediately becoming fully vested.

Debt_and_Capital_Lease_Obligat1

Debt and Capital Lease Obligations (Tables)	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Schedule of Future Minimum Lease Payments for Capital Leases	'
	The following is a schedule, by year, of the future minimum lease payments for the capital lease together with the present value of the net minimum lease payments:
	(In thousands)
	Remaining 2013	$	541
	2014	2,168
	2015	2,168
	2016	590
	Total minimum lease payments	$	5,467
	Less interest at rates ranging from 5.21% to 5.46% (before tax)	390
	Net minimum lease payments	$	5,077
	Less current portion	1,931
	Total long-term capital lease obligation	$	3,146

Mineral_Properties_and_Mine_De1

Mineral Properties and Mine Development (Tables)	9 Months Ended
	Sep. 30, 2013
Extractive Industries [Abstract]	'
Schedule of Mineral Properties and Mine Development	'
	Mineral properties and mine development reflected in the accompanying balance sheets consisted of the following:
	(In thousands)	September 30,			December 31, 2012
		2013
	Mineral Properties:
	Ontario, Canada
	Marathon property	$	169,916		$	169,916
	Coldwell Complex property	14,056			14,056
	San Juan, Argentina
	Altar property	101,970			392,387
	Mine Development:
	Montana, United States of America
	Stillwater Mine	$	515,565		$	464,882
	East Boulder Mine	173,897			155,878
	Ontario, Canada
	Marathon	39,393			28,083
		$	1,014,797		$	1,225,202
	Less accumulated depletion and amortization	(355,498		)	(325,977		)
	Total mineral properties and mine development	$	659,299		$	899,225

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2013
Property, Plant and Equipment [Abstract]	'
Schedule of Property, Plant and Equipment	'
	Property, plant and equipment reflected in the accompanying balance sheets consisted of the following:
	(In thousands)	September 30,			December 31, 2012
		2013
	Machinery and equipment	$	132,012		$	107,957
	Buildings and structural components	156,372			145,347
	Land	8,692			8,418
	Construction-in-progress:
	Stillwater Mine	2,896			18,515
	East Boulder Mine	481			888
	Marathon	720			238
	Processing facilities and other	8,177			11,247
		$	309,350		$	292,610
	Less accumulated depreciation	(188,245		)	(169,933		)
	Total property, plant, and equipment	$	121,105		$	122,677

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Financial Information Related To The Company's Business Segments	'
	The following financial information relates to the Company’s business segments:
	(In thousands)								South American Properties
	Three Months Ended September 30, 2013	Mine		PGM		Canadian						All Other			Total
		Production		Recycling		Properties
	Revenues	$	123,193	$	156,814	$	—		$	—		$	—		$	280,007
	Depletion, depreciation and amortization	$	15,057	$	285	$	—		$	—		$	—		$	15,342
	General and administrative expenses	$	—	$	—	$	245		$	322		$	8,749		$	9,316
	Interest income	$	—	$	867	$	6		$	23		$	206		$	1,102
	Interest expense	$	—	$	—	$	—		$	—		$	5,556		$	5,556
	Income (loss) before impairment charge and income taxes	$	24,223	$	20,553	$	(1,941	)	$	5,470		$	(14,570	)	$	33,735
	Impairment charge	$	—	$	—	$	—		$	290,417		$	—		$	290,417
	Income (loss) after impairment charge, before income taxes	$	24,223	$	20,553	$	(1,941	)	$	(284,947	)	$	(14,570	)	$	(256,682	)
	Capital expenditures	$	26,425	$	153	$	3,036		$	—		$	1,837		$	31,451
	Total assets	$	529,980	$	110,503	$	257,030		$	111,113		$	502,863		$	1,511,489
	(In thousands)								South American Properties
	Three Months Ended September 30, 2012	Mine		PGM		Canadian						All Other			Total
		Production		Recycling		Properties
	Revenues	$	107,057	$	73,987	$	—		$	—		$	—		$	181,044
	Depletion, depreciation and amortization	$	13,843	$	264	$	—		$	—		$	—		$	14,107
	General and administrative expenses	$	—	$	—	$	661		$	251		$	8,970		$	9,882
	Interest income	$	—	$	472	$	15		$	44		$	(260	)	$	271
	Interest expense	$	—	$	—	$	—		$	—		$	1,493		$	1,493
	Income (loss) before income taxes	$	23,307	$	1,884	$	(1,282	)	$	4,821		$	(13,818	)	$	14,912
	Capital expenditures	$	19,530	$	61	$	3,558		$	6		$	2,220		$	25,375
	Total assets	$	452,734	$	63,105	$	245,351		$	425,322		$	277,985		$	1,464,497
	(In thousands)								South
									American
	Nine Months Ended September 30, 2013	Mine		PGM		Canadian			Properties			All Other			Total
		Production		Recycling		Properties
	Revenues	$	364,249	$	432,897	$	—		$	—		$	—		$	797,146
	Depletion, depreciation and amortization	$	43,824	$	804	$	—		$	—		$	—		$	44,628
	General and administrative expenses	$	—	$	—	$	952		$	2,264		$	32,630		$	35,846
	Interest income	$	—	$	2,638	$	15		$	165		$	698		$	3,516
	Interest expense	$	—	$	—	$	—		$	—		$	17,646		$	17,646
	Income (loss) before impairment charge and income taxes	$	83,382	$	31,873	$	(4,024	)	$	7,434		$	(69,053	)	$	49,612
	Impairment charge	$	—	$	—	$	—		$	290,417		$	—		$	290,417
	Income (loss) after impairment charge, before income taxes	$	83,382	$	31,873	$	(4,024	)	$	(282,983	)	$	(69,053	)	$	(240,805	)
	Capital expenditures	$	75,966	$	285	$	9,189		$	100		$	5,647		$	91,187
	Total assets	$	529,980	$	110,503	$	257,030		$	111,113		$	502,863		$	1,511,489
	(In thousands)								South
									American
	Nine Months Ended September 30, 2012	Mine		PGM		Canadian			Properties			All Other			Total
		Production		Recycling		Properties
	Revenues	$	339,951	$	256,919	$	—		$	—		$	—		$	596,870
	Depletion, depreciation and amortization	$	42,848	$	793	$	—		$	—		$	—		$	43,641
	General and administrative expenses	$	—	$	—	$	2,436		$	2,793		$	27,248		$	32,477
	Interest income	$	—	$	1,661	$	24		$	166		$	(145	)	$	1,706
	Interest expense	$	—	$	—	$	12		$	—		$	4,349		$	4,361
	Income (loss) before income taxes	$	77,879	$	7,912	$	(6,174	)	$	(2,861	)	$	(40,724	)	$	36,032
	Capital expenditures	$	73,354	$	115	$	6,881		$	6		$	4,332		$	84,688
	Total assets	$	452,734	$	63,105	$	245,351		$	425,322		$	277,985		$	1,464,497

