Payables and Accruals [Abstract] Accrued Expenses Accrued Liabilities, Current [Abstract] Defined contribution plan Other Postretirement Benefits Payable Professional fees Accrued Professional Fees, Current Accrued payroll and related benefits Employee-related Liabilities, Current Sales and use tax Sales and Excise Tax Payable, Current Bonus accrual Accrued Bonuses, Current Interest payable Interest Payable, Current Advance from customer Customer Advances, Current Withholding taxes Accrued Payroll Taxes Amount payable to noncontrolling interest Amount payable to noncontrolling interest Amount payable to noncontrolling interest Other accrued expenses Other Accrued Liabilities, Current Total accrued expenses Accrued Liabilities, Current Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill Schedule of Goodwill [Table Text Block] Schedule of amortizable intangible assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Expected Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Equity [Abstract] Debt Conversion [Table] Debt Conversion [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 5.50% Convertible Notes, net of discount, due February 2018 Five Point Fifty Percent Convertible Senior Notes due Two Thousand Eighteen [Member] Five Point Fifty Percent Convertible Senior Notes due Two Thousand Eighteen [Member] 6.00% Convertible Notes, net of discount, due September 2017 six percent convertible senior notes [Member] six percent convertible senior notes [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Convertible Debt Convertible Debt [Member] Senior Notes Senior Notes [Member] Debt Conversion Description [Axis] Debt Conversion Description [Axis] Debt Conversion, Name [Domain] Debt Conversion, Name [Domain] Convertible Senior Notes, 5.50% and 6.00% Convertible Senior Notes, 5.50% and 6.00% [Member] Convertible Senior Notes, 5.50% and 6.00% [Member] Debt Conversion [Line Items] Debt Conversion [Line Items] Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Debt Conversion, Converted Instrument, Shares Issued Debt Conversion, Converted Instrument, Shares Issued Debt Instrument, Face Amount Debt Instrument, Face Amount Deferred taxes on component of convertible debt Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature Goodwill Goodwill Difference between consideration transferred to the holder and the fair value of liability component Difference between consideration transferred to the holder and the fair value of liability component Difference between consideration transferred to the holder and the fair value of liability component Income Tax Disclosure [Abstract] United States Income (Loss) from Continuing Operations before Income Taxes, Domestic Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Loss from continuing operations before income taxes and equity earnings Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Award Type [Domain] Equity Award [Domain] PBRSUs Performance Shares [Member] RSUs Restricted Stock Units (RSUs) [Member] Restricted Stock Restricted Stock [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Summary of Activity Related to Stock-based Awards Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Schedule of Finite-Lived and Indefinite-lived Intangible Assets [Table] Schedule of Finite-Lived and Indefinite-lived Intangible Assets [Table] Schedule of Finite-Lived and Indefinite-lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Customer relationships Customer Relationships [Member] Rare earths quotas Rare Earth Quotas [Member] Rare Earth Quotas [Member] Patents Patents [Member] Trade names Trade Names [Member] Land use rights Use Rights [Member] Other Other Intangible Assets [Member] Finite-Lived and Indefinite-lived Intangible Assets [Line Items] [Line Items] Finite-Lived and Indefinite-lived Intangible Assets [Line Items] [Line Items] Finite-Lived and Indefinite-lived Intangible Assets [Line Items] [Line Items] Finite-Lived and Indefinite-lived Intangible Assets [Roll Forward] Finite-Lived and Indefinite-lived Intangible Assets [Roll Forward] Finite-Lived and Indefinite-lived Intangible Assets [Roll Forward] Gross carrying amount Finite-lived Intangible Assets [Roll Forward] At period start Finite-Lived Intangible Assets, Gross Additions Finite-lived Intangible Assets Acquired Foreign currency translation adjustment Finite-Lived Intangible Assets, Translation Adjustments Impairment Impairment of Intangible Assets, Finite-lived At period end Accumulated Amortization Accumulated Amortization of Intangible Assets Roll Forward [Roll Forward] Accumulated Amortization of Intangible Assets Roll Forward [Roll Forward] At period start Finite-Lived Intangible Assets, Accumulated Amortization Amortization Amortization of Intangible Assets Adjustments Accumulated Amortization, Finite-lived, Adjustments Accumulated Amortization, Adjustments Impairment Accumulated Amortization, Impairments Accumulated Amortization, Impairments At period end Net book value Intangible Assets, Net (Excluding Goodwill) Investments, Debt and Equity Securities [Abstract] Schedule of Equity and Cost Method Investments [Table] [Table] Schedule of Equity and Cost Method Investments [Table] [Table] Schedule of Equity and Cost Method Investments [Table] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Boulder Wind Power, Inc. Boulder Wind Power, Inc. [Member] Boulder Wind Power, Inc. [Member] Intermetallics Japan Joint Venture (IMJ) Intermetallics Japan Joint Venture (IMJ) [Member] Intermetallics Japan Joint Venture (IMJ) [Member] Keli Ganzhou Keli Rare Earth New Material [Member] Ganzhou Keli Rare Earth New Material [Member] Ingal Stade Ingal Stade GmbH [Member] Ingal Stade GmbH [Member] Other investments Other equity method investments [Member] Other equity method investments [Member] Schedule of Equity and Cost Method Investments [Table] [Line Items] Schedule of Equity and Cost Method Investments [Table] [Line Items] [Line Items] for Schedule of Equity and Cost Method Investments [Table] Equity and Cost Method Investment [Roll Forward] Equity and Cost Method Investment [Roll Forward] Equity and Cost Method Investment [Roll Forward] Beginning of period Cost Method Investments Additions Payments to Acquire Other Investments Impairment Cost-method Investments, Other than Temporary Impairment End of period Beginning of period Equity Method Investments Additions Payments to Acquire Equity Method Investments Equity (loss) income Income (Loss) from Equity Method Investments Dividends Proceeds from Equity Method Investment, Dividends or Distributions Adjustment to investments classification Adjustment to investments classification Adjustment to investments classification Impairment Equity Method Investment, Other than Temporary Impairment Equity (loss) income Cost-method Investments, Realized Gain (Loss) Income (Loss) from Equity Method Investments, excluding other-than-temporary impairment Income (Loss) from Equity Method Investments, excluding other-than-temporary impairment Income (Loss) from Equity Method Investments, excluding other-than-temporary impairment End of period Beginning of period Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Impairment Equity and Cost Method Investment, Other than Temporary Impairment Equity and Cost Method Investment, Other than Temporary Impairment End of period Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Officers, Directors and Other Related Parties Officers, Directors and Other Related Parties [Member] Officers, Directors and Other Related Parties [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Additional Paid-In Capital Additional Paid-in Capital [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Proceeds from Related Party Debt Proceeds from Related Party Debt Debt Instrument, Face Amount, Underwriter Option to Purchase Additional Principal Debt Instrument, Face Amount, Underwriter Option to Purchase Additional Principal Debt Instrument, Face Amount, Underwriter Option to Purchase Additional Principal Proceeds from Issuance of Long-term Debt Proceeds from Issuance of Long-term Debt Debt Instrument, Convertible, Conversion Ratio Debt Instrument, Convertible, Conversion Ratio Debt Instrument, Convertible, Conversion Price Debt Instrument, Convertible, Conversion Price Debt Instrument, Threshold Percentage Above Which Company Has Right To Redeem Notes Debt Instrument, Threshold Percentage Above Which Company Has Right To Redeem Notes Debt Instrument, Threshold Percentage Above Which Company Has Right To Redeem Notes Debt Instrument, Convertible, Threshold Trading Days Debt Instrument, Convertible, Threshold Trading Days Debt Instrument, Convertible, Threshold Consecutive Trading Days Debt Instrument, Convertible, Threshold Consecutive Trading Days Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt Gain on extinguishment of convertible notes, net Gains (Losses) on Extinguishment of Debt Goodwill Schedule of future minimum rental payments for operating leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of minimum payments for purchase obligations Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Amount Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] 3.25% Convertible Notes due June 2016 three and a quarter convertible senior notes [Member] three and a quarter convertible senior notes [Member] 6.00% Convertible Notes due September 2017 5.50% Convertible Notes due February 2018 10% Senior Secured Notes due June 2020 ten percent senior secured notes [Member] ten percent senior secured notes [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long-term Debt, Excluding Current Maturities Long-term Debt, Excluding Current Maturities Long-term Debt, Fair Value Long-term Debt, Fair Value Earnings Per Share [Abstract] Schedule of loss per share, basic and diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Trade accounts receivable, net (Note 3) Accounts Receivable, Net, Current Inventory (Note 5) Inventory, Net Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Non-current assets: Assets, Noncurrent [Abstract] Deposits (Note 6) Deposits Assets, Noncurrent Property, plant and equipment, net (Note 7) Property, Plant and Equipment, Net Inventory (Note 5) Inventory, Noncurrent Intangible assets, net (Note 9) Investments (Note 10) Long-term Investments Goodwill (Note 9) Other non-current assets Other Assets, Noncurrent Total non-current assets Assets, Noncurrent Total assets Assets LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Trade accounts payable Accounts Payable, Trade, Current Accrued expenses (Note 12) Debt and capital lease obligations (Note 14) Long-term Debt and Capital Lease Obligations, Current Other current liabilities Other Liabilities, Current Total current liabilities Liabilities, Current Non-current liabilities: Liabilities, Noncurrent [Abstract] Asset retirement obligation (Note 13) Mine Reclamation and Closing Liability, Noncurrent Deferred tax liabilities (Note 15) Deferred Tax Liabilities, Net, Noncurrent Debt and capital lease obligations (Note 14) Long-term Debt and Capital Lease Obligations Other non-current liabilities Other Liabilities, Noncurrent Total non-current liabilities Liabilities, Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 19) Commitments and Contingencies Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, $0.001 par value; 700,000,000 shares authorized at December 31, 2014 and 350,000,000 at December 31, 2013 (Note 16) Common Stock, Value, Issued Preferred stock, $0.001 par value; 5,000,000 shares authorized at December 31, 2013 (Note 16) Preferred Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated deficit Retained Earnings (Accumulated Deficit) Total Molycorp stockholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total stockholders’ equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and stockholders’ equity Liabilities and Equity Property, Plant and Equipment [Abstract] Property, Plant and Equipment, net Property, Plant and Equipment Disclosure [Text Block] Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Stock Common Stock [Member] Class of Stock [Line Items] Class of Stock [Line Items] Issuance of shares (in shares) Stock Issued During Period, Shares, New Issues Shares Issued During Period, Shares, New Issues, Underwriters Option to Purchase within 30 days Shares Issued During Period, Shares, New Issues, Underwriters Option to Purchase within 30 days Shares Issued During Period, Shares, New Issues, Underwriters Option to Purchase within 30 days Offering Price Per Share, Underwriters Offering Price Per Share, Underwriters Offering Price Per Share, Underwriters Shares Issued During Period, Shares, New Issues, Underwriter Fees Shares Issued During Period, Shares, New Issues, Underwriter Fees Shares Issued During Period, Shares, New Issues, Underwriter Fees Shares Issued During Period, Shares, New Issues, Purchased by Related Parties Shares Issued During Period, Shares, New Issues, Purchased by Related Parties Shares Issued During Period, Shares, New Issues, Purchased by Related Parties Net proceeds from sale of common stock Proceeds from Issuance of Common Stock Offering Price Per Share Offering Price Per Share Offering Price Per Share Own-share Lending Arrangement, Shares, Maximum Shares Allowed Own-share Lending Arrangement, Shares, Maximum Shares Allowed Own-share Lending Arrangement, Shares, Maximum Shares Allowed Own-share Lending Arrangement, Shares, Issued Own-share Lending Arrangement, Shares, Issued Own-share Lending Arrangement, Shares, Issued, Offered in Registered Public Offering, Price Per Share Own-share Lending Arrangement, Shares, Issued, Offered in Registered Public Offering, Price Per Share Own-share Lending Arrangement, Shares, Issued, Offered in Registered Public Offering, Price Per Share 2015 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2016 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2017 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2018 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Five Thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Net Change in Operating Assets and Liabilities -- None. No documentation exists for this element. -- Decrease (increase) in operating assets: Increase (Decrease) in Operating Assets [Abstract] Trade accounts receivable Increase (Decrease) in Accounts Receivable Inventory Increase (Decrease) in Inventories Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Increase (decrease) in operating liabilities: Increase (Decrease) in Operating Liabilities [Abstract] Accounts payable Increase (Decrease) in Accounts Payable Income tax payable Increase (Decrease) in Income Taxes Payable, Net of Income Taxes Receivable Interest payable Increase (Decrease) in Interest Payable, Net Asset retirement obligation Increase (Decrease) in Asset Retirement Obligations Accrued expenses Increase (Decrease) in Accrued Liabilities Net change in operating assets and liabilities Increase (Decrease) in Operating Capital Compensation and Retirement Disclosure [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Pension Plan and Other Postretirement Benefit Plan Other Pension Plan, Postretirement or Supplemental Plans [Member] Pension Plan Pension Plan [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Molycorp Canada Molycorp Canada [Member] Molycorp Canada [Member] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Groups, Including Discontinued Operations, Name [Domain] Disposal Groups, Including Discontinued Operations, Name [Domain] Anderson, Indiana Manufacturing Facility Anderson, Indiana Manufacturing Facility [Member] Anderson, Indiana Manufacturing Facility [Member] Defined Benefit Plan, Asset Categories [Axis] Defined Benefit Plan, Asset Categories [Axis] Plan Asset Categories [Domain] Plan Asset Categories [Domain] Debt Securities Debt Securities [Member] Equity Securities Equity Securities [Member] Interest-bearing Deposits Interest-bearing Deposits [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Company matching contribution as a percentage of the first 3.0% compensation contributed by each eligible employee Defined Contribution Plan, Employer Match, Level One Defined Contribution Plan, Employer Match, Level One Percentage of each employee's compensation eligible for Company match of 100% in defined contribution plan Defined Contribution Plan, Employer Match Employee Contribution Level One Defined Contribution Plan, Employer Match Employee Contribution Level One Company matching contribution as a percentage of the next 2.0% of compensation contributed by each eligible employee Defined Contribution Plan, Employer Match Level Two Defined Contribution Plan, Employer Match Level Two Percentage of each employee's compensation eligible for Company match of 50% in defined contribution plan Defined Contribution Plan, Employer Match Employee Contribution Level Two Defined Contribution Plan, Employer Match Employee Contribution Level Two Safe harbor matching contribution vesting percentage Defined contribution plan safe harbor matching contribution vesting percentage Defined contribution plan, safe harbor matching contribution vesting percentage Vesting percentage of discretionary matching contribution after 3 years of service Defined contribution plan, vesting percentage of discretionary matching contribution after three years of service Defined contribution plan, vesting percentage of discretionary matching contribution after three years of service Period of service after which employees vest in Company contributions Defined Contribution Plan, Requisite Service Period for Employee Vesting Defined Contribution Plan, Requisite Service Period for Employee Vesting Expenses related to defined contribution plan Defined Contribution Plan, Cost Recognized Defined contribution plan, accrued expense Defined contribution plan, accrued expense Defined contribution plan, accrued expense Number of participants Defined Benefit Plan, Number of Participants Defined Benefit Plan, Number of Participants Benefit obligation Defined Benefit Plan, Benefit Obligation Funded status of plan Defined Benefit Plan, Funded Status of Plan Fair value of plan assets Defined Benefit Plan, Fair Value of Plan Assets Risks and Uncertainties [Abstract] Concentration Risk [Table] Concentration Risk [Table] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Cerium products Cerium Products [Member] Represents the cerium products. Neo Powders Neo Powders [Member] Neo Powders [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Product Concentration Sales Revenue, Goods, Net [Member] Chemicals and Oxides Chemicals and Oxides [Member] Chemicals and Oxides [Member] Daido Electronics Daido Electronics [Member] Daido Electronics [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Magnetic Materials and Alloys Magnetic Materials and Alloys [Member] Magnetic Materials and Alloys [Member] Concentrations Concentration Risk [Line Items] Entity-wide revenue, major customers Concentration Risk, Percentage Sales to related party Revenue from Related Parties Related party receivables Accounts Receivable, Related Parties Business Combinations [Abstract] Acquisitions Business Combination Disclosure [Text Block] Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Net Change in Operating Assets and Liabilities Net Change in Operating Assets and Liabilities Disclosure [Text Block] Disclosure of net change in operating assets and liabilities during the period. Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Chinese Land Use Rights Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other current assets Other Current Assets [Member] Inventory Inventories [Member] Property, plant and equipment Property, Plant and Equipment [Member] Other non-current assets Other Noncurrent Assets [Member] Other current liabilities Other Current Liabilities [Member] Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss) [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Revenues Sales [Member] Costs of sales Cost of Sales [Member] Foreign exchange gain Foreign Currency Gain (Loss) [Member] Net loss Net Income (Loss) [Member] Net Income (Loss) [Member] Foreign currency translation adjustments Accumulated Translation Adjustment [Member] Comprehensive loss Other Comprehensive Income (Loss) [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Finite-lived intangible asset useful life Finite-Lived Intangible Asset, Useful Life Out-of-Period Adjustments, Interim Periods of Fiscal Year Quantifying Misstatement in Current Year Financial Statements, Amount Statement of Cash Flows [Abstract] Statement [Table] Statement [Table] 10% Senior Secured Notes, net of discount, due June 2020 Statement [Line Items] Statement [Line Items] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net loss Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net loss to net cash from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation, amortization and accretion Depreciation, Depletion and Amortization Deferred income tax benefit Deferred Income Tax Noncash Expense Benefit The noncash component of income tax expense for the period representing the increase (decrease) in the entity's deferred tax assets and liabilities pertaining to continuing operations. Inventory write-downs Inventory Write-down Including Stockpile Inventories Inventory Write-down Including Stockpile Inventories Release of inventory step-up value Release of inventory step-up value Release of inventory step-up value Impairment of goodwill and other long-lived assets Asset Impairment Charges Impairment of investments Other than Temporary Impairment Losses, Investments Stock-based compensation Share-based Compensation Equity in results of affiliates Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Gain on extinguishment of convertible notes, net PIK interest Paid-in-Kind Interest Change in fair value of embedded derivative Embedded Derivative, Loss on Embedded Derivative Amortization of issuance costs Amortization of Financing Costs Impairment of other receivables Impairment of Other Receivables Impairment of Other Receivables Other operating activities Other Noncash Income (Expense) Net change in operating assets and liabilities (Note 22) Net cash used in operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Cash paid in connection with acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Investment in joint ventures Payments to Acquire Interest in Joint Venture Dividends received from equity investment Capital expenditures Payments to Acquire Property, Plant, and Equipment Acquisition of exploration rights Payments to Acquire Mineral Rights Recovery from insurance claims Proceeds from Insurance Settlement, Investing Activities Other investing activities Payments for (Proceeds from) Productive Assets Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Issuance of shares to Molymet Proceeds from Contributed Capital Repayments of debt Repayments of Debt Issuance of Convertible Notes Proceeds from Convertible Debt Issuance of 10% Senior Secured Notes Proceeds from Issuance of Senior Long-term Debt Payments of preferred dividends Payments of Ordinary Dividends, Preferred Stock and Preference Stock Dividends paid to noncontrolling interests Payments of Ordinary Dividends, Noncontrolling Interest Proceeds from debt Proceeds from Bank Debt Debt issuance costs Payments of Debt Issuance Costs Proceeds from the 2014 Financings (Note 14) Proceeds from Issuance of Secured Debt Partial repayment of convertible notes Repayments of Convertible Debt Other financing