Stillwater Mining (SWC) 10-Q 28 Oct 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 27, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Entity Registrant Name	STILLWATER MINING CO /DE/
Entity Central Index Key	931,948
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		121,078,842

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
REVENUES
Mine Production	$ 106,926	$ 86,359	$ 299,123	$ 331,065
PGM Recycling	89,591	81,982	196,515	222,980
Other	100	100	300	300
Total revenues	196,617	168,441	495,938	554,345
Costs of metals sold
Mine Production	65,580	69,004	208,612	229,676
PGM Recycling	86,178	78,928	188,712	216,074
Total costs of metals sold (excludes depletion, depreciation and amortization)	151,758	147,932	397,324	445,750
Depletion, depreciation and amortization
Mine Production	17,587	15,132	55,173	48,943
PGM Recycling	184	230	569	738
Total depletion, depreciation and amortization	17,771	15,362	55,742	49,681
Total costs of revenues	169,529	163,294	453,066	495,431
Exploration	499	827	4,934	2,667
Reorganization	0	1,658	0	1,658
General and administrative	8,692	8,911	25,300	27,652
Gain on sale of long-term investments	(196)	0	(678)	0
Loss on long-term investments	0	151	0	204
Impairment of non-producing mineral properties	0	0	0	46,772
Loss (gain) on disposal of property, plant and equipment	82	(219)	(72)	(216)
Total costs and expenses	178,606	174,622	482,550	574,168
OPERATING INCOME (LOSS)	18,011	(6,181)	13,388	(19,823)
OTHER INCOME (EXPENSE)
Other	9	17	95	918
Loss on extinguishment of debt, net	0	(4,010)	0	(4,010)
Interest income	1,213	766	2,883	2,192
Interest expense, net of capitalized interest	(3,958)	(5,097)	(12,207)	(15,713)
Foreign currency transaction gain, net	466	12	1,660	149
INCOME (LOSS) BEFORE INCOME TAX (PROVISION) BENEFIT	15,741	(14,493)	5,819	(36,287)
Income tax (provision) benefit	(3,142)	2,464	(2,367)	8,127
NET INCOME (LOSS)	12,599	(12,029)	3,452	(28,160)
Net loss attributable to noncontrolling interest	0	(151)	0	(11,808)
NET INCOME (LOSS) ATTRIBUTABLE TO COMMON STOCKHOLDERS	12,599	(11,878)	3,452	(16,352)
Other comprehensive income, net of tax
Net unrealized (loss) gain on investments available-for-sale and deferred compensation	(193)	(34)	337	149
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO COMMON STOCKHOLDERS	12,406	(11,912)	3,789	(16,203)
Comprehensive loss attributable to noncontrolling interest	0	(151)	0	(11,808)
TOTAL COMPREHENSIVE INCOME (LOSS)	$ 12,406	$ (12,063)	$ 3,789	$ (28,011)
Weighted average shares of common stock outstanding
Basic (in shares)	121,077	120,960	121,069	120,746
Diluted (in shares)	121,634	120,960	121,438	120,746
Basic income (loss) per share attributable to common stockholders (in usd per share)	$ 0.10	$ (0.10)	$ 0.03	$ (0.14)
Diluted income (loss) per share attributable to common stockholders (in usd per share)	$ 0.10	$ (0.10)	$ 0.03	$ (0.14)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 112,967	$ 147,336
Investments, at fair value (Note 12)	326,445	316,429
Inventories	140,781	102,072
Trade receivables	1,404	800
Prepaid expenses	4,626	2,821
Other current assets	21,240	21,628
Total current assets	607,463	591,086
Mineral properties	112,480	112,480
Mine development, net	480,266	460,751
Property, plant and equipment, net	103,223	109,957
Other noncurrent assets	4,478	4,115
Total assets	1,307,910	1,278,389
Current liabilities
Accounts payable	24,202	18,205
Accrued compensation and benefits	30,431	30,046
Property, production and franchise taxes payable	12,406	13,907
Current portion of long-term debt and capital lease obligations	0	657
Income taxes payable	647	0
Other current liabilities	6,910	5,286
Total current liabilities	74,596	68,101
Long-term debt	269,059	255,099
Deferred income taxes	19,390	22,761
Accrued workers compensation	6,420	6,070
Asset retirement obligation	11,376	11,027
Other noncurrent liabilities	11,351	6,102
Total liabilities	392,192	369,160
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; 121,078,216 and 121,049,471 issued and outstanding at September 30, 2016 and December 31, 2015, respectively	1,211	1,210
Paid-in capital	1,101,982	1,099,283
Accumulated deficit	(187,615)	(191,067)
Accumulated other comprehensive income (loss)	140	(197)
Total stockholders’ equity	915,718	909,229
Total liabilities and equity	$ 1,307,910	$ 1,278,389

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2016	Dec. 31, 2015
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)	121,078,216	121,049,471
Common stock, shares outstanding (in shares)	121,078,216	121,049,471

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 3,452	$ (28,160)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depletion, depreciation and amortization	55,742	49,681
Gain on sale of long-term investments	(678)	0
Loss on long-term investments	0	204
Loss on extinguishment of debt, net	0	4,010
Impairment of non-producing mineral properties	0	46,772
Amortization / accretion on investment premium / discount	1,772	1,688
Gain on disposal of property, plant and equipment	(72)	(216)
Foreign currency transaction gain, net	(1,660)	(149)
Deferred income taxes	(2,103)	(12,192)
Accretion of asset retirement obligation	637	589
Amortization of deferred debt issuance costs	662	1,665
Accretion of convertible debenture debt discount	13,297	12,985
Share based compensation and other benefits	2,744	9,489
Non-cash capitalized interest	(4,334)	(2,809)
Changes in operating assets and liabilities:
Inventories	(39,067)	2,280
Trade receivables	(604)	554
Prepaid expenses	(1,805)	(1,674)
Accounts payable	3,048	413
Accrued compensation and benefits	385	(62)
Property, production and franchise taxes payable	1,195	170
Income taxes payable	648	0
Accrued workers compensation	350	32
Other operating assets	351	(7,607)
Other operating liabilities	4,196	(1,982)
NET CASH PROVIDED BY OPERATING ACTIVITIES	38,156	75,681
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(61,980)	(83,386)
Proceeds from sale of long-term investments	1,099	0
Proceeds from disposal of property, plant and equipment	162	387
Purchases of investments	(234,269)	(230,392)
Proceeds from maturities and sales of investments	223,095	153,902
NET CASH USED IN INVESTING ACTIVITIES	(71,893)	(159,489)
CASH FLOWS FROM FINANCING ACTIVITIES
Payments on debt and capital lease obligations	(658)	(62,582)
Proceeds from issuance of common stock	26	60
NET CASH USED IN FINANCING ACTIVITIES	(632)	(62,522)
CASH AND CASH EQUIVALENTS
Net decrease	(34,369)	(146,330)
Balance at beginning of period	147,336	280,286
BALANCE AT END OF PERIOD	$ 112,967	$ 133,956

General

General	9 Months Ended
	Sep. 30, 2016
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 fairly present the financial position of Stillwater Mining Company (the Company) at September 30, 2016 , and the results of its operations for the three and nine months ended September 30, 2016 and 2015, and cash flows for the nine months ended September 30, 2016 and 2015 . The results of operations for the first nine months of 2016 are not necessarily indicative of the results to be expected for the 2016 year. The accompanying consolidated financial statements in this Quarterly Report on Form 10-Q should be read in conjunction with the consolidated financial statements and notes thereto included in the Company's 2015 Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 22, 2016 (Form 10-K). All inter-company 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 (GAAP) 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. Developments in Accounting Pronouncements On May 28, 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers , which requires an entity to recognize the amount of revenue it expects to be entitled to for the transfer of promised goods or services to customers. In August 2015, the FASB issued ASU 2015-14, Deferral of the Effective Date , which defers the effective date of ASU 2014-09 by one year to January 1, 2018. ASU 2014-09 will replace most existing revenue recognition guidance in GAAP. The standard permits the use of either the retrospective or cumulative effect transition method. The Company continues to evaluate the effect that ASU 2014-09 will have on its consolidated financial statements and disclosures and has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting. Early adoption is not permitted. On April 7, 2015, as part of its initiative to simplify and reduce complexity in financial statements, the FASB issued ASU 2015-03, Interest - Imputation, (Subtopic 835-30): Simplifying the Presentation of Debt Issuance. This ASU requires the debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of the debt liability. Also, it requires retrospective application for all prior periods presented in the financial statements and a disclosure of the nature of and reason for the change in accounting principle, the transition method, a description of the prior-period information that has been retrospectively adjusted and the effect of the change on the financial statement line items. ASU 2015-03 is effective for financial statements issued for fiscal years beginning after December 31, 2015, and interim periods within those fiscal years. Early adoption was permitted for financial statements that had not been previously issued. The Company elected early adoption of ASU 2015-03 in the first quarter of 2016 and reclassified Deferred debt issue costs against the related liability for all periods presented. Prior to the adoption of ASU 2015-03, the balance reported at December 31, 2015 for total Long-term debt and capital lease obligations was $258.9 million , and after adoption and reclassification of Deferred debt issue costs of $3.8 million , the total balance reported at December 31, 2015 became $255.1 million . On July 22, 2015, as part of its initiative to simplify and reduce complexity in financial statements, the FASB issued ASU 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory. ASU 2015-11, changes the measurement principle for inventory from the lower of cost or market to the lower of cost and net realizable value. ASU 2015-11 is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The Company is evaluating the effect that ASU 2015-11 will have on its consolidated financial statements and disclosures. The Company does not expect this initiative to have a significant impact on its ongoing financial reporting. The ASU requires prospective adoption and permits early adoption. On February 25, 2016, the FASB issued ASU 2016-02, Leases, (Topic 840) , which requires an entity that leases assets, with terms of more than 12 months, to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. ASU 2016-02 is effective for financial statements issued for fiscal years beginning after December 31, 2018, and interim periods within those fiscal years. The Company is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and disclosures and has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting. Early adoption is permitted. On March 30, 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employees Shared-Based Payment Accounting. The ASU will change several aspects within share based payments: (1) accounting for income taxes, (2) classification of excess tax benefits, (3) forfeitures, (4) minimum statutory tax withholding requirements, (5) classification of employee taxes paid when an employer withholds shares for tax-withholding purposes, (6) practical expedient - expected term, (7) intrinsic value, and (8) eliminating the indefinite deferral. ASU 2016-09 is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The Company is evaluating the effect that ASU 2016-09 will have on its consolidated financial statements and disclosures and has not yet quantified the effect of the standard on its ongoing financial reporting. Early adoption is permitted in any interim or annual period provided that the entire ASU is adopted.