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 30, 2013
Investments, Debt and Equity Securities [Abstract]	'
Schedule of Available-for-sale Securities	'
	The amortized cost, gross unrealized gains, gross unrealized losses, and fair market value of available-for-sale investment securities by major security type and class of security for the periods ended September 30, 2013 and December 31, 2012, are as follows:
				Investments
	(In thousands)			Amortized cost				Gross unrealized gains		Gross unrealized losses			Fair market value
	2013
		Federal agency notes		$	106,281			$	115	$	—		$	106,396
		Commercial paper		123,252				14		(488		)	122,778
		Mutual funds		1,211				548		—			1,759
		Total		$	230,744			$	677	$	(488	)	$	230,933
	2012
		Federal agency notes		$	124,682			$	37	$	(4	)	$	124,715
		Commercial paper		137,661				3		(396		)	137,268
		Mutual funds		1,556				261		—			1,817
		Total		$	263,899			$	301	$	(400	)	$	263,800
Schedule of Maturities of Available-for-sale Securities	'
	The maturities of available-for-sale securities at September 30, 2013, are as follows:
	(In thousands)	Amortized cost				Fair market value
	Federal agency notes
	Due in one year or less	$	52,523			$	52,565
	Due after one year through two years	53,758				53,831
	Total	$	106,281			$	106,396
	Commercial paper
	Due in one year or less	$	93,227			$	92,895
	Due after one year through two years	30,025				29,883
	Total	$	123,252			$	122,778

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Components Of Inventories	'
	Inventories reflected in the accompanying balance sheets consisted of the following:
	(In thousands)	September 30,		December 31, 2012
		2013
	Metals inventory
	Raw ore	$	3,199	$	3,505
	Concentrate and in-process	63,517		51,498
	Finished goods	88,885		74,942
		155,601		129,945
	Materials and supplies	26,287		23,263
	Total inventory	$	181,888	$	153,208