activities Proceeds from (Payments for) Other Financing Activities Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash Effect of Exchange Rate on Cash and Cash Equivalents, Continuing Operations Net change in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of the period Cash and cash equivalents at end of period Summary of the current and non-current portions of the debt outstanding Schedule of Debt [Table Text Block] Schedule of Convertible Debt Convertible Debt [Table Text Block] Schedule of Maturities of Long-term Debt Schedule of Maturities of Long-term Debt [Table Text Block] Reconciliation of Principal to Net Carrying Amount of Long-term Debt Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Future Minimum Lease Payments for Capital Leases Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block] Common stock, par value Common Stock, Par or Stated Value Per Share Common stock, authorized Common Stock, Shares Authorized Preferred stock, par value Preferred Stock, Par or Stated Value Per Share Preferred stock, authorized Preferred Stock, Shares Authorized Employee Stock Purchase Plan Employee Stock [Member] RSAs, RSUs and PBRSUs Restricted Stock Awards, Restricted Stock Units and Performance Based Restricted Stock Units [Member] Restricted Stock Awards, Restricted Stock Units and Performance Based Restricted Stock Units [Member] Number of shares available for grant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Vesting period (in years) Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Percentage of units vesting Share Based Compensation Arrangement by Share Based Payment Award, Award Vesting Percentage Represents the percentage of units vesting on the basis of the achievement of certain management objectives measured by specified levels of total shareholder return. Matching contribution by entity (as a percent) Share Based Compensation Arrangement by Share Based Payment Award Matching Contribution by Entity as Percentage of Converted Restricted Stock Units Represents matching contribution by entity as a percentage of converted RSUs. Compensation cost not yet recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Weighted-average period for unrecognized compensation costs Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Supplemental Cash Flow Elements [Abstract] Supplemental Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Revenues and Costs of Sales Revenue Recognition Sales of Goods and Cost of Sales [Policy Text Block] [Policy Text Block] Revenue Recognition Sales of Goods and Cost of Sales [Policy Text Block] [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Trade Accounts Receivable Receivables, Policy [Policy Text Block] Inventory Inventory, Policy [Policy Text Block] Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Mineral Properties and Development Costs Mineral Properties and Development Costs [Policy Text Block] Mineral Properties and Development Costs [Policy Text Block] Intangible Assets Intangible Assets, Finite-Lived, Policy [Policy Text Block] Recoverability of Long-Lived Depreciable/Amortizable Assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Recoverability of Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Investments Investment, Policy [Policy Text Block] Business Combinations Business Combinations Policy [Policy Text Block] Asset Retirement Obligation Asset Retirement Obligations, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Foreign Currency Foreign Currency Transactions and Translations Policy [Policy Text Block] Comprehensive Income (Loss) Comprehensive Income, Policy [Policy Text Block] Earnings (Loss) per Share Earnings Per Share, Policy [Policy Text Block] Research and Development Research and Development Expense, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Income Statement [Abstract] Revenues Sales Revenue, Goods, Net Costs of sales: Cost of Goods Sold [Abstract] Costs excluding depreciation and amortization Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization Depreciation and amortization Cost of Goods Sold, Depreciation and Amortization Gross (loss) profit Gross Profit Operating expenses: Costs and Expenses [Abstract] Selling, general and administrative Selling, General and Administrative Expense Corporate development Business Combination, Acquisition Related Costs Depreciation, amortization and accretion Depreciation, Depletion and Amortization, Nonproduction Research and development Research and Development Expense Impairment of goodwill and other long-lived assets Operating loss Operating Income (Loss) Other (expense) income: Nonoperating Income (Expense) [Abstract] Other (expense) income Other Nonoperating Income (Expense) Foreign exchange (loss) gain, net Foreign Currency Transaction Gain (Loss), before Tax Interest expense, net of capitalized interest Interest Income (Expense), Nonoperating, Net Gain on extinguishment of convertible notes, net Impairment of investments at cost Total other expense Nonoperating Income (Expense) Income tax benefit Income Tax Expense (Benefit) Equity in loss of affiliates Loss from continuing operations Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest Loss from discontinued operations, net of tax Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Net loss Net loss (income) attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net loss attributable to Molycorp stockholders Net Income (Loss) Attributable to Parent Other comprehensive loss, net of tax: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Actuarial (loss) gain Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax Comprehensive loss Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive (loss) income attributable to: Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Molycorp stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Loss per share of common stock (Note 17): Basic: Earnings Per Share, Basic [Abstract] Continuing operations (in dollars per share) Income (Loss) from Continuing Operations, Per Basic Share Discontinued operations (in dollars per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share Basic (in dollars per share) Earnings Per Share, Basic Diluted: Earnings Per Share, Diluted [Abstract] Continuing operations (in dollars per share) Income (Loss) from Continuing Operations, Per Diluted Share Discontinued operations (in dollars per share) Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share Diluted (in dollars per share) Earnings Per Share, Diluted Inventory Disclosure [Abstract] Inventory, Current [Table] Inventory, Current [Table] Inventory [Axis] Inventory [Axis] Inventory [Domain] Inventory [Domain] Rare earth metals Rare earth metals [Member] Rare earth metals [Member] Stockpile Stockpile [Member] Stockpile [Member] Inventory [Line Items] Inventory [Line Items] Abnormal production costs expensed in the period Production Costs Expended that Would Have Been Allocated to Additional Tons Produced Production Costs Expended that Would Have Been Allocated to Additional Tons Produced Write-down to the lower of cost or market Inventory Write-down Write-downs of stockpile inventory Charges to Cost of Sales Based on Production Levels and Write-Down of Inventory Charges to Cost of Sales Based on Production Levels and Write-Down of Inventory Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Springing Maturity on Term Loans Springing Maturity on 12% Term Loans [Member] Springing Maturity on 12% Term Loans [Member] Strike Warrants Strike Warrants [Member] Strike Warrants [Member] Share Purchase Agreement Share Purchase Agreement [Member] Share Purchase Agreement [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Assets: Assets, Fair Value Disclosure [Abstract] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Liabilities: Liabilities, Fair Value Disclosure [Abstract] Derivative liabilities Derivative Liability Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Convertible Debt Securities Convertible Debt Securities [Member] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Exploration rights Exploration rights [Member] Exploration rights [Member] 5.00% Debentures, net of discount, due December 2017 five percent subordinated convertible notes [Member] five percent subordinated convertible notes [Member] Convertible Subordinated Debt Convertible Subordinated Debt [Member] Share Exchange [Axis] Share Exchange [Axis] Share Exchange [Axis] Share Exchange, Company [Domain] Share Exchange, Company [Domain] Share Exchange, Company [Domain] Molycorp Molycorp [Member] Molycorp [Member] MCP Exchangeco Inc. MCP Exchangeco Inc. [Member] MCP Exchangeco Inc. [Member] Molymet Molymet [Member] Molymet [Member] Property, plant and equipment at cost Property, Plant and Equipment, Gross Issuance of shares for acquisition of exploration rights (in shares) Stock Issued During Period, Shares, Purchase of Assets Sale of Stock, Price Per Share Sale of Stock, Price Per Share Payments to acquire exploration rights Tangible Asset Impairment Charges Tangible Asset Impairment Charges Issuance of shares for conversion of Debentures (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Stock price Share Price Underwriting discounts and commissions underwriting discounts and commissions underwriting discounts and commissions, percentage Flat fee paid to underwriters flat fee paid to underwriters flat fee paid to underwriters Primary shares purchased by insiders primary shares purchased by insiders primary shares purchased by insiders Common stock issued to acquire the entity (in shares) Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Fair value of Molycorp common stock and Exchangeable Shares issued Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Conversion of Exchangeable Shares Exchangeable Shares converted Exchangeable Shares converted Stock Issued During Period, Value, New Issues Stock Issued During Period, Value, New Issues Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Price Per Share of Common Stock Issued Price Per Share of Common Stock Issued Represents the price per share of common stock issued. Number of Days to Calculate Common Stock Price Number of Days to Calculate Common Stock Price Represents the number of days based on which the price of common stock was determined. Premium Percentage Added to Common Stock Price Premium Percentage Added to Common Stock Price Represents the premium percentage added to the common stock price. Summarizes the purchase prices and opening balance sheets for the acquisitions Schedule of Business Acquisitions, by Acquisition [Table Text Block] Summary of actual and pro forma information Business Acquisition, Pro Forma Information [Table Text Block] Schedule of Transaction Costs Schedule of Business Acquisitions, Transaction Costs by Type [Table Text Block] Schedule of Business Acquisitions, Transaction Costs by Type [Table Text Block] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Balance, beginning of year Unrecognized Tax Benefits Tax position related to current year: Unrecognized Tax Benefits, Tax Position Related to Current Year [Abstract] -- None. No documentation exists for this element. -- Additions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Tax positions related to prior years: Unrecognized Tax Benefits, Tax Position Related to Prior Years [Abstract] -- None. No documentation exists for this element. -- Additions Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Settlements Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Statute of limitations closures Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Balance, end of year Schedule of Components of Income Tax Expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Income before Income Tax, Domestic and Foreign Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Income Tax Contingencies Summary of Income Tax Contingencies [Table Text Block] Related Party Transactions [Abstract] Related-Party Transactions Related Party Transactions Disclosure [Text Block] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Intermetallics Japan Corporate Joint Venture [Member] Other Nonoperating Income (Expense) Other Nonoperating Income (Expense) [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Daido Daido Steel Co. Ltd [Member] Represents Daido Steel Co., Ltd (Daido), a co-venturer in a corporate joint venture of the entity. A corporate joint venture refers to a corporation owned and operated by a small group of businesses (the joint venturers) as a separate and specific business or project for the mutual benefit of the members of the group. Mitsubishi Mitsubishi Corporation [Member] Represents Mitsubishi Corporation (Mitsubishi), a co-venturer in a corporate joint venture of the entity. A corporate joint venture refers to a corporation owned and operated by a small group of business (the joint venturers) as a separate and specific business or project for the mutual benefit of the members of the group. Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Investment in Boulder Wind Power's Series B convertible preferred stock Impairment of investments Capital contribution ratio (as a percent) Equity Method Investment, Ownership Percentage Contributions to complete acquisition Proceeds from Sale of Equity Method Investments Proceeds from Sale of Equity Method Investments Gain (Loss) on Sale of Equity Investments Gain (Loss) on Sale of Equity Investments Fair Value of the Equity Investment of a Business Acquisition Fair Value of the Equity Investment of a Business Acquisition Fair Value of the Equity Investment of a Business Acquisition Gains (Losses) on Extinguishment of Debt, before Write off of Deferred Debt Issuance Cost Gains (Losses) on Extinguishment of Debt, before Write off of Deferred Debt Issuance Cost Assets Held under Capital Leases Assets Held under Capital Leases [Member] Molycorp Mountain Pass facility Molycorp Mountain Pass Facility [Member] Represents the details pertaining to the Molycorp Mountain Pass facility. Property, Plant and Equipment, Additions Property, Plant and Equipment, Additions Property, Plant and Equipment, Additions, Gross of Capitalized Interest Property, Plant and Equipment, Additions, Gross of Capitalized Interest Property, Plant and Equipment, Additions, Gross of Capitalized Interest Interest Costs Capitalized Interest Costs Capitalized Depreciation Depreciation Concentrations Concentration Risk Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Schedule of Condensed Balance Sheet Condensed Balance Sheet [Table Text Block] Schedule of Condensed Income Statement and Comprehensive Income Schedule of Condensed Income Statement and Comprehensive Income [Table Text Block] Schedule of Condensed Income Statement and Comprehensive Income [Table Text Block] Schedule of Condensed Cash Flow Statement Condensed Cash Flow Statement [Table Text Block] Schedule of Out-of-Period Adjustments Schedule of Error Corrections and Prior Period Adjustments [Table Text Block] Schedule of accrued expenses Schedule of Accrued Liabilities [Table Text Block] Segment Reporting [Abstract] Schedule of segment information Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block] Extractive Industries [Abstract] Issuance of shares for investment in mining property Sale of stock, price per share Deferred tax assets: Deferred Tax Assets, Gross [Abstract] Current: Deferred Tax Assets, Gross, Current [Abstract] Deferred Tax Assets, Gross, Current [Abstract] Inventory Deferred Tax Assets, Inventory Other Deferred Tax Assets, Other Current Represents the current portion of the tax effects as of the balance sheet date of the amount of estimated future tax deductions arising from other temporary differences not otherwise specified in the taxonomy. Total current Deferred Tax Assets, Gross, Current Non-current: Deferred Tax Assets, Gross, Noncurrent [Abstract] Deferred Tax Assets, Gross, Noncurrent [Abstract] Asset retirement obligation Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Asset Retirement Obligations Mineral resources Deferred Tax Assets, Mineral Resources, Noncurrent Represents the non-current portion of the tax effect as of the balance sheet date of the amount of estimated future tax deductions arising from mineral resources. Property, plant and equipment and intangible assets Deferred Tax Assets, Property, Plant and Equipment and Intangible Assets Deferred Tax Assets, Property, Plant and Equipment and Intangible Assets Stock compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Net operating losses Deferred Tax Assets, Operating Loss Carryforwards Research and energy tax credits and expenditures Deferred Tax Assets, Tax Credit Carryforwards, Research and Energy Deferred Tax Assets, Tax Credit Carryforwards, Research and Energy Alternative Minimum Tax Credit Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax Unrealized foreign exchange Deferred Tax Assets, Unrealized Currency Losses Investments Deferred Tax Assets, Investments Other Deferred Tax Assets, Other Noncurrent Represents the non-current portion of the tax effect as of the balance sheet date of the amount of estimated future tax deductions arising from other temporary differences not otherwise specified in the taxonomy. Total non-current Deferred Tax Assets, Gross, Noncurrent Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Current Deferred Tax Liabilities, Gross, Current [Abstract] Deferred Tax Liabilities, Gross, Current [Abstract] Inventory Deferred Tax Liabilities, Inventory Other Deferred Tax Liabilities Other Current Represents the current portion of the amount of the estimated future tax effects attributable to other temporary differences not otherwise specified in this taxonomy that were expensed for tax purposes but capitalized in conformity with generally accepted accounting principles, or which were recognized as revenue under GAAP but not for tax purposes, which will reverse in future periods. Total current Deferred Tax Liabilities, Gross, Current Non-current: Deferred Tax Liabilities, Gross, Noncurrent [Abstract] Deferred Tax Liabilities, Gross, Noncurrent [Abstract] Asset retirement obligation Deferred Tax Liabilities, Asset Retirement Obligations Deferred Tax Liabilities, Asset Retirement Obligations Foreign subsidiary earnings and withholding taxes Deferred Tax Liabilities, Undistributed Foreign Earnings Property, plant, equipment and intangible assets Deferred Tax Liabilities, Property, Plant and Equipment and Intangible Assets Deferred Tax Liabilities, Property, Plant and Equipment and Intangible Assets Convertible debt (Notes), share lending and other financing arrangements Deferred Tax Liabilities, Financing Arrangements Other Deferred Tax Liabilities, Other Noncurrent Deferred Tax Liabilities, Other Noncurrent Total non-current Deferred Tax Liabilities, Gross, Noncurrent Net deferred taxes, before valuation allowance Deferred Tax Assets, Liabilities Gross Represents the gross amount of deferred tax assets and liabilities before valuation allowance as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities. A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods. Valuation allowance Deferred Tax Assets, Valuation Allowance Total deferred tax Deferred Tax Assets, Net Deposits [Abstract] Deposits Deposits Disclosure [Text Block] The entire disclosure for deposits. Schedule of changes in operating assets and liabilities, net of the effects of acquisitions and dispositions Cash Flow, Operating Capital [Table Text Block] Company Background Nature of Operations [Text Block] Interest rate Asset Retirement Obligation Disclosure [Abstract] Asset Retirement Obligation [Table] Asset Retirement Obligation [Table] Represents the information related to asset retirement obligations. Asset Retirement Obligation [Line Items] Asset Retirement Obligation [Line Items] -- None. No documentation exists for this element. -- Asset retirement obligation activity Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] Balance at beginning of period Asset Retirement Obligation Obligations settled Asset Retirement Obligation, Liabilities Settled Accretion expense Asset Retirement Obligation, Accretion Expense Revisions in estimated cash flows Asset Retirement Obligation, Revision of Estimate Loss on settlement Asset Retirement Obligation Loss on Liabilities Settled Represents the loss on settlement of liabilities related to asset retirement obligation. Balance at end of period Asset Retirement Obligation [Abstract] Asset Retirement Obligation [Abstract] Asset retirement obligation, current Asset Retirement Obligation, Current Depreciation expense Asset Retirement Obligation, Depreciation Expense Asset Retirement Obligation, Depreciation Expense Asset Retirement Obligation, Estimated Future Undiscounted Cash Flows Asset Retirement Obligation, Estimated Future Undiscounted Cash Flows Asset Retirement Obligation, Estimated Future Undiscounted Cash Flows Recorded Third-Party Environmental Recoveries, Discount Rate Recorded Third-Party Environmental Recoveries, Discount Rate Revisions in estimated cash flows Loss on settlement Financial assurance requirement satisfied with surety bonds Reclamation Surety Bonds The amount of surety bonds with governmental agencies to secure reclamation obligations. 3.25% Convertible Notes, net of discount, due June 2016 Long-term Debt, Gross Long-term Debt, Gross Unamortized debt discount Debt Instrument, Unamortized Discount Net carrying amount Capital Requirements [Table] Capital Requirements [Table] Capital Requirements [Table] Secured Debt Secured Debt [Member] Capital Expenditure Project [Axis] Capital Expenditure Project [Axis] Capital Expenditure Project [Axis] Capital Expenditure Project [Domain] Capital Expenditure Project [Domain] Capital Expenditure Project [Domain] Expansion Capital Expenditures Maintenance and Other Expansion Capital Expenditures [Member] Maintenance and Other Expansion Capital Expenditures [Member] 12% Term Loans and 12% Equipment Financing Term Loans 12 Percent and Equipment Financing 12 Percent [Member] Term Loans 12 Percent and Equipment Financing 12 Percent [Member] Magnequench Term Loan Magnequench 12 Percent Term Loan [Member] Magnequench 12 Percent Term Loan [Member] Capital Expenditures [Line Items] Capital Expenditures [Line Items] Capital Expenditures [Line Items] Debt Instrument, Obligation to Offer to Repurchase If Contingencies Are Not Met, Equal to Percent of Aggregate Principal Plus Accrued and Unpaid Interest Debt Instrument, Obligation to Offer to Repurchase If Contingencies Are Not Met, Equal to Percent of Aggregate Principal Plus Accrued and Unpaid Interest Debt Instrument, Obligation to Offer to Repurchase If Contingencies Are Not Met, Equal to Percent of Aggregate Principal Plus Accrued and Unpaid Interest Expected capital expenditures in 2015 Expected Future Capital Expenditures, Estimated Capital Expenditures in Next Fiscal Year Expected Future Capital Expenditures, Estimated Capital Expenditures in Next Fiscal Year Expected capital expenditures in 2016 Expected Future Capital Expenditures, Estimated Capital Expenditures, Year Two Expected Future Capital Expenditures, Estimated Capital Expenditures, Year Two Interest Paid Interest Paid Debt and Lease Financing Commitment Capacity Debt and Lease Financing Commitment Capacity Debt and Lease Financing Commitment Capacity Proceeds from issuance of secured debt Debt and Lease Financing Commitment Capacity, Availability Contingent Upon Achieving Performance Targets Debt Instrument, Unused Borrowing, Availability Contingent