Sales

Sales	9 Months Ended
	Sep. 30, 2016
Sales Revenue, Goods, Net [Abstract]
Sales	SALES MINE PRODUCTION The Company mines and processes ores 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 a third-party refiner for final processing from which they are sold to customers with whom the Company has established trading relationships. Refined platinum group metals (PGMs) in sponge form are transferred upon sale from the Company’s account at the third-party refiner to the account of the purchaser. By-product metals are normally sold at market price to customers, brokers or outside refiners. Copper and nickel by-products are typically sold at a discount to the quoted market prices. By-product sales (gold, nickel, mined rhodium, copper and silver) are included in revenues from Mine Production. During each of the three months ended September 30, 2016 and 2015 , by-product sales totaled $6.1 million and $5.0 million , respectively. For the nine months ended September 30, 2016 and 2015 , by-product sales totaled $17.4 million and $18.7 million , respectively. In July 2014, the Company executed five -year supply and refining agreements with Johnson Matthey (JM). Under the terms of these agreements, JM has an exclusive five -year right to refine all of the PGM filter cake the Company produces at its Columbus, Montana facilities. JM also has the right to purchase all of the Company's mine production of palladium and platinum at competitive market prices (except for platinum sales under the Company's sales agreement with Tiffany & Co., which are specifically excluded from the JM agreements) and has the right to bid for any recycling volumes the Company has available. Other provisions of the agreements include a good-faith effort by JM to assist in growing the Company's recycling volumes and the sharing of market intelligence to the extent permitted by law. The Company has the right to exit the JM PGM supply arrangement in return for the payment of a nominal fee. In addition, the Company, in its sole discretion, may elect to terminate the refining arrangement after July 2018. In accordance with the terms of the JM PGM supply agreement, all Company sales of mined PGMs, other than the platinum sales under the Company's sales agreement with Tiffany & Co., were to JM for the nine months ended September 30, 2016 and 2015. PGM RECYCLING The Company purchases spent catalyst materials from third-parties for recycling and processes these materials within its facilities in Columbus, Montana to recover palladium, platinum and rhodium for sale. The Company has entered into sourcing arrangements for catalyst materials with various suppliers. Under these sourcing arrangements the Company may advance cash as general working capital or against a shipment of material shortly before actually receiving the physical shipment at the Company's processing facilities. These advances are included in Other current assets on the Company’s Consolidated Balance Sheets until such time as the materials have been physically received and title has transferred to the Company, at which time the advance is reclassified 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 cash advance was made until the out-turn date of the inventory from the final refiner. The Company also accepts material supplied from third-parties on a tolling basis, processing it for a fee and returning the recovered metals to the supplier. TOTAL SALES Total sales to significant customers as a percentage of total revenues for the three and nine months ended September 30, 2016 and 2015 were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 (1) 2016 (1) 2015 (1) Customer A 65 % 70 % 71 % 75 % Customer B 11 % — — — Customer C 10 % — — — 86 % 70 % 71 % 75 % (1) The "-" symbol represents less than 10% of total revenues.

Asset Impairment

Asset Impairment	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Asset Impairment	ASSET IMPAIRMENT In accordance with the FASB Accounting Standards Codification 360, Property Plant and Equipment, (ASC 360-10) , the Company reviews and evaluates its long-lived assets for impairment when events and changes in circumstances indicate that the related carrying amounts of such assets may not be recoverable and may exceed their fair value. For purposes of determining impairment, assets are grouped at the lowest level for which identifiable cash flows (including estimated future cash flows from non-operating properties) are largely independent of the cash flows of other groups of assets and liabilities. The Company determined there were no material events or circumstances requiring the Company to test long-lived assets for impairment at September 30, 2016 . However, during the second quarter of 2015, the Company concluded that there was evidence to suggest that there had been a significant decrease in the fair value of the Marathon mineral properties. Accordingly, the Company performed an analysis that indicated the carrying value of the Marathon mineral properties exceeded its recoverable amount at June 30, 2015. The Company undertook an assessment of the fair value of its Marathon mineral properties, which included the examination of recent comparable transactions. At June 30, 2015, the Company recorded an impairment charge of $46.8 million (before-tax) against the carrying value of the Marathon mineral properties in Canada, reducing its carrying value to an estimated fair value of $8.6 million .

Noncontrolling Interest

Noncontrolling Interest	9 Months Ended
	Sep. 30, 2016
Noncontrolling Interest [Abstract]
Noncontrolling Interest	NONCONTROLLING INTEREST In the fourth quarter of 2015, the Company purchased the 25% interest held by Mitsubishi Corporation (Mitsubishi) in Stillwater Canada Inc (SCI), the Company's subsidiary, which holds the Marathon PGM-copper assets. The Company paid total cash consideration of $5.2 million which equaled $1.0 million in cash and 25% of the total cash and cash equivalents held by SCI. Prior to the repurchase, Mitsubishi's 25% interest in SCI's net loss for each period was shown as Net loss attributable to noncontrolling interest in the Company's Consolidated Statements of Comprehensive Income (Loss) . The amount of the loss was added back to the Company's reported Net (loss) income in each period in arriving at Net (loss) income attributable to common stockholders . The reported Net loss attributable to noncontrolling interest for the three and nine months ended September 30, 2015 was $0.2 million and $11.8 million , respectively.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2016
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 PGM market commodity prices. COMMODITY DERIVATIVES PGM Recycling The Company customarily enters into fixed forward sales contracts relating to PGM recycling of catalyst and other industrial sourced materials. Under these 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 to set in advance the pricing for metals acquired and processed in its recycling segment. The metals from PGM recycled materials are sold forward at the time of purchase and delivered against the fixed forward contracts when the ounces are recovered. Because this forward price is also used to set the acquisition price the Company pays for recycling materials, this arrangement significantly reduces exposure to PGM price volatility. The Company believes such transactions qualify for the exception to hedge accounting treatment and has elected to account for these transactions as normal purchases and normal sales. All of the Company's fixed forward sales contracts open at September 30, 2016 , will settle at various periods through March 2017 . 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. At September 30, 2016 , and December 31, 2015 , no margin deposits were outstanding or due. The following is a summary of the Company's outstanding commodity derivatives in its Recycling Business Segment at September 30, 2016 : PGM Recycling: Fixed Forward Contracts Platinum Palladium Rhodium Settlement Period Ounces Average Price/Ounce Ounces Average Price/Ounce Ounces Average Price/Ounce Fourth Quarter 2016 36,116 $ 1,077 68,527 $ 675 9,775 $ 631 First Quarter 2017 3,988 $ 1,063 6,091 $ 698 1,483 $ 651

Share Compensation Plans

Share Compensation Plans	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share Compensation Plans	SHARE COMPENSATION PLANS EQUITY PLANS The Company sponsors equity plans (the Plans) that enable the Company to grant equity-based compensation to employees and non-employee directors. The Company currently issues restricted stock units as incentive compensation under the Plans. In total, approximately 11.6 million shares of common stock have been authorized for issuance under the Plans, including approximately 5.0 million , 5.2 million , and 1.4 million authorized shares under the 2012 Equity Incentive Plan, 2004 Equity Incentive Plan and the General Employee Plan, respectively. Approximately 3.8 million shares were available and reserved for issuance under the 2012 Equity Incentive Plan at September 30, 2016 . 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. NONVESTED SHARES Time-Based Restricted Stock Unit Awards Time-based restricted stock unit awards provide the participant with the right to receive a number of shares of the Company's common stock upon vesting of the awards provided the participant is employed by the Company on the vesting date. Time-based awards are valued using the Company's common stock price on the date of grant. Time-based awards are not entitled to any dividend equivalents with respect to the restricted stock units unless otherwise determined by the Board, nor any dividends on stock that may be delivered in settlement of the restricted stock units unless and until the stock is issued in settlement of the restricted stock units. Nonvested time-based share activity during the nine months ended September 30, 2016 , is detailed in the following table: Nonvested Shares Weighted-Average Grant-Date Fair Value Nonvested time-based shares at January 1, 2016 186,655 $ 13.97 Granted 206,974 8.03 Vested (33,080 ) 13.88 Forfeited — — Nonvested time-based shares at March 31, 2016 360,549 $ 10.68 Granted 2,652 10.13 Vested (2,747 ) 14.24 Forfeited (565 ) 13.02 Nonvested time-based shares at June 30, 2016 359,889 $ 10.63 Granted 2,233 14.32 Vested (1,919 ) 13.18 Forfeited (3,546 ) 11.10 Nonvested time-based shares at September 30, 2016 356,657 $ 10.63 Total compensation expense, included within General and administrative in the Company's Consolidated Statements of Comprehensive Income (Loss) related to grants of time-based nonvested shares was $0.5 million and $0.4 million , in the three months ended September 30, 2016 and 2015 , respectively, and $1.5 million and $1.2 million , respectively, for the nine months ended September 30, 2016 and 2015 . Performance-Based Restricted Stock Unit Awards The Company grants performance-based restricted stock unit awards under its Long Term Incentive Plan (LTIP). The payout of the awards is dependent upon distinct components with separate sub-targets. The sub-targets are either market-based or performance-based and classified as either equity or liability. The market-based sub-targets are valued using a Monte Carlo simulation valuation model on the date of grant. The fair value of the liability-classified sub-targets are re-measured each reporting period. The existence of a market condition requires recognition of compensation cost for the performance restricted stock unit awards over the requisite period regardless of whether the market condition is satisfied. Total compensation expense, included within General and administrative in the Company's Consolidated Statements of Comprehensive Income (Loss) , related to grants of performance-based restricted stock unit awards for the three months ended September 30, 2016 and 2015 was $0.5 million and $0.3 million , respectively, and $1.3 million and $1.0 million , respectively, for each of the nine months ended September 30, 2016 and 2015 . A performance-based restricted stock unit award provides the participant with the right to receive a number of shares of the Company's common stock depending on achievement of specific measurable performance criteria. The number of shares earned is determined at the end of each performance period, generally three years , based on the actual performance criteria predetermined by the Compensation Committee at the time of grant. In the period when it becomes probable that the performance criteria will be achieved, the Company recognizes expense for the proportionate share of the total fair value of the grant related to the vesting period that has already lapsed. The remaining cost of the grant is expensed over the balance of the vesting period. For awards that contain performance-based conditions, and for which the Company determines it is no longer probable that it will achieve the minimum performance criteria specified in the Plan, the Company reverses all of the previously recognized compensation expense in the period when such a determination is made. Performance-based restricted stock unit awards are not entitled to any dividend equivalents with respect to the restricted stock units unless otherwise determined by the Board, nor any dividends on stock that may be delivered in settlement of the restricted stock units unless and until the stock is issued in settlement of the restricted stock units. Share activity under nonvested performance-based restricted stock unit awards activity during the first nine months of 2016 is detailed in the following table: Nonvested Shares Weighted-Average Grant-Date Fair Value Nonvested performance-based shares at January 1, 2016 379,277 $ 15.34 Granted * 186,285 11.45 Vested — Forfeited — Nonvested performance-based shares at March 31, 2016 565,562 $ 14.06 No activity — Nonvested performance-based shares at June 30, 2016 565,562 $ 14.06 Forfeited (2,695 ) Nonvested performance-based shares at September 30, 2016 562,867 $ 12.28 * The number of performance-based shares granted is based on the target award amounts in the performance restricted stock unit award agreements. The following table presents the compensation expense of the nonvested shares outstanding at September 30, 2016 , to be recognized over the remaining vesting periods: (In thousands) Time-based shares Performance -based shares Remaining 2016 $ 548 $ 611 2017 1,203 1,796 2018 587 933 2019 8 — Total $ 2,346 $ 3,340