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis	'
	Financial assets and liabilities measured at fair value on a recurring basis at September 30, 2013 and December 31, 2012, consisted of the following:
	(In thousands)	Fair Value Measurements
	At September 30, 2013	Total		Level 1		Level 2		Level 3
	Mutual funds	$	1,759	$	1,759	$	—	$	—
	Investments
	Federal agency notes	$	106,396	$	—	$	106,396	$	—
	Commercial paper	$	122,778	$	—	$	122,778	$	—
	(In thousands)	Fair Value Measurements
	At December 31, 2012	Total		Level 1		Level 2		Level 3
	Mutual funds	$	1,817	$	1,817	$	—	$	—
	Investments
	Federal agency notes	$	124,715	$	—	$	124,715	$	—
	Commercial paper	$	137,268	$	—	$	137,268	$	—
Financial Assets And Liabilities Measured At Fair Value On A Nonrecurring Basis	'
	ssets and liabilities measured at fair value on a nonrecurring basis at September 30, 2013 and December 31, 2012, consisted of the following:
	(In thousands)	Fair Value Measurements
	At September 30, 2013	Total		Level 1		Level 2		Level 3
	Altar mineral property	$	101,970	$	—	$	—	$	101,970
	1.875% Convertible debentures	$	2,245	$	—	$	2,245	$	—
	1.75% Convertible debentures	$	282,587	$	—	$	282,587	$	—
	Exempt facility revenue bonds	$	31,377	$	—	$	—	$	31,377
	Long-term investments	$	1,149	$	1,149	$	—	$	—
	(In thousands)	Fair Value Measurements
	At December 31, 2012	Total		Level 1		Level 2		Level 3
	1.875% Convertible debentures	$	166,292	$	—	$	166,292	$	—
	1.75% Convertible debentures	$	302,466	$	—	$	302,466	$	—
	Exempt facility revenue bonds	$	29,968	$	—	$	—	$	29,968
	Long-term investments	$	2,922	$	2,922	$	—	$	—

Sales_Narrative_Details

Sales (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Sales [Line Items]	'	'	'	'
Platinum group metals purity percentage	'	'	99.95%	'
Rhodium purity percentage	'	'	99.90%	'
Revenues from by-product sales	$6.70	$7.20	$21.10	$23.60
Palladium [Member]	'	'	'	'
Sales [Line Items]	'	'	'	'
Maximum percentage of production committed under supply agreements	'	'	93.00%	'
Platinum [Member]	'	'	'	'
Sales [Line Items]	'	'	'	'
Maximum percentage of production committed under supply agreements	'	'	88.00%	'
Minimum [Member]	'	'	'	'
Sales [Line Items]	'	'	'	'
Targeted 2013 mine production (in ounces)	'	'	505,000	'
Maximum [Member]	'	'	'	'
Sales [Line Items]	'	'	'	'
Targeted 2013 mine production (in ounces)	'	'	515,000	'

Sales_Percentage_Of_Total_Reve

Sales (Percentage Of Total Revenues From Significant Customers) (Details) (Sales Revenue, Goods, Net [Member], Customer Concentration Risk [Member])	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Revenue, Major Customer [Line Items]	'		'		'		'
Major customer, percentage of total revenues	58.00%	[1]	62.00%	[1]	69.00%	[1]	71.00%	[1]
Customer A	'		'		'		'
Revenue, Major Customer [Line Items]	'		'		'		'
Major customer, percentage of total revenues	30.00%	[1]	28.00%	[1]	28.00%	[1]	26.00%	[1]
Customer B	'		'		'		'
Revenue, Major Customer [Line Items]	'		'		'		'
Major customer, percentage of total revenues	14.00%	[1]	16.00%	[1]	14.00%	[1]	17.00%	[1]
Customer C	'		'		'		'
Revenue, Major Customer [Line Items]	'		'		'		'
Major customer, percentage of total revenues	14.00%	[1]	0.00%	[1]	14.00%	[1]	0.00%	[1]
Customer D	'		'		'		'
Revenue, Major Customer [Line Items]	'		'		'		'
Major customer, percentage of total revenues	0.00%	[1]	18.00%	[1]	13.00%	[1]	18.00%	[1]
Customer E	'		'		'		'
Revenue, Major Customer [Line Items]	'		'		'		'
Major customer, percentage of total revenues	0.00%	[1]	0.00%	[1]	0.00%	[1]	10.00%	[1]
[1]	The “—” symbol represents less than 10% of total revenues

Asset_Impairment_Details

Asset Impairment (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013
						Altar Property [Member]
						San Juan Argentina [Member]
Impaired Long-Lived Assets Held and Used [Line Items]	'	'	'	'	'	'
Impairment charge	$290,417	$0	$290,417	$0	'	$290,400
Mineral properties	$285,942	'	$285,942	'	$576,359	$102,000

Noncontrolling_Interest_Detail

Noncontrolling Interest (Details) (USD $)	1 Months Ended	9 Months Ended
	Mar. 31, 2012	Sep. 30, 2013	Dec. 31, 2012
Noncontrolling Interest [Line Items]	'	'	'
Maximum PGM production purchase percentage	'	100.00%	'
Transaction closing date	'April 2012	'	'
Noncontrolling interest	'	$50,644,000	$51,761,000
Additional Paid-in Capital [Member]	'	'	'
Noncontrolling Interest [Line Items]	'	'	'
Issuance of noncontrolling interest	42,500,000	'	'
Expenses incurred for issuance of noncontrolling interest	1,100,000	'	'
Noncontrolling Interest [Member]	'	'	'
Noncontrolling Interest [Line Items]	'	'	'
Noncontrolling interest	'	50,644,000	'
Stillwater Canada Inc [Member]	'	'	'
Noncontrolling Interest [Line Items]	'	'	'
Noncontrolling interest, ownership percentage by noncontrolling owners	25.00%	'	'
Cost of acquired entity, cash paid by third party	81,250,000	'	'
Contribution, initial cash call, amount paid by third party	13,600,000	'	'

