Document and Entity Information [Abstract] Document And Entity Information [Abstract] Statement [Table] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Common Class A [Member] Common Stock, Class A [Member] Common Stock, Class A Common Class B [Member] Common Stock, Class B [Member] Common Stock, Class B Statement [Line Items] Document Type Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Period Focus Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Condensed Consolidated Statements of Operations [Abstract] Revenue [Abstract] Revenue: Revenue, Net Revenue from Sale of Materials Sales Revenue, Services, Other Service Revenue Revenues Revenues, Total Total Revenue Costs and Expenses [Abstract] Costs and Expenses: Cost of Goods Sold Cost of Raw Materials Shipments Site Operating Costs Direct Operating Costs Selling, General and Administrative Expense Selling, General and Administrative Expenses Share Based Compensation Associated with Initial Public Offering Share based compensation associated with IPO Share based compensation associated with initial public offering Share based compensation associated with initial public offering. Depreciation Depreciation Amortization Amortization Costs and Expenses Total Costs and Expenses Operating Income (Loss) Income from Operations Interest Income Expense Net Interest Expense, Net Interest Expense Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Cumulative Effects of Changes in Accounting Principles, Noncontrolling Interest Income Before Income Taxes Income Tax Expense (Benefit) Income Tax Expense Net Income (Loss) Attributable to Parent Net Income Net Income Income (Loss) Attributable to Noncontrolling Interest Net loss attributable to noncontrolling interests Accretion on Preferred Stock Accretion on preferred stock Accretion on preferred stock. Earnings per Share [Abstract] Net Income per Share: Earnings Per Share, Basic Basic Earnings Per Share, Diluted Diluted Weighted Average Number of Shares Outstanding [Abstract] Weighted Average Number of Shares Outstanding Average Common Shares Outstanding: Weighted Average Number of Shares Outstanding, Basic Basic Basic average common shares outstanding Weighted Average Number of Shares Outstanding, Diluted Diluted Diluted average common shares outstanding Condensed Consolidated Balance Sheets [Abstract] Common Stock [Member] Common Stock Total Shares Assets [Abstract] Assets Cash and Cash Equivalents, at Carrying Value Cash at end of period Cash at beginning of period Cash and cash equivalents Accounts Receivable, Net, Current Inventory, Net Inventories Total inventories Prepaid Expense and Other Assets, Current Prepaid and other current assets Deferred Tax Assets, Net, Current Deferred tax asset Assets, Current Total current assets Property, Plant and Equipment, Net Property, plant and equipment, net Deferred Finance Costs, Noncurrent, Net Goodwill, Goodwill Intangible Assets, Net (Excluding Goodwill) Other Assets, Noncurrent Other noncurrent assets Assets Total assets Total assets Liabilities and Stockholders' Equity Liabilities and Stockholders' Equity [Abstract] Accounts Payable, Current Accounts payable Accounts Payable, Other, Current Accounts payable overdraft Employee-related Liabilities, Current Salaries, wages and related benefits Accrued Liabilities, Current Accrued expenses Line of Credit, Current Line of Credit, Current Revolving bank borrowings Long-term Debt, Current Maturities Current portion of long-term debt Liabilities, Current Total current liabilities Long-term Debt, Excluding Current Maturities Long-term debt Deferred Tax Liabilities, Net, Noncurrent Deferred tax liability Other Liabilities, Noncurrent Other noncurrent liabilities Liabilities Total liabilities Stockholders' Equity [Abstract] Stockholders' equity (deficit): Common Stock, Value, Issued Common Stock Additional Paid in Capital, Common Stock Capital in excess of par value Retained Earnings (Accumulated Deficit) Accumulated deficit Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive (loss) Stockholders' Equity Attributable to Parent Total TMS International Corp. stockholders' equity Stockholders' Equity Attributable to Noncontrolling Interest Noncontrolling interests Ending balances, amount Beginning balance, amount Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total stockholders' equity Liabilities and Equity Total liabilities and stockholders equity Preferred Class A [Member] Redeemable, Convertible Preferred Stock, Class A [Member] Allowance for Doubtful Accounts Receivable Accounts receivable, allowance for doubtful accounts Accumulated Amortization of Noncurrent Deferred Finance Costs Deferred financing costs, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Other intangibles, accumulated amortization Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Par or Stated Value Per Share Common stock, par value Restricted shares, Initial public offering price per share Common Stock, Shares, Issued Common stock, shares issued Common stock issued Common Stock, Shares, Outstanding Common stock, shares outstanding Common stock shares outstanding Preferred Stock, Shares Authorized Preferred stock, shares authorized Preferred Stock, Par or Stated Value Per Share Preferred stock, par value Preferred Stock, Shares Outstanding Preferred stock, shares outstanding Condensed Consolidated Statements of Cash Flows [Abstract] Net Cash Provided by (Used in) Operating Activities [Abstract] Cash flows from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile Net Income to net cash provided by operating activities: Depreciation, Depletion and Amortization Less: Depreciation and Amortization Depreciation and Amortization Amortization of Financing Costs Amortization of deferred financing costs and original issue discount Deferred Income Tax Expense (Benefit) Deferred income tax Provision for Doubtful Accounts Provision for bad debts Share-based Compensation Non cash share based compensation cost Share-based compensation expense Increase (Decrease) in Operating Capital [Abstract] Increase (decrease) from changes in: Increase (Decrease) in Accounts Receivable Accounts receivable Increase (Decrease) in Inventories, Total Inventories Increase (Decrease) in Prepaid Expense and Other Assets Prepaid and other current assets Increase (Decrease) in Other Noncurrent Assets Other noncurrent assets Increase (Decrease) in Accounts Payable Accounts payable and cash overdraft Increase (Decrease) in Accrued Liabilities Accrued expenses Increase (Decrease) in Other Noncurrent Liabilities Other noncurrent liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Other, net Net Cash Provided by (Used in) Operating Activities Net cash provided