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
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. These assets and liabilities reflect 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. In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Company considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. The Company has a valuation allowance in 2016 and 2015 to reflect the estimated amount of deferred tax assets which may not be realized, which principally relate to foreign and state net operating losses, capital losses, and certain tax credits. The Company recognized an income tax provision for the three months ended September 30, 2016 of $3.1 million and an income tax benefit of $2.5 million , for the three months ended September 30, 2015. The Company recognized an income tax provision for the nine months ended September 30, 2016 of $2.4 million and an income tax benefit of $8.1 million , for the nine months ended September 30, 2015. The current year income and the discrete charge of $3.5 million for an increase in the provision for uncertain tax positions, are primarily responsible for the tax provision for the nine months ended September 30, 2016 . The partial restructure of internal operations and the creation of a separate metal sales and trading subsidiary was responsible for $8.3 million of the total $10.6 million discrete income tax benefit recognized for the nine months ended September 30, 2015. The Company’s policy is to recognize interest and penalties on unrecognized tax benefits in Income tax (provision) benefit in the Company's Consolidated Statements of Comprehensive Income (Loss) . The Company had unrecognized tax benefits of $3.7 million at September 30, 2016 . Interest and penalties of $0.1 million have been accrued at September 30, 2016 . The Company anticipates there could be a change in uncertain tax positions during the next twelve months. The Company made income tax payments of $0.3 million and $13.1 million in the nine months ended September 30, 2016 and 2015 , respectively. Tax years still open for examination by the taxing authorities are the years ended December 31, 2015, 2014, 2013, 2012 and 2011, although net operating loss and credit carryforwards from all years are subject to examination and adjustment for the three years following the year in which the carryforwards are utilized.

Debt and Capital Lease Obligati

Debt and Capital Lease Obligations	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Debt and Capital Lease Obligations	DEBT AND CAPITAL LEASE OBLIGATIONS 1.75% CONVERTIBLE DEBENTURES In October 2012, the Company issued $396.75 million aggregate principal amount of 1.75% senior unsecured convertible debentures due October 15, 2032 ( 1.75% debentures). Each $1,000 principal amount of these 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 each debenture with a warrant initially exercisable for 30.2481 shares at an exercise price of $16.53 per share (also 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 at face value, plus accrued and unpaid interest, on October 15th, of each of 2019, 2024, 2029, and upon the occurrence of certain corporate events. The Company will have the right to call the 1.75% debentures at any time on or after October 20, 2019. The 1.75% debentures were bifurcated under 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 in 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 . In the third quarter of 2015, the Company repurchased $61.6 million of outstanding principal under the 1.75% debentures, paying cash of $59.4 million . The Company reduced the debt component by $50.7 million , which included a reduction of the debt discount by $10.9 million . The difference between the book value and the fair value (including $0.7 million of debt and equity issuance costs) of the debt component resulted in a $4.2 million loss. 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 at September 30, 2016 was approximately $268.6 million , which is net of unamortized discount of $63.5 million and $3.2 million deferred debt issue costs. The balance outstanding at December 31, 2015 was $254.6 million , which was net of unamortized discount of $76.8 million and $3.8 million of deferred debt issue costs. 1.875% CONVERTIBLE DEBENTURES Holders of the remaining $0.5 million of outstanding 1.875% debentures may require the Company to redeem their 1.875% debentures at face value 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. Effective March 22, 2013, the Company has the right at its discretion to redeem the remaining $0.5 million of outstanding 1.875% debentures for cash at any time prior to maturity. In the third quarter of 2015, the Company repurchased $1.7 million of the outstanding principal of the 1.875% debentures, paying cash of $1.6 million and recording a gain of approximately $0.1 million . The outstanding balance at September 30, 2016 and December 31, 2015 , of $0.5 million aggregate principal amount, is reported as a long-term debt obligation. ASSET-BACKED REVOLVING CREDIT FACILITY In December 2011, the Company signed 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 this facility and simultaneously expanded its maximum line of credit to $125.0 million , incurring additional debt issuance costs of $0.2 million . The Company also paid an unused line fee on the committed but unutilized balance under the facility at a rate per annum of 0.375% or 0.5% , depending on utilization of the facility. The Company terminated this credit facility on December 31, 2015, incurring expenses and fees of approximately $0.2 million . The following table reflects the amortization of debt issuance costs, interest expense and cash payments on the Company's outstanding debt for the three and nine months ended September 30, 2016 and 2015: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2016 2015 2016 2015 1.75% Convertible Debentures Amortization of debt issuance costs $ 225 $ 240 $ 662 $ 714 Interest expense, net of capitalized interest $ 3,731 $ 4,760 $ 11,532 $ 14,685 Cash payments for interest $ — $ 423 $ 2,933 $ 3,894 1.875% Convertible Debentures Interest expense, net of capitalized interest $ 2 $ 7 $ 5 $ 23 Cash payments for interest $ 5 $ 21 $ 10 $ 42 Asset-Backed Revolving Credit Facility Amortization of debt issuance costs $ — $ 69 $ — $ 204 Fees $ — $ 253 $ — $ 839 Capital Lease Interest expense $ — $ 21 $ 8 $ 87 Cash payments for interest $ — $ 21 $ 8 $ 87 The Company's total current and long-term debt balances at September 30, 2016 and December 31, 2015 were as follows: September 30, 2016 December 31, 2015 (In thousands) Current Long-Term Current Long-Term 1.75% Convertible Debentures Aggregate principal $ — $ 335,150 $ — $ 335,150 Debt discount — (63,456 ) — (76,754 ) Deferred debt issue costs — (3,159 ) — (3,821 ) Debt balance — 268,535 — 254,575 1.875% Convertible Debentures — 524 — 524 Capital lease obligation — — 580 — Small land purchase — — 77 — Total debt balances $ — $ 269,059 $ 657 $ 255,099 CAPITALIZED INTEREST The Company capitalizes interest incurred on its various debt instruments as a cost of specific and identified areas under development. For the three months ended September 30, 2016 and 2015 , the Company capitalized interest of $2.3 million and $1.5 million , respectively. For the nine months ended September 30, 2016 and 2015 , the Company capitalized interest of $6.2 million and $4.2 million , respectively. Capitalized interest is recorded as a reduction to Interest expense in the Company's Consolidated Statements of Comprehensive Income (Loss) .

Mineral Properties and Mine Dev

Mineral Properties and Mine Development	9 Months Ended
	Sep. 30, 2016
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: September 30, December 31, (In thousands) 2016 2015 Mineral Properties: Montana, United States of America Stillwater Mine $ 1,950 $ 1,950 Ontario, Canada Marathon properties 8,560 8,560 San Juan, Argentina Altar property 101,970 101,970 Mine Development: Montana, United States of America Stillwater Mine 751,630 697,781 East Boulder Mine 231,251 220,281 1,095,361 1,030,542 Accumulated depletion and amortization (502,615 ) (457,311 ) Total mineral properties and mine development, net $ 592,746 $ 573,231

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment reflected in the accompanying consolidated balance sheets consisted of the following: September 30, December 31, (In thousands) 2016 2015 Machinery and equipment $ 163,297 $ 161,292 Buildings and structural components 174,279 173,580 Land 11,740 11,740 Construction-in-progress: Stillwater Mine 6,666 2,615 East Boulder Mine 513 435 Marathon 148 148 Processing facilities and other 1,376 1,982 358,019 351,792 Accumulated depreciation (254,796 ) (241,835 ) Total property, plant, and equipment, net $ 103,223 $ 109,957 The Company's total capital outlay for mine development and property, plant and equipment for the nine months ended September 30, 2016 and 2015 were as follows: September 30, (In thousands) 2016 2015 Stillwater Mine $ 60,345 $ 70,172 East Boulder Mine 11,508 13,548 Other 642 4,599 Total U.S. capital expenditures 72,495 88,319 Foreign capital expenditures — 46 Non-cash capitalized interest and depreciation (7,551 ) (6,756 ) Change in accounts payables for capital expenditures (2,964 ) 1,777 Cash capital spend for the period $ 61,980 $ 83,386