Derivative_Instruments_Company

Derivative Instruments (Company's Outstanding Commodity Derivatives) (Details)	9 Months Ended
	Sep. 30, 2013
	oz
Fourth Quarter 2013 | Platinum [Member]	'
Derivative [Line Items]	'
Ounces	36,280
Average Price	1,457
Fourth Quarter 2013 | Palladium [Member]	'
Derivative [Line Items]	'
Ounces	62,903
Average Price	724
Fourth Quarter 2013 | Rhodium [Member]	'
Derivative [Line Items]	'
Ounces	9,764
Average Price	982
First Quarter 2014 | Platinum [Member]	'
Derivative [Line Items]	'
Ounces	3,014
Average Price	1,453
First Quarter 2014 | Palladium [Member]	'
Derivative [Line Items]	'
Ounces	5,197
Average Price	726
First Quarter 2014 | Rhodium [Member]	'
Derivative [Line Items]	'
Ounces	1,472
Average Price	970

ShareBased_Compensation_Narrat

Share-Based Compensation (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
Share data in Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
	Plan		Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Number of stock plans	3	'	3	'
Number of terminated stock plans	2	'	2	'
Vesting period	'	'	'3 years	'
Award expiration period	'	'	'10 years	'
Accelerated equity based compensation expense	$0	$0	$9,063,000	$0
Cash received from stock options exercised	'	'	100,000	100,000
Compensation Expense Of Nonvested Shares Outstanding Remainder of Fiscal Year	'	'	4,500	'
Share-based compensation cost related to nonvested shares not yet recognized in 2014	'	'	17,600	'
Share-based compensation cost related to nonvested shares not yet recognized in 2015	'	'	17,800	'
Share-based compensation cost related to nonvested shares not yet recognized in 2016	'	'	9,900	'
Stillwater Mining Company [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Common stock shares authorized for issuance	16.4	'	16.4	'
Maximum [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Cash received from stock options exercised	'	'	'	100,000
Restricted Stock Units (RSUs) [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Share-based compensation expense	0	2,800,000	14,600,000	6,500,000
Restricted Stock Units (RSUs) [Member] | General and administrative expense	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Share-based compensation expense	5,500,000	'	'	'
Restricted Stock Units (RSUs) [Member] | Accelerated Vesting [Member] | Accelerated equity based compensation expense	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Accelerated equity based compensation expense	9,100,000	'	'	'
Stock Options [Member] | General and administrative expense	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Share-based compensation expense	$0	$22,900	$41,400	$78,200
2004 and 2012 Plans Combined [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Shares available and reserved for grant	5	'	5	'
2012 Equity Incentive Plan [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Common stock shares authorized for issuance	5	'	5	'
2004 Equity Incentive Plan [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Common stock shares authorized for issuance	5.2	'	5.2	'
General Employee Plan [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Common stock shares authorized for issuance	1.4	'	1.4	'
1994 Incentive Plan [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Common stock shares authorized for issuance	4.8	'	4.8	'

ShareBased_Compensation_Change

Share-Based Compensation (Changes In The Company's Nonvested Shares) (Details) (USD $)	3 Months Ended	9 Months Ended	3 Months Ended
	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2013
	Restricted Stock Units (RSUs) [Member]	Restricted Stock Units (RSUs) [Member]	Non Vested Shares [Member]
Nonvested Shares	'	'	'
Nonvested Shares, Beginning Balance	'	1,149,333	'
Nonvested Shares, Granted	44,942	469,498	3,149
Nonvested Shares, Vested	-949,448	-712,401	0
Nonvested Shares, Forfeited	-133	-250	100
Nonvested Shares, Ending Balance	1,541	906,180	4,590
Weighted-Average Grant-Date Fair Value	'	'	'
Nonvested shares, Weighted-Average Grant-Date Fair Value, Beginning Balance (in usd per share)	'	$14.38	'
Nonvested shares, Weighted-Average Grant-Date Fair Value, Granted (in usd per share)	$12.47	$13.89	$11.57
Nonvested shares, Weighted-Average Grant-Date Fair Value, Vested (in usd per share)	$14.53	$13.73	$0
Nonvested shares, Weighted-Average Grant-Date Fair Value, Forfeited (in usd per share)	$13.99	$15.79	$10.82
Nonvested shares, Weighted-Average Grant-Date Fair Value, Ending Balance (in usd per share)	$11.85	$14.63	$11.68