Upon Achieving Performance Targets Debt Instrument, Unused Borrowing, Availability Contingent Upon Achieving Performance Targets Unused borrowing capacity, amount Debt Instrument, Unused Borrowing Capacity, Amount Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Line Items] Business Acquisition [Line Items] Recognized Transaction Costs Recognized Transaction Costs Recognized Transaction Costs Corporate development: Corporate Development [Abstract] Corporate Development [Abstract] Legal, accounting and advisory fees Other expenses: Other Expenses [Abstract] Contingent forward contract loss Business Acquisition, Cost of Acquired Entity, Contingent Forward Contract Loss Business Acquisition, Cost of Acquired Entity, Contingent Forward Contract Loss Interest expense: Interest Expense [Abstract] Bridge loan fee Business Acquisition, Cost of Acquired Entity, Bridge Loan Fee Business Acquisition, Cost of Acquired Entity, Bridge Loan Fee Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Postretirement benefit liability Accumulated Defined Benefit Plans Adjustment [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Beginning balance Change in other comprehensive loss before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Net income (loss) reclassified from AOCI Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Ending balance Stock-based compensation expense Allocated Share-based Compensation Expense Schedule of Equity Method Investments Equity Method Investments [Table Text Block] Schedule of Cost Method Investments Schedule of Cost Method Investments [Table Text Block] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Previously Reported Scenario, Previously Reported [Member] JAMR Jiangyin Jia Hua Advanced Material Resources Co Ltd [Member] Jiangyin Jia Hua Advanced Material Resources Co Ltd [Member] Business Acquisition [Line Items] Total purchase consideration Business Combination, Consideration Transferred Cash consideration paid for Molycorp Canada (in CAD per share) Business Acquisition, Purchase Price Allocation, Cash Paid Per Share Business Acquisition, Purchase Price Allocation, Cash Paid Per Share Share consideration paid for Molycorp Canada (in shares) Business Acquisition, Purchase Price Allocation, Equity Interests Issued and Issuable, Share Exchange Ratio Business Acquisition, Purchase Price Allocation, Equity Interests Issued and Issuable, Share Exchange Ratio Cash consideration Payments to Acquire Businesses, Gross Notional amount of derivatives Derivative, Notional Amount Fair value of Molycorp common stock issued Goodwill, additional impairment loss from final purchase price allocation Goodwill, additional impairment loss from final purchase price allocation Goodwill, additional impairment loss from final purchase price allocation Impairment of goodwill and other intangible assets Goodwill, Impairment Loss Finite-Lived Assets, Useful Life, Minimum Finite-Lived Assets, Useful Life, Minimum Finite-Lived Assets, Useful Life, Minimum Finite-Lived Assets, Useful Life, Maximum Finite-Lived Assets, Useful Life, Maximum Finite-Lived Assets, Useful Life, Maximum Direct Transaction Expenses Excluded from Nonrecurring Expense Nonrecurring Costs Nonrecurring Costs Additional equity acquired Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent, Percentage Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent, Percentage Equity interest, total Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent, Ownership Interest after Purchase, Percentage Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent, Ownership Interest after Purchase, Percentage Additional equity interest, purchase price Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent Purchase of equity interest, cash portion Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent, Cash Portion Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent, Cash Portion Purchase of equity interest, cash portion of accrued interest Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent, Cash Portion, Interest Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Purchase of Interest by Parent, Cash Portion, Interest Discontinued Operations and Disposal Groups [Abstract] Discontinued Operations Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Asset Retirement Obligation Asset Retirement Obligation Disclosure [Text Block] Series A Mandatory Convertible Preferred Stock Preferred Stock [Member] Preferred Stock, Dividend Rate, Percentage Preferred Stock, Dividend Rate, Percentage Mandatory Convertible Preferred Stock Price Per Share Mandatory Convertible Preferred Stock Price Per Share The price per share of mandatory convertible preferred stock. Convertible Preferred Stock, Shares Issued upon Conversion, Conversion Rate Convertible Preferred Stock, Shares Issued upon Conversion, Conversion Rate Convertible Preferred Stock, Shares Issued upon Conversion, Conversion Rate Convertible Preferred Stock, Shares Issued upon Conversion Convertible Preferred Stock, Shares Issued upon Conversion Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Payments of Ordinary Dividends, Preferred Stock and Preference Stock Preferred Stock, Dividends Per Share, Declared Preferred Stock, Dividends Per Share, Declared Notes Payable to Banks Notes Payable to Banks [Member] Bank loans due February 2015 - June 2017 Bank Loans Due September 2017 [Member] Bank Loans Due September 2017 [Member] Debt, Weighted Average Interest Rate Debt, Weighted Average Interest Rate Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Remaining Borrowing Capacity Debt maturities, excluding capital leases Long-term Debt, Fiscal Year Maturity [Abstract] 2015 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2016 Long-term Debt, Maturities, Repayments of Principal in Year Two 2017 Long-term Debt, Maturities, Repayments of Principal in Year Three 2018 Long-term Debt, Maturities, Repayments of Principal in Year Four 2019 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Total Long-term Debt Current Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Total current Current Income Tax Expense (Benefit) Deferred Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) Foreign Deferred Foreign Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Total deferred Deferred Income Tax Expense (Benefit) Total tax benefit Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Intersegment Eliminations Intersegment Eliminations [Member] Operating Segments Operating Segments [Member] Resources Resources [Member] Resources [Member] Rare Metals Rare Metals [Member] Rare Metals [Member] Corporate and other Corporate and Other [Member] Segment Information Segment Reporting Information [Line Items] Number of segments Number of Operating Segments Revenues: Segment Reporting Information, Revenue for Reportable Segment [Abstract] Revenues Revenues Total revenues OIBDA Operating Income (Loss) before Depreciation, Amortization and Accretion Operating Income (Loss) before Depreciation, Amortization and Accretion Depreciation, amortization and accretion Depreciation, Depletion And Amortization from production and nonproduction. Depreciation, depletion and amortization from production and nonproduction. Other expense Interest expense, net of capitalized interest Impairment of investment at cost Total assets Capital expenditures Subsidiary Guarantor Financial Information Condensed Financial Statements [Text Block] 12.00% Term Loans, due September 2019 Term Loan 12 Percent [Member] Term Loan 12 Percent [Member] 12.00% Equipment Financing, due September 2019 Equipment Financing 12 Percent [Member] Equipment Financing 12 Percent [Member] Molycorp Canada and Molycorp Silmet Molycorp Canada and Molycorp Silmet [Member] Molycorp Canada and Molycorp Silmet [Member] Total debt, Current Long-term Debt, Current Maturities Capital lease obligations, Current Capital Lease Obligations, Current Total debt and capital lease obligations, Current Total debt, Non-Current Capital lease obligations, Non-Current Capital Lease Obligations, Noncurrent Total debt and capital lease obligations, Non-Current Summary of Supplemental Cash Flow Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Employee Benefit Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Segment Information Segment Reporting Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Convertible Preferred Stock Convertible Preferred Stock [Member] Total Molycorp Stockholders' Equity Parent [Member] Accumulated deficit Retained Earnings [Member] Noncontrolling interests Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance at the beginning of period Balance at the beginning of the period (in shares) Shares, Outstanding Stock-based compensation Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Stock-based compensation (in shares) Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Issuance of shares (Note 16) Issuance of shares for interest in Molycorp Canada (Note 16) Stock Issued During Period, Value, Acquisitions Issuance of shares for interest in Molycorp Canada (Note 16) (in shares) Stock Issued During Period, Shares, Acquisitions Issuance of shares for acquisition of exploration rights (Note 8) Stock Issued During Period, Value, Purchase of Assets Components of convertible notes (Note 14) Issuance of shares for conversion of Debentures Stock Issued During Period, Value, Conversion of Convertible Securities Issuance of Primary Shares (Note 16) Stock Issued During Period, Value, New Primary Issues Stock Issued During Period, Value, New Primary Issues Issuance of Primary Shares (Note 16) (in shares) Stock Issued During Period, Shares, New Primary Issues Stock Issued During Period, Shares, New Primary Issues Issuance of Borrowed Shares (Note 16) Stock issued during the period, value, loaned shares Stock issued during the period, value, loaned shares Issuance of Borrowed Shares (Note 16) (in shares) Stock issued during the period, shares, loaned shares Stock issued during the period, shares, loaned shares Share-lending arrangements (Note 16) Adjustments to Additional Paid in Capital, Stock Issued, Own-share Lending Arrangement, Issuance Costs Issuance of Warrants (Note 16) Adjustments to Additional Paid in Capital, Warrant Issued Exchange of Convertible Notes (Note 14) Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments Net (loss) income Preferred dividends Dividends, Preferred Stock, Cash Distribution to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Acquisition of noncontrolling interest (Note 11) Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Other comprehensive loss Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Stockholders' Equity, Other Balance at the end of the period Balance at the end of the period (in shares) Interest cost Interest Expense, Debt Preliminary Allocation of Consideration Transferred as of December 31, 2012 Final Allocation of Consideration Transferred Restatement Adjustment [Member] Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract] Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract] Cash consideration Total purchase consideration Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Restricted cash Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Restricted Cash Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Restricted Cash Accounts receivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Inventory Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory Prepaid expenses and other current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Property, plant and equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Investments Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Investments Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Investments Intangible assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Deferred tax charges Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Charges Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Charges Deferred tax assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Noncurrent Goodwill Goodwill, Gross Other non-current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets Accounts payable and accrued expenses Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Debt Business Acquisition, Purchase Price Allocation, Debt Business Acquisition, Purchase Price Allocation, Debt Other current liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other Deferred tax liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent Other non-current liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other Non-controlling interests Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value Total purchase consideration Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred Unaudited proforma Business Acquisition, Pro Forma Information [Abstract] Revenues Business Acquisition, Pro Forma Revenue Net income (loss) Business Acquisition, Pro Forma Net Income (Loss) Net income (loss) attributable to Molycorp Business Acquisitions, Pro Forma Net Income (Loss) Attributable to Parent The pro forma net income or loss attributable to the parent entity during the period as if the business combination or combinations had been completed at the beginning of the period. EPS Basic (in dollars per share) Business Acquisition, Pro Forma Earnings Per Share, Basic Quarterly Financial Information Disclosure [Abstract] Gross loss Loss before income taxes and equity earnings Net loss attributable to Molycorp stockholders (Loss) income per share of common stock from continuing operations Basic (in dollars per share) Diluted (in dollars per share) Quarterly Financial Data [Table] Quarterly Financial Data [Table] Quarterly Financial Data [Table] Chemicals and Oxides and Rare Metals Chemicals and Oxides and Rare Metals [Member] Chemicals and Oxides and Rare Metals [Member] Restatement Adjustment Adjustments for Error Corrections [Axis] Adjustments for Error Corrections [Axis] Adjustments for Error Correction [Domain] Adjustments for Error Correction [Domain] Own-share Lending Arrangement Own-share Lending Arrangement [Member] Own-share Lending Arrangement [Member] Quarterly Financial Data [Line Items] Quarterly Financial Data [Line Items] [Line Items] for Quarterly Financial Data [Table] Equity Method Investment, Other than Temporary Impairment Impairment of Intangible Assets (Excluding Goodwill) Impairment of Intangible Assets (Excluding Goodwill) Schedule of Condensed Financial Statements [Table] Condensed Financial Statements [Table] Parent Parent Company [Member] Guarantor Subsidiaries Guarantor Subsidiaries [Member] Non-Guarantor Subsidiaries Non-Guarantor Subsidiaries [Member] Eliminations Consolidation, Eliminations [Member] Condensed Consolidating Statements of Operations and Comprehensive Income Condensed Income Statements, Captions [Line Items] Interest income (expense) from intercompany notes Interest Income (Expense) from Intercompany Notes, Net Interest Income (Expense) from Intercompany Notes, Net Equity loss from consolidated subsidiaries Equity Earnings from Consolidated Subsidiaries Equity Earnings from Consolidated Subsidiaries Actuarial loss Own-share Lending Arrangement, Shares, Outstanding Own-share Lending Arrangement, Shares, Outstanding Fair value Own-share Lending Arrangement, Shares, Outstanding, Value Increase to balance sheet captions: Balance Sheet Related Disclosures [Abstract] Property, plant and equipment, net Increase to statements of operations and comprehensive loss captions: Interest expense, net of capitalized interest Own-share Lending Arrangement [Abstract] Own-share Lending Arrangement [Abstract] Interest cost expensed Deferred Finance Costs Own-share Lending Arrangement Issuance Costs, Interest Cost Expensed Deferred Finance Costs Own-share Lending Arrangement Issuance Costs, Interest Cost Expensed Interest cost capitalized Deferred Finance Costs Own-share Lending Arrangement Issuance Costs, Capitalized Interest Costs Deferred Finance Costs Own-share Lending Arrangement Issuance Costs, Capitalized Interest Costs Unamortized issuance cost Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Net Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Amortization Expense Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Amortization Expense Debt and Capital Lease Obligations Debt Disclosure [Text Block] Schedules of Deposits Schedules of Deposits [Table Text Block] Schedules of Deposits [Table Text Block] Interest Expense Interest Expense [Member] Other Expense Other Expense [Member] Liability Class [Axis] Liability Class [Axis] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Derivative Liability Derivative Financial Instruments, Liabilities [Member] Valuation Technique [Axis] Valuation Technique [Axis] Valuation Technique [Domain] Valuation Technique [Domain] Income Approach Valuation Technique Income Approach Valuation Technique [Member] Fair Value Inputs, Probability Factor Fair Value Inputs, Probability Factor Fair Value Inputs, Probability Factor Gain (Loss) Included in Earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Fair Value Inputs, Equity-risk Premium Fair Value Inputs, Equity-risk Premium Fair Value Inputs, Equity-risk Premium Fair Value Inputs, Risk Premium Fair Value Inputs, Risk Premium Fair Value Inputs, Risk Premium Fair Value Inputs, Size Premium Fair Value Inputs, Size Premium Fair Value Inputs, Size Premium Fair Value Inputs, Growth Rate Fair Value Inputs, Growth Rate Fair Value Inputs, Growth Rate Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Condensed Consolidating Statements of Cash Flows Condensed Financial Statements, Captions [Line Items] Net cash (used in) provided by operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations Cash flows from investing activities: Intercompany advances made Payments for Net intercompany Advances Payments for Net intercompany Advances Repayments from non-guarantor Payments for (Proceeds from) Repayments of Notes Receivable from Non-Guarantor Payments for (Proceeds from) Repayments of Notes Receivable from Non-Guarantor Loans to guarantors Payments To (Proceeds From) Loans to Guarantor Payments To (Proceeds From) Loans to Guarantor Other investing activities Loans to Parent Loans to Parent Loans to Parent Notes receivable to non-guarantor Payments for (Proceeds from) Notes Receivable to Non-Guarantor Payments for (Proceeds from) Notes Receivable to Non-Guarantor Loans to subsidiaries Payments to (Proceeds from) Loans to Subsidiaries Payments to (Proceeds from) Loans to Subsidiaries Repayments from subsidiaries Payments for (Proceeds from) Subsidiaries Loan Repayments Payments for (Proceeds from) Subsidiaries Loan Repayments Investment in subsidiaries Payments for (Proceeds from) Investment in Subsidiaries Payments for (Proceeds from) Investment in Subsidiaries Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations Borrowing from non-guarantor Payments For (Proceeds From) Borrowing from Non-guarantor Payments For (Proceeds From) Borrowing from Non-guarantor Borrowings from parent Payments for (Proceeds from) Borrowings from Parent Payments for (Proceeds from) Borrowings from Parent Borrowings from guarantor Payments for (Proceeds from) Notes Receivable from Guarantor Payments for (Proceeds from) Notes Receivable from Guarantor Repayments to parent Payments for (Proceeds from) Repayments to Parent Payments for (Proceeds from) Repayments to Parent Intercompany advances owed Proceeds from Net Intercompany Advances Proceeds from Net Intercompany Advances Repayments of borrowings to guarantor Payments for (Proceeds from) Repayments of Notes Receivable from Guarantor Payments for (Proceeds from) Repayments of Notes Receivable from Guarantor Capital contributions from parent company Proceeds from Contributions from Parent Proceeds from Convertible Debt Borrowings from guarantor Proceeds from Borrowing from Guarantor Proceeds from Borrowing from Guarantor Repayments to guarantor Payments For (Proceeds From) Borrowing from Guarantor Payments For (Proceeds From) Borrowing from Guarantor Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Before June 1, 2016 Before June 1, 2016 [Member] Before June 1, 2016 [Member] After June 1, 2016 After June 1, 2016 [Member] After June 1, 2016 [Member] Before June 1, 2015 Before June 1, 2015 [Member] Before June 1, 2015 [Member] Redemption price of principal amount redemption price of principal amount redemption price of principal amount Repayments of convertible debt Aggregate principal amount debt instrument, convertible, conversion face amount debt instrument, convertible, conversion face amount Debt Instrument, Repurchased Face Amount Debt Instrument, Repurchased Face Amount Debt Instrument, Repurchase Amount Debt Instrument, Repurchase Amount Debt Instrument, Redeemable Debt, Redemption Percentage of Principal Amount Debt Instrument, Redeemable Debt, Redemption Percentage of Principal Amount Debt Instrument, Redeemable Debt, Redemption Percentage of Principal Amount Debt Instrument, Redeemable Debt, Redeemable Principal from Proceeds from Equity Debt Instrument, Redeemable Debt, Redeemable Principal from Proceeds from Equity Debt Instrument, Redeemable Debt, Redeemable Principal from Proceeds from Equity Debt Instrument, Redeemable Debt, Redeemable Percentage of Principal from Proceed from Equity Debt Instrument, Redeemable Debt, Redeemable Percentage of Principal from Proceed from Equity Debt Instrument, Redeemable Debt, Redeemable Percentage of Principal from Proceed from Equity Debt Instrument, Collateral, Excluded Assets, Asset Fair Market Value, Maximum Debt Instrument, Collateral, Excluded Assets, Asset Fair Market Value, Maximum Debt Instrument, Collateral, Excluded Assets, Asset Fair Market Value, Maximum Debt Instrument, Collateral, Excluded Assets, Cash Collateral for Line of Credits or Hedging Obligations, Maximum Debt Instrument, Collateral, Excluded Assets, Cash Collateral for Line of Credits or Hedging Obligations, Maximum Debt Instrument, Collateral, Excluded Assets, Cash Collateral for Line of Credits or Hedging Obligations, Maximum Debt Instruments, Collateral, Excluded Assets, Voting Stock of Foreign Subsidiaries, Percent, Minimum Debt Instruments, Collateral, Excluded Assets, Voting Stock of Foreign Subsidiaries, Percent, Minimum Debt Instruments, Collateral, Excluded Assets, Voting Stock of Foreign Subsidiaries, Percent, Minimum Schedule of Operating Leased Assets [Table] Schedule of Operating Leased Assets [Table] Office space, trailers and certain equipment Office Space Trailers and Equipment [Member] Represents the office spaces, trailers and certain equipment. Future Operating Lease Commitments Operating Leased Assets [Line Items] Remaining annual minimum payments under operating leases Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating lease obligations, total minimum payments Operating Leases, Future Minimum Payments Due Operating lease obligations, Less Than 1 Year Operating Leases, Future Minimum Payments Due, Next Twelve Months Operating lease obligations, 1 -3 Years Operating Leases, Future Minimum Payments, Due in Years One to Three Operating Leases, Future Minimum Payments, Due in Years One to Three Operating lease obligations, 4 - 5 Years Operating Leases, Future Minimum Payments, Due in Four and Five Years Operating lease obligations, More Than 5 Years Operating Leases, Future Minimum Payments, Due Thereafter Operating leases rent expense net Operating Leases, Rent Expense, Net Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Beginning of period