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2016
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 has agreements in place to sell its PGMs from mine production. 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 materials to recover the PGMs contained in the materials. The Company purchases catalyst materials processed by the PGM Recycling segment from third-party suppliers for its own account and sells the recovered metals directly, and it also accepts catalyst materials from 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 mineral property assets. The exploration-stage Marathon mineral properties include a large PGM and copper deposit located near the town of Marathon, Ontario, Canada as well as additional mineral properties located adjacent to the Marathon properties. The South American Properties segment consists of the Peregrine Metals Ltd. assets. The principal Peregrine property is the Altar property, an exploration-stage copper-gold resource located in the San Juan province of Argentina. The All Other group primarily consists of assets, including cash and cash equivalents, investments, revenues, and expenses of various corporate and support functions. 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, 2016 Mine Production PGM Recycling Canadian Properties All Other Total Revenues $ 106,926 $ 89,591 $ — $ — $ 100 $ 196,617 Costs of metals sold $ 65,580 $ 86,178 $ — $ — $ — $ 151,758 Depletion, depreciation and amortization $ 17,587 $ 184 $ — $ — $ — $ 17,771 General and administrative expenses $ — $ — $ 204 $ 381 $ 8,107 $ 8,692 Interest income $ — $ 617 $ 1 $ — $ 595 $ 1,213 Interest expense $ — $ — $ — $ — $ 3,958 $ 3,958 Income (loss) before income taxes $ 23,759 $ 3,876 $ (353 ) $ (258 ) $ (11,283 ) $ 15,741 Capital expenditures $ 23,557 $ 4 $ — $ — $ (7 ) $ 23,554 Total assets $ 624,814 $ 88,153 $ 25,549 $ 103,351 $ 466,043 $ 1,307,910 (In thousands) South American Properties Three Months Ended September 30, 2015 Mine Production PGM Recycling Canadian Properties * All Other Total Revenues $ 86,359 $ 81,982 $ — $ — $ 100 $ 168,441 Costs of metals sold $ 69,004 $ 78,928 $ — $ — $ — $ 147,932 Depletion, depreciation and amortization $ 15,132 $ 230 $ — $ — $ — $ 15,362 General and administrative expenses $ — $ — $ 275 $ 100 $ 8,536 $ 8,911 Interest income $ — $ 437 $ 1 $ 4 $ 324 $ 766 Interest expense $ — $ — $ — $ — $ 5,097 $ 5,097 Income (loss) before income taxes $ 2,224 $ 3,261 $ (577 ) $ (339 ) $ (19,062 ) $ (14,493 ) Capital expenditures $ 24,661 $ 57 $ — $ — $ 450 $ 25,168 Total assets $ 608,198 $ 70,113 $ 27,078 $ 104,265 $ 507,533 $ 1,317,187 * Total assets includes cash and cash equivalents of $17.1 million . (In thousands) South American Nine Months Ended September 30, 2016 Mine Production PGM Recycling Canadian Properties All Other Total Revenues $ 299,123 $ 196,515 $ — $ — $ 300 $ 495,938 Costs of metals sold $ 208,612 $ 188,712 $ — $ — $ — $ 397,324 Depletion, depreciation and amortization $ 55,173 $ 569 $ — $ — $ — $ 55,742 General and administrative expenses $ — $ — $ 543 $ 1,064 $ 23,693 $ 25,300 Interest income $ — $ 1,376 $ 2 $ 1 $ 1,504 $ 2,883 Interest expense $ — $ — $ — $ — $ 12,207 $ 12,207 Income (loss) before income taxes $ 35,338 $ 8,611 $ (740 ) $ (2,886 ) $ (34,504 ) $ 5,819 Capital expenditures $ 61,410 $ 14 $ — $ — $ 556 $ 61,980 Total assets $ 624,814 $ 88,153 $ 25,549 $ 103,351 $ 466,043 $ 1,307,910 (In thousands) South American Nine Months Ended September 30, 2015 Mine Production PGM Recycling Canadian Properties * All Other Total Revenues $ 331,065 $ 222,980 $ — $ — $ 300 $ 554,345 Costs of metals sold $ 229,676 $ 216,074 $ — $ — $ — $ 445,750 Depletion, depreciation and amortization $ 48,943 $ 738 $ — $ — $ — $ 49,681 General and administrative expenses $ — $ — $ 790 $ 454 $ 26,408 $ 27,652 Interest income $ — $ 1,256 $ 7 $ 23 $ 906 $ 2,192 Interest expense $ — $ — $ — $ — $ 15,713 $ 15,713 Income (loss) before impairment charge and income tax provision $ 52,446 $ 7,424 $ (1,364 ) $ (1,216 ) $ (46,805 ) $ 10,485 Impairment charge $ — $ — $ 46,772 $ — $ — $ 46,772 Income (loss) after impairment charge and income tax provision $ 52,446 $ 7,424 $ (48,136 ) $ (1,216 ) $ (46,805 ) $ (36,287 ) Capital expenditures $ 77,370 $ 221 $ — $ 46 $ 5,749 $ 83,386 Total assets $ 608,198 $ 70,113 $ 27,078 $ 104,265 $ 507,533 $ 1,317,187 * Total assets includes cash and cash equivalents of $17.1 million .

Investments

Investments	9 Months Ended
	Sep. 30, 2016
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 value in the financial statements with unrealized gains or losses recorded in Other comprehensive income in the Company's Consolidated Statements of Comprehensive Income (Loss) . At the time the securities are sold or otherwise disposed of, gross realized gains and losses are included in Net income (loss). Gross realized gains and losses are based on the carrying value (cost, net of discounts or premiums) of the sold investment. The amounts reclassified out of Other comprehensive income during the three and nine months ended September 30, 2016 and 2015 were insignificant. The amortized cost, gross unrealized gains, gross unrealized losses, and fair value of available-for-sale investment securities by major security type and class of security at September 30, 2016 and December 31, 2015 were as follows: Investments (In thousands) Amortized cost Gross unrealized gains Gross unrealized losses Fair value 2016 Federal agency notes $ 290,279 $ 73 $ (85 ) $ 290,267 Commercial paper 36,130 48 — 36,178 Subtotal 326,409 121 (85 ) 326,445 Mutual funds 757 189 — 946 Total $ 327,166 $ 310 $ (85 ) $ 327,391 2015 Federal agency notes $ 285,276 $ — $ (519 ) $ 284,757 Commercial paper 31,730 — (58 ) 31,672 Subtotal 317,006 — (577 ) 316,429 Mutual funds 482 261 — 743 Total $ 317,488 $ 261 $ (577 ) $ 317,172 The mutual funds included in the investment table above are included in Other noncurrent assets on the Company's Consolidated Balance Sheets . Included in the investments balance at September 30, 2016 and December 31, 2015 is $18.5 million which has been reserved as collateral on the Company's undrawn letters of credit of approximately $17.5 million . The maturities of available-for-sale securities at September 30, 2016 were as follows: (In thousands) Amortized cost Fair value Federal agency notes Due in one year or less $ 223,442 $ 223,423 Due after one year through two years 66,837 66,844 Total $ 290,279 $ 290,267 Commercial paper Due in one year or less $ 14,235 $ 14,242 Due after one year through three years 21,895 21,936 Total $ 36,130 $ 36,178 The Company has long-term investments in various Canadian junior exploration companies, recorded on the Company's Consolidated Balance Sheets at cost. The Company sold its investment in Coro Mining and completed a partial sale of its investment in Benton Resources in the third quarter of 2016 and recorded a combined gain of $0.2 million . For the nine months ended September 30, 2016 , the Company recorded gains on sale of its long-term investments of approximately $0.7 million . The Company determined there was no impairment for the remaining long-term investments for the three and nine months ended September 30, 2016 . For the three and nine months ended September 30, 2015, the Company determined that certain of its remaining long-term investments were other than temporarily impaired and recorded a loss of approximately $0.2 million . These long-term investments totaled less than $0.1 million at September 30, 2016 and $0.5 million at December 31, 2015 , and are recorded in Other noncurrent assets on the Company's Consolidated Balance Sheets .

Inventories

Inventories	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Inventories	INVENTORIES The Company carries items in its inventories at the lower of cost or market value. If the market value in any period falls below the carrying value, the carrying value of the inventory item is reduced to its market value. 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 reduction to inventory value was necessary in the first nine months of 2016 or 2015 . The costs of PGM mined 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, depletion, depreciation and amortization and other overhead costs relating to mining and processing activities incurred as of such date. Costs are aggregated and averaged for mined material carried in inventory. The costs of PGM recycling 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. Costs incurred are allocated and tracked separately for each specific lot of recycling material (including material tolled on behalf of others). Inventories reflected in the accompanying balance sheets consisted of the following: September 30, December 31, (In thousands) 2016 2015 Metals inventory Raw ore $ 4,753 $ 4,234 Concentrate and in-process 71,495 43,727 Finished goods 46,057 32,618 Total metals inventory 122,305 80,579 Materials and supplies 18,476 21,493 Total inventories $ 140,781 $ 102,072

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2016
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 shares of common stock 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 or nonvested shares were exercised or vested, the contingently issuable shares were issued and the Company’s convertible debt was converted. In calculating earnings per share attributable to common stockholders for the third quarter of 2016, reported consolidated net income attributable to common stockholders was adjusted for the interest expense, net of capitalized interest (including amortization expense of deferred debt fees associated with the convertible debentures), and the related income tax effect. The Company currently has only one class of shares of capital stock outstanding. The following table shows the reconciliation of the computation of basic and diluted shares and the related impact on income for the three and nine months ended September 30, 2016 : Three Months Ended Nine Months Ended September 30, 2016 September 30, 2016 (In thousands, except per share amounts) Income (Numerator) Weighted Average Shares (Denominator) Per Share Amount Income (Numerator) Weighted Average Shares (Denominator) Per Share Amount Basic EPS Net income attributable to common stockholders $ 12,599 121,077 $ 0.10 $ 3,452 121,069 $ 0.03 Effect of Dilutive Securities Stock options — 1 — 1 Nonvested time-based shares — 166 — 68 Contingently issuable shares — 368 — 300 1.875% Convertible debentures, net of tax 1 22 — — Diluted EPS Net income attributable to common stockholders $ 12,600 121,634 $ 0.10 $ 3,452 121,438 $ 0.03 No adjustment was made to the reported net loss attributable to common stockholders when calculating diluted loss per share attributable to common stockholders for the three and nine months ended September 30, 2015 because the Company reported a consolidated net loss attributable to common stockholders and inclusion of these shares would have been anti-dilutive. Potential dilutive common shares include those associated with outstanding stock options, restricted stock units, contingently issuable shares and convertible debentures. The following table shows the shares that were excluded from the computation of diluted earnings per share for the three months and nine months ended September 30, 2016 and 2015: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2016 2015 2016 2015 Stock options 3 6 — 6 Nonvested time-based shares 1 44 10 50 Contingently issuable shares 222 218 234 218 1.875% Convertible debentures, net of tax — 22 22 22 1.75% Convertible debentures, net of tax 30,413 30,413 30,413 30,413

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2016
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, 2016 and December 31, 2015 , consisted of the following: (In thousands) Fair Value Measurements At September 30, 2016 Total Level 1 Level 2 Level 3 Money market fund $ 35,863 $ 35,863 $ — $ — Mutual funds $ 946 $ 946 $ — $ — Investments Federal agency notes $ 290,267 $ — $ 290,267 $ — Commercial paper $ 36,178 $ — $ 36,178 $ — (In thousands) Fair Value Measurements At December 31, 2015 Total Level 1 Level 2 Level 3 Money market fund $ 54,761 $ 54,761 $ — $ — Mutual funds $ 743 $ 743 $ — $ — Investments Federal agency notes $ 284,757 $ — $ 284,757 $ — Commercial paper $ 31,672 $ — $ 31,672 $ — The money market funds are recorded in Cash and cash equivalents on the Company's Consolidated Balance Sheets . The fair value of the mutual funds is based on market prices that are readily available and are recorded in Other noncurrent assets on the Company's Consolidated Balance Sheets . 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, 2016 and December 31, 2015 , consisted of the following: (In thousands) Fair Value Measurements At September 30, 2016 Total Level 1 Level 2 Level 3 1.875% Convertible debentures $ 524 $ — $ 524 $ — 1.75% Convertible debentures $ 316,170 $ — $ 316,170 $ — (In thousands) Fair Value Measurements At December 31, 2015 Total Level 1 Level 2 Level 3 1.875% Convertible Debentures $ 524 $ — $ 524 $ — 1.75% Convertible Debentures $ 285,446 $ — $ 285,446 $ — Long-term investments $ 524 $ 524 $ — $ — The Company determined the fair value of the liability component of its outstanding 1.75% convertible debentures at September 30, 2016 and December 31, 2015 by using observable market based information for debt instruments of similar amounts and duration. The Company used the book value of its outstanding 1.875% convertible debentures to represent the fair value at September 30, 2016 and December 31, 2015 . The fair value of the Company's long-term investments in certain Canadian junior exploration companies at December 31, 2015 is based on quoted market prices which are readily available.

Related Parties

Related Parties	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Related Parties	RELATED PARTIES The Company purchased Mitsubishi's 25% ownership interest in SCI, the Company's subsidiary, in the fourth quarter of 2015. The Company made PGM sales of $15.2 million to Mitsubishi in the three months ended September 30, 2015 , and $38.7 million , for the nine months ended September 30, 2015 .

