Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] 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] Contract-Based Intangible Assets [Member] Contract-Based Intangible Assets [Member] Customer-Related Intangible Assets [Member] Customer-Related Intangible Assets [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Amortizable intangible assets, gross Intangible Assets, Gross (Excluding Goodwill) Accumulated intangible asset amortization Finite-Lived Intangible Assets, Accumulated Amortization Amortizable intangible assets, net Intangible Assets, Net (Excluding Goodwill) Average useful life of finite-lived intangible assets Finite-Lived Intangible Asset, Useful Life Statement of Cash Flows [Abstract] Statement [Table] Statement [Table] Statement [Line Items] Statement [Line Items] Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net income (loss) Net Income (Loss) Attributable to Parent Adjustments to reconcile net income (loss) to net cash (used in) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Immediate recognition of net actuarial loss Defined Benefit Plan, Actuarial Gain (Loss) Interest on paid-in-kind toggle notes Paid-in-Kind Interest Gain on early extinguishment of debt Gain (Loss) on Extinguishment of Debt Gain on sale of assets Gain (Loss) on Sale of Assets and Asset Impairment Charges Inventory valuation adjustment Other Noncash Expense Changes in operating assets and liabilities: Increase (Decrease) in Operating Liabilities [Abstract] Accounts receivable – (increase) decrease Increase (Decrease) in Accounts Receivable Inventories, net – (increase) decrease Increase (Decrease) in Inventories Payables under SWU purchase agreements – increase (decrease) Increase (Decrease) in Accounts Payable, Trade Deferred revenue, net of deferred costs – increase (decrease) Increase (Decrease) in Deferred Revenue Accounts payable and other liabilities – (decrease) Increase (Decrease) in Accounts Payable and Accrued Liabilities Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Net Cash (Used in) Operating Activities Net Cash Provided by (Used in) Operating Activities Cash Flows Provided by Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Deposits for surety bonds - net (increase) decrease Increase (Decrease) in Restricted Cash Proceeds from sales of assets Proceeds from Sale of Productive Assets Net Cash Provided by (Used in) Investing Activities Net Cash Provided by (Used in) Investing Activities Cash Flows Used in Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Repurchase of debt Repayments of Debt Net Cash (Used in) Financing Activities Net Cash Provided by (Used in) Financing Activities Net (Decrease) Cash and Cash Equivalents, Period Increase (Decrease) Cash and Cash Equivalents at Beginning of Period Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents at End of Period Supplemental Cash Flow Information: Supplemental Cash Flow Information [Abstract] Interest paid Interest Paid, Net Conversion of interest payable-in-kind to long-term debt Notes Issued Earnings Per Share [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Interest expense Interest Expense, Debt Inventory, Net [Abstract] Schedule of Inventories Schedule of Inventory, Current [Table Text Block] General Discussion of Pension and Other Postretirement Benefits [Abstract] Pension and Postretirement Health and Life Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Cost of Sales [Member] Cost of Sales [Member] Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Defined Benefit Plans Disclosures, Defined Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Pension Plan, Defined Benefit [Member] Pension Plan [Member] Other Postretirement Benefit Plan [Member] Other Postretirement Benefit Plan [Member] Actuarial (gain) loss from remeasurement, net Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets Income Statement [Abstract] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Separative Work Units [Member] Separative Work Units [Member] Separative Work Units (SWU) [Member] - SWU is a standard unit of measurement that represents the effort required to transform a given amount of natural uranium into two components: enriched uranium having a higher percentage of the uranium-235 isotope (“U235”) and depleted uranium having a lower percentage of U235. The SWU contained in LEU is calculated using an industry standard formula based on the physics of enrichment. The amount of enrichment deemed to be contained in LEU under this formula is commonly referred to as its SWU component and the quantity of natural uranium used in the production of LEU under this formula is referred to as its uranium component. Uranium [Member] Uranium [Member] Uranium [Member] - Natural uranium or the uranium component of Low Enriched Uranium (LEU). Revenue: Revenues [Abstract] Revenue, Goods Sales Revenue, Goods, Net Contract services Contracts Revenue Total Revenue Revenues Cost of Sales: Cost of Revenue [Abstract] Separative work units and uranium Cost of Goods Sold Contract services Contract Revenue Cost Total cost of sales Cost of Revenue Gross profit (loss) Gross Profit Advanced technology costs Research and Development Expense Selling, general and administrative Selling, General and Administrative Expense Amortization of intangible assets Amortization of Intangible Assets Special charges for workforce reductions Restructuring Charges Other (income) Other Operating Income Operating (loss) Operating Income (Loss) Interest (income) Investment Income, Interest Income (loss) before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Provision (benefit) for income taxes Income Tax Expense (Benefit) Net income (loss) Net income (loss) per share - basic and diluted Earnings Per Share, Basic and Diluted Weighted-average number of shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted Average Number of Shares Outstanding, Basic and Diluted Weighted Average Number of Shares Outstanding, Basic and Diluted Separative work units inventory Separative work units inventory Carrying amount as of the balance sheet date of separative work unit ("SWU") inventory. SWU is held as the SWU component of low enriched uranium. A SWU is the standard measure of uranium enrichment using a standard formula derived from the physics of enrichment. SWU costs are based on production costs and purchase costs. SWU inventory is valued at the lower of cost or market. Uranium inventory Uranium Inventory Carrying amount as of the balance sheet date of uranium inventory. Uranium is held in the form of natural uranium and as the uranium component of low enriched uranium. Uranium inventory is valued at the lower of cost or market. Materials and supplies Other Inventory, Supplies, Gross Inventories Inventory, Net Separative work units owed to customers and suppliers Separative work units owed to customers and suppliers Separative work units owed to customers and suppliers Uranium owed to customers and suppliers Uranium owed to customers and suppliers Uranium owed to customers and suppliers Inventories owed to customers and suppliers Inventories owed to customers and suppliers Cost of SWU and uranium inventories owed related to the transfer of title from USEC to customer at fabricator whereby fabricator has elected to order less material from USEC than is required. Amounts owed are satisfied when fabricator orders future bulk deliveries. Separative work units net of liability Separative work units net of liability Separative work units inventory net of liability Uranium inventory net of liability Uranium inventory net of liability Uranium inventory net of liability Inventories, net Inventory net of Liability Inventory net of Liability Restructuring and Related Activities [Abstract] Restructuring and Related Costs [Table Text Block] Restructuring and Related Costs [Table Text Block] Accounts Receivable, Net, Current [Abstract] Schedule of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Net Income (Loss) Per Share Earnings Per Share [Text Block] Segment Reporting Information, Revenue for Reportable Segment [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Low Enriched Uranium Segment [Member] Low Enriched Uranium Segment [Member] Low Enriched Uranium Segment [Member] Contract Services Segment [Member] Contract Services Segment [Member] Contract Services Segment [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Revenues [Abstract] Revenue, Contract Services Gross Profit Fair Value Disclosures [Abstract] Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Disclosure Items [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Cash and cash equivalents Deferred compensation asset Cash Surrender Value, Fair Value Disclosure Deferred compensation obligation Obligations, Fair Value Disclosure Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] 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] Long-term debt, gross Long-term Debt, Gross Long-term debt, fair value Long-term Debt, Fair Value Schedule of Intangible Assets and Excess Reorganization Value [Table Text Block] Schedule of Intangible Assets and Excess Reorganization Value [Table Text Block] Schedule of Intangible Assets and Excess Reorganization Value [Table Text Block] Debt Disclosure [Abstract] Debt Debt Disclosure [Text Block] Schedule of Income Per Share [Table] Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table] Income Per Share Calculation [Line Items] Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] Weighted average common shares Weighted Average Number of Shares Issued, Basic Denominator for basic calculation Weighted Average Number of Shares Outstanding, Basic Denominator for diluted calculation Net loss per share - basic and diluted Share-based Compensation [Abstract] Restricted Stock or Unit Expense Restricted Stock or Unit Expense Stock or Unit Option Plan Expense Stock or Unit Option Plan Expense Allocated Share-based Compensation Expense Allocated Share-based Compensation Expense Accounts Receivable Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Legal Entity of Counterparty, Type [Axis] Legal Entity of Counterparty, Type [Axis] Legal Entity Type of Counterparty [Domain] Legal Entity Type of Counterparty [Domain] Government [Member] Government [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts Receivable, Gross, Noncurrent Accounts Receivable, Gross, Noncurrent Accounts Receivable, Net, Noncurrent Accounts Receivable, Net, Noncurrent Other long-term liabilities Other Liabilities, Noncurrent Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum [Member] Maximum [Member] Repurchase of debt Extinguishment of Debt, Amount Repurchase of debt, fair value Debt Instrument, Repurchase Amount Debt instrument interest rate Debt Instrument, Interest Rate, Stated Percentage Gain on early extinguishment of debt Write off of deferred financing cost Write off of Deferred Debt Issuance Cost Debt Interest Rate, PIK Debt Interest Rate, PIK Debt Interest Rate, PIK Paid-in-Kind Interest Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Segment Information Segment Reporting Disclosure [Text Block] Statement of Financial Position [Abstract] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] ASSETS Assets [Abstract] Current Assets Assets, Current [Abstract] Accounts receivable, net Accounts Receivable, Net, Current Inventories Deferred costs associated with deferred revenue Other Deferred Costs, Net Other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Property, Plant and Equipment, Net Property, Plant and Equipment, Net Deposits for surety bonds Deposits Assets, Noncurrent Intangible assets Other long-term assets Other Assets, Noncurrent Total Assets Assets LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) Liabilities and Equity [Abstract] Current Liabilities Liabilities, Current [Abstract] Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Payables under SWU purchase agreements Accounts Payable, Current Inventories owed to customers and suppliers Deferred revenue Deferred Revenue and Credits, Current Decontamination and decommissioning obligations - current Asset Retirement Obligation, Current Total current liabilities Liabilities, Current Long-term debt Long-term Debt Postretirement health and life benefit obligations Other Postretirement Defined Benefit Plan, Liabilities, Noncurrent Pension benefit liabilities Defined Benefit Pension Plan, Liabilities, Noncurrent Decontamination and decommissioning obligations - long-term Asset Retirement Obligations, Noncurrent Total liabilities Liabilities, Noncurrent Commitments and contingencies (Note 12) Commitments and Contingencies Stockholders' Deficit Stockholders' Equity Attributable to Parent [Abstract] Common stock Common Stock, Value, Issued Excess of capital over par value Additional Paid in Capital Accumulated deficit Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income (loss), net of tax Accumulated Other Comprehensive Income (Loss), Net of Tax Total stockholders' deficit Stockholders' Equity Attributable to Parent Total Liabilities and Stockholders’ Equity (Deficit) Liabilities and Equity Inventories provided by customers and suppliers Inventories Provided by Customers and Suppliers Uranium held by USEC to which title was held by customers and suppliers and for which no assets or liabilities were recorded on the balance sheet Decline in Uranium Quantities Provided by Customers and Suppliers Decline in Uranium Quantities Provided by Customers and Suppliers Decline in Uranium Quantities Provided by Customers and Suppliers Decline in Uranium Spot Price Indicator Decline in Uranium Spot Price Indicator Decline in Uranium Spot Price Indicator Inventory write-down Inventory Write-down Property, Plant and Equipment [Abstract] Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] Utility Customer Receivables Utility Customer Receivables Utility Customer Receivables Contract Services Customer Receivables Contract Services Customer Receivables Contract Services Customer Receivables Accounts Receivable, Net Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Contract Reduction [Member] Contract Termination [Member] Minimum [Member] Minimum [Member] CFCAA funding threshold related to liability under ERISA CFCAA funding threshold related to liability under ERISA CFCAA funding threshold related to liability under ERISA Decontamination and decommissioning obligations - total Asset Retirement Obligation D&D financial assurance ARO financial assurance ARO financial assurance 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] Equity Award [Domain] Equity Award [Domain] Employee Stock Option [Member] Employee Stock Option [Member] Restricted Stock Units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] Option Indexed to Issuer's Equity, Type [Axis] Option Indexed to Issuer's Equity, Type [Axis] Option Indexed to Issuer's Equity, Type [Domain] Option Indexed to Issuer's Equity, Type [Domain] Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted-average period in years of costs to be recognized 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, Grants in Period, Gross Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Pension Plan, Defined Benefit [Member] Defined Benefit Plan, Asset Categories [Axis] Defined Benefit Plan, Asset Categories [Axis] Plan Asset Categories [Domain] Plan Asset Categories [Domain] Industry Sector [Axis] Industry Sector [Axis] Industry Sector [Domain] Industry Sector [Domain] Equity Securities by Entity Size [Axis] Equity Securities by Entity Size [Axis] Equity Securities, Entity Size [Domain] Equity Securities, Entity Size [Domain] Equity Securities by Investment Objective [Axis] Equity Securities by Investment Objective [Axis] Equity Securities, Investment Objective [Domain] Equity Securities, Investment Objective [Domain] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Schedule of Net Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Par Value $.10 per Share [Member] Common Stock [Member] Excess of Capital over Par Value [Member] Additional Paid-in Capital [Member] Accumulated Deficit [Member] Retained Earnings [Member] Accumulated Other Comprehensive Income (Loss) [Member] AOCI Attributable to Parent [Member] Beginning Balance Other comprehensive income, net of tax (Note 13) Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax Restricted and other common stock issued, net of amortization Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Ending Balance Inventories Inventory Disclosure [Text Block] Options excluded from diluted net income per share Options with exercise price greater than market price Options with exercise price greater than market price Exercise price of excluded options Investment Options, Exercise