Goodwill acquired Goodwill, Acquired During Period Impairment End of period Condensed Consolidating Balance Sheets Condensed Balance Sheet Statements, Captions [Line Items] Trade accounts receivable, net Inventory Deposits Inventory Intangible assets, net Investments in consolidated subsidiaries Intercompany accounts receivable Intercompany Accounts Receivable Intercompany Accounts Receivable Accrued expenses Debt and capital lease obligations Asset retirement obligation Deferred tax liabilities Debt and capital lease obligations Intercompany accounts payable Intercompany accounts payable Intercompany accounts payable Common stock Preferred stock Number of Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested at the beginning of the period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Unvested at the end of the period (in shares) Weighted Average Grant-Date Price Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Unvested shares at the beginning of the period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Unvested shares at the end of the period (in dollars per share) Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] China CHINA Japan JAPAN Thailand THAILAND Hong Kong HONG KONG South Korea KOREA, REPUBLIC OF Singapore SINGAPORE North America North America [Member] Europe Europe [Member] Other Asia Other Asia [Member] Other Asia [Member] Other Other Countries [Member] Other Countries [Member] Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Long-lived assets Long-Lived Assets Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block] Accounting Changes and Error Corrections Accounting Changes and Error Corrections [Text Block] Schedule of Share-Lending Arrangements Schedule of Share-Lending Arrangements [Table Text Block] Schedule of Share-Lending Arrangements [Table Text Block] Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs [Table Text Block] Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Accrued Expenses Accounts Payable and Accrued Liabilities Disclosure [Text Block] Class of Warrant or Right [Table] Class of Warrant or Right [Table] Class of Warrant or Right [Axis] Class of Warrant or Right [Axis] Class of Warrant or Right [Domain] Class of Warrant or Right [Domain] Penny Warrants Penny Warrants [Member] Penny Warrants [Member] Class of Warrant or Right [Line Items] Class of Warrant or Right [Line Items] Number of securities called by warrants Class of Warrant or Right, Number of Securities Called by Warrants or Rights Strike price Class of Warrant or Right, Exercise Price of Warrants or Rights Warrants and Rights Outstanding Warrants and Rights Outstanding Payments of Stock Issuance Costs Payments of Stock Issuance Costs Term (years) Fair Value Assumptions, Expected Term Risk-free interest rate Fair Value Assumptions, Risk Free Interest Rate Volatility Fair Value Assumptions, Expected Volatility Rate Dividend yield Fair Value Assumptions, Expected Dividend Rate Fair Value Inputs, Discount for Lack of Marketability Fair Value Inputs, Discount for Lack of Marketability Fair Value Assumptions, Application of Discount for Lack of Marketability, Share Price Fair Value Assumptions, Application of Discount for Lack of Marketability, Share Price Fair Value Assumptions, Application of Discount for Lack of Marketability, Share Price Schedule of Quarterly Financial Information Schedule of Quarterly Financial Information [Table Text Block] Investments Cost and Equity Method Investments Disclosure [Text Block] Going Concern Liquidity Disclosure [Policy Text Block] Net cash paid for: Supplemental Cash Flow Information [Abstract] Income taxes Income Taxes Paid Interest, net of capitalized interest Interest Paid, Net Non-cash financing activities and investing activities: Noncash Investing and Financing Items [Abstract] Change in accrued capital expenditures Capital Expenditures Incurred but Not yet Paid Conversion of debt securities to equity securities Debt Conversion, Converted Instrument, Amount Acquisition of exploration rights Noncash or Part Noncash Acquisition, Mining Rights Acquired Noncash or Part Noncash Acquisition, Mining Rights Acquired Debt assumed from business acquisitions Noncash or Part Noncash Acquisition, Debt Assumed Issuance of common stock for business acquisitions Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued, Value Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued, Value Fixed assets additions under capital lease Noncash or Part Noncash Acquisition, Fixed Assets Acquired Deposits [Table] Deposits [Table] Deposits [Table] Deposit, By Third Party Name [Axis] Deposit, By Third Party Name [Axis] Deposit, By Third Party Name [Axis] Deposits, By Third Party Name [Domain] Deposits, By Third Party Name [Domain] Deposits, By Third Party Name [Domain] Kern River Gas Transmission Company Kern River Gas Transmission Company [Member] Represents the Kern River Gas Transmission Company with which the entity has natural gas transportation lease agreement. Deposits [Line Items] Deposits [Line Items] Deposits [Line Items] Escrow arrangement with Kern River Gas Transmission Company (Kern River) Escrow Deposit Construction insurance program Deposits for Construction Insurance Program Represents the construction insurance program deposit of the entity. Collateral placed against the surety bonds issued to California state and regional agencies for the closure and reclamation obligations at the Mountain Pass facility, and other deposits Restricted Cash and Cash Equivalents Schedule of property, plant and equipment Property, Plant and Equipment [Table Text Block] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Table] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Table] Napanee Facility Napanee Facility [Member] Napanee Facility [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Revenues Disposal Group, Including Discontinued Operation, Revenue Costs of sales Disposal Group, Including Discontinued Operation, Costs of Goods Sold Selling, general and administrative expenses Disposal Group, Including Discontinued Operations, Selling, General and Administrative Expense Disposal Group, Including Discontinued Operations, Selling, General and Administrative Expense Depreciation Disposal Group, Including Discontinued Operation, Depreciation and Amortization Operating loss Disposal Group, Including Discontinued Operation, Operating Income (Loss) Impairment loss Disposal Group, Including Discontinued Operations, Asset Impairments Disposal Group, Including Discontinued Operations, Asset Impairments Income tax Discontinued Operation, Tax Effect of Income (Loss) from Disposal of Discontinued Operation Net loss Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block] Schedule of Goodwill [Table] Fair Value, Inputs, Level 3 Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Patents Goodwill, Fair Value excess over Carrying Value, Percent Goodwill, Fair Value excess over Carrying Value, Percent Goodwill, Fair Value excess over Carrying Value, Percent Goodwill, impairment loss from initial purchase price allocation Goodwill, impairment loss from initial purchase price allocation Goodwill, impairment loss from initial purchase price allocation fair value input, customer attrition Fair Value Inputs, Customer Attrition Fair Value Inputs, Customer Attrition Amortization expense Intangible assets not subject to amortization Indefinite-Lived Intangible Assets (Excluding Goodwill) Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Public Float Entity Public Float Inventory Inventory Disclosure [Text Block] Schedule of activity in asset retirement obligation Schedule of Change in Asset Retirement Obligation [Table Text Block] Schedule of Inventory Schedule of Inventory Current and Noncurrent [Table Text Block] Tabular disclosure of the carrying amount as of the balance sheet date of both current and noncurrent merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process. Schedule of Charges to Cost of Sales Based on Normal Production Levels and Write-Down of Inventory Schedule of Charges to Cost of Sales Based on Normal Production Levels and Write-Down of Inventory [Table Text Block] Charges to Cost of Sales Based on Normal production levels and write-down of inventory [Table Text Block] Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Federal tax computed at the statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount State taxes, net of federal benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Change in valuation allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Impairment of goodwill and other long-lived assets Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount Changes related to uncertain tax positions Effective Income Tax Rate Reconciliation, Tax Settlement, Amount Federal and State tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Amount Foreign income tax rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Foreign translation adjustments Effective Income Tax Reconciliation, Foreign Translation Adjustments, Amount Effective Income Tax Reconciliation, Foreign Translation Adjustments, Amount Change in applicable law Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Other items, net Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Dividends on Convertible Preferred Stock Preferred Stock Dividends, Income Statement Impact Loss attributable to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Continuing operations Income (Loss) from Continuing Operations Attributable to Parent Discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Weighted average common shares outstanding—basic Weighted Average Number of Shares Outstanding, Basic Basic loss per share from: Weighted average common shares outstanding—diluted Weighted Average Number of Shares Outstanding, Diluted Diluted loss per share from: Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation [Table] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Workforce Labor Force Concentration Risk [Member] Employees covered by collective bargaining agreement under facility Workforce Subject to Collective Bargaining Arrangements [Member] Molycorp Silmet Molycorp Silmet [Member] Represents the AS Silmet facility located in Silmet, Estonia (now known as Molycorp Silmet AS), acquired by the entity. Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Consolidated Class Action Consolidated Class Action [Member] Consolidated Class Action [Member] Purported Class Action Purported Class Action [Member] Purported Class Action [Member] Plant Modernization and Expansion Commitments Unrecorded Unconditional Purchase Obligation [Line Items] Number of employees Entity Number of Employees Concentration risk (as a percent) Surety bonds placed to secure the closure and reclamation obligations Number of claims Loss Contingency, Pending Claims, Number Number of stockholder derivative lawsuits Number of Stockholder Derivative Lawsuits The number of stockholder derivative lawsuits. Fair Value Measurements, Recurring and Nonrecurring Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Income Taxes Income Tax Disclosure [Text Block] Unaudited Supplementary Data Quarterly Financial Information [Text Block] Loss per Share Earnings Per Share [Text Block] 2015 Capital Leases, Future Minimum Payments, Remainder of Fiscal Year 2016 Capital Leases, Future Minimum Payments Due in Two Years 2017 Operating Leases, Future Minimum Payments, Due in Three Years 2018 Capital Leases, Future Minimum Payments Due in Four Years 2019 Capital Leases, Future Minimum Payments Due in Five Years Thereafter Capital Leases, Future Minimum Payments Due Thereafter Total Capital Leases, Future Minimum Payments Due Imputed interest included in total future minimum lease payments at December 31, 2014 Capital Leases, Future Minimum Payments, Interest Included in Payments Parent Term Loan Parent 12 Percent Term Loan [Member] Parent 12 Percent Term Loan [Member] Unused borrowing, availability contingent upon achieving performance targets Proceeds from debt, net of issuance costs Proceeds from Debt, Net of Issuance Costs Payment to reduce interest rate Debt Instrument, Payment to Reduce Interest Rate Debt Instrument, Payment to Reduce Interest Rate Payments of financing costs Payments of Financing Costs Gain (loss) on extinguishment of debt Proceeds from issuance of secured debt including unused borrowing capacity, amount Debt Instrument, Proceeds from Issuance of Secured Debt including Unused Borrowing Capacity, Amount Debt Instrument, Proceeds from Issuance of Secured Debt including Unused Borrowing Capacity, Amount Condition to be met for two consecutive fiscal quarters, Minimum EBITDA Debt Instrument, Condition to be Met for Two Consecutive Fiscal Quarters, Minimum Earnings before Interest, Taxes, Depreciation, and Amortization Debt Instrument, Condition to be Met for Two Consecutive Fiscal Quarters, Minimum Earnings before Interest, Taxes, Depreciation, and Amortization Condition to be met, production equal to or greater than Debt Instrument, Condition to be Met, Production Equal To or Greater Than Line of Credit Facility, Covenant , Production Facility Capacity Interest rate, stated percentage, payment in cash Debt Instrument, Interest Rate, Stated Percentage, Payment in Cash Debt Instrument, Interest Rate, Stated Percentage, Payment in Cash Interest rate, stated percentage, (PIK) interest Debt Instrument, Interest Rate, Stated Percentage, Payment in Kind (PIK) Interest Debt Instrument, Interest Rate, Stated Percentage, Payment in Kind (PIK) Interest Unused borrowing capacity, fee Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Carrying amount, aggregate amount of principal to be paid down Debt Instrument, Carrying Amount, Aggregate Amount of Principal to be Paid Down Debt Instrument, Carrying Amount, Aggregate Amount of Principal to be Paid Down Debt Instrument, Term Debt Instrument, Term Principal amount Cash interest Total interest cost Interest Expense Minimum Lease Payments, Sale Leaseback Transactions, Fiscal Year Maturity Minimum Lease Payments, Sale Leaseback Transactions, Fiscal Year Maturity [Abstract] Next Twelve Months Minimum Lease Payments, Sale Leaseback Transactions, Next Twelve Months Within Two Years Minimum Lease Payments, Sale Leaseback Transactions, within Two Years Within Three Years Minimum Lease Payments, Sale Leaseback Transactions, within Three Years Within Four Years Minimum Lease Payments, Sale Leaseback Transactions, within Four Years Within Five Years Minimum Lease Payments, Sale Leaseback Transactions, within Five Years Sale leaseback transactions, Possible Payment Adjustment, Years Two Through Five Minimum Lease Payments, Sale Leaseback Transactions, Possible Payment Adjustment, Years Two Through Five Minimum Lease Payments, Sale Leaseback Transactions, Possible Payment Adjustment, Years Two Through Five Sale leaseback transactions, Possible Payment Adjustment, Additional Payment on Five-Year Anniversary Minimum Lease Payments, Sale Leaseback Transactions, Possible Payment Adjustment, Additional Payment on Five-Year Anniversary Minimum Lease Payments, Sale Leaseback Transactions, Possible Payment Adjustment, Additional Payment on Five-Year Anniversary Sale leaseback transactions, Additional Payment on Five-Year Anniversary Minimum Lease Payments, Sale Leaseback Transactions, Additional Payment on Five-Year Anniversary Minimum Lease Payments, Sale Leaseback Transactions, Additional Payment on Five-Year Anniversary Early Payment Premium Percentage Early Payment Premium Percentage [Abstract] Early Payment Premium Percentage [Abstract] Percent of Principal, Prior to First Anniversary Early Payment Premium Percentage, Percent of Principal, Prior to First Anniversary Early Payment Premium Percentage, Percent of Principal, Prior to First Anniversary Percent of Principal, Prior to Second Anniversary Early Payment Premium Percentage, Percent of Principal, Prior to Second Anniversary Early Payment Premium Percentage, Percent of Principal, Prior to Second Anniversary Percent of Principal, Prior to Third Anniversary Early Payment Premium Percentage, Percent of Principal, Prior to Third Anniversary Early Payment Premium Percentage, Percent of Principal, Prior to Third Anniversary Percent of Principal, Prior to Fourth Anniversary Early Payment Premium Percentage, Percent of Principal, Prior to Fourth Anniversary Early Payment Premium Percentage, Percent of Principal, Prior to Fourth Anniversary Percent of Principal, After to Fourth Anniversary Early Payment Premium Percentage, Percent of Principal, After to Fourth Anniversary Early Payment Premium Percentage, Percent of Principal, After to Fourth Anniversary Resulting from an Asset Sale, Percent of Principal Early Payment Premium Percentage, Resulting from an Asset Sale, Percent of Principal Early Payment Premium Percentage, Resulting from an Asset Sale, Percent of Principal Maximum Principal Amount of Debt Secured by the Pari Passu Collateral Maximum Principal Amount of Debt Secured by the Pari Passu Collateral Maximum Principal Amount of Debt Secured by the Pari Passu Collateral Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] TMT Toda Magnequench Magnetic Materials Co Ltd. [Member] Toda Magnequench Magnetic Materials Co Ltd. [Member] Compounds Compounds [Member] Compounds [Member] Metals Metals [Member] Metals [Member] Gallium Metal Gallium Metal [Member] Gallium Metal [Member] Related Party Transactions Related Party Transaction [Line Items] Purchases made from related party Related Party Transaction, Purchases from Related Party Accounts Payable, Related Parties Accounts Payable, Related Parties Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Grants in Period, Weighted Average Grant Date Fair Value, Total Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Grants in Period, Weighted Average Grant Date Fair Value, Total Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Grants in Period, Weighted Average Grant Date Fair Value, Total Current: Inventory, Net [Abstract] Concentrate stockpiles Inventory Concentrate Stockpiles, Net of Reserves, Current Carrying amount of inventories of mineral concentrate classified as current as of the balance sheet date. Raw materials Inventory, Raw Materials, Net of Reserves Work in process Inventory, Work in Process, Net of Reserves Finished goods Inventory, Finished Goods, Net of Reserves Materials and supplies Inventory, Supplies, Net of Reserves Total current Long-term: Inventory, Noncurrent [Abstract] Concentrate stockpiles Inventory Concentrate Stockpiles, Net of Reserves, Non Current Carrying amount of inventories of mineral concentrate classified as noncurrent as of the balance sheet date. Raw materials Inventory Raw Materials Net of Reserves Noncurrent Represents the carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of unprocessed items to be consumed in the manufacturing or production process classified as noncurrent assets. Total long-term Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Schedule of Error Corrections and Prior Period Adjustment Restatement [Table] Error Corrections and Prior Period Adjustments Restatement [Line Items] Error Corrections and Prior Period Adjustments Restatement [Line Items] Number of Classification Errors Affecting the Condensed Consolidating Balance Sheets Number of Classification Errors Affecting the Condensed Consolidating Balance Sheets Number of Classification Errors Affecting the Condensed Consolidating Balance Sheets Number of Classification Errors Affecting the Condensed Consolidating Statements of Cash Flows Number of Classification Errors Affecting the Condensed Consolidating Statements of Cash Flows Number of Classification Errors Affecting the Condensed Consolidating Statements of Cash Flows Condensed Consolidating Balance Sheets Condensed Consolidating Statements of Cash Flows Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table] Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table] Tax Credit Carryforward Expiration [Axis] Tax Credit Carryforward Expiration [Axis] Tax Credit Carryforward Expiration [Axis] Tax Credit Carryforward Expiration [Domain] Tax Credit Carryforward Expiration [Domain] [Domain] for Tax Credit Carryforward Expiration [Axis] Indefinite Carryforward Indefinite Carryforward [Member] Indefinite Carryforward [Member] Expiring between 2028 and 2032 Expiring between 2024 and 2032 [Member] Expiring between 2024 and 2032 [Member] Expiring in 2023 Expiring in 2023 [Member] Expiring in 2023 [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] IRS Internal Revenue Service (IRS) [Member] State State and Local Jurisdiction [Member] Foreign Tax Authority Foreign Tax Authority [Member] Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] Goodwill, Impairment Loss Deferred tax liabilities, net Valuation allowance Unrecognized Tax Benefits, Period Increase (Decrease) Unrecognized Tax Benefits, Period Increase (Decrease) Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Deferred income tax expense due to elimination of intercompany balances and transactions Deferred Income Tax Expense (Benefit) due to Elimination of Intercompany Balances and Transactions Deferred Income Tax Expense (Benefit) due to Elimination of Intercompany Balances and Transactions Income tax payable due to elimination of intercompany balances and transactions Income Tax Payable due to Elimination of Intercompany Balances and Transactions Income Tax Payable due to Elimination of Intercompany Balances and Transactions Tax credit carryforward Tax Credit Carryforward, Amount Operating Loss Carryforwards Operating Loss Carryforwards Mineral Properties Mineral Industries Disclosures [Text Block] Purchase obligations and other commitment, Total Unrecorded Unconditional Purchase Obligation Purchase obligations and other commitment, Less Than 1 Year Unrecorded Unconditional Purchase Obligation, Due in Next Twelve Months Purchase obligations and other commitment, 1 - 3 Years Unrecorded Unconditional Purchase Obligation Due in Years One to Three Unrecorded Unconditional Purchase Obligation Due in Years One to Three Purchase obligations and other commitment, 4 - 5 Years Unrecorded Unconditional Purchase Obligation Due in Years Four and Five Unrecorded Unconditional Purchase Obligation Due in Years Four and Five Purchase obligations and other commitment, More Than Five Years Unrecorded Unconditional Purchase Obligation, Due after Five Years Land Land [Member] Land improvements (15 to 30 years) Land Improvements [Member] Buildings and improvements (4 to 40 years) Building and Building Improvements [Member] Plant and equipment (2 to 15 years) Machinery and Equipment [Member] Vehicles (7 years) Vehicles [Member] Computer software (5 years) Computer Software, Intangible Asset [Member] Furniture and fixtures (5 years) Furniture and Fixtures [Member] Construction in progress Construction in Progress [Member] Natural gas delivery facility under capital lease (10 years) Natural gas delivery facility under capital lease [Member] Natural gas delivery facility under capital lease [Member] Mining equipment under capital lease (7 years) Mining equipment under capital lease [Member] Mining equipment under capital lease [Member] Mineral properties (Note 8) Mining Properties and Mineral Rights [Member] Capital Leased Assets, Gross Capital Leased Assets, Gross Less accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, plant and equipment, net Property, Plant and Equipment, Useful Life Property, Plant and Equipment, Useful Life