General (Policies)

General (Policies)	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Use of Estimates	The preparation of the Company’s consolidated financial statements in conformity with United States generally accepted accounting principles (GAAP) 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.
New Accounting Pronouncements	On May 28, 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers , which requires an entity to recognize the amount of revenue it expects to be entitled to for the transfer of promised goods or services to customers. In August 2015, the FASB issued ASU 2015-14, Deferral of the Effective Date , which defers the effective date of ASU 2014-09 by one year to January 1, 2018. ASU 2014-09 will replace most existing revenue recognition guidance in GAAP. The standard permits the use of either the retrospective or cumulative effect transition method. The Company continues to evaluate the effect that ASU 2014-09 will have on its consolidated financial statements and disclosures and has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting. Early adoption is not permitted. On April 7, 2015, as part of its initiative to simplify and reduce complexity in financial statements, the FASB issued ASU 2015-03, Interest - Imputation, (Subtopic 835-30): Simplifying the Presentation of Debt Issuance. This ASU requires the debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of the debt liability. Also, it requires retrospective application for all prior periods presented in the financial statements and a disclosure of the nature of and reason for the change in accounting principle, the transition method, a description of the prior-period information that has been retrospectively adjusted and the effect of the change on the financial statement line items. ASU 2015-03 is effective for financial statements issued for fiscal years beginning after December 31, 2015, and interim periods within those fiscal years. Early adoption was permitted for financial statements that had not been previously issued. The Company elected early adoption of ASU 2015-03 in the first quarter of 2016 and reclassified Deferred debt issue costs against the related liability for all periods presented. Prior to the adoption of ASU 2015-03, the balance reported at December 31, 2015 for total Long-term debt and capital lease obligations was $258.9 million , and after adoption and reclassification of Deferred debt issue costs of $3.8 million , the total balance reported at December 31, 2015 became $255.1 million . On July 22, 2015, as part of its initiative to simplify and reduce complexity in financial statements, the FASB issued ASU 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory. ASU 2015-11, changes the measurement principle for inventory from the lower of cost or market to the lower of cost and net realizable value. ASU 2015-11 is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The Company is evaluating the effect that ASU 2015-11 will have on its consolidated financial statements and disclosures. The Company does not expect this initiative to have a significant impact on its ongoing financial reporting. The ASU requires prospective adoption and permits early adoption. On February 25, 2016, the FASB issued ASU 2016-02, Leases, (Topic 840) , which requires an entity that leases assets, with terms of more than 12 months, to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. ASU 2016-02 is effective for financial statements issued for fiscal years beginning after December 31, 2018, and interim periods within those fiscal years. The Company is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and disclosures and has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting. Early adoption is permitted. On March 30, 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employees Shared-Based Payment Accounting. The ASU will change several aspects within share based payments: (1) accounting for income taxes, (2) classification of excess tax benefits, (3) forfeitures, (4) minimum statutory tax withholding requirements, (5) classification of employee taxes paid when an employer withholds shares for tax-withholding purposes, (6) practical expedient - expected term, (7) intrinsic value, and (8) eliminating the indefinite deferral. ASU 2016-09 is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. The Company is evaluating the effect that ASU 2016-09 will have on its consolidated financial statements and disclosures and has not yet quantified the effect of the standard on its ongoing financial reporting. Early adoption is permitted in any interim or annual period provided that the entire ASU is adopted.

Sales (Tables)

Sales (Tables)	9 Months Ended
	Sep. 30, 2016
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 months ended September 30, 2016 and 2015 were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2016 2015 (1) 2016 (1) 2015 (1) Customer A 65 % 70 % 71 % 75 % Customer B 11 % — — — Customer C 10 % — — — 86 % 70 % 71 % 75 % (1) The "-" symbol represents less than 10% of total revenues.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Company's outstanding commodity derivatives	The following is a summary of the Company's outstanding commodity derivatives in its Recycling Business Segment at September 30, 2016 : PGM Recycling: Fixed Forward Contracts Platinum Palladium Rhodium Settlement Period Ounces Average Price/Ounce Ounces Average Price/Ounce Ounces Average Price/Ounce Fourth Quarter 2016 36,116 $ 1,077 68,527 $ 675 9,775 $ 631 First Quarter 2017 3,988 $ 1,063 6,091 $ 698 1,483 $ 651

Share Compensation Plans (Table

Share Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Changes In The Company's Nonvested Shares	Share activity under nonvested performance-based restricted stock unit awards activity during the first nine months of 2016 is detailed in the following table: Nonvested Shares Weighted-Average Grant-Date Fair Value Nonvested performance-based shares at January 1, 2016 379,277 $ 15.34 Granted * 186,285 11.45 Vested — Forfeited — Nonvested performance-based shares at March 31, 2016 565,562 $ 14.06 No activity — Nonvested performance-based shares at June 30, 2016 565,562 $ 14.06 Forfeited (2,695 ) Nonvested performance-based shares at September 30, 2016 562,867 $ 12.28 * The number of performance-based shares granted is based on the target award amounts in the performance restricted stock unit award agreements. Nonvested time-based share activity during the nine months ended September 30, 2016 , is detailed in the following table: Nonvested Shares Weighted-Average Grant-Date Fair Value Nonvested time-based shares at January 1, 2016 186,655 $ 13.97 Granted 206,974 8.03 Vested (33,080 ) 13.88 Forfeited — — Nonvested time-based shares at March 31, 2016 360,549 $ 10.68 Granted 2,652 10.13 Vested (2,747 ) 14.24 Forfeited (565 ) 13.02 Nonvested time-based shares at June 30, 2016 359,889 $ 10.63 Granted 2,233 14.32 Vested (1,919 ) 13.18 Forfeited (3,546 ) 11.10 Nonvested time-based shares at September 30, 2016 356,657 $ 10.63
Compensation Expense of Nonvested Shares	The following table presents the compensation expense of the nonvested shares outstanding at September 30, 2016 , to be recognized over the remaining vesting periods: (In thousands) Time-based shares Performance -based shares Remaining 2016 $ 548 $ 611 2017 1,203 1,796 2018 587 933 2019 8 — Total $ 2,346 $ 3,340

Debt and Capital Lease Obliga26

Debt and Capital Lease Obligations (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Schedule of Debt Issuance Costs, Interest Expense and Cash Paid For Interest	The following table reflects the amortization of debt issuance costs, interest expense and cash payments on the Company's outstanding debt for the three and nine months ended September 30, 2016 and 2015: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2016 2015 2016 2015 1.75% Convertible Debentures Amortization of debt issuance costs $ 225 $ 240 $ 662 $ 714 Interest expense, net of capitalized interest $ 3,731 $ 4,760 $ 11,532 $ 14,685 Cash payments for interest $ — $ 423 $ 2,933 $ 3,894 1.875% Convertible Debentures Interest expense, net of capitalized interest $ 2 $ 7 $ 5 $ 23 Cash payments for interest $ 5 $ 21 $ 10 $ 42 Asset-Backed Revolving Credit Facility Amortization of debt issuance costs $ — $ 69 $ — $ 204 Fees $ — $ 253 $ — $ 839 Capital Lease Interest expense $ — $ 21 $ 8 $ 87 Cash payments for interest $ — $ 21 $ 8 $ 87
Schedule of Current and Long-term Debt	The Company's total current and long-term debt balances at September 30, 2016 and December 31, 2015 were as follows: September 30, 2016 December 31, 2015 (In thousands) Current Long-Term Current Long-Term 1.75% Convertible Debentures Aggregate principal $ — $ 335,150 $ — $ 335,150 Debt discount — (63,456 ) — (76,754 ) Deferred debt issue costs — (3,159 ) — (3,821 ) Debt balance — 268,535 — 254,575 1.875% Convertible Debentures — 524 — 524 Capital lease obligation — — 580 — Small land purchase — — 77 — Total debt balances $ — $ 269,059 $ 657 $ 255,099

Mineral Properties and Mine D27

Mineral Properties and Mine Development (Tables)	9 Months Ended
	Sep. 30, 2016
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: September 30, December 31, (In thousands) 2016 2015 Mineral Properties: Montana, United States of America Stillwater Mine $ 1,950 $ 1,950 Ontario, Canada Marathon properties 8,560 8,560 San Juan, Argentina Altar property 101,970 101,970 Mine Development: Montana, United States of America Stillwater Mine 751,630 697,781 East Boulder Mine 231,251 220,281 1,095,361 1,030,542 Accumulated depletion and amortization (502,615 ) (457,311 ) Total mineral properties and mine development, net $ 592,746 $ 573,231

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	Property, plant and equipment reflected in the accompanying consolidated balance sheets consisted of the following: September 30, December 31, (In thousands) 2016 2015 Machinery and equipment $ 163,297 $ 161,292 Buildings and structural components 174,279 173,580 Land 11,740 11,740 Construction-in-progress: Stillwater Mine 6,666 2,615 East Boulder Mine 513 435 Marathon 148 148 Processing facilities and other 1,376 1,982 358,019 351,792 Accumulated depreciation (254,796 ) (241,835 ) Total property, plant, and equipment, net $ 103,223 $ 109,957
Schedule Capital Expenditures	The Company's total capital outlay for mine development and property, plant and equipment for the nine months ended September 30, 2016 and 2015 were as follows: September 30, (In thousands) 2016 2015 Stillwater Mine $ 60,345 $ 70,172 East Boulder Mine 11,508 13,548 Other 642 4,599 Total U.S. capital expenditures 72,495 88,319 Foreign capital expenditures — 46 Non-cash capitalized interest and depreciation (7,551 ) (6,756 ) Change in accounts payables for capital expenditures (2,964 ) 1,777 Cash capital spend for the period $ 61,980 $ 83,386