Price Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Land [Member] Land [Member] Leasehold Improvements [Member] Leasehold Improvements [Member] Equipment [Member] Equipment [Member] Other Capitalized Property Plant and Equipment [Member] Other Capitalized Property Plant and Equipment [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Gross Property, Plant and Equipment, Gross Property, Plant and Equipment, Additions Property, Plant and Equipment, Additions Property, Plant and Equipment, Disposals Property, Plant and Equipment, Disposals Property, Plant and Equipment, Gross Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Depreciation Depreciation Accumulated Depreciation, Depletion and Amortization, Sale or Disposal of Property, Plant and Equipment Accumulated Depreciation, Depletion and Amortization, Sale or Disposal of Property, Plant and Equipment Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, Plant and Equipment, Net Property, Plant And Equipment, Net Capital Expenditures Property, Plant And Equipment, Net Capital Expenditures Property, Plant And Equipment, Net Capital Expenditures Property, Plant and Equipment, Net Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block] Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Research and Development [Abstract] Contract Services and Advanced Technology Costs and Other Income Research, Development, and Computer Software Disclosure [Text Block] Schedule of Net Income Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Securities Excluded from Net Income Per Share Schedule of Securities Excluded from Net Income Per Share [Table Text Block] [Table Text Block] for Schedule of Securities Excluded from Net Income Per Share [Table] Statement of Comprehensive Income [Abstract] Amortization of prior service costs (credits) Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax Other comprehensive income (loss), before tax Other Comprehensive Income (Loss), before Tax Income tax expense related to items of other comprehensive income Other Comprehensive Income (Loss), Tax Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Segment Reporting Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Financial Instruments Recorded at Fair Value Fair Value, Measurement Inputs, Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Special Charges Restructuring and Related Activities Disclosure [Text Block] Share-based Goods and Nonemployee Services Transaction, Valuation Method, Risk Free Interest Rate Share-based Goods and Nonemployee Services Transaction, Valuation Method, Risk Free Interest Rate Share-based Goods and Nonemployee Services Transaction, Valuation Method, Expected Volatility Rate Share-based Goods and Nonemployee Services Transaction, Valuation Method, Expected Volatility Rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term, Simplified Method Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term, Simplified Method Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Document and Entity Information Document and Entity Information Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Trading Symbol Trading Symbol Current Fiscal Year End Date Current Fiscal Year End Date Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date 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 Schedule of Debt [Table Text Block] Schedule of Debt [Table Text Block] Fair Value Measurements Fair Value Disclosures [Text Block] Other Restructuring [Member] Other Restructuring [Member] Termination benefit costs Severance Costs DOE Share of Paducah Termination Benefit Costs DOE Share of Paducah Termination Benefit Costs DOE Share of Paducah Termination Benefit Costs Payments for one-time termination benefits Payments for Restructuring Restructuring liability Restructuring Reserve Postretirement Health and Life Benefits Plans [Member] Service costs Defined Benefit Plan, Service Cost Interest costs Defined Benefit Plan, Interest Cost Expected return on plan assets (gains) Defined Benefit Plan, Expected Return on Plan Assets Actuarial (gain) loss from remeasurement, net Amortization of prior service costs (credits), net Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Net periodic benefit cost (credit) Defined Benefit Plan, Net Periodic Benefit Cost Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Debt increase for paid and accrued PIK interest Debt Instrument, Increase (Decrease), Other, Net Repurchase of debt Write off of deferred financing cost Deferred financing costs Debt Issuance Costs, Noncurrent, Net Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] 2017 ORNL Contract [Member] 2017 ORNL Contract [Member] 2017 ORNL Contract [Member] 2016 ORNL Contract [Member] 2016 ORNL Contract [Member] 2016 ORNL Contract [Member] 2015 ORNL Contract [Member] 2015 ORNL Contract1 [Member] 2015 ORNL Contract1 [Member] Scenario, Forecast [Member] Scenario, Forecast [Member] Contract value 2017 ORNL Contract value 2017 ORNL Contract value Contract monthly revenue UT-Battelle contract monthly revenue UT-Battelle contract monthly revenue Contract milestone payments Contract milestone payments Contract milestone payments Contract revenue current work UT-Battelle contract revenue current work UT-Battelle contract revenue current work Contract revenue past work UT-Battelle contract revenue past work UT-Battelle contract revenue past work D&D Expense Environmental Remediation Expense Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Termination benefit costs Other Restructuring Costs Other Restructuring Costs Payments for Tenant Improvements Payments for Tenant Improvements