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Tax Contingency [Line Items]	'	'	'	'
Income tax benefit (provision)	$54,698,000	($2,109,000)	$47,468,000	$1,508,000
Cash paid for income taxes	2,400,000	4,800,000	'	'
State and Local Jurisdiction [Member]	'	'	'	'
Income Tax Contingency [Line Items]	'	'	'	'
Tax provision impact of unpaid tax	1,600,000	'	1,600,000	'
San Juan Argentina [Member] | Altar Property [Member]	'	'	'	'
Income Tax Contingency [Line Items]	'	'	'	'
Income tax benefit from reduction of carrying value of property	($63,800,000)	'	($63,900,000)	'

Debt_and_Capital_Lease_Obligat2

Debt and Capital Lease Obligations (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

7-May-13

Mar. 15, 2013

Oct. 31, 2009

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Mar. 31, 2008

Oct. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Dec. 31, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Jan. 13, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Aug. 08, 2013

Director

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.75% Convertible Debentures [Member]

1.75% Convertible Debentures [Member]

1.75% Convertible Debentures [Member]

1.75% Convertible Debentures [Member]

8% Series 2000 [Member]

8% Series 2000 [Member]

8% Series 2000 [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Credit Agreement [Member]

Subsequent Event [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Credit Agreement [Member]

Debt Instruments [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt, principal amount

'

'

'

'

'

'

'

'

'

'

'

'

$181,500,000

$396,750,000

$396,750,000

$396,750,000

$396,750,000

$30,000,000

'

$30,000,000

'

'

'

'

'

'

'

'

'

'

'

Debt, maturity date

'

'

'

'

'

'

'

'

'

15-Mar-28

'

'

'

'

'

'

'

1-Jul-20

'

'

'

'

'

'

'

'

'

'

'

'

'

Stated interest rate

'

'

'

'

'

'

'

1.88%

'

1.88%

'

1.88%

'

'

1.75%

1.75%

1.75%

8.00%

'

8.00%

'

'

'

'

'

'

'

'

'

'

'

Convertible debt, frequency of interest payment

'

'

'

'

'

'

'

'

'

'semi-annually on March 15 and September 15 of each year

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Conversion ratio amount per share

'

'

'

'

'

'

'

'

'

$1,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock issuable on conversion of debt per $1,000 (in shares)

'

'

'

'

'

'

'

'

'

42.5351

'

'

'

'

'

'

60.4961

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt conversion price (in usd per share)

'

'

'

'

'

'

'

$23.51

'

$23.51

'

'

'

'

$16.53

'

$16.53

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Convertible debentures exchanged for shares, value

'

'

'

'

'

'

15,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Convertible debentures exchanged for shares, shares

'

'

'

'

'

'

1,840,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Repayments of convertible debentures

'

'

'

'

'

164,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Convertible debentures

'

'

'

'

'

166,500,000

'

2,200,000

'

2,200,000

'

2,200,000

'

'

269,900,000

'

269,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortization expense related to issuance costs

'

'

1,294,000

944,000

'

'

'

0

200,000

200,000

700,000

'

'

'

300,000

'

900,000

'

'

'

'

'

'

200,000

200,000

'

'

100,000

100,000

'

'

Interest expense

'

'

'

'

'

'

'

10,500

'

700,000

2,300,000

'

'

'

5,700,000

'

16,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash paid for interest

'

'

200,000

100,000

'

'

'

21,000

1,600,000

1,600,000

3,100,000

'

'

'

'

'

3,200,000

1,200,000

1,200,000

'

'

'

'

'

'

'

'

'

'

'

'

Embedded conversion feature, warrant, conversion ratio

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

30.2481

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Embedded conversion feature, warrant, conversion price (in usd per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$16.53

'

$16.53

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Adjustments to equity, component of convertible debt treated as additional debt discount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

141,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt and equity issuance costs

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

12,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt and equity issuance costs amortization period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'7 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net proceeds from offering

'

'

'

'

'

'

'

'

'

'

'

'

'

384,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Effective interest rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

8.50%

'

8.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term debt, balance outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

29,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Unamortized discount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

126,800,000

'

126,800,000

400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit agreement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100,000,000

'

'

'

'

125,000,000

'

'

'

'

'

Debt issuance costs

'

'

0

219,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,100,000

'

'

'

'

'

'

'

'

'

'

Borrowing base comprised eligible accounts receivable

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

85.00%

'

'

'

'

'

'

'

Borrowing base comprised eligible accounts inventories

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

70.00%

'

'

'

'

'

'

'

Percentage of total borrowing capacity remaining when covenant takes effect

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

30.00%

'

30.00%

'

Letter of credit sub-facility

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

60,000,000

'

60,000,000

'

'

'

'

'

'

'

Basis spread over LIBOR

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2.25%

'

'

2.75%

'

Unused line fee on committed but unutilized commitments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.38%

'

'

0.50%

'

Number of new directors elected

'

'

'

'

4

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of directors retained

'

'

'

'

4

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Undrawn letters of credit issued as collateral for sureties

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

17,500,000

Asset-backed revolving credit facility fees recognized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

300,000

200,000

800,000

700,000

'

'

'

'

'

'