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2016
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, 2016 Mine Production PGM Recycling Canadian Properties All Other Total Revenues $ 106,926 $ 89,591 $ — $ — $ 100 $ 196,617 Costs of metals sold $ 65,580 $ 86,178 $ — $ — $ — $ 151,758 Depletion, depreciation and amortization $ 17,587 $ 184 $ — $ — $ — $ 17,771 General and administrative expenses $ — $ — $ 204 $ 381 $ 8,107 $ 8,692 Interest income $ — $ 617 $ 1 $ — $ 595 $ 1,213 Interest expense $ — $ — $ — $ — $ 3,958 $ 3,958 Income (loss) before income taxes $ 23,759 $ 3,876 $ (353 ) $ (258 ) $ (11,283 ) $ 15,741 Capital expenditures $ 23,557 $ 4 $ — $ — $ (7 ) $ 23,554 Total assets $ 624,814 $ 88,153 $ 25,549 $ 103,351 $ 466,043 $ 1,307,910 (In thousands) South American Properties Three Months Ended September 30, 2015 Mine Production PGM Recycling Canadian Properties * All Other Total Revenues $ 86,359 $ 81,982 $ — $ — $ 100 $ 168,441 Costs of metals sold $ 69,004 $ 78,928 $ — $ — $ — $ 147,932 Depletion, depreciation and amortization $ 15,132 $ 230 $ — $ — $ — $ 15,362 General and administrative expenses $ — $ — $ 275 $ 100 $ 8,536 $ 8,911 Interest income $ — $ 437 $ 1 $ 4 $ 324 $ 766 Interest expense $ — $ — $ — $ — $ 5,097 $ 5,097 Income (loss) before income taxes $ 2,224 $ 3,261 $ (577 ) $ (339 ) $ (19,062 ) $ (14,493 ) Capital expenditures $ 24,661 $ 57 $ — $ — $ 450 $ 25,168 Total assets $ 608,198 $ 70,113 $ 27,078 $ 104,265 $ 507,533 $ 1,317,187 * Total assets includes cash and cash equivalents of $17.1 million . (In thousands) South American Nine Months Ended September 30, 2016 Mine Production PGM Recycling Canadian Properties All Other Total Revenues $ 299,123 $ 196,515 $ — $ — $ 300 $ 495,938 Costs of metals sold $ 208,612 $ 188,712 $ — $ — $ — $ 397,324 Depletion, depreciation and amortization $ 55,173 $ 569 $ — $ — $ — $ 55,742 General and administrative expenses $ — $ — $ 543 $ 1,064 $ 23,693 $ 25,300 Interest income $ — $ 1,376 $ 2 $ 1 $ 1,504 $ 2,883 Interest expense $ — $ — $ — $ — $ 12,207 $ 12,207 Income (loss) before income taxes $ 35,338 $ 8,611 $ (740 ) $ (2,886 ) $ (34,504 ) $ 5,819 Capital expenditures $ 61,410 $ 14 $ — $ — $ 556 $ 61,980 Total assets $ 624,814 $ 88,153 $ 25,549 $ 103,351 $ 466,043 $ 1,307,910 (In thousands) South American Nine Months Ended September 30, 2015 Mine Production PGM Recycling Canadian Properties * All Other Total Revenues $ 331,065 $ 222,980 $ — $ — $ 300 $ 554,345 Costs of metals sold $ 229,676 $ 216,074 $ — $ — $ — $ 445,750 Depletion, depreciation and amortization $ 48,943 $ 738 $ — $ — $ — $ 49,681 General and administrative expenses $ — $ — $ 790 $ 454 $ 26,408 $ 27,652 Interest income $ — $ 1,256 $ 7 $ 23 $ 906 $ 2,192 Interest expense $ — $ — $ — $ — $ 15,713 $ 15,713 Income (loss) before impairment charge and income tax provision $ 52,446 $ 7,424 $ (1,364 ) $ (1,216 ) $ (46,805 ) $ 10,485 Impairment charge $ — $ — $ 46,772 $ — $ — $ 46,772 Income (loss) after impairment charge and income tax provision $ 52,446 $ 7,424 $ (48,136 ) $ (1,216 ) $ (46,805 ) $ (36,287 ) Capital expenditures $ 77,370 $ 221 $ — $ 46 $ 5,749 $ 83,386 Total assets $ 608,198 $ 70,113 $ 27,078 $ 104,265 $ 507,533 $ 1,317,187 * Total assets includes cash and cash equivalents of $17.1 million .

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Securities	The amortized cost, gross unrealized gains, gross unrealized losses, and fair value of available-for-sale investment securities by major security type and class of security at September 30, 2016 and December 31, 2015 were as follows: Investments (In thousands) Amortized cost Gross unrealized gains Gross unrealized losses Fair value 2016 Federal agency notes $ 290,279 $ 73 $ (85 ) $ 290,267 Commercial paper 36,130 48 — 36,178 Subtotal 326,409 121 (85 ) 326,445 Mutual funds 757 189 — 946 Total $ 327,166 $ 310 $ (85 ) $ 327,391 2015 Federal agency notes $ 285,276 $ — $ (519 ) $ 284,757 Commercial paper 31,730 — (58 ) 31,672 Subtotal 317,006 — (577 ) 316,429 Mutual funds 482 261 — 743 Total $ 317,488 $ 261 $ (577 ) $ 317,172
Schedule of Maturities of Available-for-sale Securities	The maturities of available-for-sale securities at September 30, 2016 were as follows: (In thousands) Amortized cost Fair value Federal agency notes Due in one year or less $ 223,442 $ 223,423 Due after one year through two years 66,837 66,844 Total $ 290,279 $ 290,267 Commercial paper Due in one year or less $ 14,235 $ 14,242 Due after one year through three years 21,895 21,936 Total $ 36,130 $ 36,178

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Components of Inventories	Inventories reflected in the accompanying balance sheets consisted of the following: September 30, December 31, (In thousands) 2016 2015 Metals inventory Raw ore $ 4,753 $ 4,234 Concentrate and in-process 71,495 43,727 Finished goods 46,057 32,618 Total metals inventory 122,305 80,579 Materials and supplies 18,476 21,493 Total inventories $ 140,781 $ 102,072

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Reconciliation of Computation of Basic and Diluted Shares and the Related Impact on Income	The following table shows the reconciliation of the computation of basic and diluted shares and the related impact on income for the three and nine months ended September 30, 2016 : Three Months Ended Nine Months Ended September 30, 2016 September 30, 2016 (In thousands, except per share amounts) Income (Numerator) Weighted Average Shares (Denominator) Per Share Amount Income (Numerator) Weighted Average Shares (Denominator) Per Share Amount Basic EPS Net income attributable to common stockholders $ 12,599 121,077 $ 0.10 $ 3,452 121,069 $ 0.03 Effect of Dilutive Securities Stock options — 1 — 1 Nonvested time-based shares — 166 — 68 Contingently issuable shares — 368 — 300 1.875% Convertible debentures, net of tax 1 22 — — Diluted EPS Net income attributable to common stockholders $ 12,600 121,634 $ 0.10 $ 3,452 121,438 $ 0.03
Anti-dilutive Shares Excluded From Computation of Diluted Earnings Per Share	The following table shows the shares that were excluded from the computation of diluted earnings per share for the three months and nine months ended September 30, 2016 and 2015: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2016 2015 2016 2015 Stock options 3 6 — 6 Nonvested time-based shares 1 44 10 50 Contingently issuable shares 222 218 234 218 1.875% Convertible debentures, net of tax — 22 22 22 1.75% Convertible debentures, net of tax 30,413 30,413 30,413 30,413

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2016
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, 2016 and December 31, 2015 , consisted of the following: (In thousands) Fair Value Measurements At September 30, 2016 Total Level 1 Level 2 Level 3 Money market fund $ 35,863 $ 35,863 $ — $ — Mutual funds $ 946 $ 946 $ — $ — Investments Federal agency notes $ 290,267 $ — $ 290,267 $ — Commercial paper $ 36,178 $ — $ 36,178 $ — (In thousands) Fair Value Measurements At December 31, 2015 Total Level 1 Level 2 Level 3 Money market fund $ 54,761 $ 54,761 $ — $ — Mutual funds $ 743 $ 743 $ — $ — Investments Federal agency notes $ 284,757 $ — $ 284,757 $ — Commercial paper $ 31,672 $ — $ 31,672 $ —
Financial Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis	Assets and liabilities measured at fair value on a nonrecurring basis at September 30, 2016 and December 31, 2015 , consisted of the following: (In thousands) Fair Value Measurements At September 30, 2016 Total Level 1 Level 2 Level 3 1.875% Convertible debentures $ 524 $ — $ 524 $ — 1.75% Convertible debentures $ 316,170 $ — $ 316,170 $ — (In thousands) Fair Value Measurements At December 31, 2015 Total Level 1 Level 2 Level 3 1.875% Convertible Debentures $ 524 $ — $ 524 $ — 1.75% Convertible Debentures $ 285,446 $ — $ 285,446 $ — Long-term investments $ 524 $ 524 $ — $ —

General (Details)

General (Details) - Accounting Standards Update 2015-03 [Member] $ in Millions	Dec. 31, 2015USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Long-term debt	$ 255.1
Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Long-term debt	258.9
Scenario, Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Long-term debt	$ 3.8

Sales (Details)

Sales (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Sales Revenue, Goods, Net [Abstract]
Revenues from by-product sales		$ 6.1	$ 5	$ 17.4	$ 18.7
Term of refining agreement	5 years
Customer concentration risk [Member] | Total revenues [Member]
Revenue, Major Customer [Line Items]
Sales to significant customers (10% or more), percentage of total revenues		86.00%	70.00%	71.00%	75.00%
Customer concentration risk [Member] | Total revenues [Member] | Customer A [Member]
Revenue, Major Customer [Line Items]
Sales to significant customers (10% or more), percentage of total revenues		65.00%	70.00%	71.00%	75.00%
Customer concentration risk [Member] | Total revenues [Member] | Customer B [Member]
Revenue, Major Customer [Line Items]
Sales to significant customers (10% or more), percentage of total revenues		11.00%
Customer concentration risk [Member] | Total revenues [Member] | Customer C [Member]
Revenue, Major Customer [Line Items]
Sales to significant customers (10% or more), percentage of total revenues		10.00%

Asset Impairment (Details)

Asset Impairment (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment charge	$ 0	$ 0		$ 0	$ 46,772
Marathon Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment charge			$ 46,800
Mineral properties, fair value			$ 8,600

Noncontrolling Interest (Detail

Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Noncontrolling Interest [Abstract]
Noncontrolling interest, ownership percentage by noncontrolling owners		25.00%
Purchase of noncontrolling interest, total consideration		$ 5,200
Purchase of noncontrolling interest, net of cash acquired		$ 1,000
Net income (loss) attributable to noncontrolling interest	$ 0		$ (151)	$ 0	$ (11,808)

Derivative Instruments (Company

Derivative Instruments (Company's Outstanding Commodity Derivatives) (Details)	9 Months Ended
	Sep. 30, 2016oz$ / oz
Fourth Quarter 2016 [Member] | Platinum [Member]
Derivative [Line Items]
Ounces | oz	36,116
Average Price/Ounce | $ / oz	1,077
Fourth Quarter 2016 [Member] | Palladium [Member]
Derivative [Line Items]
Ounces | oz	68,527
Average Price/Ounce | $ / oz	675
Fourth Quarter 2016 [Member] | Rhodium [Member]
Derivative [Line Items]
Ounces | oz	9,775
Average Price/Ounce | $ / oz	631
First Quarter 2017 [Member] | Platinum [Member]
Derivative [Line Items]
Ounces | oz	3,988
Average Price/Ounce | $ / oz	1,063
First Quarter 2017 [Member] | Palladium [Member]
Derivative [Line Items]
Ounces | oz	6,091
Average Price/Ounce | $ / oz	698
First Quarter 2017 [Member] | Rhodium [Member]
Derivative [Line Items]
Ounces | oz	1,483
Average Price/Ounce | $ / oz	651

Share Compensation Plans (Narra

Share Compensation Plans (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	11.6		11.6
Nonvested time-based shares [Member] | General and administrative expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 0.5	$ 0.4	$ 1.5	$ 1.2
Nonvested performance-based shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Nonvested performance-based shares [Member] | General and administrative expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 0.5	$ 0.3	$ 1.3	$ 1
2004 and 2012 Plans Combined [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available and reserved for grant	3.8		3.8
2012 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	5		5
2004 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	5.2		5.2
General Employee Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance	1.4		1.4