by( used in) operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Cash flows from investing activities: Payments to Acquire Property, Plant, and Equipment, Total Capital Expenditures Proceeds from Sale of Property, Plant, and Equipment Proceeds from sale of equipment Payments to Acquire Businesses, Net of Cash Acquired Acquisition Contingent payment for acquired business, Contingent payment for acquired business Contingent payment for acquired business Payments to Acquire Businesses and Interest in Affiliates Cash flows related to IU International, net Net Cash Provided by (Used in) Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Cash flows from financing activities: Repayments of Lines of Credit Revolving credit facility borrowing (repayments), net Proceeds from Issuance of Common Stock Net proceeds from initial public offering Repayments of Long-term Debt Repayment of debt Proceeds from Noncontrolling Interests Contributions from noncontrolling interests Net Cash Provided by (Used in) Financing Activities Net cash (used in) provided by financing activities Cash and Cash Equivalents, at Carrying Value [Abstract] Cash and cash equivalents: Cash and Cash Equivalents, Period Increase (Decrease) Net (decrease) increase in cash Consolidated Statements of Changes in Stockholders' Equity (Deficit) [Abstract] Statement, Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Capital In Excess Of Par Value [Member] Capital in Excess of Par Value Capital in excess of par value. Retained Earnings [Member] Accumulated Deficit Accumulated Other Comprehensive Income [Member] Accumulated Other Comprehensive Income (Loss) Parent [Member] TMS International Corp. Noncontrolling Interest [Member] Noncontrolling Interest Beginning balance, shares Ending Balances, shares Shares, Outstanding Stock Issued During Period Shares Conversion of Convertible Securities Conversion of preferred shares, shares Restricted Stock Issuance Associated With Initial Public Offering Shares Restricted stock issuance associated with initial public offering. Issuance of restricted stock associated with the IPO, shares Issuance of Primary Shares and Recapitalization of Existing Shares Issuance of Primary Shares and Recapitalization of Existing Shares. Issuance of primary shares and recapitalization of existing shares, shares Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Share-based compensation costs Accumulated Dividend on Preferred Stock Value Accumulated dividend on preferred stock value. Accumulating dividend on class A preferred stock Stock Issued During Period, Value, Conversion of Convertible Securities Conversion of preferred shares Restricted Stock Issuance Associated With Initial Public Offering Restricted stock issuance associated with initial public offering. Issuance of restricted stock associated with the IPO Issuance of Primary Shares and Recapitalization of Existing Shares Value Issuance of primary shares and recapitalization of existing shares. Issuance of primary shares and recapitalization of existing shares Noncontrolling Interest, Increase from Equity Issuance or Sale of Parent Equity Interest (Acquisition of) Investment by noncontrolling interest Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income (loss) Statements of Consolidated Comprehensive Income (Loss) [Abstract] Nature of Operations [Abstract] Nature Of Operations [Abstract] Nature of Operations Nature of Operations [Text Block] Basis of Presentation [Abstract] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Earnings per Share Earnings Per Share [Text Block] Inventories [Abstract] Inventory Disclosure [Text Block] Inventories Income Taxes [Abstract] Income Tax Disclosure [Text Block] Income Taxes Debt [Abstract] Long-term Debt [Text Block] Debt Derivative Financial Instruments and Fair Values [Abstract] Derivative Financial Instruments and Fair Values Derivative Instruments and Hedging Activities Disclosure [Text Block] Stockholders' Equity (Deficit) [Abstract] Stockholders' Equity Note Disclosure [Text Block] Stockholders' Equity (Deficit) Stock Based Compensation [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock Based Compensation Operating Segments [Abstract] Segment Reporting Disclosure [Text Block] Operating Segments Retirement and Pension Plans [Abstract] Retirement and Pension Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Fair Value of Financial Instruments [Abstract] Fair Value Of Financial Instruments [Abstract] Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Commitments and Contingencies [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Business Combinations [Abstract] Business Combination Disclosure [Text Block] Business Combinations Commercial Arbitration Award [Abstract] Commercial arbitration award [Abstract]. Commercial Arbitration Award Disclosure [Text Block] Commercial arbitration award disclosure [Text Block]. Commercial Arbitration Award Related-Party Transactions [Abstract] Related Party Transactions Disclosure [Text Block] Related-Party Transactions Recent Accounting Pronouncements [Abstract] Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Text Block] Recent Accounting Pronouncements Schedule of Weighted Average Number of Shares [Table Text Block] Schedule of Reconciliation of Basic Weighted Average Shares Outstanding to the Dilutive Weighted Average Shares Outstanding Schedule of Inventory, Current [Table Text Block] Schedule of Inventories Schedule of Debt Schedule of Debt [Table Text Block] Schedule of Maturities of Long-term Debt [Table Text Block] Indebtedness line items on the condensed consolidated balance sheets Notional amount Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Designated as cash flow hedging instruments Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] Weighted-average fair value assumptions Information by Reportable Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Reconciliation of Earnings Before Interest, Taxes, Depreciation and Amortization Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plans [Domain] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Post Employment Benefit Plans [Member] Post employment benefit plans. Post-Employment Benefit Plans [Member] Components of Net Pension Expense (Benefit) Recognized Schedule of Net Benefit Costs [Table Text Block] Fair Value Compared to Carrying Value of Financial Instruments [Table Text Block] Fair Value Compared to the Carrying Value Fair value compared to the carrying value of financial instruments. Number Of Customer Number of customer Number of customer sites Number of Countries in which Entity Operates Number of countries, operations Basis Of Presentation [Table] Basis of presentation [Table]