Capital Lease Obligation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Capital lease obligations incurred during the period

'

700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments on capital lease obligations

'

'

1,600,000

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash paid for interest

'

'

200,000

100,000

'

'

'

21,000

1,600,000

1,600,000

3,100,000

'

'

'

'

'

3,200,000

1,200,000

1,200,000

'

'

'

'

'

'

'

'

'

'

'

'

Capital lease obligations

5,100,000

'

5,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Capitalized Interest

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Capitalized interest

$1,200,000

$300,000

$3,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt_and_Capital_Lease_Obligat3

Debt and Capital Lease Obligation (Schedule of Future Minimum Lease Payments for Capital Leases) (Details) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Present Value of Net Minimum Lease Payments	'
Remaining 2013	$541
2014	2,168
2015	2,168
2016	590
Total minimum lease payments	5,467
Less interest at rates ranging from 5.21% to 5.46% (before tax)	390
Net minimum lease payments	5,077
Less current portion	1,931
Total long-term capital lease obligation	$3,146
Minimum [Member]	'
Present Value of Net Minimum Lease Payments	'
Capital lease, interest rate	5.21%
Maximum [Member]	'
Present Value of Net Minimum Lease Payments	'
Capital lease, interest rate	5.46%

Mineral_Properties_and_Mine_De2

Mineral Properties and Mine Development (Schedule of Mineral Properties) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Mining Properties, Mineral Rights and Mine Development [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Mineral properties and mine development, gross	$1,014,797	$1,225,202
Less accumulated depletion and amortization	-355,498	-325,977
Total mineral properties and mine development	659,299	899,225
Ontario Canada [Member] | Mining Properties and Mineral Rights [Member] | Marathon Property [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Mineral properties and mine development, gross	169,916	169,916
Ontario Canada [Member] | Mining Properties and Mineral Rights [Member] | Coldwell Complex Property [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Mineral properties and mine development, gross	14,056	14,056
Ontario Canada [Member] | Mine Development [Member] | Marathon Property [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Mineral properties and mine development, gross	39,393	28,083
San Juan Argentina [Member] | Mining Properties and Mineral Rights [Member] | Altar Property [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Mineral properties and mine development, gross	101,970	392,387
Montana, United States of America [Member] | Mine Development [Member] | Stillwater Mine [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Mineral properties and mine development, gross	515,565	464,882
Montana, United States of America [Member] | Mine Development [Member] | East Boulder Mine [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Mineral properties and mine development, gross	$173,897	$155,878

Property_Plant_and_Equipment_S

Property, Plant and Equipment (Schedule of Property, Plant and Equipment) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property, plant, and equipment, gross	$309,350	$292,610
Less accumulated depreciation	-188,245	-169,933
Total property, plant, and equipment	121,105	122,677
Machinery and equipment	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant, and equipment, gross	132,012	107,957
Buildings and structural components	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant, and equipment, gross	156,372	145,347
Land	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant, and equipment, gross	8,692	8,418
Construction-in progress | Stillwater Mine [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant, and equipment, gross	2,896	18,515
Construction-in progress | East Boulder Mine [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant, and equipment, gross	481	888
Construction-in progress | Marathon [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant, and equipment, gross	720	238
Construction-in progress | Processing Facilities and Other [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant, and equipment, gross	$8,177	$11,247

Segment_Information_Narrative_

Segment Information (Narrative) (Details)	9 Months Ended
	Sep. 30, 2013
	Business_Component
Mine Production [Member]	'
Segment Reporting Information [Line Items]	'
Number of business components	2
Stillwater Mining Company [Member]	'
Segment Reporting Information [Line Items]	'
Number of business segments	5