Share Compensation Plans (Chang

Share Compensation Plans (Changes In The Company's Nonvested Shares) (Details) - $ / shares	3 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Nonvested time-based shares [Member]
Nonvested Shares
Nonvested Shares, Beginning Balance	359,889	360,549	186,655
Nonvested Shares, Granted	2,233	2,652	206,974
Nonvested Shares, Vested	(1,919)	(2,747)	(33,080)
Nonvested Shares, Forfeited	(3,546)	(565)	0
Nonvested Shares, Ending Balance	356,657	359,889	360,549
Weighted-Average Grant-Date Fair Value
Nonvested shares, Weighted-Average Grant-Date Fair Value, Beginning Balance (in usd per share)	$ 10.63	$ 10.68	$ 13.97
Nonvested shares, Weighted-Average Grant-Date Fair Value, Granted (in usd per share)	14.32	10.13	8.03
Nonvested shares, Weighted-Average Grant-Date Fair Value, Vested (in usd per share)	13.18	14.24	13.88
Nonvested shares, Weighted-Average Grant-Date Fair Value, Forfeited (in usd per share)	11.10	13.02	0
Nonvested shares, Weighted-Average Grant-Date Fair Value, Ending Balance (in usd per share)	$ 10.63	$ 10.63	$ 10.68
Nonvested performance-based shares [Member]
Nonvested Shares
Nonvested Shares, Beginning Balance	565,562	565,562	379,277
Nonvested Shares, Granted			186,285
Nonvested Shares, Vested			0
Nonvested Shares, Forfeited	(2,695)		0
Nonvested Shares, Ending Balance	562,867	565,562	565,562
Weighted-Average Grant-Date Fair Value
Nonvested shares, Weighted-Average Grant-Date Fair Value, Beginning Balance (in usd per share)	$ 14.06	$ 14.06	$ 15.34
Nonvested shares, Weighted-Average Grant-Date Fair Value, Granted (in usd per share)			11.45
Nonvested shares, Weighted-Average Grant-Date Fair Value, Vested (in usd per share)
Nonvested shares, Weighted-Average Grant-Date Fair Value, Forfeited (in usd per share)
Nonvested shares, Weighted-Average Grant-Date Fair Value, Ending Balance (in usd per share)	$ 12.28	$ 14.06	$ 14.06

Share Compensation Plans (Compe

Share Compensation Plans (Compensation Expense of Nonvested Shares) (Details) $ in Thousands	Sep. 30, 2016USD ($)
Nonvested time-based shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining 2,016	$ 548
2,017	1,203
2,018	587
2,019	8
Total	2,346
Nonvested performance-based shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining 2,016	611
2,017	1,796
2,018	933
2,019	0
Total	$ 3,340

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income tax (provision) benefit	$ (3,142)	$ 2,464	$ (2,367)	$ 8,127
Discrete income tax benefit (provision)			(3,500)	10,600
Discrete income tax benefit, restructure of internal operations and creation of subsidiary				8,300
Uncertain tax benefits	3,700		3,700
Interest and penalties accrued	$ 100		100
Cash paid for income taxes			$ 300	$ 13,100

Debt and Capital Lease Obliga43

Debt and Capital Lease Obligations (Narrative) (Details)	Dec. 31, 2015USD ($)	Oct. 31, 2012USD ($)$ / sharesshares	Jan. 31, 2012USD ($)	Dec. 31, 2011USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)
Debt Instruments
Gain (loss) on extinguishment of debt, net					$ 0	$ (4,010,000)	$ 0	$ (4,010,000)
Credit facility termination fees	$ 200,000
Capitalized Interest
Capitalized interest					$ 2,300,000	$ 1,500,000	$ 6,200,000	$ 4,200,000
1.75% Convertible Debentures [Member]
Debt Instruments
Stated interest rate	1.75%				1.75%	1.75%	1.75%	1.75%
Convertible debt ratio		0.0604961
1.875% Convertible Debentures [Member]
Debt Instruments
Stated interest rate	1.875%				1.875%	1.875%	1.875%	1.875%
Convertible debentures	$ 500,000
Convertible Debt [Member] | 1.75% Convertible Debentures [Member]
Debt Instruments
Debt, principal amount		$ 396,750,000
Stated interest rate		1.75%
Debt conversion price (in usd per share) | $ / shares		$ 16.53
Embedded conversion feature, warrant, conversion ratio (in shares) | shares		30.2481
Embedded conversion feature, warrant, conversion price (in usd per share) | $ / shares		$ 16.53
Effective term of debt instrument		7 years
Adjustments to equity, component of convertible debt treated as additional debt discount		$ 141,600,000
Debt issuance costs		$ 12,400,000
Debt and equity issuance costs amortization period		7 years
Principal amount of debt repurchased						$ 61,600,000
Cash paid to repurchase debt						59,400,000
Reduction of debt component						50,700,000
Reduction of debt discount						10,900,000
Write off of debt and equity issuance costs						700,000
Gain (loss) on extinguishment of debt, net						(4,200,000)
Effective interest rate		8.50%
Convertible debentures	254,600,000				$ 268,600,000		$ 268,600,000
Unamortized discount	76,754,000				63,456,000		63,456,000
Deferred debt issue costs	$ 3,821,000				$ 3,159,000		$ 3,159,000
Convertible Debt [Member] | 1.875% Convertible Debentures [Member]
Debt Instruments
Stated interest rate					1.875%		1.875%
Principal amount of debt repurchased						1,700,000
Cash paid to repurchase debt						1,600,000
Gain (loss) on extinguishment of debt, net						$ 100,000
Convertible debentures					$ 500,000		$ 500,000
Revolving Credit Facility [Member] | Credit Agreement [Member]
Debt Instruments
Debt issuance costs			$ 200,000	$ 1,100,000
Credit agreement			$ 125,000,000	$ 100,000,000
Revolving Credit Facility [Member] | Credit Agreement [Member] | Minimum [Member]
Debt Instruments
Commitment fee on unutilized borrowing capacity			0.375%
Revolving Credit Facility [Member] | Credit Agreement [Member] | Maximum [Member]
Debt Instruments
Commitment fee on unutilized borrowing capacity			0.50%

Debt and Capital Lease Obliga44

Debt and Capital Lease Obligations (Amortization of Debt Issuance Costs, Interest Expense and Cash Payments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Oct. 31, 2012
Debt Instrument [Line Items]
Amortization of debt issuance costs			$ 662	$ 1,665
1.75% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate	1.75%	1.75%	1.75%	1.75%	1.75%
1.875% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate	1.875%	1.875%	1.875%	1.875%	1.875%
Convertible Debt [Member] | 1.75% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate						1.75%
Amortization of debt issuance costs	$ 225	$ 240	$ 662	$ 714
Interest expense, net of capitalized interest	3,731	4,760	11,532	14,685
Cash payments for interest	$ 0	423	$ 2,933	3,894
Convertible Debt [Member] | 1.875% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate	1.875%		1.875%
Interest expense, net of capitalized interest	$ 2	7	$ 5	23
Cash payments for interest	5	21	10	42
Revolving Credit Facility [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Amortization of debt issuance costs	0	69	0	204
Fees	0	253	0	839
Capital Lease [Member]
Debt Instrument [Line Items]
Interest expense, net of capitalized interest	0	21	8	87
Cash payments for interest	$ 0	$ 21	$ 8	$ 87

Debt and Capital Lease Obliga45

Debt and Capital Lease Obligations (Current and Long-Term Debt Balances) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Oct. 31, 2012
Current
Capital lease obligation	$ 0	$ 580
Small land purchase	0	77
Total debt balances, Current	0	657
Long-Term
Debt balance	269,059	255,099
Capital lease obligation	0	0
Small land purchase	$ 0	$ 0
1.75% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate	1.75%	1.75%	1.75%
1.875% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate	1.875%	1.875%	1.875%
Convertible Debt [Member] | 1.75% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate				1.75%
Current
Debt, Current	$ 0	$ 0
Long-Term
Aggregate principal	335,150	335,150
Debt discount	(63,456)	(76,754)
Deferred debt issue costs	(3,159)	(3,821)
Debt balance	$ 268,535	254,575
Convertible Debt [Member] | 1.875% Convertible Debentures [Member]
Debt Instrument [Line Items]
Stated interest rate	1.875%
Current
Debt, Current	$ 0	0
Long-Term
Aggregate principal	$ 524	$ 524

Mineral Properties and Mine D46

Mineral Properties and Mine Development (Schedule of Mineral Properties) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Mining Properties, Mineral Rights and Mine Development [Member]
Property, Plant and Equipment [Line Items]
Mineral properties and mine development, gross	$ 1,095,361	$ 1,030,542
Accumulated depletion and amortization	(502,615)	(457,311)
Total mineral properties and mine development, net	592,746	573,231
Montana, United States of America [Member] | Mining Properties and Mineral Rights [Member] | Stillwater Mine [Member]
Property, Plant and Equipment [Line Items]
Mineral properties and mine development, gross	1,950	1,950
Montana, United States of America [Member] | Mine Development [Member] | Stillwater Mine [Member]
Property, Plant and Equipment [Line Items]
Mineral properties and mine development, gross	751,630	697,781
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	231,251	220,281
Ontario, Canada [Member] | Mining Properties and Mineral Rights [Member] | Marathon Property [Member]
Property, Plant and Equipment [Line Items]
Mineral properties and mine development, gross	8,560	8,560
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	$ 101,970

Property, Plant and Equipment47

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 358,019		$ 358,019		$ 351,792
Accumulated depreciation	(254,796)		(254,796)		(241,835)
Total property, plant, and equipment, net	103,223		103,223		109,957
Payments to Acquire Productive Assets [Abstract]
Non-cash capitalized interest and depreciation			(7,551)	$ (6,756)
Change in accounts payables for capital expenditures			(2,964)	1,777
Cash capital spend for the period	23,554	$ 25,168	61,980	83,386
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	163,297		163,297		161,292
Buildings and structural components [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	174,279		174,279		173,580
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	11,740		11,740		11,740
Construction-in progress [Member] | Stillwater Mine [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	6,666		6,666		2,615
Construction-in progress [Member] | East Boulder Mine [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	513		513		435
Construction-in progress [Member] | Marathon Property [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	148		148		148
Construction-in progress [Member] | Processing Facilities and Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 1,376		1,376		$ 1,982
United States [Member]
Payments to Acquire Productive Assets [Abstract]
Capital expenditures			72,495	88,319
United States [Member] | Stillwater Mine [Member]
Payments to Acquire Productive Assets [Abstract]
Capital expenditures			60,345	70,172
United States [Member] | East Boulder Mine [Member]
Payments to Acquire Productive Assets [Abstract]
Capital expenditures			11,508	13,548
United States [Member] | Other Mine [Member]
Payments to Acquire Productive Assets [Abstract]
Capital expenditures			642	4,599
Non-US [Member]
Payments to Acquire Productive Assets [Abstract]
Capital expenditures			$ 0	$ 46

Segment Information (Narrative)

Segment Information (Narrative) (Details)	9 Months Ended
	Sep. 30, 2016SegmentBusiness_Component
Segment Reporting Information [Line Items]
Number of business segments | Segment	5
Mine Production [Member]
Segment Reporting Information [Line Items]
Number of business components | Business_Component	2

Segment Information (Financial

Segment Information (Financial Information Related To The Company's Business Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 196,617	$ 168,441	$ 495,938	$ 554,345
Costs of metals sold	151,758	147,932	397,324	445,750
Depletion, depreciation and amortization	17,771	15,362	55,742	49,681
General and administrative expenses	8,692	8,911	25,300	27,652
Interest income	1,213	766	2,883	2,192
Interest expense	3,958	5,097	12,207	15,713
Income (loss) before impairment charge and income tax provision				10,485
Impairment charge	0	0	0	46,772
INCOME (LOSS) BEFORE INCOME TAX (PROVISION) BENEFIT	15,741	(14,493)	5,819	(36,287)
Capital expenditures	23,554	25,168	61,980	83,386
Total assets	1,307,910	1,317,187	1,307,910	1,317,187	$ 1,278,389
Cash and cash equivalents	112,967	133,956	112,967	133,956	$ 147,336	$ 280,286
Mine Production [Member] | Business Segments [Member]
Segment Reporting Information [Line Items]
Revenues	106,926	86,359	299,123	331,065
Costs of metals sold	65,580	69,004	208,612	229,676
Depletion, depreciation and amortization	17,587	15,132	55,173	48,943
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 tax provision				52,446
Impairment charge				0
INCOME (LOSS) BEFORE INCOME TAX (PROVISION) BENEFIT	23,759	2,224	35,338	52,446
Capital expenditures	23,557	24,661	61,410	77,370
Total assets	624,814	608,198	624,814	608,198
PGM Recycling [Member] | Business Segments [Member]
Segment Reporting Information [Line Items]
Revenues	89,591	81,982	196,515	222,980
Costs of metals sold	86,178	78,928	188,712	216,074
Depletion, depreciation and amortization	184	230	569	738
General and administrative expenses	0	0	0	0
Interest income	617	437	1,376	1,256
Interest expense	0	0	0	0
Income (loss) before impairment charge and income tax provision				7,424
Impairment charge				0
INCOME (LOSS) BEFORE INCOME TAX (PROVISION) BENEFIT	3,876	3,261	8,611	7,424
Capital expenditures	4	57	14	221
Total assets	88,153	70,113	88,153	70,113
Canadian Properties [Member] | Business Segments [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Costs of metals sold	0	0	0	0
Depletion, depreciation and amortization	0	0	0	0
General and administrative expenses	204	275	543	790
Interest income	1	1	2	7
Interest expense	0	0	0	0
Income (loss) before impairment charge and income tax provision				(1,364)
Impairment charge				46,772
INCOME (LOSS) BEFORE INCOME TAX (PROVISION) BENEFIT	(353)	(577)	(740)	(48,136)
Capital expenditures	0	0	0	0
Total assets	25,549	27,078	25,549	27,078
Cash and cash equivalents		17,100		17,100
South American Properties [Member] | Business Segments [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Costs of metals sold	0	0	0	0
Depletion, depreciation and amortization	0	0	0	0
General and administrative expenses	381	100	1,064	454
Interest income	0	4	1	23
Interest expense	0	0	0	0
Income (loss) before impairment charge and income tax provision				(1,216)
Impairment charge				0
INCOME (LOSS) BEFORE INCOME TAX (PROVISION) BENEFIT	(258)	(339)	(2,886)	(1,216)
Capital expenditures	0	0	0	46
Total assets	103,351	104,265	103,351	104,265
All Other [Member] | Business Segments [Member]
Segment Reporting Information [Line Items]
Revenues	100	100	300	300
Costs of metals sold	0	0	0	0
Depletion, depreciation and amortization	0	0	0	0
General and administrative expenses	8,107	8,536	23,693	26,408
Interest income	595	324	1,504	906
Interest expense	3,958	5,097	12,207	15,713
Income (loss) before impairment charge and income tax provision				(46,805)
Impairment charge				0
INCOME (LOSS) BEFORE INCOME TAX (PROVISION) BENEFIT	(11,283)	(19,062)	(34,504)	(46,805)
Capital expenditures	(7)	450	556	5,749
Total assets	$ 466,043	$ 507,533	$ 466,043	$ 507,533

Investments (Narrative) (Detail

Investments (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Investments reserved as collateral on undrawn letters of credit	$ 18,500,000		$ 18,500,000		$ 18,500,000
Gain on sale of long term investment	196,000	$ 0	678,000	$ 0
Impairment of investments	0	$ 200,000	0	$ 200,000
Other Noncurrent Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Long-term investments (less than for 2016)	100,000		100,000		500,000
Letter of Credit [Member]
Schedule of Available-for-sale Securities [Line Items]
Undrawn letters of credit	$ 17,500,000		$ 17,500,000		$ 17,500,000

Investments (Schedule of Availa

Investments (Schedule of Available-for-sale Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 327,166	$ 317,488
Gross unrealized gains	310	261
Gross unrealized losses	(85)	(577)
Fair value	327,391	317,172
Subtotal [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	326,409	317,006
Gross unrealized gains	121	0
Gross unrealized losses	(85)	(577)
Fair value	326,445	316,429
Federal agency notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	290,279	285,276
Gross unrealized gains	73	0
Gross unrealized losses	(85)	(519)
Fair value	290,267	284,757
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	36,130	31,730
Gross unrealized gains	48	0
Gross unrealized losses	0	(58)
Fair value	36,178	31,672
Mutual funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	757	482
Gross unrealized gains	189	261
Gross unrealized losses	0	0
Fair value	$ 946	$ 743

Investments (Schedule of Maturi

Investments (Schedule of Maturities of Available-for-sale Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 327,166	$ 317,488
Fair value	327,391	317,172
Federal agency notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost, due in one year or less	223,442
Fair value, due in one year or less	223,423
Amortized cost, due after one year through three years	66,837
Fair value, due after one year through three years	66,844
Amortized cost	290,279	285,276
Fair value	290,267	284,757
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost, due in one year or less	14,235
Fair value, due in one year or less	14,242
Amortized cost, due after one year through three years	21,895
Fair value, due after one year through three years	21,936
Amortized cost	36,130	31,730
Fair value	$ 36,178	$ 31,672

Inventories (Components Of Inve

Inventories (Components Of Inventories) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Metals inventory
Raw ore	$ 4,753	$ 4,234
Concentrate and in-process	71,495	43,727
Finished goods	46,057	32,618
Total metals inventory	122,305	80,579
Materials and supplies	18,476	21,493
Total inventories	$ 140,781	$ 102,072

Earnings Per Share (Reconciliat

Earnings Per Share (Reconciliation of Computation of Basic and Diluted Shares and the Related Impact on Income) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Basic EPS
Net income attributable to common stockholders	$ 12,599	$ (11,878)	$ 3,452	$ (16,352)
Basic EPS, Weighted Average Shares (Denominator) (in shares)	121,077	120,960	121,069	120,746
Basic EPS, Per Share Amount (in usd per share)	$ 0.10	$ (0.10)	$ 0.03	$ (0.14)
Effect of Dilutive Securities
Stock options (in shares)	1		1
Nonvested time-based shares (in shares)	166		68
Contingently issuable shares (in shares)	368		300
1.875% Convertible debentures, net of tax	$ 1		$ 0
1.875% Convertible debentures, net of tax (in shares)	22		0
Diluted EPS
Net income attributable to common stockholders	$ 12,600		$ 3,452
Diluted EPS, Weighted Average Shares (Denominator) (in shares)	121,634	120,960	121,438	120,746
Diluted EPS, Per Share Amount (in usd per share)	$ 0.10	$ (0.10)	$ 0.03	$ (0.14)
1.875% Convertible Debentures [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stated interest rate	1.875%	1.875%	1.875%	1.875%	1.875%

Earnings Per Share (Anti-diluti

Earnings Per Share (Anti-dilutive Shares Excluded From Calculation of Diluted Earnings Per Share) (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted earnings per share	3	6	0	6
Nonvested time-based shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted earnings per share	1	44	10	50
Contingently issuable shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted earnings per share	222	218	234	218
1.875% Convertible Debentures [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stated interest rate	1.875%	1.875%	1.875%	1.875%	1.875%
1.875% Convertible Debentures [Member] | Convertible debentures [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted earnings per share	0	22	22	22
1.75% Convertible Debentures [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stated interest rate	1.75%	1.75%	1.75%	1.75%	1.75%
1.75% Convertible Debentures [Member] | Convertible debentures [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted earnings per share	30,413	30,413	30,413	30,413

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details)	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
1.875% Convertible Debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	1.875%	1.875%	1.875%
1.75% Convertible Debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	1.75%	1.75%	1.75%

Fair Value Measurements (Financ

Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 326,445	$ 316,429
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market fund	35,863	54,761
Mutual funds	946	743
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market fund	35,863	54,761
Mutual funds	946	743
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market fund	0	0
Mutual funds	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market fund	0	0
Mutual funds	0	0
Fair Value, Measurements, Recurring [Member] | Federal Agency Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	290,267	284,757
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	290,267	284,757
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	36,178	31,672
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	36,178	31,672
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 (Fina58

Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On A Nonrecurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
1.875% Convertible Debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	1.875%	1.875%	1.875%
1.75% Convertible Debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	1.75%	1.75%	1.75%
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		$ 524
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		524
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		0
Fair Value, Measurements, Nonrecurring [Member] | 1.875% Convertible Debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible debentures, fair value	$ 524	524
Fair Value, Measurements, Nonrecurring [Member] | 1.875% Convertible Debentures [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible debentures, fair value	0	0
Fair Value, Measurements, Nonrecurring [Member] | 1.875% Convertible Debentures [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible debentures, fair value	524	524
Fair Value, Measurements, Nonrecurring [Member] | 1.875% Convertible Debentures [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible debentures, fair value	0	0
Fair Value, Measurements, Nonrecurring [Member] | 1.75% Convertible Debentures [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible debentures, fair value	316,170	285,446
Fair Value, Measurements, Nonrecurring [Member] | 1.75% Convertible Debentures [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible debentures, fair value	0	0
Fair Value, Measurements, Nonrecurring [Member] | 1.75% Convertible Debentures [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible debentures, fair value	316,170	285,446
Fair Value, Measurements, Nonrecurring [Member] | 1.75% Convertible Debentures [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible debentures, fair value	$ 0	$ 0

Related Parties (Narrative) (De

Related Parties (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2015
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners			25.00%
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Revenue from related parties	$ 15.2	$ 38.7