Segment_Information_Financial_

Segment Information (Financial Information Related To The Company's Business Segments) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	$280,007	$181,044	$797,146	$596,870	'
Depletion, depreciation and amortization	15,342	14,107	44,628	43,641	'
General and administrative expenses	9,316	9,882	35,846	32,477	'
Interest income	1,102	271	3,516	1,706	'
Interest expense	5,556	1,493	17,646	4,361	'
Income (loss) before impairment charge and income taxes	33,735	'	49,612	'	'
Impairment charge	290,417	0	290,417	0	'
Income (loss) after impairment charge, before income taxes	-256,682	14,912	-240,805	36,032	'
Capital expenditures	31,451	25,375	91,187	84,688	'
Total assets	1,511,489	1,464,497	1,511,489	1,464,497	1,890,763
Mine Production [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	123,193	107,057	364,249	339,951	'
Depletion, depreciation and amortization	15,057	13,843	43,824	42,848	'
General and administrative expenses	0	0	0	0	'
Interest income	0	0	0	0	'
Interest expense	0	0	0	0	'
Income (loss) before impairment charge and income taxes	24,223	'	83,382	'	'
Impairment charge	0	'	0	'	'
Income (loss) after impairment charge, before income taxes	24,223	23,307	83,382	77,879	'
Capital expenditures	26,425	19,530	75,966	73,354	'
Total assets	529,980	452,734	529,980	452,734	'
PGM Recycling [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	156,814	73,987	432,897	256,919	'
Depletion, depreciation and amortization	285	264	804	793	'
General and administrative expenses	0	0	0	0	'
Interest income	867	472	2,638	1,661	'
Interest expense	0	0	0	0	'
Income (loss) before impairment charge and income taxes	20,553	'	31,873	'	'
Impairment charge	0	'	0	'	'
Income (loss) after impairment charge, before income taxes	20,553	1,884	31,873	7,912	'
Capital expenditures	153	61	285	115	'
Total assets	110,503	63,105	110,503	63,105	'
Canadian Properties [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	0	0	0	0	'
Depletion, depreciation and amortization	0	0	0	0	'
General and administrative expenses	245	661	952	2,436	'
Interest income	6	15	15	24	'
Interest expense	0	0	0	12	'
Income (loss) before impairment charge and income taxes	-1,941	'	-4,024	'	'
Impairment charge	0	'	0	'	'
Income (loss) after impairment charge, before income taxes	-1,941	-1,282	-4,024	-6,174	'
Capital expenditures	3,036	3,558	9,189	6,881	'
Total assets	257,030	245,351	257,030	245,351	'
South American Properties [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	0	0	0	0	'
Depletion, depreciation and amortization	0	0	0	0	'
General and administrative expenses	322	251	2,264	2,793	'
Interest income	23	44	165	166	'
Interest expense	0	0	0	0	'
Income (loss) before impairment charge and income taxes	5,470	'	7,434	'	'
Impairment charge	290,417	'	290,417	'	'
Income (loss) after impairment charge, before income taxes	-284,947	4,821	-282,983	-2,861	'
Capital expenditures	0	6	100	6	'
Total assets	111,113	425,322	111,113	425,322	'
All Other [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Revenues	0	0	0	0	'
Depletion, depreciation and amortization	0	0	0	0	'
General and administrative expenses	8,749	8,970	32,630	27,248	'
Interest income	206	-260	698	-145	'
Interest expense	5,556	1,493	17,646	4,349	'
Income (loss) before impairment charge and income taxes	-14,570	'	-69,053	'	'
Impairment charge	0	'	0	'	'
Income (loss) after impairment charge, before income taxes	-14,570	-13,818	-69,053	-40,724	'
Capital expenditures	1,837	2,220	5,647	4,332	'
Total assets	$502,863	$277,985	$502,863	$277,985	'

Investments_Narrative_Details

Investments (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Loss on long-term investments	$112,000	$1,697,000	$1,766,000	$1,697,000
Other Noncurrent Assets [Member]	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Long-term investments	$1,100,000	'	$1,100,000	'

Investments_Schedule_of_Availa

Investments (Schedule of Available-for-sale Securities) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	$230,744	$263,899
Gross unrealized gains	677	301
Gross unrealized losses	-488	-400
Fair market value	230,933	263,800
Federal agency notes [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	106,281	124,682
Gross unrealized gains	115	37
Gross unrealized losses	0	-4
Fair market value	106,396	124,715
Commercial paper [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	123,252	137,661
Gross unrealized gains	14	3
Gross unrealized losses	-488	-396
Fair market value	122,778	137,268
Mutual funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	1,211	1,556
Gross unrealized gains	548	261
Gross unrealized losses	0	0
Fair market value	$1,759	$1,817

Investments_Schedule_of_Maturi

Investments (Schedule of Maturities of Available-for-sale Securities) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	$230,744	$263,899
Fair market value	230,933	263,800
Federal agency notes [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost, due in one year or less	52,523	'
Fair market value, due in one year or less	52,565	'
Amortized cost, due after year one through two years	53,758	'
Fair market value, due after year one through two years	53,831	'
Amortized cost	106,281	124,682
Fair market value	106,396	124,715
Commercial paper [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost, due in one year or less	93,227	'
Fair market value, due in one year or less	92,895	'
Amortized cost, due after year one through two years	30,025	'
Fair market value, due after year one through two years	29,883	'
Amortized cost	123,252	137,661
Fair market value	$122,778	$137,268

Inventories_Components_Of_Inve

Inventories (Components Of Inventories) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Metals inventory	'	'
Raw ore	$3,199	$3,505
Concentrate and in-process	63,517	51,498
Finished goods	88,885	74,942
Metals inventory	155,601	129,945
Materials and supplies	26,287	23,263
Total inventory	$181,888	$153,208

Earnings_Per_Share_Narrative_D

Earnings Per Share (Narrative) (Details)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2012

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Stock Options, Market Price Less Than Exercise Price [Member]

Stock Options, Market Price Less Than Exercise Price [Member]

Convertible Debt Securities [Member]

Convertible Debt Securities [Member]

Convertible Debt Securities [Member]

Convertible Debt Securities [Member]

1.75% Convertible Debentures [Member]

1.75% Convertible Debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock options included in diluted weighted average shares calculation

137,518

48,742

144,179

58,793

'

'

'

'

'

'

'

'

'

'

Outstanding nonvested shares included in diluted weighted average shares calculation

'

718,977

'

870,870

'

'

'

'

'

'

'

'

'

'

Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount

'

'

'

'

118,928

123,996

36,100,000

7,100,000

38,000,000

7,100,000

'

'

'

'

Stated interest rate

'

'

'

'

'

'

'

'

'

'

1.75%

1.75%

1.88%

1.88%

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Mar. 15, 2013

Dec. 31, 2012

Mar. 31, 2008

Sep. 30, 2013

Dec. 31, 2012

Oct. 31, 2012

Sep. 30, 2013

8% Series 2000 [Member]

8% Series 2000 [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.875% Convertible debentures [Member]

1.75% Convertible Debentures [Member]

1.75% Convertible Debentures [Member]

1.75% Convertible Debentures [Member]

San Juan Argentina [Member]

Altar Property [Member]

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Mineral properties value before impairment chages

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$392,400,000

Mineral properties

285,942,000

'

285,942,000

'

576,359,000

'

'

'

'

'

'

'

'

'

102,000,000

Impairment charge

290,417,000

0

290,417,000

0

'

'

'

'

'

'

'

'

'

'

290,400,000

Debt, principal amount

'

'

'

'

'

30,000,000

30,000,000

'

'

'

181,500,000

396,750,000

396,750,000

396,750,000

'

Stated interest rate

'

'

'

'

'

8.00%

8.00%

1.88%

'

1.88%

'

1.75%

1.75%

'

'

Convertible debentures

'

'

'

'

'

'

'

$2,200,000

$166,500,000

$2,200,000

'

$269,900,000

'

'

'

Fair_Value_Measurements_Financ

Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	$229,174	$261,983
Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Mutual funds	1,759	1,817
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Mutual funds	1,759	1,817
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Mutual funds	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Mutual funds	0	0
Fair Value, Measurements, Recurring [Member] | Federal Agency Notes [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	106,396	124,715
Fair Value, Measurements, Recurring [Member] | Federal Agency Notes [Member] | Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Federal Agency Notes [Member] | Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	106,396	124,715
Fair Value, Measurements, Recurring [Member] | Federal Agency Notes [Member] | Level 3 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	122,778	137,268
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member] | Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	0	0
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member] | Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	122,778	137,268
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member] | Level 3 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Investments	$0	$0

Fair_Value_Measurements_Financ1

Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On A Nonrecurring Basis) (Details) (Fair Value, Measurements, Nonrecurring [Member], USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Altar mineral property	$101,970	'
Exempt facility revenue bonds	31,377	29,968
Long-term investments	1,149	2,922
Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Altar mineral property	0	'
Exempt facility revenue bonds	0	0
Long-term investments	1,149	2,922
Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Altar mineral property	0	'
Exempt facility revenue bonds	0	0
Long-term investments	0	0
Level 3 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Altar mineral property	101,970	'
Exempt facility revenue bonds	31,377	29,968
Long-term investments	0	0
1.875% Convertible debentures [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Convertible debentures, fair value	2,245	166,292
1.875% Convertible debentures [Member] | Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Convertible debentures, fair value	0	0
1.875% Convertible debentures [Member] | Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Convertible debentures, fair value	2,245	166,292
1.875% Convertible debentures [Member] | Level 3 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Convertible debentures, fair value	0	0
1.75% Convertible Debentures [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Convertible debentures, fair value	282,587	302,466
1.75% Convertible Debentures [Member] | Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Convertible debentures, fair value	0	0
1.75% Convertible Debentures [Member] | Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Convertible debentures, fair value	282,587	302,466
1.75% Convertible Debentures [Member] | Level 3 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Convertible debentures, fair value	$0	$0

Correction_of_Immaterial_Error1

Correction of Immaterial Error (Details) (USD $)	9 Months Ended		3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2012
			Immaterial Error Correction [Member]	Immaterial Error Correction [Member]
			Restatement Adjustment [Member]	Restatement Adjustment [Member]
Deferred tax (expense) benefit	$60,743	$4,913	$100	$4,600

Related_Parties_Narrative_Deta

Related Parties (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2013
	Mitsubishi Corporation [Member]	Mitsubishi Corporation [Member]	Mitsubishi Corporation [Member]	Mitsubishi Corporation [Member]	Stillwater Canada Inc [Member]	Stillwater Canada Inc [Member]
						Mitsubishi Corporation [Member]
Related Party Transaction [Line Items]	'	'	'	'	'	'
Noncontrolling interest, ownership percentage by noncontrolling owners	'	'	'	'	25.00%	25.00%
Revenue from related parties	$82.80	$51.10	$222.50	$156.30	'	'